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• 1721. [Article] Three essays on the effectiveness of Oregon's land-use planning system : economic analysis with quasi-experimental methods

  Oregon's land use planning system is often recognized as having been successful in its goals of limiting urban sprawl and protecting resource lands from development. However, it is difficult to quantify ...

  Citation × Citation Citation Abstract Copy Title: Three essays on the effectiveness of Oregon's land-use planning system : economic analysis with quasi-experimental methods Author: Dempsey, Judith Oregon's land use planning system is often recognized as having been successful in its goals of limiting urban sprawl and protecting resource lands from development. However, it is difficult to quantify the impact of these regulations, because we cannot observe what would have happened in the absence of land use planning. The three essays in this dissertation explore the effects of Oregon's land use planning regulations on development patterns in the state, and also examine how the land use regulations are administered at the local level. The first essay in this dissertation asks if Oregon’s land use regulations have successfully restricted sprawl outside of urban areas. Urban containment policies, including Urban Growth Boundaries (UGBs), are a common tool used by city planners to promote compact development. We analyze how well UGBs do in containing development using fine-scale GIS data on cities in Oregon. Earlier studies on UGBs yield mixed results, with some authors finding no effects of UGBs on housing market variables and urbanization rates and others finding significant effects. A challenge in measuring these effects is that the location of the UGB is unlikely to be an exogenous determinant of a land parcel's value for development. The panel structure of our dataset allows us to estimate the UGB's effect on the probability of development using a difference-in-difference estimator. This estimator controls for time-invariant unobservable variables and common temporal effects among parcels, thereby mitigating the potential for biased estimates due to the endogeneity of the UGB's location. We also pursue a novel approach to controlling for time-varying factors inspired by regression discontinuity design. We find that UGBs are effective in containing development in many of the Oregon cities we examine, although there are some cities in which development rates are the same inside and outside of the UGB. Our results show that we would greatly overstate the effects of the UGBs were we to evaluate cross-sectional differences in development rates, as is common in previous studies. Besides the creation of UGBs, another goal of Oregon's land use regulations is to encourage citizen involvement in the planning process. The second essay in this dissertation examines the use of voter annexation as a form of citizen involvement. More specifically, this paper addresses the following two questions. First, does voter annexation cause changes in city demographics and characteristics? Second, assuming that a city votes for amendments and annexations to the UGB and city limits, what factors impact the outcome of the vote? We analyze the first question using the method of propensity score matching, which has not previously been used to explore this topic. This allows us to account for the endogeneity that stems from the fact that cities with certain characteristics may be more likely to use voter annexation in the first place. The second question, which is only evaluated for cities that employ voter annexation, is analyzed with the use of the logit model. Oregon's land use regulations must be approved at the state level, but are administered locally. Therefore, unlike past studies, we are able to isolate specific differences in the way the program is administered, and are not evaluating the stringency of the program itself. Previous studies have found that voter-approved annexation causes developers to provide more public goods and increase the scale of development, thereby shifting community demographics. Once a land use decision is on the ballot, it is also noted that cities that are whiter, wealthier, and more liberal are more likely to pass referenda that promote preservation and restrict development. For the first question, we compare specific demographic indicators between the two groups of cities. Contrary to the results of previous studies, we find no effect of voter annexation on these indicators. Our results for the second question indicate that the characteristics of the voting process itself impact the outcome more than community characteristics, which also differs from the results of previous analyses. The third essay in this dissertation is an extension of the first essay, and focuses on the impact of Oregon's land use regulations on the protection of land in riparian corridors and land that has been designated for exclusive farm use (EFU). Riparian corridors are protected with the use of Oregon Goal 5, which focuses on development of natural resource lands inside of UGBs, while EFU land is protected with the use of Oregon Goal 3, which focuses on protection of agricultural land at the county level. The LCT dataset that was used in the first essay is also used in this essay. EFU land by definition has no probability of development in the initial period. Land located in riparian corridors may also face different initial levels of protection than other land. We deal with this endogeneity, and also account for location inside or outside of a UGB, with the use of the difference -in-difference-in-differences estimator. This is an approach that has not been used to explore the effect of Oregon's land use regulations on these land categories. Most of the past studies that have examined the impact of land use planning on development of agricultural land in Oregon have relied on analysis of general trends and indicators, and have concluded that land use regulations have been successful in protecting this land. Previous research on riparian zone protection has focused on protection of aquatic wildlife, and for the most part has not examined the protection of riparian corridors inside of UGBs. The limited studies that have studied the effect of these regulations in UGBs have determined them to be effective in slowing, but not stopping, development in these areas. Overall, we find that Oregon's land use regulations have been successful in protecting both county level agricultural land and riparian corridors located inside of UGBs from development. It is less clear whether these regulations have protected riparian corridors located inside of UGBs from other anthropogenic uses. Title: Three essays on the effectiveness of Oregon's land-use planning system : economic analysis with quasi-experimental methods Author: Dempsey, Judith Oregon's land use planning system is often recognized as having been successful in its goals of limiting urban sprawl and protecting resource lands from development. However, it is difficult to quantify the impact of these regulations, because we cannot observe what would have happened in the absence of land use planning. The three essays in this dissertation explore the effects of Oregon's land use planning regulations on development patterns in the state, and also examine how the land use regulations are administered at the local level. The first essay in this dissertation asks if Oregon’s land use regulations have successfully restricted sprawl outside of urban areas. Urban containment policies, including Urban Growth Boundaries (UGBs), are a common tool used by city planners to promote compact development. We analyze how well UGBs do in containing development using fine-scale GIS data on cities in Oregon. Earlier studies on UGBs yield mixed results, with some authors finding no effects of UGBs on housing market variables and urbanization rates and others finding significant effects. A challenge in measuring these effects is that the location of the UGB is unlikely to be an exogenous determinant of a land parcel's value for development. The panel structure of our dataset allows us to estimate the UGB's effect on the probability of development using a difference-in-difference estimator. This estimator controls for time-invariant unobservable variables and common temporal effects among parcels, thereby mitigating the potential for biased estimates due to the endogeneity of the UGB's location. We also pursue a novel approach to controlling for time-varying factors inspired by regression discontinuity design. We find that UGBs are effective in containing development in many of the Oregon cities we examine, although there are some cities in which development rates are the same inside and outside of the UGB. Our results show that we would greatly overstate the effects of the UGBs were we to evaluate cross-sectional differences in development rates, as is common in previous studies. Besides the creation of UGBs, another goal of Oregon's land use regulations is to encourage citizen involvement in the planning process. The second essay in this dissertation examines the use of voter annexation as a form of citizen involvement. More specifically, this paper addresses the following two questions. First, does voter annexation cause changes in city demographics and characteristics? Second, assuming that a city votes for amendments and annexations to the UGB and city limits, what factors impact the outcome of the vote? We analyze the first question using the method of propensity score matching, which has not previously been used to explore this topic. This allows us to account for the endogeneity that stems from the fact that cities with certain characteristics may be more likely to use voter annexation in the first place. The second question, which is only evaluated for cities that employ voter annexation, is analyzed with the use of the logit model. Oregon's land use regulations must be approved at the state level, but are administered locally. Therefore, unlike past studies, we are able to isolate specific differences in the way the program is administered, and are not evaluating the stringency of the program itself. Previous studies have found that voter-approved annexation causes developers to provide more public goods and increase the scale of development, thereby shifting community demographics. Once a land use decision is on the ballot, it is also noted that cities that are whiter, wealthier, and more liberal are more likely to pass referenda that promote preservation and restrict development. For the first question, we compare specific demographic indicators between the two groups of cities. Contrary to the results of previous studies, we find no effect of voter annexation on these indicators. Our results for the second question indicate that the characteristics of the voting process itself impact the outcome more than community characteristics, which also differs from the results of previous analyses. The third essay in this dissertation is an extension of the first essay, and focuses on the impact of Oregon's land use regulations on the protection of land in riparian corridors and land that has been designated for exclusive farm use (EFU). Riparian corridors are protected with the use of Oregon Goal 5, which focuses on development of natural resource lands inside of UGBs, while EFU land is protected with the use of Oregon Goal 3, which focuses on protection of agricultural land at the county level. The LCT dataset that was used in the first essay is also used in this essay. EFU land by definition has no probability of development in the initial period. Land located in riparian corridors may also face different initial levels of protection than other land. We deal with this endogeneity, and also account for location inside or outside of a UGB, with the use of the difference -in-difference-in-differences estimator. This is an approach that has not been used to explore the effect of Oregon's land use regulations on these land categories. Most of the past studies that have examined the impact of land use planning on development of agricultural land in Oregon have relied on analysis of general trends and indicators, and have concluded that land use regulations have been successful in protecting this land. Previous research on riparian zone protection has focused on protection of aquatic wildlife, and for the most part has not examined the protection of riparian corridors inside of UGBs. The limited studies that have studied the effect of these regulations in UGBs have determined them to be effective in slowing, but not stopping, development in these areas. Overall, we find that Oregon's land use regulations have been successful in protecting both county level agricultural land and riparian corridors located inside of UGBs from development. It is less clear whether these regulations have protected riparian corridors located inside of UGBs from other anthropogenic uses. Close

• 1722. [Article] The oligocene and miocene geology of the Tillamook embayment Tillamook County, northwest Oregon

  Eleven sedimentary and volcanic rock units are mapped and described in the thesis area, and chronicle the dynamic geologic history of the Tillamook embayment from the Oligocene through the middle Mlocene. ...

  Citation × Citation Citation Abstract Copy Title: The oligocene and miocene geology of the Tillamook embayment Tillamook County, northwest Oregon Author: Parker, Michael J. (Michael John), 1958- Eleven sedimentary and volcanic rock units are mapped and described in the thesis area, and chronicle the dynamic geologic history of the Tillamook embayment from the Oligocene through the middle Mlocene. The oldest unit is the Zemorrian to early Saucesian Smuggler Cove formation, a bathyal tuffaceous mudstone with some thin- to thick-bedded tuff layers deposited on the middle to upper continental slope during a period of explosive silicic volcanism in the Western Cascade arc. Uppermost Smuggler Cove strata are coarser grained, grading upward to arkosic turbidite sandstone and mudstone and thick bloturbated silty sandstone deposited on the outer shelf during marine regression. This regression heralded the progradation of the overlying shallow-marine Bewley Creek formation (informal) depositional system. The Bewley Creek formation (informal) is proposed in this study for a sequence of pumiceous, volcaniclastic-rich lower Miocene feldspathic litharenites and lithic arkoses deposited during the Pillarlan-stage near the mouth of an ancestral Columbia River. The unit grades from bioturbated silty sandstone to fine-grained hummocky cross-stratified and coarser grained channelized sandstones deposited within, or peripheral to a wave-dominated delta or ebb tidal-delta channel complex. Progradatlon of the Bewley Creek formation may have been caused, in part, by increased volcaniclastic sedimentation attending a pulse of explosive volcanism in the adjacent Western Cascade arc. Reduced volcanic activity, possibly coupled with basin subsidence or eustatic sea level rise, resulted in deposition of mudstones of the Sutton Creek member (informal; proposed) of the Nye Mudstone. The Saucesian Sutton Creek member consists of bathyal, laminated, carbonaceous, and moderately tuffaceous mudstone deposited in an upper continental slope basin. The upper part of the unit contains common lithic to arkosic turbidite sandstone interbeds within nested channel-fill deposits. These strata represent a channelized shelf-slope break environment adjacent to the shallow-marine Angora Peak member of the Astoria Formation depositlonal system. Subsequent marine regression resulted in progradation of the Pillarian- to Newportian-stage arkosic-micaceous sandstone-rich Angora Peak member into the Tillamook embayment. Grainsize analysis, sandstone petrography, scanning electron microscopy, and heavy mineral analyses suggest these lower to middle Miocene mollusk-bearing, fine- to medium-grained sandstones were predominantly deposited near the mouth of an ancestral Columbia River. They accumulated on a high-energy Inner shelf within or down drift of a wave-dominated delta or ebb-tidal delta complex, evidenced by paleocurrent analyses, hummocky cross-stratification and trough cross-stratified submarine channel-fill sequences. The Angora Peak member disconformably overlies Zemorrian mudstones of the Smuggler Cove formation at Cape Kiwanda suggesting local uplift and erosion in that area, followed by Newportian stage transgression in the Tillamook embayment. Exotic cobbles and boulders of two mica granite and sedimentary quartzite at Cape Kiwanda were probably derived from the Idaho Batholith and Precambrian sandstone terrains in Montana, transported via an ancestral Columbia River and longshore current to the shelf possibly bound within tree root bundles. The Netarts Bay member (informal) of the Astoria Formation Is proposed In this study for a late Sauceslan package of fine-grained to pebbly amalgamated and interbedded turbidite, grainflow, and fluldized flow friable thick-bedded lithic arkoses. These massive sandstones contain large penecontemporaneously emplaced channel wall-blocks and naller slltstone rip-ups. These lower to middle Miocene strata were deposited in a submarine canyon head and channel complex offshore of the shallow-marine Angora Peak member depositlonal system. Netarts Bay strata cut Into the underlying Angora Peak shelf strata, and cut and Interfinger with bathyal slope mudstones of the Cannon Beach member of the Astoria Formation. The overlying lower Cannon Beach member Is composed of laminated bathyal mudstones with rare turbidite sandstone interbeds deposited in a coarse clastic-starved slope environment. Upper Cannon Beach member strata In the Tillamook area are characterized by micaceous arkosic and lithic arkosic turbidite sandstones that underlie and occur within nested channel-fill sequences. Bloturbated carbonaceous cross-bedded sandstone In the upper Cannon Beach member records shallowing of the Tillamook embayment to a channelized upper slope to shelf environment. The Tillamook embayment was uplifted and dissected prior to the arrival of six to ten Intracanyon subaerial and submarine lava flows of the Columbia River Basalt Group. These middle Miocene flows, delineatedon the basis of geochemical composition and magnetic polarity, Include (in stratigraphic order) the Grouse Creek (R2 low MgO-low T102), Winterwater (N2 low MgO-low Ti02), and Sentinel Bluffs (high MgO) units of the Grande Ronde Basalt, and the Ginkgo unit of the Frenchman Springs member of the Wanapum Basalt. Orientation of Grande Ponde Basalt foreset-bedded pillow palagonite complexes and lava delta sequences indicate that these Columbia River Basalt units flowed westward into the Tillainook embayment, possibly through a saddle in the ancestral Oregon Coast Range. Marine transgression and deposition of hummocky cross-stratified arkosic marine strata of the Sandstone of Whale Cove followed emplacement of the last Grande Ronde flows. This was succeeded by a regression, as Indicated by the overlying subaerial plagioclase-phyric Ginkgo Unit flow of the Frenchman Springs Basalt. Locally, Winterwater and Sentinel Bluffs unit basalt occur as brecciated peperitic sills and dikes. These were emplaced through the process of "auto-invasion" when dense lava injected downward Into semi-lithifled Tertiary strata under the influence of both a pressure head augmented by flashing steam, and steam blasting. The thesis area is crossed by a complex network of high-angle northwest- and northeast-tending normal and reverse faults, and both low and high-angle east-trending reverse and thrust faults. These faults may have developed through a north-south compressional tectonic regime, a dextral shear couple, or a combination of these two tectonic regimes. Many faults cut Columbia River Basalt units and are thus middle Miocene or younger in age. Tertiary strata including the Columbia River Basalts are also folded within a broad westward-plunging syncline which suggests a middle Miocene or younger compressional event. Source rock analyses indicate that the mudstones of the Cannon Beach member, Sutton Creek member, and Smuggler Cove formation contain type III kerogen capable of generating natural gas only. Although these rocks have thermally innature vitrinite reflectance values, they contain sufficiently high total organic carbon content to be considered potential lean source rocks. Arkosic sandstones of the Angora Peak and Netarts Bay members have fair to good reservoir rock characteristics, and may represent reservoirs offshore for matured hydrocarbons generated from deeply buried source rocks. Title: The oligocene and miocene geology of the Tillamook embayment Tillamook County, northwest Oregon Author: Parker, Michael J. (Michael John), 1958- Eleven sedimentary and volcanic rock units are mapped and described in the thesis area, and chronicle the dynamic geologic history of the Tillamook embayment from the Oligocene through the middle Mlocene. The oldest unit is the Zemorrian to early Saucesian Smuggler Cove formation, a bathyal tuffaceous mudstone with some thin- to thick-bedded tuff layers deposited on the middle to upper continental slope during a period of explosive silicic volcanism in the Western Cascade arc. Uppermost Smuggler Cove strata are coarser grained, grading upward to arkosic turbidite sandstone and mudstone and thick bloturbated silty sandstone deposited on the outer shelf during marine regression. This regression heralded the progradation of the overlying shallow-marine Bewley Creek formation (informal) depositional system. The Bewley Creek formation (informal) is proposed in this study for a sequence of pumiceous, volcaniclastic-rich lower Miocene feldspathic litharenites and lithic arkoses deposited during the Pillarlan-stage near the mouth of an ancestral Columbia River. The unit grades from bioturbated silty sandstone to fine-grained hummocky cross-stratified and coarser grained channelized sandstones deposited within, or peripheral to a wave-dominated delta or ebb tidal-delta channel complex. Progradatlon of the Bewley Creek formation may have been caused, in part, by increased volcaniclastic sedimentation attending a pulse of explosive volcanism in the adjacent Western Cascade arc. Reduced volcanic activity, possibly coupled with basin subsidence or eustatic sea level rise, resulted in deposition of mudstones of the Sutton Creek member (informal; proposed) of the Nye Mudstone. The Saucesian Sutton Creek member consists of bathyal, laminated, carbonaceous, and moderately tuffaceous mudstone deposited in an upper continental slope basin. The upper part of the unit contains common lithic to arkosic turbidite sandstone interbeds within nested channel-fill deposits. These strata represent a channelized shelf-slope break environment adjacent to the shallow-marine Angora Peak member of the Astoria Formation depositlonal system. Subsequent marine regression resulted in progradation of the Pillarian- to Newportian-stage arkosic-micaceous sandstone-rich Angora Peak member into the Tillamook embayment. Grainsize analysis, sandstone petrography, scanning electron microscopy, and heavy mineral analyses suggest these lower to middle Miocene mollusk-bearing, fine- to medium-grained sandstones were predominantly deposited near the mouth of an ancestral Columbia River. They accumulated on a high-energy Inner shelf within or down drift of a wave-dominated delta or ebb-tidal delta complex, evidenced by paleocurrent analyses, hummocky cross-stratification and trough cross-stratified submarine channel-fill sequences. The Angora Peak member disconformably overlies Zemorrian mudstones of the Smuggler Cove formation at Cape Kiwanda suggesting local uplift and erosion in that area, followed by Newportian stage transgression in the Tillamook embayment. Exotic cobbles and boulders of two mica granite and sedimentary quartzite at Cape Kiwanda were probably derived from the Idaho Batholith and Precambrian sandstone terrains in Montana, transported via an ancestral Columbia River and longshore current to the shelf possibly bound within tree root bundles. The Netarts Bay member (informal) of the Astoria Formation Is proposed In this study for a late Sauceslan package of fine-grained to pebbly amalgamated and interbedded turbidite, grainflow, and fluldized flow friable thick-bedded lithic arkoses. These massive sandstones contain large penecontemporaneously emplaced channel wall-blocks and naller slltstone rip-ups. These lower to middle Miocene strata were deposited in a submarine canyon head and channel complex offshore of the shallow-marine Angora Peak member depositlonal system. Netarts Bay strata cut Into the underlying Angora Peak shelf strata, and cut and Interfinger with bathyal slope mudstones of the Cannon Beach member of the Astoria Formation. The overlying lower Cannon Beach member Is composed of laminated bathyal mudstones with rare turbidite sandstone interbeds deposited in a coarse clastic-starved slope environment. Upper Cannon Beach member strata In the Tillamook area are characterized by micaceous arkosic and lithic arkosic turbidite sandstones that underlie and occur within nested channel-fill sequences. Bloturbated carbonaceous cross-bedded sandstone In the upper Cannon Beach member records shallowing of the Tillamook embayment to a channelized upper slope to shelf environment. The Tillamook embayment was uplifted and dissected prior to the arrival of six to ten Intracanyon subaerial and submarine lava flows of the Columbia River Basalt Group. These middle Miocene flows, delineatedon the basis of geochemical composition and magnetic polarity, Include (in stratigraphic order) the Grouse Creek (R2 low MgO-low T102), Winterwater (N2 low MgO-low Ti02), and Sentinel Bluffs (high MgO) units of the Grande Ronde Basalt, and the Ginkgo unit of the Frenchman Springs member of the Wanapum Basalt. Orientation of Grande Ponde Basalt foreset-bedded pillow palagonite complexes and lava delta sequences indicate that these Columbia River Basalt units flowed westward into the Tillainook embayment, possibly through a saddle in the ancestral Oregon Coast Range. Marine transgression and deposition of hummocky cross-stratified arkosic marine strata of the Sandstone of Whale Cove followed emplacement of the last Grande Ronde flows. This was succeeded by a regression, as Indicated by the overlying subaerial plagioclase-phyric Ginkgo Unit flow of the Frenchman Springs Basalt. Locally, Winterwater and Sentinel Bluffs unit basalt occur as brecciated peperitic sills and dikes. These were emplaced through the process of "auto-invasion" when dense lava injected downward Into semi-lithifled Tertiary strata under the influence of both a pressure head augmented by flashing steam, and steam blasting. The thesis area is crossed by a complex network of high-angle northwest- and northeast-tending normal and reverse faults, and both low and high-angle east-trending reverse and thrust faults. These faults may have developed through a north-south compressional tectonic regime, a dextral shear couple, or a combination of these two tectonic regimes. Many faults cut Columbia River Basalt units and are thus middle Miocene or younger in age. Tertiary strata including the Columbia River Basalts are also folded within a broad westward-plunging syncline which suggests a middle Miocene or younger compressional event. Source rock analyses indicate that the mudstones of the Cannon Beach member, Sutton Creek member, and Smuggler Cove formation contain type III kerogen capable of generating natural gas only. Although these rocks have thermally innature vitrinite reflectance values, they contain sufficiently high total organic carbon content to be considered potential lean source rocks. Arkosic sandstones of the Angora Peak and Netarts Bay members have fair to good reservoir rock characteristics, and may represent reservoirs offshore for matured hydrocarbons generated from deeply buried source rocks. Close

• 1723. [Article] Structure of the southern Mormon Mountains, Clark County, Nevada and regional structural synthesis : fold-thrust and basin-range structure in southern Nevada, southwest Utah, and northwest Arizona

  Detailed geologic mapping in the Mormon Mountains and new geophysical data provide significant insight into contractional and extensional tectonics in southern Nevada, southwest Utah, and northwest Arizona. ...

  Citation × Citation Citation Abstract Copy Title: Structure of the southern Mormon Mountains, Clark County, Nevada and regional structural synthesis : fold-thrust and basin-range structure in southern Nevada, southwest Utah, and northwest Arizona Author: Carpenter, James Anthony Detailed geologic mapping in the Mormon Mountains and new geophysical data provide significant insight into contractional and extensional tectonics in southern Nevada, southwest Utah, and northwest Arizona. The rocks in the region were complexly deformed during two distinct tectonic episodes. Numerous interrelated events occurred within each episode. The first tectonic episode, related to the Sevier orogeny, was characterized by east-west crustal shortening which culminated in thin-skinned decollement style folding and thrusting during the Cretaceous. The Virgin-Beaver Dam Mountains anticline, a Laramide-type basement-involved uplift, represents the only thick-skinned contractional structure in the region. The second tectonic episode, related to basin-range rifting, was characterized by east-west crustal extension which was accommodated by high-angle normal faults, with dips averaging 60 degrees, in the brittle upper crust. In this area, basin-range rifting initiated in the Oligocene and continued to Recent time. Relations in the North Muddy Mountains in southern Nevada suggest that the Muddy Mountain thrust sheet advanced and overrode the Weiser syncline during the Cenomanian and may have continued to advance in Turonian time. In the southern Mormon Mountains, the Cambrian Bonanza King Formation lies in the hanging wall flat position in thrust contact with the overturned Petrified Forest Member of the Triassic Chinle Formation at the footwall ramp. The thrust sheet advanced eastward more than 30 km from the place of origin. Thrust imbrication, and probably the formation of hanging wall horses, likely occurred as the Muddy Mountain thrust sheet encountered and ascended up the footwall ramp zone (composed largely of competent carbonate rocks) where slices of the thrust sheet (hanging wall horses) splayed of f and accreted to the footwall ramp zone. A detailed retrodeformable (balanced) regional structure section suggests that fold-thrust shortening at the latitude of the Mormon Mountains is a minimum of about 26%. Extension-related structures overprint older fold-thrust structures in the Mormon Mountains. The west-plunging east-trending Candy Peak syncline is one of a family of fold structures related to basin-range rifting. The syncline formed in pre-Miocene time in association with the northeast-striking Reber Mountain normal fault directly north and the northeast-striking Dry Canyon right-lateral strike-slip fault directly south. The Tortoise Flat synform, which lies southeast of the Dry Canyon fault, developed in Miocene and possibly Pliocene time by right-lateral flexure of early Miocene Horse Spring beds as a result of drag associated with the Dry Canyon fault. The Dry Canyon fault and the Tortoise Flat synform are interpreted to be part of the right-lateral Moapa Peak-Reber Mountain shear zone system in the southern Mormon Mountains. Therefore, the time of formation of the Moapa Peak-Reber Mountain shear zone system is pre-Miocene to possibly Pliocene. The shear zone system formed in response to different amounts of west-directed extension-related movement of the hanging wall block of the high-angle Virgin Beaver Dam Mountains fault, which initiated in the Oligocene. From this, the timing of the Moapa Peak-Reber Mountain shear zone, system is interpreted as Oligocene to Miocene, and possibly Pliocene. The interpretation of 261 km of seismic reflection sections suggests that large-displacement high-angle normal faults, typically with 60 degrees of dip, control horst and graben structure and accommodate extension by simple shear in the upper brittle crust. Such faults likely extend to depths of 15 to 18 km. Below this depth extension is thought to be accommodated by penetrative ductile deformation. A detailed retrodeformable (balanced) regional structure section suggests that basin-range extension at the latitude of the Mormon Mountains is about 17%. The Virgin-Beaver Dam Mountains high-angle normal fault is a large-displacement master fault in the area, having more than 8,000 in of normal vertical separation at the latitude of the Virgin Valley basin depocenter. Miocene doming and uplift of the Mormon Mountains occurred in response to displacement on the Virgin-Beaver Dam Mountains fault. The Virgin Valley basin formed as the hanging wall block downdropped, and the Mormon Mountains dome formed by relative uplift at the opposite end of the hanging wall block. Half-grabens, and tilted, folded, and faulted range blocks characterize basin-range crustal structure. Depositional growth relations are interpreted in basins from fanning-upward reflector geometry, and the wedge-shape of Oligocene to Recent syntectonic basin-fill sediments. Non-overlapping opposing east- and west-tilted half-grabens compose the Meadow Valley-California Wash basin. Seismic sections, gravity data, well data, and geologic mapping demonstrate that the Mormon Peak, Tule Springs Hills, and Beaver Dam/Castle Cliff "detachments," which were thought to be rooted low-angle normal faults, do not exist. The Mormon Peak and Beaver Dam/Castle Cliff low-angle normal faults are denudational fault planes below gravity slid masses. The widely distributed translocated Paleozoic blocks, which were thought to be remnant pieces of large hanging wall sheets ("extensional allochthons"), are disjunct rootless gravity slide blocks of minor tectonic significance. A large number of these rootless slide blocks lie on Pliocene and Quaternary basin-fill deposits. The Muddy Mountain-Tule Springs thrust, of Sevier age, was not reactivated as a crustal penetrating Tule Springs Hills low-angle normal fault, but is affected by small-scale gravity slide features. Rootless gravity slide blocks, secondary features to high-angle normal faults, commonly occur from instability as a result of the loss of lateral support induced by block faulting and the associated erosion of range blocks. Title: Structure of the southern Mormon Mountains, Clark County, Nevada and regional structural synthesis : fold-thrust and basin-range structure in southern Nevada, southwest Utah, and northwest Arizona Author: Carpenter, James Anthony Detailed geologic mapping in the Mormon Mountains and new geophysical data provide significant insight into contractional and extensional tectonics in southern Nevada, southwest Utah, and northwest Arizona. The rocks in the region were complexly deformed during two distinct tectonic episodes. Numerous interrelated events occurred within each episode. The first tectonic episode, related to the Sevier orogeny, was characterized by east-west crustal shortening which culminated in thin-skinned decollement style folding and thrusting during the Cretaceous. The Virgin-Beaver Dam Mountains anticline, a Laramide-type basement-involved uplift, represents the only thick-skinned contractional structure in the region. The second tectonic episode, related to basin-range rifting, was characterized by east-west crustal extension which was accommodated by high-angle normal faults, with dips averaging 60 degrees, in the brittle upper crust. In this area, basin-range rifting initiated in the Oligocene and continued to Recent time. Relations in the North Muddy Mountains in southern Nevada suggest that the Muddy Mountain thrust sheet advanced and overrode the Weiser syncline during the Cenomanian and may have continued to advance in Turonian time. In the southern Mormon Mountains, the Cambrian Bonanza King Formation lies in the hanging wall flat position in thrust contact with the overturned Petrified Forest Member of the Triassic Chinle Formation at the footwall ramp. The thrust sheet advanced eastward more than 30 km from the place of origin. Thrust imbrication, and probably the formation of hanging wall horses, likely occurred as the Muddy Mountain thrust sheet encountered and ascended up the footwall ramp zone (composed largely of competent carbonate rocks) where slices of the thrust sheet (hanging wall horses) splayed of f and accreted to the footwall ramp zone. A detailed retrodeformable (balanced) regional structure section suggests that fold-thrust shortening at the latitude of the Mormon Mountains is a minimum of about 26%. Extension-related structures overprint older fold-thrust structures in the Mormon Mountains. The west-plunging east-trending Candy Peak syncline is one of a family of fold structures related to basin-range rifting. The syncline formed in pre-Miocene time in association with the northeast-striking Reber Mountain normal fault directly north and the northeast-striking Dry Canyon right-lateral strike-slip fault directly south. The Tortoise Flat synform, which lies southeast of the Dry Canyon fault, developed in Miocene and possibly Pliocene time by right-lateral flexure of early Miocene Horse Spring beds as a result of drag associated with the Dry Canyon fault. The Dry Canyon fault and the Tortoise Flat synform are interpreted to be part of the right-lateral Moapa Peak-Reber Mountain shear zone system in the southern Mormon Mountains. Therefore, the time of formation of the Moapa Peak-Reber Mountain shear zone system is pre-Miocene to possibly Pliocene. The shear zone system formed in response to different amounts of west-directed extension-related movement of the hanging wall block of the high-angle Virgin Beaver Dam Mountains fault, which initiated in the Oligocene. From this, the timing of the Moapa Peak-Reber Mountain shear zone, system is interpreted as Oligocene to Miocene, and possibly Pliocene. The interpretation of 261 km of seismic reflection sections suggests that large-displacement high-angle normal faults, typically with 60 degrees of dip, control horst and graben structure and accommodate extension by simple shear in the upper brittle crust. Such faults likely extend to depths of 15 to 18 km. Below this depth extension is thought to be accommodated by penetrative ductile deformation. A detailed retrodeformable (balanced) regional structure section suggests that basin-range extension at the latitude of the Mormon Mountains is about 17%. The Virgin-Beaver Dam Mountains high-angle normal fault is a large-displacement master fault in the area, having more than 8,000 in of normal vertical separation at the latitude of the Virgin Valley basin depocenter. Miocene doming and uplift of the Mormon Mountains occurred in response to displacement on the Virgin-Beaver Dam Mountains fault. The Virgin Valley basin formed as the hanging wall block downdropped, and the Mormon Mountains dome formed by relative uplift at the opposite end of the hanging wall block. Half-grabens, and tilted, folded, and faulted range blocks characterize basin-range crustal structure. Depositional growth relations are interpreted in basins from fanning-upward reflector geometry, and the wedge-shape of Oligocene to Recent syntectonic basin-fill sediments. Non-overlapping opposing east- and west-tilted half-grabens compose the Meadow Valley-California Wash basin. Seismic sections, gravity data, well data, and geologic mapping demonstrate that the Mormon Peak, Tule Springs Hills, and Beaver Dam/Castle Cliff "detachments," which were thought to be rooted low-angle normal faults, do not exist. The Mormon Peak and Beaver Dam/Castle Cliff low-angle normal faults are denudational fault planes below gravity slid masses. The widely distributed translocated Paleozoic blocks, which were thought to be remnant pieces of large hanging wall sheets ("extensional allochthons"), are disjunct rootless gravity slide blocks of minor tectonic significance. A large number of these rootless slide blocks lie on Pliocene and Quaternary basin-fill deposits. The Muddy Mountain-Tule Springs thrust, of Sevier age, was not reactivated as a crustal penetrating Tule Springs Hills low-angle normal fault, but is affected by small-scale gravity slide features. Rootless gravity slide blocks, secondary features to high-angle normal faults, commonly occur from instability as a result of the loss of lateral support induced by block faulting and the associated erosion of range blocks. Close

• 1724. [Article] Age-specific and lifetime reproductive success of known age Northern Spotted Owls on four study areas in Oregon and Washington

  Northern Spotted Owls (Strix occidentalis caurina) are a long-lived forest owl and range-wide declines in their numbers have resulted in the species being listed as threatened under the endangered species ...

  Citation × Citation Citation Abstract Copy Title: Age-specific and lifetime reproductive success of known age Northern Spotted Owls on four study areas in Oregon and Washington Author: Loschl, Peter J. Northern Spotted Owls (Strix occidentalis caurina) are a long-lived forest owl and range-wide declines in their numbers have resulted in the species being listed as threatened under the endangered species act. While many studies have been focused on population trends and reproductive performance of Spotted Owls from different age-classes, none have examined age related performance or lifetime reproductive success of individual owls. Using data from known age Spotted Owls on four long-term demography studies in Oregon and Washington, I conducted separate analyses to examine the functional relationship of age and reproductive success, measured as the number of young fledged (NYF), and to examine lifetime reproductive success. In my age-specific analysis, I used a mixed models approach to account for repeated measures on individual owls. I found that the standard 3-level age-class approach (1-year-old, 2-year-old, adult) often used in Spotted Owl research was a poor fit relative to curvilinear and threshold models that allowed for age-dependent variation beyond age 3. A quadratic age effect was more often supported for males, whereas a threshold effect indicating a linear increase in NYF from ages 1 to 4 was most supported in the analyses of female data. Females tended to achieve a maximum in reproductive performance at earlier ages than males, and there appeared to be a negative relationship between the age when a maximum in mean NYF was reached and overall fecundity, as reported in earlier studies. Temporal variability in numbers of young fledged at each age was best modeled with a categorical year variable as opposed to a cyclic biennial ("even-odd") year effect. Lifetime reproductive success of Spotted Owls, measured as the total numbers of fledglings and recruits produced by individuals, varied widely. For owls with relatively complete data, the number of lifetime fledglings ranged from 0 to 20 and the number of lifetime offspring that were observed as recruits within study areas ranged from 0 to 7. There was a significant positive relationship between the number of lifetime young fledged and the number that later recruited locally. Seventy five percent of females and 67% of males bred at least once. Whereas 17% of females and 16% of males produced 50% of the offspring fledged by each sex, only 9% of females and 7% of males produced 50% of the banded young that were later observed as recruits. Thirty nine percent of females and 30% of males produced no fledglings and 64% of females and 69% of males produced no local recruits. Thus while most owls fledged at least 1 offspring, most did not produce any fledglings that recruited locally during the study. Cumulative proportions of individual owls that first bred at different ages indicated that females tended to initiate their breeding at earlier ages than males. Whereas 36% of females bred first at ages 1 or 2, only 19% of males bred first before age 3. Of the owls that bred, 98% of females and 91% of males bred at least once by age 6. Compared to owls on the three Oregon study areas, owls on the Cle Elum Study Area in the eastern Cascades of Washington bred early (>50% by age 2), had higher mean numbers of fledglings (>1) at most ages, and had short mean lifespans (6 years). On the Oregon study areas, owls first bred at later ages (>50% at age ≥3), had lower mean numbers of fledglings (0.4–0.7) at most ages, and had longer mean lifespans (7–9 years). These patterns appear consistent with a compensatory relationship between reproduction and survival that was suggested in at least one previous study. Life history theory is also consistent with the idea that where lower and more variable non-juvenile survival occurs (as has been documented on Cle Elum), selection pressure for earlier breeding and greater offspring production at each attempt are to be expected. Nevertheless, it is unclear if local conditions such as prey abundance, harsh winter conditions, or predation pressure act proximately to influence reproduction and survival of Spotted Owls in these studies, or if the variability in patterns of age-specific reproductive success and components of lifetime reproduction on these study areas reflect adaptive life history responses among populations of Spotted Owls. It is likely that both plasticity and life history adaptations underlie the differences and patterns that were revealed, but tests of these hypotheses were beyond the scope of my study. Title: Age-specific and lifetime reproductive success of known age Northern Spotted Owls on four study areas in Oregon and Washington Author: Loschl, Peter J. Northern Spotted Owls (Strix occidentalis caurina) are a long-lived forest owl and range-wide declines in their numbers have resulted in the species being listed as threatened under the endangered species act. While many studies have been focused on population trends and reproductive performance of Spotted Owls from different age-classes, none have examined age related performance or lifetime reproductive success of individual owls. Using data from known age Spotted Owls on four long-term demography studies in Oregon and Washington, I conducted separate analyses to examine the functional relationship of age and reproductive success, measured as the number of young fledged (NYF), and to examine lifetime reproductive success. In my age-specific analysis, I used a mixed models approach to account for repeated measures on individual owls. I found that the standard 3-level age-class approach (1-year-old, 2-year-old, adult) often used in Spotted Owl research was a poor fit relative to curvilinear and threshold models that allowed for age-dependent variation beyond age 3. A quadratic age effect was more often supported for males, whereas a threshold effect indicating a linear increase in NYF from ages 1 to 4 was most supported in the analyses of female data. Females tended to achieve a maximum in reproductive performance at earlier ages than males, and there appeared to be a negative relationship between the age when a maximum in mean NYF was reached and overall fecundity, as reported in earlier studies. Temporal variability in numbers of young fledged at each age was best modeled with a categorical year variable as opposed to a cyclic biennial ("even-odd") year effect. Lifetime reproductive success of Spotted Owls, measured as the total numbers of fledglings and recruits produced by individuals, varied widely. For owls with relatively complete data, the number of lifetime fledglings ranged from 0 to 20 and the number of lifetime offspring that were observed as recruits within study areas ranged from 0 to 7. There was a significant positive relationship between the number of lifetime young fledged and the number that later recruited locally. Seventy five percent of females and 67% of males bred at least once. Whereas 17% of females and 16% of males produced 50% of the offspring fledged by each sex, only 9% of females and 7% of males produced 50% of the banded young that were later observed as recruits. Thirty nine percent of females and 30% of males produced no fledglings and 64% of females and 69% of males produced no local recruits. Thus while most owls fledged at least 1 offspring, most did not produce any fledglings that recruited locally during the study. Cumulative proportions of individual owls that first bred at different ages indicated that females tended to initiate their breeding at earlier ages than males. Whereas 36% of females bred first at ages 1 or 2, only 19% of males bred first before age 3. Of the owls that bred, 98% of females and 91% of males bred at least once by age 6. Compared to owls on the three Oregon study areas, owls on the Cle Elum Study Area in the eastern Cascades of Washington bred early (>50% by age 2), had higher mean numbers of fledglings (>1) at most ages, and had short mean lifespans (6 years). On the Oregon study areas, owls first bred at later ages (>50% at age ≥3), had lower mean numbers of fledglings (0.4–0.7) at most ages, and had longer mean lifespans (7–9 years). These patterns appear consistent with a compensatory relationship between reproduction and survival that was suggested in at least one previous study. Life history theory is also consistent with the idea that where lower and more variable non-juvenile survival occurs (as has been documented on Cle Elum), selection pressure for earlier breeding and greater offspring production at each attempt are to be expected. Nevertheless, it is unclear if local conditions such as prey abundance, harsh winter conditions, or predation pressure act proximately to influence reproduction and survival of Spotted Owls in these studies, or if the variability in patterns of age-specific reproductive success and components of lifetime reproduction on these study areas reflect adaptive life history responses among populations of Spotted Owls. It is likely that both plasticity and life history adaptations underlie the differences and patterns that were revealed, but tests of these hypotheses were beyond the scope of my study. Close

• 1725. [Article] Magma dynamics and evolution in continental arcs : insights from the Central Andes

  Constraining the magma evolution and dynamics that lead to the eruption of large volume continental arc systems is fundamental to our understanding of continental crust formation. An investigation into ...

  Citation × Citation Citation Abstract Copy Title: Magma dynamics and evolution in continental arcs : insights from the Central Andes Author: Grocke, Stephanie B. Constraining the magma evolution and dynamics that lead to the eruption of large volume continental arc systems is fundamental to our understanding of continental crust formation. An investigation into the magmagenesis that results in the formation of the Central Volcanic Zone (CVZ) in the Andes of South America, situated atop overthickened continental crust (<80 km thick), provides insights into large volume silicic magma reservoirs and how they evolve prior to their potentially catastrophic explosive eruption on the Earth’s surface. A focused case study of the Cerro Guacha Caldera Complex (CGCC), a nested volcanic system in the Altiplano-Puna Volcanic Complex of SW Bolivia, puts constraints on the progressive stages of development of the magmatic underpinnings of the caldera complex. Whole rock data, in conjunction with matrix glass, mineral compositions and melt inclusions, are used to infer processes that gave rise to the formation of the Guacha II Caldera, the younger of two main collapse features, formed from the supereruption of the Tara Ignimbrite (>800 km³ DRE) at 3.49 ± 0.01 Ma. The eruptive history of the Guacha II Caldera from pre-caldera to post-caldera is fully represented, allowing magma dynamics associated with a complete caldera cycle, from pre-climactic (catastrophic caldera-forming) magma accumulation through to post-climactic effusions that are part of the resurgent history of the caldera, to be examined. Analysis of the high-K, calcalkaline suite of andesite to high Si-rhyolite Tara pyroclastic deposits provides insights into the storage conditions and magma dynamics leading up to a supervolcanic eruption. The Tara eruptive products define a liquid line of descent from the basal andesite lava (62 wt % SiO₂) to the high-silica rhyolite post-collapse Chajnantor Dome lava (78 wt.% SiO₂), with major and trace element trends consistent with fractionation of quartz, plagioclase, orthopyroxene, hornblende, sanidine, biotite, and Fe-Ti oxides. Isotope ratios span a significant range in ⁸⁷Sr/⁸⁶Sr (0.709 to 0.713) and a relatively narrow range in ¹⁴³Nd/¹⁴⁴Nd (0.512179 to 0.512297) and δ¹⁸O[subscript (qtz)] (+8.68 to +8.43‰). These data require AFC processes to explain both the isotope and trace element compositions in the Tara magmas. Geothermobarometry reveals pre-eruptive temperatures (~800 - 950 °C), pressures (~200 MPa), and H₂O contents (~5 wt%) that suggest storage of a large-volume rhyodacite magma reservoir between 5 and 9 km depth in the upper crust. Analyses of quartz-hosted melt inclusions from pumices in the climactic plinian and ignimbrite phase of eruption reveal that pre-eruptive H₂O contents in the plinian pumice overlap with those in the ignimbrite pumice (2.2 to 6.0 and 2.1 to 5.4 wt.% H₂O, respectively). The ignimbrite magma, however, contains higher CO₂ (<630 versus <300 ppm) suggesting a vertically arranged pre-climactic magma column from 7.5 km to 4 km depth, which is in agreement with the geothermobarometry from mineral analysis. Andesite recharge can account for significant compositional heterogeneities identified in the Tara magmas. Variations in trace element concentrations from melt inclusions from each of the three eruptive phases also suggest that the large-volume pre-climactic reservoir, as well as the remnant magma, contained significant chemical heterogeneities due to variations in the degree of crystal fractionation and the influence of recharge magma. Based on Ti diffusion in quartz, we estimate that the recharge event occurred within <100 years of eruption and may signal the onset of the pressurization of the system that led to eruption. The following petrogenetic model is proposed for the Tara magmatic system: andesite recharge magma ascended into a large-volume rhyodacite magma reservoir in the upper crust, where it cooled and crystallized to form a small volume of rhyolite, crystal-poor, residual melt. Andesite erupted onto what is now the Guacha II caldera-floor, and was followed by an explosive plinian eruption that produced a rhyolite pumice fall deposit outside the caldera to the east and south. Based on melt inclusions, the plinian eruption tapped a less-evolved, crystal poor (~10 vol.%), more roofward liquid that syneruptively mixed with the highly crystalline (<30 vol.%), large volume rhyodacite magma reservoir. Caldera collapse was accompanied by an explosive eruption of the large-volume rhyodacite magma reservoir and subsequent column collapse, resulting in a pyroclastic flow that produced the >800 km³ Tara ignimbrite. Extrusion of three post-caldera domes followed caldera collapse. Subtle differences between these domes invoke separate coexisting "pods" of magma that evolved independently from one another from the remnant magma that is represented by the ignimbrite. Analyses of quartz-hosted melt inclusions from the post-collapse Chajnantor Dome suggest that the highly-differentiated remnant magma contained no detectable CO₂ and low H₂O contents, representative of a degassed magma. The eruptive transition during the climactic eruption was not controlled by the volatile budget of the melt but more likely by external factors such as vent geometry and conduit evolution. Post climactic effusive volcanism reflects the degassed nature of the remnant magma. Using a suite of volcanic rocks from the CVZ, we quantify the effect of assimilation of continental crust on magmatic oxygen fugacity (ƒO₂). We use several proxies to estimate the ƒO₂ recorded by lavas, pumice and scoria: 1) whole rock Fe³⁺/ΣFe ratios, 2) Fe³⁺/ΣFe ratios in quartz-hosted melt inclusions, and 3) Fe-Ti oxide oxybarometry. Samples span a range of crustal contribution, as indicated by their radiogenic isotope compositions (⁸⁷Sr/⁸⁶Sr = 0.705-0.713), and cover the full suite of magma compositions erupted during the Neogene history of the arc (52 - 74 wt.% SiO₂). Some samples show excellent agreement across multiple ƒO₂ proxies. In other cases, where pumices show evidence of alteration in hand-sample for example, the ƒO₂ recorded by bulk Fe³⁺/ΣFe ratios is two orders of magnitude more oxidized than corresponding ratios from melt inclusions or Fe-Ti oxides. This suggests modification of whole rock Fe³⁺/ΣFe ratios, but not melt inclusion Fe³⁺/ΣFe ratios, by syn- or post-eruptive processes and that care must be taken when relying on bulk techniques to determine magmatic ƒO₂. We cannot resolve any oxidation due to crystal fractionation in our sample suite. Crustal assimilation, however, can oxidize arc magmas. The increase in ƒO₂ due to crustal assimilation reaches, but does not exceed, ~1 log unit - even in the Andes, where crustal assimilation is extreme. Title: Magma dynamics and evolution in continental arcs : insights from the Central Andes Author: Grocke, Stephanie B. Constraining the magma evolution and dynamics that lead to the eruption of large volume continental arc systems is fundamental to our understanding of continental crust formation. An investigation into the magmagenesis that results in the formation of the Central Volcanic Zone (CVZ) in the Andes of South America, situated atop overthickened continental crust (<80 km thick), provides insights into large volume silicic magma reservoirs and how they evolve prior to their potentially catastrophic explosive eruption on the Earth’s surface. A focused case study of the Cerro Guacha Caldera Complex (CGCC), a nested volcanic system in the Altiplano-Puna Volcanic Complex of SW Bolivia, puts constraints on the progressive stages of development of the magmatic underpinnings of the caldera complex. Whole rock data, in conjunction with matrix glass, mineral compositions and melt inclusions, are used to infer processes that gave rise to the formation of the Guacha II Caldera, the younger of two main collapse features, formed from the supereruption of the Tara Ignimbrite (>800 km³ DRE) at 3.49 ± 0.01 Ma. The eruptive history of the Guacha II Caldera from pre-caldera to post-caldera is fully represented, allowing magma dynamics associated with a complete caldera cycle, from pre-climactic (catastrophic caldera-forming) magma accumulation through to post-climactic effusions that are part of the resurgent history of the caldera, to be examined. Analysis of the high-K, calcalkaline suite of andesite to high Si-rhyolite Tara pyroclastic deposits provides insights into the storage conditions and magma dynamics leading up to a supervolcanic eruption. The Tara eruptive products define a liquid line of descent from the basal andesite lava (62 wt % SiO₂) to the high-silica rhyolite post-collapse Chajnantor Dome lava (78 wt.% SiO₂), with major and trace element trends consistent with fractionation of quartz, plagioclase, orthopyroxene, hornblende, sanidine, biotite, and Fe-Ti oxides. Isotope ratios span a significant range in ⁸⁷Sr/⁸⁶Sr (0.709 to 0.713) and a relatively narrow range in ¹⁴³Nd/¹⁴⁴Nd (0.512179 to 0.512297) and δ¹⁸O[subscript (qtz)] (+8.68 to +8.43‰). These data require AFC processes to explain both the isotope and trace element compositions in the Tara magmas. Geothermobarometry reveals pre-eruptive temperatures (~800 - 950 °C), pressures (~200 MPa), and H₂O contents (~5 wt%) that suggest storage of a large-volume rhyodacite magma reservoir between 5 and 9 km depth in the upper crust. Analyses of quartz-hosted melt inclusions from pumices in the climactic plinian and ignimbrite phase of eruption reveal that pre-eruptive H₂O contents in the plinian pumice overlap with those in the ignimbrite pumice (2.2 to 6.0 and 2.1 to 5.4 wt.% H₂O, respectively). The ignimbrite magma, however, contains higher CO₂ (<630 versus <300 ppm) suggesting a vertically arranged pre-climactic magma column from 7.5 km to 4 km depth, which is in agreement with the geothermobarometry from mineral analysis. Andesite recharge can account for significant compositional heterogeneities identified in the Tara magmas. Variations in trace element concentrations from melt inclusions from each of the three eruptive phases also suggest that the large-volume pre-climactic reservoir, as well as the remnant magma, contained significant chemical heterogeneities due to variations in the degree of crystal fractionation and the influence of recharge magma. Based on Ti diffusion in quartz, we estimate that the recharge event occurred within <100 years of eruption and may signal the onset of the pressurization of the system that led to eruption. The following petrogenetic model is proposed for the Tara magmatic system: andesite recharge magma ascended into a large-volume rhyodacite magma reservoir in the upper crust, where it cooled and crystallized to form a small volume of rhyolite, crystal-poor, residual melt. Andesite erupted onto what is now the Guacha II caldera-floor, and was followed by an explosive plinian eruption that produced a rhyolite pumice fall deposit outside the caldera to the east and south. Based on melt inclusions, the plinian eruption tapped a less-evolved, crystal poor (~10 vol.%), more roofward liquid that syneruptively mixed with the highly crystalline (<30 vol.%), large volume rhyodacite magma reservoir. Caldera collapse was accompanied by an explosive eruption of the large-volume rhyodacite magma reservoir and subsequent column collapse, resulting in a pyroclastic flow that produced the >800 km³ Tara ignimbrite. Extrusion of three post-caldera domes followed caldera collapse. Subtle differences between these domes invoke separate coexisting "pods" of magma that evolved independently from one another from the remnant magma that is represented by the ignimbrite. Analyses of quartz-hosted melt inclusions from the post-collapse Chajnantor Dome suggest that the highly-differentiated remnant magma contained no detectable CO₂ and low H₂O contents, representative of a degassed magma. The eruptive transition during the climactic eruption was not controlled by the volatile budget of the melt but more likely by external factors such as vent geometry and conduit evolution. Post climactic effusive volcanism reflects the degassed nature of the remnant magma. Using a suite of volcanic rocks from the CVZ, we quantify the effect of assimilation of continental crust on magmatic oxygen fugacity (ƒO₂). We use several proxies to estimate the ƒO₂ recorded by lavas, pumice and scoria: 1) whole rock Fe³⁺/ΣFe ratios, 2) Fe³⁺/ΣFe ratios in quartz-hosted melt inclusions, and 3) Fe-Ti oxide oxybarometry. Samples span a range of crustal contribution, as indicated by their radiogenic isotope compositions (⁸⁷Sr/⁸⁶Sr = 0.705-0.713), and cover the full suite of magma compositions erupted during the Neogene history of the arc (52 - 74 wt.% SiO₂). Some samples show excellent agreement across multiple ƒO₂ proxies. In other cases, where pumices show evidence of alteration in hand-sample for example, the ƒO₂ recorded by bulk Fe³⁺/ΣFe ratios is two orders of magnitude more oxidized than corresponding ratios from melt inclusions or Fe-Ti oxides. This suggests modification of whole rock Fe³⁺/ΣFe ratios, but not melt inclusion Fe³⁺/ΣFe ratios, by syn- or post-eruptive processes and that care must be taken when relying on bulk techniques to determine magmatic ƒO₂. We cannot resolve any oxidation due to crystal fractionation in our sample suite. Crustal assimilation, however, can oxidize arc magmas. The increase in ƒO₂ due to crustal assimilation reaches, but does not exceed, ~1 log unit - even in the Andes, where crustal assimilation is extreme. Close

• 1726. [Article] Coastal sand dunes of Oregon and Washington

  In Part I the environment of the coastal dunes of Oregon and Washington is analyzed. Most of the substratum is a narrow foreland or terrace, in part submerged, that borders the mountain front. Temperature ...

  Citation × Citation Citation Abstract Copy Title: Coastal sand dunes of Oregon and Washington Author: Cooper, William Skinner, 1884- In Part I the environment of the coastal dunes of Oregon and Washington is analyzed. Most of the substratum is a narrow foreland or terrace, in part submerged, that borders the mountain front. Temperature is relatively low in summer and rarely reaches the freezing point in winter. Winter precipitation is heavy, and there is almost no snow; there is a pronounced deficiency in precipitation in summer. The summer wind is a very constant afternoon sea breeze from north to northwest; winter winds are variable but include frequent southwest gales. Longshore currents are governed by the seasonal winds, moving southward in summer and northward in winter. The regional vegetation is dense, tall conifer forest. The influence of man has been comparatively slight: in prehistoric times the starting of forest fires; in historic time moderate disturbance due to grazing and recent efforts to control the movement of the sand. Part II deals with forms and processes. The simplest combination of elements comprises sand, wind, and water. Interaction of these produces two patterns. In the transverse-ridge pattern the individual unit is a ridge essentially normal to the summer wind and moving with it; it is asymmetric in profile with gentle windward slope and steep leeward slope (slipface). Origin and maintenance of this profile are explained in accordance with principles developed in the field of aerodynamics, and conclusions arrived at deductively are confirmed by slow-motion photography of smoke streams on the dunes. The oblique-ridge pattern occurs only where there is full exposure to both seasonal winds, plenty of space, and plenty of sand. These conditions are met only in Region III (Coos Bay dune sheet). The units are much more massive than the transverse ridges and are essentially stationary. Their trend lies between the means of summer and winter winds. A theoretical explanation of their origin and maintenance is presented, and the oblique ridges and the "longitudinal dunes" of certain desert regions are compared. Neither transverse nor oblique ridge is found in stabilized condition. The factor vegetation added to the other three-sand, wind, and water-promotes stabilization. On a prograding shore, successive beach ridges are quickly captured and fixed, and retain their initial form indefinitely. On a retrograding shore the processes are exceedingly complex and involve repeated stabilization and rejuvenation. Two cases are presented: flat shore, with and without abundant sand supply; stabilized dune masses undergoing erosion. In the latter case, the commoner, development involves the following phases: trough blowout, merging of troughs, reduction to deflation base, and precipitation ridge, which may in time become completely stabilized while still retaining its characteristic form. In places sheltered from one or the other of the seasonal winds, usually the summer wind, giant parabola dunes, which may likewise become fixed by vegetation, develop. Part III is a description of the dune localities of the Oregon-Washington coast and an account of their history. Forty per cent of this coast bears dunes of greater or lesser magnitude. Thirty dune localities are grouped in four regions. Region I includes four localities north of Tillamook Head, Oregon, making a continuous strip 53 km long, that bears the parallel beach-dune-ridge pattern associated with progradation. The forms in Regions II, III, and IV, heterogeneous and complex, are those characteristic of retrograding shores. The two principal stabilized forms are the precipitation ridge and the parabola dune. In Regions II, III, and IV the existing features came into being mainly during the last grand period of sea-level rise, and the seaward portions of massive parabola complexes have been sliced away in varying degree by the advancing sea. The beach-ridge dunes of Region I were formed during the period of comparatively stable sea level, with a probable small net lowering, which followed the maximum of sea advance and has extended to the present. Progradation here during this period, in contrast with almost none south of Tillamook Head, has been possible because of the ample bed load carried to the coast by the Columbia River. South of Tillamook Head there is, in a number of well-distributed localities, evidence of three episodes of advance. The first is represented by the strip of thoroughly stabilized dunes that nearly everywhere forms the inner marginal part of the dune complexes. This episode reached its culmination before the sea had attained its maximum of advance-attested by the slicing away of portions of completely stabilized masses. The second advance for the most part fell short of the first, though in a few places it overpassed the limits of the latter; present condition ranges from complete stabilization to vigorous activity. The third episode is represented by active dunes with open access to the shore. In certain localities there are only an inner strip of stabilized dunes and an outer zone of active dunes. It is assumed that in these the visible effects of the second and third episodes have merged. An earlier cycle of dune development, similar to the modern one in character and extent, is proved by eolian sediments containing altered podzolic soils, which make a minor part of the mantle of unconsolidated materials that lies upon the rock platform of the 30-m terrace. The dunes of which these masses are remnants were formed during the next-to-the-last grand period of submergence. Development of the dunes of Regions II, III, and IV, associated with the grand period of submergence, is assigned to the period of deglaciation that followed the Wisconsin maximum, and mainly to the period of rapid deglaciation that began after the Valders-Mankato advance. The beach-ridge dunes of Region I, on the other hand, have developed in their entirety in the time since sea-level rise was succeeded by stability. By analogy, the earlier cycle of dune development was associated with the waning phase of Illinoian glaciation, and it may be assumed that similar dune cycles were associated with the earlier glaciations of the Pleistocene. Title: Coastal sand dunes of Oregon and Washington Author: Cooper, William Skinner, 1884- In Part I the environment of the coastal dunes of Oregon and Washington is analyzed. Most of the substratum is a narrow foreland or terrace, in part submerged, that borders the mountain front. Temperature is relatively low in summer and rarely reaches the freezing point in winter. Winter precipitation is heavy, and there is almost no snow; there is a pronounced deficiency in precipitation in summer. The summer wind is a very constant afternoon sea breeze from north to northwest; winter winds are variable but include frequent southwest gales. Longshore currents are governed by the seasonal winds, moving southward in summer and northward in winter. The regional vegetation is dense, tall conifer forest. The influence of man has been comparatively slight: in prehistoric times the starting of forest fires; in historic time moderate disturbance due to grazing and recent efforts to control the movement of the sand. Part II deals with forms and processes. The simplest combination of elements comprises sand, wind, and water. Interaction of these produces two patterns. In the transverse-ridge pattern the individual unit is a ridge essentially normal to the summer wind and moving with it; it is asymmetric in profile with gentle windward slope and steep leeward slope (slipface). Origin and maintenance of this profile are explained in accordance with principles developed in the field of aerodynamics, and conclusions arrived at deductively are confirmed by slow-motion photography of smoke streams on the dunes. The oblique-ridge pattern occurs only where there is full exposure to both seasonal winds, plenty of space, and plenty of sand. These conditions are met only in Region III (Coos Bay dune sheet). The units are much more massive than the transverse ridges and are essentially stationary. Their trend lies between the means of summer and winter winds. A theoretical explanation of their origin and maintenance is presented, and the oblique ridges and the "longitudinal dunes" of certain desert regions are compared. Neither transverse nor oblique ridge is found in stabilized condition. The factor vegetation added to the other three-sand, wind, and water-promotes stabilization. On a prograding shore, successive beach ridges are quickly captured and fixed, and retain their initial form indefinitely. On a retrograding shore the processes are exceedingly complex and involve repeated stabilization and rejuvenation. Two cases are presented: flat shore, with and without abundant sand supply; stabilized dune masses undergoing erosion. In the latter case, the commoner, development involves the following phases: trough blowout, merging of troughs, reduction to deflation base, and precipitation ridge, which may in time become completely stabilized while still retaining its characteristic form. In places sheltered from one or the other of the seasonal winds, usually the summer wind, giant parabola dunes, which may likewise become fixed by vegetation, develop. Part III is a description of the dune localities of the Oregon-Washington coast and an account of their history. Forty per cent of this coast bears dunes of greater or lesser magnitude. Thirty dune localities are grouped in four regions. Region I includes four localities north of Tillamook Head, Oregon, making a continuous strip 53 km long, that bears the parallel beach-dune-ridge pattern associated with progradation. The forms in Regions II, III, and IV, heterogeneous and complex, are those characteristic of retrograding shores. The two principal stabilized forms are the precipitation ridge and the parabola dune. In Regions II, III, and IV the existing features came into being mainly during the last grand period of sea-level rise, and the seaward portions of massive parabola complexes have been sliced away in varying degree by the advancing sea. The beach-ridge dunes of Region I were formed during the period of comparatively stable sea level, with a probable small net lowering, which followed the maximum of sea advance and has extended to the present. Progradation here during this period, in contrast with almost none south of Tillamook Head, has been possible because of the ample bed load carried to the coast by the Columbia River. South of Tillamook Head there is, in a number of well-distributed localities, evidence of three episodes of advance. The first is represented by the strip of thoroughly stabilized dunes that nearly everywhere forms the inner marginal part of the dune complexes. This episode reached its culmination before the sea had attained its maximum of advance-attested by the slicing away of portions of completely stabilized masses. The second advance for the most part fell short of the first, though in a few places it overpassed the limits of the latter; present condition ranges from complete stabilization to vigorous activity. The third episode is represented by active dunes with open access to the shore. In certain localities there are only an inner strip of stabilized dunes and an outer zone of active dunes. It is assumed that in these the visible effects of the second and third episodes have merged. An earlier cycle of dune development, similar to the modern one in character and extent, is proved by eolian sediments containing altered podzolic soils, which make a minor part of the mantle of unconsolidated materials that lies upon the rock platform of the 30-m terrace. The dunes of which these masses are remnants were formed during the next-to-the-last grand period of submergence. Development of the dunes of Regions II, III, and IV, associated with the grand period of submergence, is assigned to the period of deglaciation that followed the Wisconsin maximum, and mainly to the period of rapid deglaciation that began after the Valders-Mankato advance. The beach-ridge dunes of Region I, on the other hand, have developed in their entirety in the time since sea-level rise was succeeded by stability. By analogy, the earlier cycle of dune development was associated with the waning phase of Illinoian glaciation, and it may be assumed that similar dune cycles were associated with the earlier glaciations of the Pleistocene. Close

• 1727. [Article] Isotopic composition of respired CO2 in a small watershed : development and testing of an automated sampling system and analysis of first year data

  Warming of the terrestrial biosphere due to the anthropogenic addition of carbon dioxide to the earth’s atmosphere is becoming a major focus of scientific inquiry. Predictions of the extent of this warming ...

  Citation × Citation Citation Abstract Copy Title: Isotopic composition of respired CO2 in a small watershed : development and testing of an automated sampling system and analysis of first year data Author: Hauck, Mark J. Warming of the terrestrial biosphere due to the anthropogenic addition of carbon dioxide to the earth’s atmosphere is becoming a major focus of scientific inquiry. Predictions of the extent of this warming are hampered by uncertainty in the ability of the earth’s ecosystems to counteract this effect by sequestering carbon dioxide by increases in the mass of vegetation, soil storage, or storage in the Earth’s oceans. Measurement of the carbon isotopic composition of respired CO2 (Delta [superscript 13]C[subscript R-eco]) is becoming increasingly important to ecosystem studies because the information contained in this respiration can be an indicator of ecosystem stress and productivity. This study was conducted as part of a larger research project aimed at developing and testing the capacity for measuring Delta [superscript 13]C[subscript R-eco] in a small, steeply-sloped watershed in western Oregon. The goals of this study were: (1) to develop and test an automated system for sampling nocturnal air to be analyzed in a laboratory for isotopic composition; (2) to collect samples of the atmosphere from the nocturnal cold air drainage of a steeply sloped watershed in the HJ Andrews Experimental Forest and bring those samples back to a laboratory to be analyzed for CO2 concentration and carbon isotope composition; and (3) to conduct an initial analysis of the relationship between Delta [superscript 13]C[subscript R-eco] for the first year of deployment and two environmental forcing factors, soil moisture and atmospheric vapor pressure deficit (VPD). The automated system was designed during 2004 and 2005, tested in the laboratory during the month of April 2005, debugged in the field between August 2004 and May 2005, and deployed during the period from late May, 2005 to November 2005. The design objectives for the automated sampling system were: (1) light weight; (2) portability; (3) high reliability; (4) fast dynamic response; (5) unattended operation; and (6) the ability to capture, transport, and store samples over several days with no loss of data integrity. The automated sampling system proved capable of collecting 15 samples per sampling period and utilized a 16 loop stainless steel sample capture valve (Valcon Instruments, 7806 Bobbitt Houston, TX 77055) for sample containment. The system was designed for automated, labor free operation and uses a Campbell CR 10X datalogger (Campbell Scientific, Inc, 815 West 1800 North, Logan Utah) for both data acquisition and system control. This unique architecture was selected to enhance the ability of the system to capture samples which could be analyzed simultaneously for both CO2 concentration and Delta[superscript 13]C. The system was deployed in a steeply sloped watershed and proved to have a combination of light weight (approximately 34 kg total weight) and portability which allowed a wide range of field personnel to deploy the system without undue physical stress. Some initial issues with electrical wiring, plumbing connections, and control program bugs hampered early season performance, but once the system was debugged, it functioned reliably throughout the remainder of the field season with a minimum of operator input. Test results showed that the automated sampler had a maximum sampling frequency of 0.043 hertz, could store air samples for up to 3 days without detectable changes in either isotopic composition or CO2 concentration and displayed greater precision than the hand sampling process it replaced. Using the automated sampling system, sets of nocturnal cold air drainage samples were collected on nine evenings in 2005. The 15 samples acquired for each of these nine evenings were used to generate Keeling plots to determine a single value of the isotopic composition of ecosystem respiration (Delta [superscript 13]C[subscript R-eco]) for each sampling date. The range of Delta [superscript 13]C[subscript R-eco] over the season was 3.9 0/00 and the values of Delta [superscript 13]C[subscript R-eco] varied from -26.2 0/00 on July 13, 2005 to -22.9 0/00 on September 14, 2005. This seasonal pattern of Delta [superscript 13]C[subscript R-eco] was consistent with a forest under drought stress. Trends in ecosystem respiration over the growing season were compared to corresponding measurements of the environmental variables of soil moisture content and VPD. VPD ranged from 2.7 to 1758 Pa, but these patterns of VPD were not significantly correlated to seasonal Delta [superscript 13]C[subscript R-eco] patterns over the study period. Soil moisture content ranged between 7.2% and 44.3% over the study period and soil moisture content temporal patterns were highly correlated with rain events exceeding 4 mm. The soil moisture content pattern for the south-facing slope was significantly correlated with the seasonal Delta [superscript 13]C[subscript R-eco] pattern, although other groupings of soil moisture content were not. The automated system designed for this project met all of its design objectives and functioned adequately throughout the sampling period. The carbon isotope patterns were consistent with a forest under drought stress and the soil moisture content of the plots on the south-facing slopes of the watershed were significantly correlated to these isotope patterns. The future of this system could be enhanced by making adjustments to the supporting hardware, control program and operating procedure to enable larger quantities of samples, more rapid sampling rates, and automated hardware diagnostics. Title: Isotopic composition of respired CO2 in a small watershed : development and testing of an automated sampling system and analysis of first year data Author: Hauck, Mark J. Warming of the terrestrial biosphere due to the anthropogenic addition of carbon dioxide to the earth’s atmosphere is becoming a major focus of scientific inquiry. Predictions of the extent of this warming are hampered by uncertainty in the ability of the earth’s ecosystems to counteract this effect by sequestering carbon dioxide by increases in the mass of vegetation, soil storage, or storage in the Earth’s oceans. Measurement of the carbon isotopic composition of respired CO2 (Delta [superscript 13]C[subscript R-eco]) is becoming increasingly important to ecosystem studies because the information contained in this respiration can be an indicator of ecosystem stress and productivity. This study was conducted as part of a larger research project aimed at developing and testing the capacity for measuring Delta [superscript 13]C[subscript R-eco] in a small, steeply-sloped watershed in western Oregon. The goals of this study were: (1) to develop and test an automated system for sampling nocturnal air to be analyzed in a laboratory for isotopic composition; (2) to collect samples of the atmosphere from the nocturnal cold air drainage of a steeply sloped watershed in the HJ Andrews Experimental Forest and bring those samples back to a laboratory to be analyzed for CO2 concentration and carbon isotope composition; and (3) to conduct an initial analysis of the relationship between Delta [superscript 13]C[subscript R-eco] for the first year of deployment and two environmental forcing factors, soil moisture and atmospheric vapor pressure deficit (VPD). The automated system was designed during 2004 and 2005, tested in the laboratory during the month of April 2005, debugged in the field between August 2004 and May 2005, and deployed during the period from late May, 2005 to November 2005. The design objectives for the automated sampling system were: (1) light weight; (2) portability; (3) high reliability; (4) fast dynamic response; (5) unattended operation; and (6) the ability to capture, transport, and store samples over several days with no loss of data integrity. The automated sampling system proved capable of collecting 15 samples per sampling period and utilized a 16 loop stainless steel sample capture valve (Valcon Instruments, 7806 Bobbitt Houston, TX 77055) for sample containment. The system was designed for automated, labor free operation and uses a Campbell CR 10X datalogger (Campbell Scientific, Inc, 815 West 1800 North, Logan Utah) for both data acquisition and system control. This unique architecture was selected to enhance the ability of the system to capture samples which could be analyzed simultaneously for both CO2 concentration and Delta[superscript 13]C. The system was deployed in a steeply sloped watershed and proved to have a combination of light weight (approximately 34 kg total weight) and portability which allowed a wide range of field personnel to deploy the system without undue physical stress. Some initial issues with electrical wiring, plumbing connections, and control program bugs hampered early season performance, but once the system was debugged, it functioned reliably throughout the remainder of the field season with a minimum of operator input. Test results showed that the automated sampler had a maximum sampling frequency of 0.043 hertz, could store air samples for up to 3 days without detectable changes in either isotopic composition or CO2 concentration and displayed greater precision than the hand sampling process it replaced. Using the automated sampling system, sets of nocturnal cold air drainage samples were collected on nine evenings in 2005. The 15 samples acquired for each of these nine evenings were used to generate Keeling plots to determine a single value of the isotopic composition of ecosystem respiration (Delta [superscript 13]C[subscript R-eco]) for each sampling date. The range of Delta [superscript 13]C[subscript R-eco] over the season was 3.9 0/00 and the values of Delta [superscript 13]C[subscript R-eco] varied from -26.2 0/00 on July 13, 2005 to -22.9 0/00 on September 14, 2005. This seasonal pattern of Delta [superscript 13]C[subscript R-eco] was consistent with a forest under drought stress. Trends in ecosystem respiration over the growing season were compared to corresponding measurements of the environmental variables of soil moisture content and VPD. VPD ranged from 2.7 to 1758 Pa, but these patterns of VPD were not significantly correlated to seasonal Delta [superscript 13]C[subscript R-eco] patterns over the study period. Soil moisture content ranged between 7.2% and 44.3% over the study period and soil moisture content temporal patterns were highly correlated with rain events exceeding 4 mm. The soil moisture content pattern for the south-facing slope was significantly correlated with the seasonal Delta [superscript 13]C[subscript R-eco] pattern, although other groupings of soil moisture content were not. The automated system designed for this project met all of its design objectives and functioned adequately throughout the sampling period. The carbon isotope patterns were consistent with a forest under drought stress and the soil moisture content of the plots on the south-facing slopes of the watershed were significantly correlated to these isotope patterns. The future of this system could be enhanced by making adjustments to the supporting hardware, control program and operating procedure to enable larger quantities of samples, more rapid sampling rates, and automated hardware diagnostics. Close

• 1728. [Article] The design, meaning, and use of the Turkish salon

  This exploratory study was focused on the design, meaning and use of the Turkish salon (the sitting room for guests). The findings provided an understanding of the different aspects of people's experiences ...

  Citation × Citation Citation Abstract Copy Title: The design, meaning, and use of the Turkish salon Author: Dazkir, Sibel Seda This exploratory study was focused on the design, meaning and use of the Turkish salon (the sitting room for guests). The findings provided an understanding of the different aspects of people's experiences of their salons. Socially and personally constructed meanings were examined to gain a deeper understanding of the respondents' perspectives. Thirty one respondents participated in the study. They were recruited from two cities in Turkey: Erbaa and Ankara. The data were collected in the respondents' salons via in-depth interviews, audio and video recordings, sketches, and observations. The interviews lasted from one to three and a half hours. The qualitative data analysis revealed themes which were grouped under three main categories: environment, person, and setting. Those interrelated dimensions were discussed in detail to have a better understanding of people's relationship with their salons. Environment related dimensions were conformity, influence of others, influence of changing socio-economic environment and rise of consumerism. Person related dimensions were satisfaction with the setting, interest in home decoration, demographics such as age and income level, personalization and meaningful objects, and place attachment. Setting related dimensions included physical characteristics of the setting such as color, size, and comfort, and use of the room such as how often and why they use the salon. The findings of this study supported the idea that consumption behaviors influence people's relationship with places. With the changing economic conditions, people live more comfortably, afford items easier, and there is more variety of products to reflect self or create the ideal salon environment compared to the past. Many respondents believed that rise in consumerism, spending unnecessarily, being allured by market pervasiveness, and being able to own products easily make people inappreciative, unhappy, and dissatisfied with what they have, and cause "israf" (wastefulness or prodigality). The respondents' narratives confirmed that they tried to create an environment that satisfied them; they cared about their salon designs. Some respondents revealed being influenced by trends and other people's salons indicating the influence of the market and others on salon design. A greater percentage of the respondents from Erbaa reported paying attention to others' salon designs compared to the respondents from Ankara. Although some spouses influenced the selection of furniture, women were more in charge of their salon designs than men. Having children influenced how often they used their salons, their purchase decisions, or when they would replace their furniture. Frequency and profile of the guests influenced use of their salons. The majority of the respondents from both Erbaa and Ankara displayed or revealed interest in home decoration through their effort to design and personalize their salons, their knowledge about furniture styles, paying attention to others' salons, watching home design TV shows, and visiting furniture stores as leisure activity. Socio-economic status influenced some of the respondents' salon designs regarding originality and price of their salon furniture and décor. Other factors such as their approach to consumerism, their taste, and family status influenced their salon design in a greater degree revealing the individualistic nature of domestic interiors. Although the findings provide insight on the relationship between demographic characteristics and salon design and use, the sampling method and sample size make it impossible to draw conclusions regarding the relationship between demographic characteristics and salon design and meaning. The respondents from both Erbaa and Ankara personalized the settings to reflect their self. They designed the rooms to reflect their taste, values, beliefs, culture, experiences, family, occupation, hobbies, and so forth. They displayed meaningful objects such as souvenirs, gifts, and family photographs. Personalization of the rooms provided control over the settings, a sense of connection to their salons, and sense of belonging. Physical characteristics of the setting, especially aesthetic appeal and usability influenced the respondents' satisfaction with the rooms. Although it was possible to observe patterns regarding the type of decorative items that they used, the meanings and stories behind how they acquired the objects made their design process unique and individualistic. The majority of respondents expressed sense of belonging and attachment to their salons and homes. Spending time in the setting, sharing the place with loved ones, feeling comfortable, sense of belonging, being satisfied with the setting, sense of freedom, reflecting own taste, personalization, and memories influenced the respondents' attachment to their salons in Ankara. The respondents from Erbaa added more intangible aspects to this list such as sincerity, happiness, coziness, effort in creating the room, familiarity, and feeling at peace. Exploring the meaning of place and objects in this study provided an understanding of everyday human life experience. This study provided rich information about the relationship between people and their salons. The findings indicated that design, meaning, and use of salons were shaped by the dynamic relationship between many individual, psychological, social, socio-cultural, socio-economic, and setting related variables. The findings confirmed that salons were designed by both personal and social point of view. The respondents created sense of place personally and socially. Studying the Turkish salon provided an understanding of how the socio-economic and socio-cultural changes were perceived by the respondents in their domestic space. The results indicate that political, cultural, religious, and economic environments influence society's perception of buying and decorating. Findings of this study contribute to different fields such as interior design by providing information on design process and design preferences of the respondents; industrial design by providing information on the meanings of objects, respondents' interaction with objects, and preferences for furniture and accessories; environmental psychology by providing information on how the respondents' behavior and emotions were influenced by the design of the setting and vice versa; and cultural anthropology by revealing information on the meanings of everyday life surroundings, and the influence of socio-cultural environment on salon creation. Title: The design, meaning, and use of the Turkish salon Author: Dazkir, Sibel Seda This exploratory study was focused on the design, meaning and use of the Turkish salon (the sitting room for guests). The findings provided an understanding of the different aspects of people's experiences of their salons. Socially and personally constructed meanings were examined to gain a deeper understanding of the respondents' perspectives. Thirty one respondents participated in the study. They were recruited from two cities in Turkey: Erbaa and Ankara. The data were collected in the respondents' salons via in-depth interviews, audio and video recordings, sketches, and observations. The interviews lasted from one to three and a half hours. The qualitative data analysis revealed themes which were grouped under three main categories: environment, person, and setting. Those interrelated dimensions were discussed in detail to have a better understanding of people's relationship with their salons. Environment related dimensions were conformity, influence of others, influence of changing socio-economic environment and rise of consumerism. Person related dimensions were satisfaction with the setting, interest in home decoration, demographics such as age and income level, personalization and meaningful objects, and place attachment. Setting related dimensions included physical characteristics of the setting such as color, size, and comfort, and use of the room such as how often and why they use the salon. The findings of this study supported the idea that consumption behaviors influence people's relationship with places. With the changing economic conditions, people live more comfortably, afford items easier, and there is more variety of products to reflect self or create the ideal salon environment compared to the past. Many respondents believed that rise in consumerism, spending unnecessarily, being allured by market pervasiveness, and being able to own products easily make people inappreciative, unhappy, and dissatisfied with what they have, and cause "israf" (wastefulness or prodigality). The respondents' narratives confirmed that they tried to create an environment that satisfied them; they cared about their salon designs. Some respondents revealed being influenced by trends and other people's salons indicating the influence of the market and others on salon design. A greater percentage of the respondents from Erbaa reported paying attention to others' salon designs compared to the respondents from Ankara. Although some spouses influenced the selection of furniture, women were more in charge of their salon designs than men. Having children influenced how often they used their salons, their purchase decisions, or when they would replace their furniture. Frequency and profile of the guests influenced use of their salons. The majority of the respondents from both Erbaa and Ankara displayed or revealed interest in home decoration through their effort to design and personalize their salons, their knowledge about furniture styles, paying attention to others' salons, watching home design TV shows, and visiting furniture stores as leisure activity. Socio-economic status influenced some of the respondents' salon designs regarding originality and price of their salon furniture and décor. Other factors such as their approach to consumerism, their taste, and family status influenced their salon design in a greater degree revealing the individualistic nature of domestic interiors. Although the findings provide insight on the relationship between demographic characteristics and salon design and use, the sampling method and sample size make it impossible to draw conclusions regarding the relationship between demographic characteristics and salon design and meaning. The respondents from both Erbaa and Ankara personalized the settings to reflect their self. They designed the rooms to reflect their taste, values, beliefs, culture, experiences, family, occupation, hobbies, and so forth. They displayed meaningful objects such as souvenirs, gifts, and family photographs. Personalization of the rooms provided control over the settings, a sense of connection to their salons, and sense of belonging. Physical characteristics of the setting, especially aesthetic appeal and usability influenced the respondents' satisfaction with the rooms. Although it was possible to observe patterns regarding the type of decorative items that they used, the meanings and stories behind how they acquired the objects made their design process unique and individualistic. The majority of respondents expressed sense of belonging and attachment to their salons and homes. Spending time in the setting, sharing the place with loved ones, feeling comfortable, sense of belonging, being satisfied with the setting, sense of freedom, reflecting own taste, personalization, and memories influenced the respondents' attachment to their salons in Ankara. The respondents from Erbaa added more intangible aspects to this list such as sincerity, happiness, coziness, effort in creating the room, familiarity, and feeling at peace. Exploring the meaning of place and objects in this study provided an understanding of everyday human life experience. This study provided rich information about the relationship between people and their salons. The findings indicated that design, meaning, and use of salons were shaped by the dynamic relationship between many individual, psychological, social, socio-cultural, socio-economic, and setting related variables. The findings confirmed that salons were designed by both personal and social point of view. The respondents created sense of place personally and socially. Studying the Turkish salon provided an understanding of how the socio-economic and socio-cultural changes were perceived by the respondents in their domestic space. The results indicate that political, cultural, religious, and economic environments influence society's perception of buying and decorating. Findings of this study contribute to different fields such as interior design by providing information on design process and design preferences of the respondents; industrial design by providing information on the meanings of objects, respondents' interaction with objects, and preferences for furniture and accessories; environmental psychology by providing information on how the respondents' behavior and emotions were influenced by the design of the setting and vice versa; and cultural anthropology by revealing information on the meanings of everyday life surroundings, and the influence of socio-cultural environment on salon creation. Close

• 1729. [Article] Analysis and operational considerations of biomass extraction on steep terrain in western Oregon

  The development of bioenergy from biomass has dominated the minds of forest engineering researchers over the last decade. One of the main themes that has been generated from that research is that bioenergy ...

  Citation × Citation Citation Abstract Copy Title: Analysis and operational considerations of biomass extraction on steep terrain in western Oregon Author: Flint, Benjamin R. The development of bioenergy from biomass has dominated the minds of forest engineering researchers over the last decade. One of the main themes that has been generated from that research is that bioenergy from biomass has major operational hurdles to overcome before becoming economically feasible. More directly, the impact of the slope of the harvest area, the elevation of harvest sites and the ownership of the lands being harvested were, in this thesis, seen as major operational hurdles in western Oregon which would require further study. This thesis discusses two studies that were conducted to provide insight into the operational hurdles that are occurring in biomass development. The first of these studies was an exploratory field study conducted in the area of small wood (<16" DBH) ground‐based harvesting on steep terrain (>35%). The purpose of this study was to compare traditional (cable) and contemporary (ground‐based) harvesting methods on steep terrain in an effort to determine the economic feasibility of the differing harvest methods. To achieve the purpose of this study, a shift‐level assessment was conducted on six different harvesting systems, all of which were conducting first‐entry commercial thinning. The six different harvesting systems were a Koller K301 yarder with manual felling on steep terrain (> 35%), a Koller K301 yarder with a Ponsse Ergo harvester (double‐bogie) cutting and pre‐bunching whole trees with no processing on steep terrain (>35%), a Koller K301 yarder with a Ponsse Ergo harvester (double‐bogie) cutting with cut‐to‐length felling, processing and pre‐bunching on steep terrain (>35%), a Ponsse Ergo harvester (double‐bogie) cutting and processing for a Ponsse Buffalo King forwarder (double‐bogie) on steep terrain (>35%) with an adverse haul to the landing, a Ponsse Ergo harvester (double‐bogie) cutting and processing for a Ponsse Buffalo King forwarder (double‐bogie) on steep terrain (>35%) with a favorable haul to the landing, and a Ponsse Ergo harvester (double‐bogie) cutting and processing for a Ponsse Buffalo King forwarder on flat terrain (<35%). To evaluate economic feasibility, the productivity and cost of each harvesting system was evaluated and compared. The results of the comparison of the six harvesting systems showed that the system with the lowest harvesting cost for first‐entry commercial thinning on steep terrain was the harvester/forwarder combination; under all scenarios studied. However, this study also found that by processing and pre‐bunching using the Ponsse Ergo harvester the productivity of the yarder was increased by 79% and the harvesting cost was reduced by 50%. Although the costs of the harvester/forwarder treatments were lower than the cost of the yarder treatments, there were still significant cost reductions and productivity increases when the harvester was paired with the cable yarder. The Ponsse Ergo harvester was the focus of evaluation for operational aspects of ground based machinery on steep terrain. A detailed time study revealed that significant differences occurred in the average cycle time of the harvester when it was placed on steep terrain. Further analysis showed that the significant difference was not a product of increased slope but rather was the product of factors that were outside of the scope of this study. The harvester's productivity was impacted by within unit and outside of unit drive times (the time spent driving between trees or driving between cutting areas and the time spent driving on the return trails for access to the next cutting road, respectively). Significant differences in the average within unit drive times was found at the extreme slope classes (65+%) for all treatment units with some treatments having impacts at slopes as low as 45%. However, the changes in average within unit drive times related to slope did not represent a large enough increase in drive times across the different slope classes within each treatment to be able to conclude that slope is the sole factor for decreased production on steep terrain. Thus, there are elements outside of the scope of this study which may have an unforeseen impact on drive times within the unit. Drive time outside of the unit accounted for a loss of an average of one hour per day of productive cutting, and had a significant impact on harvester productivity. Overall, a detailed analysis of the harvester data found that slope steepness had marginal impacts on the productivity of the harvester. This indicates that further analysis may be needed to identify the elements that were not included in the scope of this study that may impact the operability of the harvester on steep terrain. The second study used to provide insight into the operational hurdles of biomass development was a biomass assessment conducted using Forest Inventory and Analysis (FIA) data provided by the U.S. Forest Service. This assessment focused on the operational factors of land ownership, slope and elevation. This study works to assess the operational considerations of biomass harvesting at the landscape scale through a biomass assessment based on the ownership group (forest service, other federal, state & local and private), the elevation characteristics and the slope characteristics of timberlands in western Oregon. This assessment focused on comparing the biomass per acre (bone dry tons, BDTons) within a given unique feature to identify the trends or relationships that exist. With respect to ownership group, this study found that forest service lands had significantly more biomass per acre (BDTons) than all other ownership types and private lands had significantly less biomass per acre (BDTons) than all other ownership types. Other federal and state & local timberlands had no significant difference with respect to biomass per acre (BDTons). In order to make true comparisons within the elevation and slope categories, the impact of ownership group on these variables had to be accounted for to remove any possible bias. Thus, the categories of elevation and slope were looked at within each ownership group (forest service, other public and private) to provide a comparison with minimal bias. The study found that the amount of biomass per acre was not significantly different with changes in slope or elevation. This thesis works to fill the gaps in the literature regarding the operational considerations of harvesting biomass on steep terrain in western Oregon. The results and conclusions will build to the body of literature already present on this topic. Title: Analysis and operational considerations of biomass extraction on steep terrain in western Oregon Author: Flint, Benjamin R. The development of bioenergy from biomass has dominated the minds of forest engineering researchers over the last decade. One of the main themes that has been generated from that research is that bioenergy from biomass has major operational hurdles to overcome before becoming economically feasible. More directly, the impact of the slope of the harvest area, the elevation of harvest sites and the ownership of the lands being harvested were, in this thesis, seen as major operational hurdles in western Oregon which would require further study. This thesis discusses two studies that were conducted to provide insight into the operational hurdles that are occurring in biomass development. The first of these studies was an exploratory field study conducted in the area of small wood (<16" DBH) ground‐based harvesting on steep terrain (>35%). The purpose of this study was to compare traditional (cable) and contemporary (ground‐based) harvesting methods on steep terrain in an effort to determine the economic feasibility of the differing harvest methods. To achieve the purpose of this study, a shift‐level assessment was conducted on six different harvesting systems, all of which were conducting first‐entry commercial thinning. The six different harvesting systems were a Koller K301 yarder with manual felling on steep terrain (> 35%), a Koller K301 yarder with a Ponsse Ergo harvester (double‐bogie) cutting and pre‐bunching whole trees with no processing on steep terrain (>35%), a Koller K301 yarder with a Ponsse Ergo harvester (double‐bogie) cutting with cut‐to‐length felling, processing and pre‐bunching on steep terrain (>35%), a Ponsse Ergo harvester (double‐bogie) cutting and processing for a Ponsse Buffalo King forwarder (double‐bogie) on steep terrain (>35%) with an adverse haul to the landing, a Ponsse Ergo harvester (double‐bogie) cutting and processing for a Ponsse Buffalo King forwarder (double‐bogie) on steep terrain (>35%) with a favorable haul to the landing, and a Ponsse Ergo harvester (double‐bogie) cutting and processing for a Ponsse Buffalo King forwarder on flat terrain (<35%). To evaluate economic feasibility, the productivity and cost of each harvesting system was evaluated and compared. The results of the comparison of the six harvesting systems showed that the system with the lowest harvesting cost for first‐entry commercial thinning on steep terrain was the harvester/forwarder combination; under all scenarios studied. However, this study also found that by processing and pre‐bunching using the Ponsse Ergo harvester the productivity of the yarder was increased by 79% and the harvesting cost was reduced by 50%. Although the costs of the harvester/forwarder treatments were lower than the cost of the yarder treatments, there were still significant cost reductions and productivity increases when the harvester was paired with the cable yarder. The Ponsse Ergo harvester was the focus of evaluation for operational aspects of ground based machinery on steep terrain. A detailed time study revealed that significant differences occurred in the average cycle time of the harvester when it was placed on steep terrain. Further analysis showed that the significant difference was not a product of increased slope but rather was the product of factors that were outside of the scope of this study. The harvester's productivity was impacted by within unit and outside of unit drive times (the time spent driving between trees or driving between cutting areas and the time spent driving on the return trails for access to the next cutting road, respectively). Significant differences in the average within unit drive times was found at the extreme slope classes (65+%) for all treatment units with some treatments having impacts at slopes as low as 45%. However, the changes in average within unit drive times related to slope did not represent a large enough increase in drive times across the different slope classes within each treatment to be able to conclude that slope is the sole factor for decreased production on steep terrain. Thus, there are elements outside of the scope of this study which may have an unforeseen impact on drive times within the unit. Drive time outside of the unit accounted for a loss of an average of one hour per day of productive cutting, and had a significant impact on harvester productivity. Overall, a detailed analysis of the harvester data found that slope steepness had marginal impacts on the productivity of the harvester. This indicates that further analysis may be needed to identify the elements that were not included in the scope of this study that may impact the operability of the harvester on steep terrain. The second study used to provide insight into the operational hurdles of biomass development was a biomass assessment conducted using Forest Inventory and Analysis (FIA) data provided by the U.S. Forest Service. This assessment focused on the operational factors of land ownership, slope and elevation. This study works to assess the operational considerations of biomass harvesting at the landscape scale through a biomass assessment based on the ownership group (forest service, other federal, state & local and private), the elevation characteristics and the slope characteristics of timberlands in western Oregon. This assessment focused on comparing the biomass per acre (bone dry tons, BDTons) within a given unique feature to identify the trends or relationships that exist. With respect to ownership group, this study found that forest service lands had significantly more biomass per acre (BDTons) than all other ownership types and private lands had significantly less biomass per acre (BDTons) than all other ownership types. Other federal and state & local timberlands had no significant difference with respect to biomass per acre (BDTons). In order to make true comparisons within the elevation and slope categories, the impact of ownership group on these variables had to be accounted for to remove any possible bias. Thus, the categories of elevation and slope were looked at within each ownership group (forest service, other public and private) to provide a comparison with minimal bias. The study found that the amount of biomass per acre was not significantly different with changes in slope or elevation. This thesis works to fill the gaps in the literature regarding the operational considerations of harvesting biomass on steep terrain in western Oregon. The results and conclusions will build to the body of literature already present on this topic. Close

• 1730. [Article] Insights into the Geochemical Evolution of the Youngest Toba Tuff (Sumatra, Indonesia) Magma Chamber Through the Lens of Zircon-hosted Melt Inclusions

  Supervolcanic eruptions are among the most catastrophic phenomena on Earth, erupting 100s-1000s of cubic kilometers of magma, and producing devastating local effects and global climate perturbations. The ...

  Citation × Citation Citation Abstract Copy Title: Insights into the Geochemical Evolution of the Youngest Toba Tuff (Sumatra, Indonesia) Magma Chamber Through the Lens of Zircon-hosted Melt Inclusions Author: Lerner, Allan (Allan Henry) Supervolcanic eruptions are among the most catastrophic phenomena on Earth, erupting 100s-1000s of cubic kilometers of magma, and producing devastating local effects and global climate perturbations. The largest supervolcanic eruption of the last 28 Ma was the 74 ka Youngest Toba Tuff (YTT) eruption from Sumatra, Indonesia, which erupted 2,800 – 5,300 km³ of magma and may have pushed the human species to the brink of extinction. Despite the global significance of such events, the magmatic evolution that builds to super-eruptions remains poorly understood. The mineral zircon provides a unique potential to gain multidimensional insights into the pre-eruptive evolution of magma chambers by combining mineral and melt inclusion chemistry with U-series mineral dating. We combine zircon U-Th dating and trace element chemistry with zircon-hosted melt inclusion chemistries and volatile abundances to investigate the magmatic evolution preceding the YTT eruption To begin, we present the first detailed study of the susceptibility of zircon-hosted inclusions to syn- or post-entrapment modification of melt compositions. We conclude that boundary layer effects are negligible in even very small zircon-hosted inclusions owing to the slow growth rate of zircon crystals. Post-entrapment crystallization (PEC) of the zircon host phase is also a trivial concern, owing to the low Zr content of most melts. PEC of other daughter phases is recognized (< ~2% amphibole and sanidine), but these effects are also minor relative to melt inclusions in many major-phase minerals. The diffusive exchange of water from zircon-hosted melt inclusions is modeled to occur in less than 10 ka, and requilibration may occur within decades-centuries. Therefore, water contents of zircon-hosted inclusions represent late-stage storage conditions rather than long-term records of magmatic water. Zircon-hosted inclusions should remain diffusively sealed to all melt species, apart from H⁺, He, and Li⁺, over typical magmatic system timescales (104-105 yrs). Therefore, we conclude that zircon is a robust, albeit small, melt inclusion host and entrapped inclusions will be largely representative of the melt environments in which they formed. We then apply the multidimensional utility of zircon to gain insights into the pre-eruptive evolution of the YTT magmatic system. YTT zircon grains have U-Th crystallization ages spanning from the ~74 ka eruption age to > 375 ka, reinforcing earlier findings that the YTT system was long-lived. A progressive increase of U in zircon growth zones from < 500 to ~1,500 ppm indicates that the YTT system, or a portion of it, became highly fractionated between 130-200 ka. A lull in zircon formation between ~110-130 ka is contemporaneous with a previously recognized increase in chemical diversity of allanite, possibly reflecting a period of enhanced thermal input into the system. We identify two main populations of zircon-hosted melt inclusions. A low-MgO type is chemically evolved (> 280 ppm Rb, ~125 ppm Ba, 25-30 ppm Sr, < 0.03 wt% MgO) and has high water contents (3.8-5.7 wt% H₂O), consistent with formation and storage in a highly fractionated crystal mush ~4-9 km deep. A high-MgO type (250-260 ppm Rb, 160-450 ppm Ba, 35-55 ppm Sr, 0.04-0.07 wt% MgO) has compositions similar to matrix glasses, and is typically less hydrous (0.5-3.5 wt% H₂O), suggesting shallow (< 3 km) formation, storage, and syn-eruptive degassing in a less evolved melt. Melt inclusions dated via U-Th measurements of their entrapping zircon zones show no clear temporal differences between the two MgO populations. Rather, melt inclusions entrapped throughout the entire YTT history have relatively invariant major element compositions, and also have no discernible temporal trends in volatile abundances. We largely attribute these findings to the narrow stability field in which zircon crystallize, which inherently limits the compositional range of zircon-hosted inclusions. Zircon-hosted melt inclusions (particularly the high-MgO type) of many ages occur within sealed reentrant melt-channels. This suggests that melt inclusions in YTT zircon grains commonly formed as the system re-established zircon saturation following periods of zircon dissolution during thermal recharge events. A number of zircon grains have melt channels actively open to the grain exterior, which are rimmed with 1-3 μm of cathodoluminescence-bright (low-U) zircon growth. These dissolution/regrowth features are texturally similar to dissolution zones and high-temperature overgrowths described previously in YTT quartz; collectively, these textures provide evidence of a major thermal perturbation(s) 10s-100s of years before the YTT eruption. We conclude that high-T, mafic recharge events occurred throughout the pre-eruptive YTT evolution, and suggest that one or more large recharge events triggered the cataclysmic 74 ka YTT eruption. Title: Insights into the Geochemical Evolution of the Youngest Toba Tuff (Sumatra, Indonesia) Magma Chamber Through the Lens of Zircon-hosted Melt Inclusions Author: Lerner, Allan (Allan Henry) Supervolcanic eruptions are among the most catastrophic phenomena on Earth, erupting 100s-1000s of cubic kilometers of magma, and producing devastating local effects and global climate perturbations. The largest supervolcanic eruption of the last 28 Ma was the 74 ka Youngest Toba Tuff (YTT) eruption from Sumatra, Indonesia, which erupted 2,800 – 5,300 km³ of magma and may have pushed the human species to the brink of extinction. Despite the global significance of such events, the magmatic evolution that builds to super-eruptions remains poorly understood. The mineral zircon provides a unique potential to gain multidimensional insights into the pre-eruptive evolution of magma chambers by combining mineral and melt inclusion chemistry with U-series mineral dating. We combine zircon U-Th dating and trace element chemistry with zircon-hosted melt inclusion chemistries and volatile abundances to investigate the magmatic evolution preceding the YTT eruption To begin, we present the first detailed study of the susceptibility of zircon-hosted inclusions to syn- or post-entrapment modification of melt compositions. We conclude that boundary layer effects are negligible in even very small zircon-hosted inclusions owing to the slow growth rate of zircon crystals. Post-entrapment crystallization (PEC) of the zircon host phase is also a trivial concern, owing to the low Zr content of most melts. PEC of other daughter phases is recognized (< ~2% amphibole and sanidine), but these effects are also minor relative to melt inclusions in many major-phase minerals. The diffusive exchange of water from zircon-hosted melt inclusions is modeled to occur in less than 10 ka, and requilibration may occur within decades-centuries. Therefore, water contents of zircon-hosted inclusions represent late-stage storage conditions rather than long-term records of magmatic water. Zircon-hosted inclusions should remain diffusively sealed to all melt species, apart from H⁺, He, and Li⁺, over typical magmatic system timescales (104-105 yrs). Therefore, we conclude that zircon is a robust, albeit small, melt inclusion host and entrapped inclusions will be largely representative of the melt environments in which they formed. We then apply the multidimensional utility of zircon to gain insights into the pre-eruptive evolution of the YTT magmatic system. YTT zircon grains have U-Th crystallization ages spanning from the ~74 ka eruption age to > 375 ka, reinforcing earlier findings that the YTT system was long-lived. A progressive increase of U in zircon growth zones from < 500 to ~1,500 ppm indicates that the YTT system, or a portion of it, became highly fractionated between 130-200 ka. A lull in zircon formation between ~110-130 ka is contemporaneous with a previously recognized increase in chemical diversity of allanite, possibly reflecting a period of enhanced thermal input into the system. We identify two main populations of zircon-hosted melt inclusions. A low-MgO type is chemically evolved (> 280 ppm Rb, ~125 ppm Ba, 25-30 ppm Sr, < 0.03 wt% MgO) and has high water contents (3.8-5.7 wt% H₂O), consistent with formation and storage in a highly fractionated crystal mush ~4-9 km deep. A high-MgO type (250-260 ppm Rb, 160-450 ppm Ba, 35-55 ppm Sr, 0.04-0.07 wt% MgO) has compositions similar to matrix glasses, and is typically less hydrous (0.5-3.5 wt% H₂O), suggesting shallow (< 3 km) formation, storage, and syn-eruptive degassing in a less evolved melt. Melt inclusions dated via U-Th measurements of their entrapping zircon zones show no clear temporal differences between the two MgO populations. Rather, melt inclusions entrapped throughout the entire YTT history have relatively invariant major element compositions, and also have no discernible temporal trends in volatile abundances. We largely attribute these findings to the narrow stability field in which zircon crystallize, which inherently limits the compositional range of zircon-hosted inclusions. Zircon-hosted melt inclusions (particularly the high-MgO type) of many ages occur within sealed reentrant melt-channels. This suggests that melt inclusions in YTT zircon grains commonly formed as the system re-established zircon saturation following periods of zircon dissolution during thermal recharge events. A number of zircon grains have melt channels actively open to the grain exterior, which are rimmed with 1-3 μm of cathodoluminescence-bright (low-U) zircon growth. These dissolution/regrowth features are texturally similar to dissolution zones and high-temperature overgrowths described previously in YTT quartz; collectively, these textures provide evidence of a major thermal perturbation(s) 10s-100s of years before the YTT eruption. We conclude that high-T, mafic recharge events occurred throughout the pre-eruptive YTT evolution, and suggest that one or more large recharge events triggered the cataclysmic 74 ka YTT eruption. Close