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• 2201. [Article] Greater Sage-grouse conservation assessment and strategy for Oregon: A plan to maintain and enhance populations and habitat

  Greater sage-grouse (Centrocercus urophasianus) were once found in most grassland and sagebrush (Artemisia spp.) habitats east of the Cascades in Oregon. European settlement and conversion of sagebrush ...

  Citation × Citation Citation Abstract Copy Title: Greater Sage-grouse conservation assessment and strategy for Oregon: A plan to maintain and enhance populations and habitat Author: Hagen, Christian Greater sage-grouse (Centrocercus urophasianus) were once found in most grassland and sagebrush (Artemisia spp.) habitats east of the Cascades in Oregon. European settlement and conversion of sagebrush steppe into agricultural production led to extirpation of the species in the Columbia Basin by the early part of the 1900s, but sagebrush rangelands have persisted, particularly in southeast Oregon. Populations have fluctuated markedly since the mid 1900s with notable declines in populations from the 1950s to early 1970s. These patterns in populations and habitat loss are similar to those observed for greater sage-grouse throughout its range. Population declines during the latter part of the 1900s lead to considerable concern for the species and subsequent conservation planning in all western states where it occurs. This management strategy is a result of this larger conservation effort by the Western Association of Fish and Wildlife Agencies. This updated and revised Plan describes Oregon Department of Fish and Wildlife’s management of greater sage-grouse and provides guidance to public land management agencies and land managers for sage-grouse conservation. Conservation actions should be encouraged on private lands as these contain some of the more productive sites, but conservation on private land is voluntary. Highlights of updates. Population goals have been revised based on statistically more robust methods for estimating population sizes. Accomplishments in conservation, research, and monitoring that have occurred since 2005 are discussed. The Core Area approach to strategically identifying important landscapes for sage-grouse is explained in detail from model development to implementation. Finally, there have been numerous publications on sage-grouse since 2005 and that literature has been updated to the document where appropriate. This management strategy and the supporting background information is intended to promote the conservation of greater sage-grouse and intact functioning sagebrush communities in Oregon. The strategy is tied to the life history of greater sage-grouse and uses the best science available. Although this strategy focuses on conservation of greater sage-grouse, the intent is to benefit conservation needs of other sagebrush-steppe species. Oregon greater sage-grouse are important to the North American population and management actions in the state will have implications on a much larger scale. This Plan recognizes that livestock ranching operations which manage for ecologically sustainable native rangelands is compatible with sage-grouse conservation, and necessary management activities to maintain a sustainable ranching operation are not considered “development actions” under the application of the Mitigation Policy to sage-grouse habitat. This Plan provides biological recommendations for long-term conservation of sage-grouse in Oregon based on the best available science. However, ODFW recognizes that land use planners and managers may need to consider these recommendations within the context of socialeconomic issues and decisions that are the responsibility of the respective governmental bodies. Thus, the intent of this plan is to inform decision-makers regarding the biological consequences of various actions on sage-grouse, but not to dictate land management decision. This document is divided into 6 sections. Section I explains the background and philosophy of conservation approaches in this strategy. Section II provides an overview of sage-grouse biology and ecology throughout the species range. Sections III and IV provide an assessment of populations and habitat, respectively, upon which management objectives are developed and their underlying assumptions and rationale are stated. In Section V, conservation guidelines are outlined, that describe actions needed and methods for achieving habitat objectives. Section VI outlines components for Plan implementation, includes a description of the structure and role of local implementation groups, and implications for public (state and federal) land management agencies. There are 6 appendices that provide supporting information, including a new appendix about socio-economics provided by the Association of Oregon Counties. Sections III to VI of the plan were expanded, because these sections are linked to the objectives and implementation of this Plan. Populations and habitat were assessed by BLM district boundaries because; the availability of habitat measures by district, each district approximates an eco-region, and BLM is the primary land manager within most of the district boundaries. The 23 years 1980-2003 are the relevant time period to establish a benchmark for sage-grouse populations and their habitats, because the factors of predator control methods (and take levels), grazing schedules, survey protocols, habitat treatments and harvest levels of sage-grouse were similar through this period. Title: Greater Sage-grouse conservation assessment and strategy for Oregon: A plan to maintain and enhance populations and habitat Author: Hagen, Christian Greater sage-grouse (Centrocercus urophasianus) were once found in most grassland and sagebrush (Artemisia spp.) habitats east of the Cascades in Oregon. European settlement and conversion of sagebrush steppe into agricultural production led to extirpation of the species in the Columbia Basin by the early part of the 1900s, but sagebrush rangelands have persisted, particularly in southeast Oregon. Populations have fluctuated markedly since the mid 1900s with notable declines in populations from the 1950s to early 1970s. These patterns in populations and habitat loss are similar to those observed for greater sage-grouse throughout its range. Population declines during the latter part of the 1900s lead to considerable concern for the species and subsequent conservation planning in all western states where it occurs. This management strategy is a result of this larger conservation effort by the Western Association of Fish and Wildlife Agencies. This updated and revised Plan describes Oregon Department of Fish and Wildlife’s management of greater sage-grouse and provides guidance to public land management agencies and land managers for sage-grouse conservation. Conservation actions should be encouraged on private lands as these contain some of the more productive sites, but conservation on private land is voluntary. Highlights of updates. Population goals have been revised based on statistically more robust methods for estimating population sizes. Accomplishments in conservation, research, and monitoring that have occurred since 2005 are discussed. The Core Area approach to strategically identifying important landscapes for sage-grouse is explained in detail from model development to implementation. Finally, there have been numerous publications on sage-grouse since 2005 and that literature has been updated to the document where appropriate. This management strategy and the supporting background information is intended to promote the conservation of greater sage-grouse and intact functioning sagebrush communities in Oregon. The strategy is tied to the life history of greater sage-grouse and uses the best science available. Although this strategy focuses on conservation of greater sage-grouse, the intent is to benefit conservation needs of other sagebrush-steppe species. Oregon greater sage-grouse are important to the North American population and management actions in the state will have implications on a much larger scale. This Plan recognizes that livestock ranching operations which manage for ecologically sustainable native rangelands is compatible with sage-grouse conservation, and necessary management activities to maintain a sustainable ranching operation are not considered “development actions” under the application of the Mitigation Policy to sage-grouse habitat. This Plan provides biological recommendations for long-term conservation of sage-grouse in Oregon based on the best available science. However, ODFW recognizes that land use planners and managers may need to consider these recommendations within the context of socialeconomic issues and decisions that are the responsibility of the respective governmental bodies. Thus, the intent of this plan is to inform decision-makers regarding the biological consequences of various actions on sage-grouse, but not to dictate land management decision. This document is divided into 6 sections. Section I explains the background and philosophy of conservation approaches in this strategy. Section II provides an overview of sage-grouse biology and ecology throughout the species range. Sections III and IV provide an assessment of populations and habitat, respectively, upon which management objectives are developed and their underlying assumptions and rationale are stated. In Section V, conservation guidelines are outlined, that describe actions needed and methods for achieving habitat objectives. Section VI outlines components for Plan implementation, includes a description of the structure and role of local implementation groups, and implications for public (state and federal) land management agencies. There are 6 appendices that provide supporting information, including a new appendix about socio-economics provided by the Association of Oregon Counties. Sections III to VI of the plan were expanded, because these sections are linked to the objectives and implementation of this Plan. Populations and habitat were assessed by BLM district boundaries because; the availability of habitat measures by district, each district approximates an eco-region, and BLM is the primary land manager within most of the district boundaries. The 23 years 1980-2003 are the relevant time period to establish a benchmark for sage-grouse populations and their habitats, because the factors of predator control methods (and take levels), grazing schedules, survey protocols, habitat treatments and harvest levels of sage-grouse were similar through this period. Close

• 2202. [Article] Epidemiological insights into Armillaria mellea root rot in a managed Ponderosa pine forest

  Root rot of ponderosa pine caused by Armillaria mellea was studied in a pine forest that had been under management for 30 years in Klickitat County, Washington. Information sources included disease survey, ...

  Citation × Citation Citation Abstract Copy Title: Epidemiological insights into Armillaria mellea root rot in a managed Ponderosa pine forest Author: Shaw, Charles G. (Charles Gardner) 1948- Root rot of ponderosa pine caused by Armillaria mellea was studied in a pine forest that had been under management for 30 years in Klickitat County, Washington. Information sources included disease survey, detailed observation and description of specific disease situations, and examination of roots in situ and removed. Roughly circular infection centers in stands of sapling and pole-sized pines appear to arise regularly from stumps of harvested old-growth trees, some of which have contained viable A. mellea for over 30 years. Distinctive concentric zones caused by the disease mark the infection centers. These zones differ in above-ground appearance, in degree of root decomposition, and in level of infection. Location of a specific zone depends on the interval since cutting of the old-growth tree, while zone width depends on tree sizes in the young stand. Distribution of root material in the interior zones is influenced most strongly by rooting characteristics of the former old-growth trees, and by activity of A. mellea and other decay agents over time, while in the young growth pines of the intermediate zones, time since lethal attack by A. mellea and tree size most influence root condition. Extensive examination of the outer zones disclosed that, in stands containing trees from 3 to 6 inches in diameter, infected root material extended into the healthy-appearing pines 11 ft beyond the outermost dead tree of the infection center, while in stands with trees up to 16 inches in diameter the extent reached 18 ft. A highly significant linear regression with good correlation was found between: 1) the extent of infected root material beyond the outermost dead tree; and 2) mean tree size of the affected stand. Infected root segments from beyond the outermost dead tree, within the region where infected and healthy roots intermingle, produced rhizomorphs, the assumed infection structures, when incubated in bags of moist quartz sand. The expansion rate of infection centers was calculated to be 2. 9 ft (0.88 m) /year. Cross plating techniques indicated that the 1500 acre study area was occupied by a single strain of A. mellea, suggesting that spores are unimportant to the field disease cycle. Current loss to disease in the 1500 acre tract is 35 cu ft per acre per yr, three times the loss in 1957. From 1957 to 1971, the proportion of the area in which disease was detectable remained constant. The increased loss resulted from death of fewer, but larger, trees in 1971. In inoculation tests on ponderosa pine seedlings, A. mellea isolates from old-growth pine stumps and from young pine trees were pathogenic, while isolates from living hardwoods were weakly or nonpathogenic. Reliable methods are described for isolating A. mellea from infected tissues and of testing the capacity of naturally infected root materials to produce rhizomorphs. The abundance of A. mellea over a three year interval following five root removal treatments increased in missed root residues. Resinous lesions were commonly found at the site of A. mellea attack. Rarely does mycelium spread proximally along a living root from one of these lesions, but growth frequently occurs from the lesion toward the root tip following, or concurrent with death of the extremity. Girdling resinous lesions on lateral roots show little effect on tree vigor, while such lesions high on the tap root kill the tree. Soon after tree death, mycelial fans spread under the bark throughout the root system. To obtain insight on how the resinous lesions retard the fungus, tests were conducted on the effects of resin on growth of A. mellea in culture. Autoclaved resin, acetone extracts of resin, water extracts of resin, and non-sterilized resin all stimulated, rather than restricted, growth over non-resin containing media. Removal of phenols from the water extract of resin with polyvinylpyrrolidone destroyed the growth stimulating effect of the resin. Propylene oxide was effective for sterilization of granulated resin. Title: Epidemiological insights into Armillaria mellea root rot in a managed Ponderosa pine forest Author: Shaw, Charles G. (Charles Gardner) 1948- Root rot of ponderosa pine caused by Armillaria mellea was studied in a pine forest that had been under management for 30 years in Klickitat County, Washington. Information sources included disease survey, detailed observation and description of specific disease situations, and examination of roots in situ and removed. Roughly circular infection centers in stands of sapling and pole-sized pines appear to arise regularly from stumps of harvested old-growth trees, some of which have contained viable A. mellea for over 30 years. Distinctive concentric zones caused by the disease mark the infection centers. These zones differ in above-ground appearance, in degree of root decomposition, and in level of infection. Location of a specific zone depends on the interval since cutting of the old-growth tree, while zone width depends on tree sizes in the young stand. Distribution of root material in the interior zones is influenced most strongly by rooting characteristics of the former old-growth trees, and by activity of A. mellea and other decay agents over time, while in the young growth pines of the intermediate zones, time since lethal attack by A. mellea and tree size most influence root condition. Extensive examination of the outer zones disclosed that, in stands containing trees from 3 to 6 inches in diameter, infected root material extended into the healthy-appearing pines 11 ft beyond the outermost dead tree of the infection center, while in stands with trees up to 16 inches in diameter the extent reached 18 ft. A highly significant linear regression with good correlation was found between: 1) the extent of infected root material beyond the outermost dead tree; and 2) mean tree size of the affected stand. Infected root segments from beyond the outermost dead tree, within the region where infected and healthy roots intermingle, produced rhizomorphs, the assumed infection structures, when incubated in bags of moist quartz sand. The expansion rate of infection centers was calculated to be 2. 9 ft (0.88 m) /year. Cross plating techniques indicated that the 1500 acre study area was occupied by a single strain of A. mellea, suggesting that spores are unimportant to the field disease cycle. Current loss to disease in the 1500 acre tract is 35 cu ft per acre per yr, three times the loss in 1957. From 1957 to 1971, the proportion of the area in which disease was detectable remained constant. The increased loss resulted from death of fewer, but larger, trees in 1971. In inoculation tests on ponderosa pine seedlings, A. mellea isolates from old-growth pine stumps and from young pine trees were pathogenic, while isolates from living hardwoods were weakly or nonpathogenic. Reliable methods are described for isolating A. mellea from infected tissues and of testing the capacity of naturally infected root materials to produce rhizomorphs. The abundance of A. mellea over a three year interval following five root removal treatments increased in missed root residues. Resinous lesions were commonly found at the site of A. mellea attack. Rarely does mycelium spread proximally along a living root from one of these lesions, but growth frequently occurs from the lesion toward the root tip following, or concurrent with death of the extremity. Girdling resinous lesions on lateral roots show little effect on tree vigor, while such lesions high on the tap root kill the tree. Soon after tree death, mycelial fans spread under the bark throughout the root system. To obtain insight on how the resinous lesions retard the fungus, tests were conducted on the effects of resin on growth of A. mellea in culture. Autoclaved resin, acetone extracts of resin, water extracts of resin, and non-sterilized resin all stimulated, rather than restricted, growth over non-resin containing media. Removal of phenols from the water extract of resin with polyvinylpyrrolidone destroyed the growth stimulating effect of the resin. Propylene oxide was effective for sterilization of granulated resin. Close

• 2203. [Article] A production function analysis of water resource productivity in Pacific Northwest agriculture

  The competition or rivalry for the use of water resources among economic sectors of the Pacific Northwest and among geographical regions of the western United States has intensified in recent years. This ...

  Citation × Citation Citation Abstract Copy Title: A production function analysis of water resource productivity in Pacific Northwest agriculture Author: Holloway, Milton L. The competition or rivalry for the use of water resources among economic sectors of the Pacific Northwest and among geographical regions of the western United States has intensified in recent years. This rivalry and the long run prospects for water shortages have increased the demand for research concerning the productivity of this resource in alternative uses. This demand exists because the distribution and use of water resources require investment which typically comes from both public and private sources. Private and public planning groups seek answers to questions regarding future water resource development alternatives. Agriculture has historically been a major user of water in the Pacific Northwest. A substantial portion of total investment in water resource development has also been in agriculture. As a result water use planners and decision making bodies are necessarily interested in water use in agriculture. The success of water resource planning requires answers to questions regarding the value of the productivity of water in all its major uses, including various aspects of water use in agriculture. Different aspects of water use in agriculture which are important to decision makers include (1) the value productivity of various kinds or types of water resource investments, (2) the value productivity of water in various kinds of agricultural production in different geographical areas, and (3) the returns to private and public investment in agricultural water resources. This study was directed to providing answers to these questions. Pacific Northwest agriculture was studied from this viewpoint. Agricultural water resources were classified as irrigation, drainage, and water related Agricultural Conservation Program (ACP) practices. These are the major classifications of water resources in which investments are made in the Pacific Northwest. Production function analysis was selected as a method of investigation. Production functions were estimated for five areas or subregions in the Pacific Northwest. These areas are composed of counties with similar patterns of production. The Agricultural Census was the primary data source, supplemented by related. U. S. Department of Agriculture publications, and various state publications. Ordinary least-squares regression (OLS) techniques were employed to derive the initial estimates of the parameters of the production function models. Tests for detecting interdependence within the independent variable set of the models revealed a considerable degree of instability in the OLS parameter estimates. This condition makes the OLS solutions (and various derivations) particularly vulnerable to change from measurement error, poor model specification, and equation form. A prior information model was selected to explicitly include available prior knowledge in the estimation process. The model selected allows (1) tests of comparability of the two information sources (prior and sample), (2) over-all contribution of prior information to the new solution set, and (3) derivation of percentage contribution of the two information sources to individual parameter estimates. The results of the study indicate that no reliable estimates of value of production from drainage and ACP were possible from the sample information. Returns to irrigation were considered lower than expected in two of the farming areas and higher than expected in another. Estimated returns were high in the area which produces primarily field crops (about nine dollars per acre foot). The area has a small level of current irrigation development. Indications are that irrigation development is probably beyond the optimum level in the area where most large projects have been developed in the past (less than four dollars per acre foot). Future development would be most profitable (assuming equal development cost) in the dryland field crop area. Estimated returns to other factor inputs indicate (1) low returns to labor in two areas, (2) generally high returns to current operating expenditures, and (3) low returns to machinery capital. Returns to cropland were about as expected in two areas (five to seven percent) but low in two other areas (about two percent). Indications are that labor mobility should be increased in the area and that future land development should be in the livestock-field crop and the field crop areas rather than the coastal area or the west-central valley areas (primarily the Willamette Valley). Title: A production function analysis of water resource productivity in Pacific Northwest agriculture Author: Holloway, Milton L. The competition or rivalry for the use of water resources among economic sectors of the Pacific Northwest and among geographical regions of the western United States has intensified in recent years. This rivalry and the long run prospects for water shortages have increased the demand for research concerning the productivity of this resource in alternative uses. This demand exists because the distribution and use of water resources require investment which typically comes from both public and private sources. Private and public planning groups seek answers to questions regarding future water resource development alternatives. Agriculture has historically been a major user of water in the Pacific Northwest. A substantial portion of total investment in water resource development has also been in agriculture. As a result water use planners and decision making bodies are necessarily interested in water use in agriculture. The success of water resource planning requires answers to questions regarding the value of the productivity of water in all its major uses, including various aspects of water use in agriculture. Different aspects of water use in agriculture which are important to decision makers include (1) the value productivity of various kinds or types of water resource investments, (2) the value productivity of water in various kinds of agricultural production in different geographical areas, and (3) the returns to private and public investment in agricultural water resources. This study was directed to providing answers to these questions. Pacific Northwest agriculture was studied from this viewpoint. Agricultural water resources were classified as irrigation, drainage, and water related Agricultural Conservation Program (ACP) practices. These are the major classifications of water resources in which investments are made in the Pacific Northwest. Production function analysis was selected as a method of investigation. Production functions were estimated for five areas or subregions in the Pacific Northwest. These areas are composed of counties with similar patterns of production. The Agricultural Census was the primary data source, supplemented by related. U. S. Department of Agriculture publications, and various state publications. Ordinary least-squares regression (OLS) techniques were employed to derive the initial estimates of the parameters of the production function models. Tests for detecting interdependence within the independent variable set of the models revealed a considerable degree of instability in the OLS parameter estimates. This condition makes the OLS solutions (and various derivations) particularly vulnerable to change from measurement error, poor model specification, and equation form. A prior information model was selected to explicitly include available prior knowledge in the estimation process. The model selected allows (1) tests of comparability of the two information sources (prior and sample), (2) over-all contribution of prior information to the new solution set, and (3) derivation of percentage contribution of the two information sources to individual parameter estimates. The results of the study indicate that no reliable estimates of value of production from drainage and ACP were possible from the sample information. Returns to irrigation were considered lower than expected in two of the farming areas and higher than expected in another. Estimated returns were high in the area which produces primarily field crops (about nine dollars per acre foot). The area has a small level of current irrigation development. Indications are that irrigation development is probably beyond the optimum level in the area where most large projects have been developed in the past (less than four dollars per acre foot). Future development would be most profitable (assuming equal development cost) in the dryland field crop area. Estimated returns to other factor inputs indicate (1) low returns to labor in two areas, (2) generally high returns to current operating expenditures, and (3) low returns to machinery capital. Returns to cropland were about as expected in two areas (five to seven percent) but low in two other areas (about two percent). Indications are that labor mobility should be increased in the area and that future land development should be in the livestock-field crop and the field crop areas rather than the coastal area or the west-central valley areas (primarily the Willamette Valley). Close

• 2204. [Article] Analysis of selected factors relating to the Neighborhood Youth Corps program in rural counties of Oregon

  Purpose of the Study There were two major purposes of this study. The first was to determine which socio-economic and educational factors normally available to Neighborhood Youth Corps personnel were associated ...

  Citation × Citation Citation Abstract Copy Title: Analysis of selected factors relating to the Neighborhood Youth Corps program in rural counties of Oregon Author: Bigsby, Robert Alexander Purpose of the Study There were two major purposes of this study. The first was to determine which socio-economic and educational factors normally available to Neighborhood Youth Corps personnel were associated with success and failure in the out-of-school program. The second purpose was to utilize these available socio-economic and educational factors identified as success or failure determiners to construct a mathematical success-failure prediction equation. Procedures Data for 302 enrollees were obtained through a random sampling of terminated out-of-school enrollees. Socio-economic information was extracted from enrollee application forms and files. Educational information was obtained from the last school attended. Stepwise multiple linear regression and classification analyses were performed on data to identify variables contributing most significantly to success or failure. For these analyses, data for enrollees were grouped by marital status, sex, and age. Analyses were performed on separated groups. Variables contributing most significantly to success and failure were utilized to construct an equation for success-failure prediction. Selected Findings 1. A higher proportion of females succeeded in the out-of-school program than did males. Forty-five and one tenth percent of the females succeeded compared to 26.9 percent of the males. 2. Factors affecting success or failure of male enrollees were (a) Enrollee age. Sixteen-year-old male enrollees failed in the program at a rate approximately four times that of older enrollees. (b) Number of siblings in enrollee's family. Male enrollees coming from families with four or more children succeed at a higher rate than enrollees with one, two, or three children. "Only children" failed at a substantially higher rate than others. (c) Highest school grade completed. There was a steady decrease in the failure rate of male enrollees as school grade completed increased. (d) Head of household employment. Single male enrollees living in homes in which the head of household worked part time succeeded at over twice the rate of those living in homes with the head of household working full time. This group also succeeded at a higher rate than those from homes in which the head of household was not working at all. 3. Factors affecting success or failure of female enrollees were: (a) Language spoken in the home. Enrollees speaking Spanish in the home succeeded at a substantially higher rate than those speaking English. (b) Social assistance. Single female enrollees whose families accepted cash welfare payments succeeded at a lower rate than those whose families did not accept welfare. (c) Stated lifetime occupational goal. Single female enrollees stating a skilled lifetime occupational goal succeeded at a higher rate than those stating other lifetime goals. Those stating no lifetime goal or a professional goal failed at a substantially higher rate than others. (d) Family living group. Single female enrollees living with their mothers only succeeded at less than one-half the rate of those living with both parents. (e) Reason for leaving school. Female enrollees who left school for disciplinary reasons failed at a very high rate. (f) Enrollee age. Sixteen-year-old female enrollees tended not to succeed at as high a rate as 17, 18, 19, and 20 year-olds. 4. Accurate prediction of both success and failure was not possible for male enrollees and married or divorced females, 5. It was possible to correctly predict success and failure in the program of single female enrollees approximately 75 percent of the time by employing five socio-economic factors. 6. An equation was developed for predicting success or failure of single female enrollees. The following factors were employed in this prediction: (a) language spoken in home, (b) family living group, (c) reason for leaving school, (d) welfare, (e) lifetime occupational goal. Title: Analysis of selected factors relating to the Neighborhood Youth Corps program in rural counties of Oregon Author: Bigsby, Robert Alexander Purpose of the Study There were two major purposes of this study. The first was to determine which socio-economic and educational factors normally available to Neighborhood Youth Corps personnel were associated with success and failure in the out-of-school program. The second purpose was to utilize these available socio-economic and educational factors identified as success or failure determiners to construct a mathematical success-failure prediction equation. Procedures Data for 302 enrollees were obtained through a random sampling of terminated out-of-school enrollees. Socio-economic information was extracted from enrollee application forms and files. Educational information was obtained from the last school attended. Stepwise multiple linear regression and classification analyses were performed on data to identify variables contributing most significantly to success or failure. For these analyses, data for enrollees were grouped by marital status, sex, and age. Analyses were performed on separated groups. Variables contributing most significantly to success and failure were utilized to construct an equation for success-failure prediction. Selected Findings 1. A higher proportion of females succeeded in the out-of-school program than did males. Forty-five and one tenth percent of the females succeeded compared to 26.9 percent of the males. 2. Factors affecting success or failure of male enrollees were (a) Enrollee age. Sixteen-year-old male enrollees failed in the program at a rate approximately four times that of older enrollees. (b) Number of siblings in enrollee's family. Male enrollees coming from families with four or more children succeed at a higher rate than enrollees with one, two, or three children. "Only children" failed at a substantially higher rate than others. (c) Highest school grade completed. There was a steady decrease in the failure rate of male enrollees as school grade completed increased. (d) Head of household employment. Single male enrollees living in homes in which the head of household worked part time succeeded at over twice the rate of those living in homes with the head of household working full time. This group also succeeded at a higher rate than those from homes in which the head of household was not working at all. 3. Factors affecting success or failure of female enrollees were: (a) Language spoken in the home. Enrollees speaking Spanish in the home succeeded at a substantially higher rate than those speaking English. (b) Social assistance. Single female enrollees whose families accepted cash welfare payments succeeded at a lower rate than those whose families did not accept welfare. (c) Stated lifetime occupational goal. Single female enrollees stating a skilled lifetime occupational goal succeeded at a higher rate than those stating other lifetime goals. Those stating no lifetime goal or a professional goal failed at a substantially higher rate than others. (d) Family living group. Single female enrollees living with their mothers only succeeded at less than one-half the rate of those living with both parents. (e) Reason for leaving school. Female enrollees who left school for disciplinary reasons failed at a very high rate. (f) Enrollee age. Sixteen-year-old female enrollees tended not to succeed at as high a rate as 17, 18, 19, and 20 year-olds. 4. Accurate prediction of both success and failure was not possible for male enrollees and married or divorced females, 5. It was possible to correctly predict success and failure in the program of single female enrollees approximately 75 percent of the time by employing five socio-economic factors. 6. An equation was developed for predicting success or failure of single female enrollees. The following factors were employed in this prediction: (a) language spoken in home, (b) family living group, (c) reason for leaving school, (d) welfare, (e) lifetime occupational goal. Close

• 2205. [Article] Volcanic stratigraphy of the Deschutes Formation, Green Ridge to Fly Creek, north-central Oregon

  About 225 lava flows and ash-flow tuffs of the Deschutes Formation (DF) were mapped at Green Ridge. The units fill east-trending paleovalleys which "sky-out" westward and dip east; the eastward dip of ...

  Citation × Citation Citation Abstract Copy Title: Volcanic stratigraphy of the Deschutes Formation, Green Ridge to Fly Creek, north-central Oregon Author: Conrey, Richard M. About 225 lava flows and ash-flow tuffs of the Deschutes Formation (DF) were mapped at Green Ridge. The units fill east-trending paleovalleys which "sky-out" westward and dip east; the eastward dip of the units decreases as they are traced eastward. The source of the units was west of Green Ridge as evidenced by the increase in the number of ash-flow tuffs and lava flows in the DF from east to west toward Green Ridge, and the presence of viscous silicic lavas and lag deposits in ash-flow tuffs on the west flank of Green Ridge. The exposed DF section at Green Ridge is 1400 feet thick, and consists mainly of basaltic andesites with subordinate diktytaxitic basalts, andesites, dacites, aphyric basaltic andesites and andesites rich in Fe and Ti, ash-flow tuffs, and sediments. The upper 400 feet of the section is devoid of ash-flow tuffs and dacites. Nine paleomagnetic polarity intervals, five normal and four reversed, are recognized in the section; tentative correlation of these intervals with the magnetic time scale suggests that the oldest DF unit exposed at Green Ridge is 6.5 Ma, and the youngest 4.4 Ma. The DF units at the crest, and west of Green Ridge are cut by at least five N- to N13W-trending, down-to-the-west normal faults in a zone about five miles wide. These faults were possibly active as much as 5 Ma; the developing faults may have provided structural pathways for the ascent of the mafic lavas in the upper 400 feet of the section. The faulting which created the Green Ridge escarpment was probably finished by 3 Ma, and perhaps earlier. The presence of dense, Fe- and Ti-rich lavas throughout the DF section implies that magmas had relatively easy access to the surface during DF time (7.6-4.4 Ma), which suggests that the E-W extensional tectonism that culminated in the formation of the Green Ridge faults was present throughout deposition of the DF. The major element chemistry of DF diktytaxitic basalts, basaltic andesites, and andesites appears to change regularly with Ti02 content, as shown by decreasing CaO/FeO* (FeO* = total Fe expressed as FeO) with increasing Ti02, and by decreasing A1203 with increasing Ti02 at constant MgO content. The basalts and basaltic andesites with the lowest Ti02 contents also have the lowest alkali contents. These chemical trends appear to be caused by plagioclase, with subordinate olivine, fractionation, and are consistent with the fact that plagioclase and olivine are virtually the only phenocryst minerals in the mafic DF rocks. It is likely that the diktytaxitic basalt with the lowest Ti02 content is a parental magma. Fractionation may account for the chemical variations within the mafic rock groups considered separately, but the progression from basalt to andesite appears to be the result of mixing of silicic and mafic magmas. The chemistry of the rocks, especially the CaO/Al203 ratios, is consistent with such mixing, as is the petrography; opaque minerals are very late crystallizers in the basalts and basaltic andesites, and there is increasing evidence for magma mixing in the series basalt through andesite. Such evidence includes multiple plagioclase populations in the same rock, both of which are resorbed, and resorbed pyroxenes and amphiboles. Three flows of plagioclase megacryst-bearing basaltic andesite occur near the top of the DF section. The plagioclase megacrysts are up to 5 cm in length, commonly contain apatite inclusions, and resemble the plagioclase in anorthosite bodies. Ilmenite megacrysts are also present. The megacrysts and the presence of highly plagioclase-fractionated aphyric lavas rich in Fe and Ti in the DF suggest that anorthosite bodies are present beneath the north-central Oregon Cascade Range. Two xenoliths of partly melted cordierite-sillimanite-quartz granulite gneiss were found in a DF ash-flow tuff. The xenoliths demonstrate that granulite-grade metamorphism and at least local partial melting of the lower crust took place beneath the north-central Oregon Cascades. Title: Volcanic stratigraphy of the Deschutes Formation, Green Ridge to Fly Creek, north-central Oregon Author: Conrey, Richard M. About 225 lava flows and ash-flow tuffs of the Deschutes Formation (DF) were mapped at Green Ridge. The units fill east-trending paleovalleys which "sky-out" westward and dip east; the eastward dip of the units decreases as they are traced eastward. The source of the units was west of Green Ridge as evidenced by the increase in the number of ash-flow tuffs and lava flows in the DF from east to west toward Green Ridge, and the presence of viscous silicic lavas and lag deposits in ash-flow tuffs on the west flank of Green Ridge. The exposed DF section at Green Ridge is 1400 feet thick, and consists mainly of basaltic andesites with subordinate diktytaxitic basalts, andesites, dacites, aphyric basaltic andesites and andesites rich in Fe and Ti, ash-flow tuffs, and sediments. The upper 400 feet of the section is devoid of ash-flow tuffs and dacites. Nine paleomagnetic polarity intervals, five normal and four reversed, are recognized in the section; tentative correlation of these intervals with the magnetic time scale suggests that the oldest DF unit exposed at Green Ridge is 6.5 Ma, and the youngest 4.4 Ma. The DF units at the crest, and west of Green Ridge are cut by at least five N- to N13W-trending, down-to-the-west normal faults in a zone about five miles wide. These faults were possibly active as much as 5 Ma; the developing faults may have provided structural pathways for the ascent of the mafic lavas in the upper 400 feet of the section. The faulting which created the Green Ridge escarpment was probably finished by 3 Ma, and perhaps earlier. The presence of dense, Fe- and Ti-rich lavas throughout the DF section implies that magmas had relatively easy access to the surface during DF time (7.6-4.4 Ma), which suggests that the E-W extensional tectonism that culminated in the formation of the Green Ridge faults was present throughout deposition of the DF. The major element chemistry of DF diktytaxitic basalts, basaltic andesites, and andesites appears to change regularly with Ti02 content, as shown by decreasing CaO/FeO* (FeO* = total Fe expressed as FeO) with increasing Ti02, and by decreasing A1203 with increasing Ti02 at constant MgO content. The basalts and basaltic andesites with the lowest Ti02 contents also have the lowest alkali contents. These chemical trends appear to be caused by plagioclase, with subordinate olivine, fractionation, and are consistent with the fact that plagioclase and olivine are virtually the only phenocryst minerals in the mafic DF rocks. It is likely that the diktytaxitic basalt with the lowest Ti02 content is a parental magma. Fractionation may account for the chemical variations within the mafic rock groups considered separately, but the progression from basalt to andesite appears to be the result of mixing of silicic and mafic magmas. The chemistry of the rocks, especially the CaO/Al203 ratios, is consistent with such mixing, as is the petrography; opaque minerals are very late crystallizers in the basalts and basaltic andesites, and there is increasing evidence for magma mixing in the series basalt through andesite. Such evidence includes multiple plagioclase populations in the same rock, both of which are resorbed, and resorbed pyroxenes and amphiboles. Three flows of plagioclase megacryst-bearing basaltic andesite occur near the top of the DF section. The plagioclase megacrysts are up to 5 cm in length, commonly contain apatite inclusions, and resemble the plagioclase in anorthosite bodies. Ilmenite megacrysts are also present. The megacrysts and the presence of highly plagioclase-fractionated aphyric lavas rich in Fe and Ti in the DF suggest that anorthosite bodies are present beneath the north-central Oregon Cascade Range. Two xenoliths of partly melted cordierite-sillimanite-quartz granulite gneiss were found in a DF ash-flow tuff. The xenoliths demonstrate that granulite-grade metamorphism and at least local partial melting of the lower crust took place beneath the north-central Oregon Cascades. Close

• 2206. [Article] Overstory Structure and Community Characteristics of Oregon Ash (Fraxinus latifolia) Forests of the Willamette Valley, Oregon

  As species of ash trees become increasingly threatened worldwide by exotic pests and pathogens, it is important to develop descriptions of their ecologies that help guide the conservation and restoration ...

  Citation × Citation Citation Abstract Copy Title: Overstory Structure and Community Characteristics of Oregon Ash (Fraxinus latifolia) Forests of the Willamette Valley, Oregon Author: Prive, Sean As species of ash trees become increasingly threatened worldwide by exotic pests and pathogens, it is important to develop descriptions of their ecologies that help guide the conservation and restoration of forests in which they are a major component. Oregon ash (Fraxinus latifolia) is a dominant tree species in wetland forests of the Willamette Valley, Oregon. It is potentially threatened by the emerald ash borer, an exotic forest insect that is expanding in range in North America. The arrival of the emerald ash borer in the western United States is expected to cause high rates of Oregon ash mortality, which will likely highly alter structural and compositional characteristics of regional riparian and wetland forests. To investigate the structural development and plant community dynamics of Willamette Valley Oregon ash forests, I quantified species structure and composition for both overstory and understory communities along gradients of stand age and soil moisture. Community Type Wetland Index (CTWI) scores were calculated for each plot by multiplying plot-level species abundances by the national wetland indicator value for each species, and were used as an approximation of local soil moisture regimes. Ash forests and early seral savannas were sampled in 102 plots within 11 wetlands between Lane and Washington Counties, Oregon. Early seral wetland savannas were dominated by herbaceous vegetation and had highly variable ash and other tree species recruitment. Young ash forests initiated on wetland sites that were formally maintained as savannas via anthropogenic disturbance. Structural development in these forests generally followed previously described post-disturbance stages: stem exclusion, understory initiation, young multi-strata, and old growth. As stands aged, tree densities decreased and mean tree diameter increased. Mean stand densities (for trees >5 cm at 1.3 m height) ranged from 1727 trees per hectare in stem exclusion stands to 348 in old growth stands, while mean tree diameter increased from 12 to 32 cm between those same stages. Furthermore, understory vegetation shifted from herbaceous to shrub and understory tree species. Oregon ash had the greatest relative dominance of all tree species at all stages of structural development. Oregon white oak (Quercus garryana) was the only other tree species commonly found in forest canopies, though it was typically far less abundant than Oregon ash. Plots in which oak was present had a greater depth to soil mottling, indicating a lower depth to the annual high water table. Oregon ash was also the most commonly regenerating tree species in all stages of structural development, and nearly 70% of ash regeneration was vegetative. Other tree regeneration was typically restricted to understory species, especially cascara (Rhamnus purshiana) in forests and hawthorn (Crataegus spp.) in savannas. Forest structural diversity increased between each stage of development. In total, 216 plant species were identified. Of these, 147 were found in forest plots. Community composition differed significantly between forests and savannas, and between "young" (stem exclusion and understory initiation) plots and "old" (young multi-strata and old growth) plots. Nonmetric multidimensional scaling (NMS) indicated that, for all wetland plots, the environmental variables most highly correlated with community composition were CTWI scores and canopy cover. For forest plots only, NMS indicated that CTWI scores and stand density were the environmental variables most related to patterns in community composition. Species richness was not correlated with canopy cover, but was negatively correlated with CTWI scores. Exotic species cover was negatively correlated with canopy cover, but was not correlated with CTWI scores. Exotic species composition was dependent on both canopy cover and CTWI scores. On wet sites, reed canary grass (Phalaris arundinacea) was particularly abundant, and was associated with low species richness. On drier sites, common exotic species included trees and shrubs such as blackberries (Rubus spp.), exotic roses (Rosa spp.), single-seeded hawthorn (Crataegus monogyna), and common pear (Pyrus communis) as well as several grass and forb species. The results of this study suggest that, although overstory tree communities are characterized by low diversity, Oregon ash forests are important for landscape-scale structural and plant community diversity in Willamette Valley wetlands. However, overstory tree communities lack diversity; Oregon ash appears to be both an early seral, colonizing species in open wetlands and a climax species that is capable of regenerating under a closed canopy. Few other trees are present regionally that are capable of maintaining a forested state in wetlands. Furthermore, closed canopy Oregon ash forests may suppress exotic species spread, and in the absence of management, overstory ash mortality may lead to increased exotic plant cover. Regardless of future forest health threats, intact Oregon ash forests, like other regional wetland-types, are currently few and limited in extent and should be considered a conservation priority. Title: Overstory Structure and Community Characteristics of Oregon Ash (Fraxinus latifolia) Forests of the Willamette Valley, Oregon Author: Prive, Sean As species of ash trees become increasingly threatened worldwide by exotic pests and pathogens, it is important to develop descriptions of their ecologies that help guide the conservation and restoration of forests in which they are a major component. Oregon ash (Fraxinus latifolia) is a dominant tree species in wetland forests of the Willamette Valley, Oregon. It is potentially threatened by the emerald ash borer, an exotic forest insect that is expanding in range in North America. The arrival of the emerald ash borer in the western United States is expected to cause high rates of Oregon ash mortality, which will likely highly alter structural and compositional characteristics of regional riparian and wetland forests. To investigate the structural development and plant community dynamics of Willamette Valley Oregon ash forests, I quantified species structure and composition for both overstory and understory communities along gradients of stand age and soil moisture. Community Type Wetland Index (CTWI) scores were calculated for each plot by multiplying plot-level species abundances by the national wetland indicator value for each species, and were used as an approximation of local soil moisture regimes. Ash forests and early seral savannas were sampled in 102 plots within 11 wetlands between Lane and Washington Counties, Oregon. Early seral wetland savannas were dominated by herbaceous vegetation and had highly variable ash and other tree species recruitment. Young ash forests initiated on wetland sites that were formally maintained as savannas via anthropogenic disturbance. Structural development in these forests generally followed previously described post-disturbance stages: stem exclusion, understory initiation, young multi-strata, and old growth. As stands aged, tree densities decreased and mean tree diameter increased. Mean stand densities (for trees >5 cm at 1.3 m height) ranged from 1727 trees per hectare in stem exclusion stands to 348 in old growth stands, while mean tree diameter increased from 12 to 32 cm between those same stages. Furthermore, understory vegetation shifted from herbaceous to shrub and understory tree species. Oregon ash had the greatest relative dominance of all tree species at all stages of structural development. Oregon white oak (Quercus garryana) was the only other tree species commonly found in forest canopies, though it was typically far less abundant than Oregon ash. Plots in which oak was present had a greater depth to soil mottling, indicating a lower depth to the annual high water table. Oregon ash was also the most commonly regenerating tree species in all stages of structural development, and nearly 70% of ash regeneration was vegetative. Other tree regeneration was typically restricted to understory species, especially cascara (Rhamnus purshiana) in forests and hawthorn (Crataegus spp.) in savannas. Forest structural diversity increased between each stage of development. In total, 216 plant species were identified. Of these, 147 were found in forest plots. Community composition differed significantly between forests and savannas, and between "young" (stem exclusion and understory initiation) plots and "old" (young multi-strata and old growth) plots. Nonmetric multidimensional scaling (NMS) indicated that, for all wetland plots, the environmental variables most highly correlated with community composition were CTWI scores and canopy cover. For forest plots only, NMS indicated that CTWI scores and stand density were the environmental variables most related to patterns in community composition. Species richness was not correlated with canopy cover, but was negatively correlated with CTWI scores. Exotic species cover was negatively correlated with canopy cover, but was not correlated with CTWI scores. Exotic species composition was dependent on both canopy cover and CTWI scores. On wet sites, reed canary grass (Phalaris arundinacea) was particularly abundant, and was associated with low species richness. On drier sites, common exotic species included trees and shrubs such as blackberries (Rubus spp.), exotic roses (Rosa spp.), single-seeded hawthorn (Crataegus monogyna), and common pear (Pyrus communis) as well as several grass and forb species. The results of this study suggest that, although overstory tree communities are characterized by low diversity, Oregon ash forests are important for landscape-scale structural and plant community diversity in Willamette Valley wetlands. However, overstory tree communities lack diversity; Oregon ash appears to be both an early seral, colonizing species in open wetlands and a climax species that is capable of regenerating under a closed canopy. Few other trees are present regionally that are capable of maintaining a forested state in wetlands. Furthermore, closed canopy Oregon ash forests may suppress exotic species spread, and in the absence of management, overstory ash mortality may lead to increased exotic plant cover. Regardless of future forest health threats, intact Oregon ash forests, like other regional wetland-types, are currently few and limited in extent and should be considered a conservation priority. Close

• 2207. [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

• 2208. [Article] Effects of a Wind Energy Development on Greater Sage-Grouse Habitat Selection and Population Demographics in Southeastern Wyoming

  Western EcoSystems Technology, Inc. and Wyoming Wildlife Consultants, LLC initiated a greater sage-grouse radio-telemetry study at an existing wind energy development in southeastern Wyoming in 2009. The ...

  Citation × Citation Citation Abstract Copy Title: Effects of a Wind Energy Development on Greater Sage-Grouse Habitat Selection and Population Demographics in Southeastern Wyoming Author: LeBeau, Chad W. Western EcoSystems Technology, Inc. and Wyoming Wildlife Consultants, LLC initiated a greater sage-grouse radio-telemetry study at an existing wind energy development in southeastern Wyoming in 2009. The University of Wyoming joined this collaborative effort in January 2010, and the National Wind Coordinating Collaborative joined the effort in March 2011. The overall goal of the research was to establish the population-level effects of wind energy development on female sage-grouse seasonal habitat selection and demography. This study represents the only situation in the US where the responses of greater sage-grouse to the infrastructure associated with a wind energy development has been investigated. Our primary objective was to discern the relationship between sage-grouse nest, brood-rearing, and summer habitat selection patterns and survival parameters and the infrastructure of an existing wind energy facility. The Seven Mile Hill (SMH) study area was located north of Interstate 80 and south of the Shirley Basin in Carbon County, Wyoming, US. A control and treatment area was included in the SMH study area, with boundaries of each of these areas determined from lek locations and radio-marked female sage-grouse distributions. The Seven Mile Hill Wind Energy Facility (SWEF; located in the treatment area) consisted of 79 General Electric 1.5-MW wind turbines and approximately 29 km of access roads. The facility became fully operational in December 2008. In addition to the SWEF, other anthropogenic features present in this portion of the study area included approximately eight km of paved roads and 26 km of overhead transmission lines. The control study area had no wind turbines and was adjacent to the SWEF and south of US Highway 30/287. There were approximately 50 km of paved roads and 17 km of overhead transmission lines in this area. The treatment area had four leks that had an average distance of 1.93 km from the nearest SWEF turbines (range = 0.53 to 4.15 km), while the control group consisted of 6 leks with an average distance of 10.99 km from the nearest SWEF turbine (range = 7.09 to 16.16 km). We captured and radio-equipped 346 (160 treatment; 186 control) female sage-grouse within an area consisting of a wind energy development and a control area absent of wind energy development in southeastern Wyoming from 2009–2014. We relocated each radio-marked female approximately twice a week during the nesting, brood rearing, and summer periods. We developed a suite of anthropogenic, vegetation, and environmental covariates to estimate habitat selection and survival for all sage-grouse during the nesting, brood rearing, and summer periods. We used a discrete choice habitat selection model to estimate the relative probability of sage-grouse nest site, brood-rearing, and summer habitat selection within both the control and treatment areas during the post-development period. We did not detect a negative impact of the wind energy facility on nest site selection during the study period. Sage-grouse rearing broods generally avoided suitable brood-rearing habitat near anthropogenic infrastructure that includes wind energy development, major paved roads and transmission lines. Although avoidance was consistent across the years of our study, avoidance of wind turbines was more pronounced in 2012-2014 compared to 2009-2011, suggesting a lag period in the ultimate population-level response to the development of a wind energy facility. Although distance to turbine was not strongly associated with summer habitat selection, the percentage of disturbance associated with wind energy infrastructure did appear to influence summer habitat selection. In addition, we estimated survival during each seasonal period to estimate the effect of the SWEF on population fitness. The SWEF did not have a negative effect on sage-grouse nest survival within the study area over the six-year period, and nest survival did not differ between nests of females captured at treatment and control area leks over the study period. The SWEF did not have a negative effect on sage-grouse brood survival within the study area over the six-year period. Survival was related to habitat features and anthropogenic features that have existed on the landscape for >10 years. Lastly, the SWEF did not have a negative effect on female sage-grouse summer survival within the study area over the six-year period. After controlling for annual and natural variability, we observed a positive effect of the SWEF on female survival when the percentage of disturbance within 0.81 km of a sage-grouse location increased from 0% to 3%. Our study is the first to estimate the impacts of wind energy development on sage-grouse habitat selection and fitness parameters. Female sage-grouse selection of seasonal habitats was variable relative to the infrastructure associated with wind energy facility, but fitness parameters did not appear to be influenced to a great degree by the infrastructure. This pattern of effect is similar to greater prairie-chicken response to a wind energy facility in Kansas but opposite of sage-grouse response to oil and gas development. Ideally, we would have preconstruction data to identify changes in the population and decipher mechanisms in sage-grouse response to infrastructure; however, we are confident that if such impacts to habitat selection and survival did occur then we would have been able to detect these changes over the 6-year study period. The lack of other studies investigating impacts from wind energy development to sage-grouse habitat selection and survival limits our ability to make inferences about the cumulative impacts of wind energy development on sage-grouse, but we were able to describe some of the impacts that wind energy developments may have on sage-grouse populations. Although we attempted to account for possible confounding factors, there is the chance that we did not detect important interactions between environmental features and habitat selection and survival patterns. Future wind energy developments should consider the potential impacts of wind energy development on sage-grouse habitat selection patterns and survival parameters. We recommend facilities similar in size that occupy similar habitats as our study be placed 1.20 km from any occupied sage-grouse nesting, brood-rearing, or summer habitats. We recommend that future research consider predator-prey mechanisms by estimating both avian and mammalian predator densities to better understand the impacts of wind energy development on sage-grouse fitness parameters and to develop appropriate mitigation measures. Title: Effects of a Wind Energy Development on Greater Sage-Grouse Habitat Selection and Population Demographics in Southeastern Wyoming Author: LeBeau, Chad W. Western EcoSystems Technology, Inc. and Wyoming Wildlife Consultants, LLC initiated a greater sage-grouse radio-telemetry study at an existing wind energy development in southeastern Wyoming in 2009. The University of Wyoming joined this collaborative effort in January 2010, and the National Wind Coordinating Collaborative joined the effort in March 2011. The overall goal of the research was to establish the population-level effects of wind energy development on female sage-grouse seasonal habitat selection and demography. This study represents the only situation in the US where the responses of greater sage-grouse to the infrastructure associated with a wind energy development has been investigated. Our primary objective was to discern the relationship between sage-grouse nest, brood-rearing, and summer habitat selection patterns and survival parameters and the infrastructure of an existing wind energy facility. The Seven Mile Hill (SMH) study area was located north of Interstate 80 and south of the Shirley Basin in Carbon County, Wyoming, US. A control and treatment area was included in the SMH study area, with boundaries of each of these areas determined from lek locations and radio-marked female sage-grouse distributions. The Seven Mile Hill Wind Energy Facility (SWEF; located in the treatment area) consisted of 79 General Electric 1.5-MW wind turbines and approximately 29 km of access roads. The facility became fully operational in December 2008. In addition to the SWEF, other anthropogenic features present in this portion of the study area included approximately eight km of paved roads and 26 km of overhead transmission lines. The control study area had no wind turbines and was adjacent to the SWEF and south of US Highway 30/287. There were approximately 50 km of paved roads and 17 km of overhead transmission lines in this area. The treatment area had four leks that had an average distance of 1.93 km from the nearest SWEF turbines (range = 0.53 to 4.15 km), while the control group consisted of 6 leks with an average distance of 10.99 km from the nearest SWEF turbine (range = 7.09 to 16.16 km). We captured and radio-equipped 346 (160 treatment; 186 control) female sage-grouse within an area consisting of a wind energy development and a control area absent of wind energy development in southeastern Wyoming from 2009–2014. We relocated each radio-marked female approximately twice a week during the nesting, brood rearing, and summer periods. We developed a suite of anthropogenic, vegetation, and environmental covariates to estimate habitat selection and survival for all sage-grouse during the nesting, brood rearing, and summer periods. We used a discrete choice habitat selection model to estimate the relative probability of sage-grouse nest site, brood-rearing, and summer habitat selection within both the control and treatment areas during the post-development period. We did not detect a negative impact of the wind energy facility on nest site selection during the study period. Sage-grouse rearing broods generally avoided suitable brood-rearing habitat near anthropogenic infrastructure that includes wind energy development, major paved roads and transmission lines. Although avoidance was consistent across the years of our study, avoidance of wind turbines was more pronounced in 2012-2014 compared to 2009-2011, suggesting a lag period in the ultimate population-level response to the development of a wind energy facility. Although distance to turbine was not strongly associated with summer habitat selection, the percentage of disturbance associated with wind energy infrastructure did appear to influence summer habitat selection. In addition, we estimated survival during each seasonal period to estimate the effect of the SWEF on population fitness. The SWEF did not have a negative effect on sage-grouse nest survival within the study area over the six-year period, and nest survival did not differ between nests of females captured at treatment and control area leks over the study period. The SWEF did not have a negative effect on sage-grouse brood survival within the study area over the six-year period. Survival was related to habitat features and anthropogenic features that have existed on the landscape for >10 years. Lastly, the SWEF did not have a negative effect on female sage-grouse summer survival within the study area over the six-year period. After controlling for annual and natural variability, we observed a positive effect of the SWEF on female survival when the percentage of disturbance within 0.81 km of a sage-grouse location increased from 0% to 3%. Our study is the first to estimate the impacts of wind energy development on sage-grouse habitat selection and fitness parameters. Female sage-grouse selection of seasonal habitats was variable relative to the infrastructure associated with wind energy facility, but fitness parameters did not appear to be influenced to a great degree by the infrastructure. This pattern of effect is similar to greater prairie-chicken response to a wind energy facility in Kansas but opposite of sage-grouse response to oil and gas development. Ideally, we would have preconstruction data to identify changes in the population and decipher mechanisms in sage-grouse response to infrastructure; however, we are confident that if such impacts to habitat selection and survival did occur then we would have been able to detect these changes over the 6-year study period. The lack of other studies investigating impacts from wind energy development to sage-grouse habitat selection and survival limits our ability to make inferences about the cumulative impacts of wind energy development on sage-grouse, but we were able to describe some of the impacts that wind energy developments may have on sage-grouse populations. Although we attempted to account for possible confounding factors, there is the chance that we did not detect important interactions between environmental features and habitat selection and survival patterns. Future wind energy developments should consider the potential impacts of wind energy development on sage-grouse habitat selection patterns and survival parameters. We recommend facilities similar in size that occupy similar habitats as our study be placed 1.20 km from any occupied sage-grouse nesting, brood-rearing, or summer habitats. We recommend that future research consider predator-prey mechanisms by estimating both avian and mammalian predator densities to better understand the impacts of wind energy development on sage-grouse fitness parameters and to develop appropriate mitigation measures. Close

• 2209. [Article] Mineralogy and geochemistry of copper deposits of the Lights Creek Stock, California : an assessment of porphyry versus iron-oxide copper origin

  The Lights Creek Stock is an 18 square kilometer copper-bearing granitoid intrusion within the Plumas Copper Belt in the northern California Sierra Nevada. Engels Mine, Superior Mine, and Moonlight Valley ...

  Citation × Citation Citation Abstract Copy Title: Mineralogy and geochemistry of copper deposits of the Lights Creek Stock, California : an assessment of porphyry versus iron-oxide copper origin Author: Stephens, Abigail E. The Lights Creek Stock is an 18 square kilometer copper-bearing granitoid intrusion within the Plumas Copper Belt in the northern California Sierra Nevada. Engels Mine, Superior Mine, and Moonlight Valley represent the main copper-mineralization in the Lights Creek district and small prospects include the Ruby Mine, and Moonlight Creek. The Moonlight Valley deposit within the Lights Creek Stock has been previously considered a porphyry copper deposit on the basis of stockwork veinlets in a granitic host. The granitic host rock of the Lights Creek Stock contains hydrothermal tourmaline and biotite as well as disseminated and vein copper-sulfides (bornite-chalcocite-chalcopyrite), and these features are supportive of porphyry-style mineralization. Nonetheless, the mineral alteration assemblages and zonation observed at Moonlight Valley and the Superior and Engels Mines differ significantly from literature descriptions of porphyry systems. Ores in the Lights Creek district are notably sulfur-poor and copper-rich. Mineralization includes copper-sulfide veins with pink potassium-feldspar selvages, tourmaline veins with albitic-chlorite selvages, and actinolite-apatite veins, as well as albite-magnetite alteration in the Kettle Rock volcanic sequence intruded by the Lights Creek Stock. These features are similar to the class of ores known as iron oxidecopper- gold (IOCG) deposits. Lights Creek represents one of several copper- and iron -bearing ore districts associated with early Mesozoic intrusions in northern Nevada and California, including both porphyry copper-skarn ores and IOCG deposits. This region is underlain by an early Mesozoic marine province of volcanic and sedimentary rocks, including evaporites, intruded by shallowly emplaced Jurassic, and in some cases, Triassic plutons (Stewart et al., 1997; Proffett and Dilles, 2008). This scenario is ideal for formation of IOCG deposits produced by advection of sedimentary brines by the heat of the intrusions (Barton and Johnson, 1996). A uranium-lead zircon age of 178.1 ± 3.9 (2s) Ma was observed from two samples of hypabyssal quartz monzonite on the east side of the Lights Creek Stock where it intrudes the Early Jurassic volcanics of the Kettle Rock sequence. The Lights Creek Stock originally contained igneous hornblende, which exhibits hydrothermal alteration to tourmaline, chlorite and local biotite associated with narrow sulfide (pyrite, chalcopyrite) and tourmaline veins. Apatite-actinolite veins and albite-alteration zones also cut the Lights Creek Stock. In the Superior Mine, east-dipping ore-bearing veins (<10 cm to 2 m wide) are zoned from central copper-rich zones (bornite, chalcopyrite, magnetite) associated with hydrothermal tourmaline and biotite alteration to outer sulfide-rich zones (chalcopyrite, pyrite, sphalerite) with sericite-chlorite alteration. Gently dipping intermineral lamprophyre dikes cut the bornite-bearing veins, but are in turn cut by the pyrite-chalcopyrite-rich veins. Similar ore zonation was observed by Storey (1981) in the northwest part of the Lights Creek Stock at the large Moonlight Valley deposit. In the Moonlight Valley, Engels Mine, and Superior Mine deposits porphyry dikes are absent. The observations are consistent with an IOCG association of copper mineralization broadly synchronous with the emplacement of the 178 Ma Lights Creek Stock. The light-colored, relatively fresh and unmineralized China Gulch Granite intrudes the east side of the Lights Creek Stock, and yielded a uranium-lead zircon age of 148.1±1.3 (2s) Ma. Quartz porphyry dikes intrude Middle Jurassic volcaniclastic and volcanic rocks of the Mount Jura sequence (Christe, 2011) west of the Lights Creek Stock along Moonlight Creek, and are here cut by quartz-tourmaline sulfide (pyrite, chalcopyrite) veins associated with strong sericitic alteration. Muscovite from this alteration zone yielded an ⁴⁰Ar-³⁹Ar plateau age of 146.05±0.88 (2s) Ma, the same age as the China Gulch Granite to the east, and suggest latest Late Jurassic age of porphyry copper mineralization. Copper-sulfides from Moonlight Valley and Superior are characterized by lead isotope values of ²⁰⁶Pb/²⁰⁴Pb ~19.4, while lead isotope values of copper-sulfides from Moonlight Creek and Engels are close to the igneous values of the Lights Creek Stock at ²⁰⁶Pb/²⁰⁴Pb ~18.6. The lead isotope data support the hypothesis that the fluids that formed the Moonlight Creek deposits and a portion of the ore of the Engels deposit were magmatic-hydrothermal, while the Moonlight Valley and Superior Mine ores are in part derived from non-magmatic fluid source reflecting an older lead source. Copper mineralization in the Lights Creek district likely included components of both porphyry-type magmatic-hydrothermal and IOCG-like non-magmatic sedimentary brine fluids. The Lights Creek Stock was emplaced in the late Early Jurassic (~178 Ma) and was in turn intruded by the younger late Late Jurassic China Gulch Granite (148 Ma). Magmatic fluids derived from the Lights Creek Stock produced tourmaline ± biotite ± magnetite ± chalcopyrite ± bornite veins in potassic alteration containing zones of hydrothermal potassium feldspar + biotite. Contemporaneously, the intrusion of the Lights Creek Stock drove advection of sedimentary brines through the adjacent metavolcanic rocks and margins of the stock. These sedimentary brines produced zones of albitic alteration and ores characterized by apatite + actinolite + titanite + magnetite + ilmenite ± chalcopyrite ± bornite ± epidote observed at Sulfide Ridge and the Superior Mine. Mixed fluids then produced zones of of albite ± chalcocite ± chalcopyrite ± tourmaline occuring at Sulfide Ridge, Superior Mine, and Moonlight Valley. In the late Late Jurassic (148 Ma), renewed magmatic activity resulted in the intrusion of the China Gulch Granite and granite porphyry dikes. The latter produced small-scale porphyrystyle mineralization along Moonlight Creek and Ruby Mine west of the Lights Creek Stock. Title: Mineralogy and geochemistry of copper deposits of the Lights Creek Stock, California : an assessment of porphyry versus iron-oxide copper origin Author: Stephens, Abigail E. The Lights Creek Stock is an 18 square kilometer copper-bearing granitoid intrusion within the Plumas Copper Belt in the northern California Sierra Nevada. Engels Mine, Superior Mine, and Moonlight Valley represent the main copper-mineralization in the Lights Creek district and small prospects include the Ruby Mine, and Moonlight Creek. The Moonlight Valley deposit within the Lights Creek Stock has been previously considered a porphyry copper deposit on the basis of stockwork veinlets in a granitic host. The granitic host rock of the Lights Creek Stock contains hydrothermal tourmaline and biotite as well as disseminated and vein copper-sulfides (bornite-chalcocite-chalcopyrite), and these features are supportive of porphyry-style mineralization. Nonetheless, the mineral alteration assemblages and zonation observed at Moonlight Valley and the Superior and Engels Mines differ significantly from literature descriptions of porphyry systems. Ores in the Lights Creek district are notably sulfur-poor and copper-rich. Mineralization includes copper-sulfide veins with pink potassium-feldspar selvages, tourmaline veins with albitic-chlorite selvages, and actinolite-apatite veins, as well as albite-magnetite alteration in the Kettle Rock volcanic sequence intruded by the Lights Creek Stock. These features are similar to the class of ores known as iron oxidecopper- gold (IOCG) deposits. Lights Creek represents one of several copper- and iron -bearing ore districts associated with early Mesozoic intrusions in northern Nevada and California, including both porphyry copper-skarn ores and IOCG deposits. This region is underlain by an early Mesozoic marine province of volcanic and sedimentary rocks, including evaporites, intruded by shallowly emplaced Jurassic, and in some cases, Triassic plutons (Stewart et al., 1997; Proffett and Dilles, 2008). This scenario is ideal for formation of IOCG deposits produced by advection of sedimentary brines by the heat of the intrusions (Barton and Johnson, 1996). A uranium-lead zircon age of 178.1 ± 3.9 (2s) Ma was observed from two samples of hypabyssal quartz monzonite on the east side of the Lights Creek Stock where it intrudes the Early Jurassic volcanics of the Kettle Rock sequence. The Lights Creek Stock originally contained igneous hornblende, which exhibits hydrothermal alteration to tourmaline, chlorite and local biotite associated with narrow sulfide (pyrite, chalcopyrite) and tourmaline veins. Apatite-actinolite veins and albite-alteration zones also cut the Lights Creek Stock. In the Superior Mine, east-dipping ore-bearing veins (<10 cm to 2 m wide) are zoned from central copper-rich zones (bornite, chalcopyrite, magnetite) associated with hydrothermal tourmaline and biotite alteration to outer sulfide-rich zones (chalcopyrite, pyrite, sphalerite) with sericite-chlorite alteration. Gently dipping intermineral lamprophyre dikes cut the bornite-bearing veins, but are in turn cut by the pyrite-chalcopyrite-rich veins. Similar ore zonation was observed by Storey (1981) in the northwest part of the Lights Creek Stock at the large Moonlight Valley deposit. In the Moonlight Valley, Engels Mine, and Superior Mine deposits porphyry dikes are absent. The observations are consistent with an IOCG association of copper mineralization broadly synchronous with the emplacement of the 178 Ma Lights Creek Stock. The light-colored, relatively fresh and unmineralized China Gulch Granite intrudes the east side of the Lights Creek Stock, and yielded a uranium-lead zircon age of 148.1±1.3 (2s) Ma. Quartz porphyry dikes intrude Middle Jurassic volcaniclastic and volcanic rocks of the Mount Jura sequence (Christe, 2011) west of the Lights Creek Stock along Moonlight Creek, and are here cut by quartz-tourmaline sulfide (pyrite, chalcopyrite) veins associated with strong sericitic alteration. Muscovite from this alteration zone yielded an ⁴⁰Ar-³⁹Ar plateau age of 146.05±0.88 (2s) Ma, the same age as the China Gulch Granite to the east, and suggest latest Late Jurassic age of porphyry copper mineralization. Copper-sulfides from Moonlight Valley and Superior are characterized by lead isotope values of ²⁰⁶Pb/²⁰⁴Pb ~19.4, while lead isotope values of copper-sulfides from Moonlight Creek and Engels are close to the igneous values of the Lights Creek Stock at ²⁰⁶Pb/²⁰⁴Pb ~18.6. The lead isotope data support the hypothesis that the fluids that formed the Moonlight Creek deposits and a portion of the ore of the Engels deposit were magmatic-hydrothermal, while the Moonlight Valley and Superior Mine ores are in part derived from non-magmatic fluid source reflecting an older lead source. Copper mineralization in the Lights Creek district likely included components of both porphyry-type magmatic-hydrothermal and IOCG-like non-magmatic sedimentary brine fluids. The Lights Creek Stock was emplaced in the late Early Jurassic (~178 Ma) and was in turn intruded by the younger late Late Jurassic China Gulch Granite (148 Ma). Magmatic fluids derived from the Lights Creek Stock produced tourmaline ± biotite ± magnetite ± chalcopyrite ± bornite veins in potassic alteration containing zones of hydrothermal potassium feldspar + biotite. Contemporaneously, the intrusion of the Lights Creek Stock drove advection of sedimentary brines through the adjacent metavolcanic rocks and margins of the stock. These sedimentary brines produced zones of albitic alteration and ores characterized by apatite + actinolite + titanite + magnetite + ilmenite ± chalcopyrite ± bornite ± epidote observed at Sulfide Ridge and the Superior Mine. Mixed fluids then produced zones of of albite ± chalcocite ± chalcopyrite ± tourmaline occuring at Sulfide Ridge, Superior Mine, and Moonlight Valley. In the late Late Jurassic (148 Ma), renewed magmatic activity resulted in the intrusion of the China Gulch Granite and granite porphyry dikes. The latter produced small-scale porphyrystyle mineralization along Moonlight Creek and Ruby Mine west of the Lights Creek Stock. Close

• 2210. [Article] Stratigraphy and sedimentology of the middle eocene Cowlitz Formation and adjacent sedimentary and volcanic units in the Longview-Kelso area, southwest Washington

  Geologic mapping of the Longview-Kelso area and the measurement and description of a composite 650-meter thick stratigraphic section of the Cowlitz Formation (Tc) in Coal Creek using bio-, magneto-, litho-, ...

  Citation × Citation Citation Abstract Copy Title: Stratigraphy and sedimentology of the middle eocene Cowlitz Formation and adjacent sedimentary and volcanic units in the Longview-Kelso area, southwest Washington Author: McCutcheon, Mark S. Geologic mapping of the Longview-Kelso area and the measurement and description of a composite 650-meter thick stratigraphic section of the Cowlitz Formation (Tc) in Coal Creek using bio-, magneto-, litho-, and sequence stratigraphy reveals a complex interplay of Cowlitz micaceous, lithic arkosic shelf to tidal/estuarine to delta plain facies associations, and Grays River basalt lava flows and interbedded basalt volcaniclastics from nearby Grays River eruptive centers (e.g., Mt. Solo and Rocky Point). The lower 100 meters of the Coal Creek section (informal unit 1, Chron 18r) consists of micaceous, lithic arkosic sandstone and siltstone and minor coals, was deposited as part of a highstand system tract (HST) at the base of 3rd order cycle number 3. This unit consists of four dominantly tidal shoaling-upward arkosic sandstone parasequences reflecting upper shoreface to delta plain depositional environments. The overlying unit 2 (Chron 18n) is defined by abundant Grays River basalt volcaniclastic interbeds that intertongue with Cowlitz lithic arkoses. This unit represents the latter part of 3rd order cycle 3, and consists of mostly fining- and thinning-upward parasequences of middle shoreface to delta plain successions of an aggradational to transgressive parasequence set. Near the top of unit 2 is a maximum marine flooding surface depositing lower shoreface lithic arkosic sandstone to shelf siltstones over upper shoreface micaceous lithic arkose. Unit 3 comprises 3rd order cycle 4 (Chron 17r), a lowstand system tract, and consists of 6 mostly fining- and thinning-upward parasequences of lower shoreface to delta plain facies associations. A parasequence or erosional boundary at the base of unit 5 (Chron 17r) consists of submarine channel-fill scoured into underlying micaceous siltstones, produced during a lowstand system tract (LST) of 3rd order cycle 5. This deep marine channel-fill sequence is overlain by thinlybedded to laminated overbank distal turbidites and hemipelagic siltstones that define the top of the Coal Creek section. These 5 informal units in Coal Creek lithologically and chronologically correlate to 5 similar informal units defined by Payne (1998) in the type section of Cowlitz Formation in Olequa Creek near Vader -30 km to the north. Middle Eocene Grays River Volcanics of the study area are mapped as two separate units: a lower unit over 150 meters thick in places, consisting of subaerial basaltic flows and invasive flows (Tgvl), intrusions (Tgvis and Tgvid), and volcaniclastics (Tgvsl); and an upper unit consisting of commonly mollusk-bearing, shallow marine basaltic sedimentary interbeds that intertongue with the Cowlitz Formation (Tgvs2), particularly Cowlitz unit 2 of the Coal Creek section. These volcaniclastic deposits are intrabasinal, derived from volcanic highlands to the west and northwest, and local phreatomagmatic tuff cones. The lower Grays River volcaniclastic unit typically overlies Grays River flows in the study area and is divided into 5 informal facies. Geochemically, Grays River flows in the study area fall within normal parameters (3 to 4% TiO2 and high iron tholeiitic basalts). However, basalt flows and bedded scoriaceous breccias near Rocky Point are anomalously low in TiO2 and are considered in this study to be a separate volcanic subunit (Rocky Point Basalts), time equivalent to and interfingering with Grays River lavas, but may represent mixing with shallower western Cascade calc-alkaline magma. Over 60 younger Grays River dikes intrude the Cowlitz Formation in Coal Creek. A dike low in the Coal Creek section is dated at 40 ± 0.36 Ma, and an invasive flow at Mt. Solo is dated at 36.98 ±.78 Ma. Volcanics capping the hills east of the Cowlitz River are chemically distinct as slightly younger western Cascade basaltic andesite flows, and two dikes east of the river are chemically distinct as western Cascade andesite. Overlying Grays River Volcanics and Cowlitz Formation in much of the study area, are clayey and commonly tuffaceous siltstones and silty sandstones, possibly of the late Eocene-early Oligocene Toutle Formation, a new unit to this area. The Toutle Formation is a mixture of wave and stream reworked micaceous and arkosic Cowlitz Formation and fresh silicic pyroclastic ash and pumice from the active western Cascade arc. An angular unconformity separates the Paleogene Grays River Volcanics, Cowlitz Formation, and Toutle Formation from the early to middle Miocene Columbia River Basalt Group. Based on lithology, geochemistry, stratigraphic relationships, and magnetic polarity, 6 individual Columbia River Basalt flows have been mapped in this study. The three lower Grande Ronde flows are of normal polarity and Ortley low MgO chemical composition. The lowermost flow (N2 Ortley #1) is absent in the Columbia Heights area, low MgO, about 10 meters thick and consists of pillow-palagonite sequences in the upper quarry on Mt. Solo. Aphyric N2 Ortley flow #2 is over 35 meters thick with well-developed upper and lower colonnade, and of intermediate MgO. N2 Ortley flow #3 is pillow-palagonite in the Storedahl Quarry and low MgO. A -4-meter thick tuffaceous overbank siltstone and basalt conglomeratic channel interbed separates the three low MgO Ortley flows from the overlying high MgO N2 Grande Ronde Sentinel Bluffs flow. A single exposure of well-developed large colonnade with sparse 1 cm labradorite laths, and reddish oxidized soil, defines the N Sand Hollow flow of the Frenchman Springs Member of the Wanapum Formation. The overlying Pomona Member is mapped based on previous work by other authors. Pliocene gravels and arkosic sand of the Troutdale Formation form upland terrace deposits up to 100 meters thick in southern parts of the study area, and represent the uplifted paleo-thalweg and overbank flood deposits of the downcutting, antecedent ancestral Columbia River. Well-rounded clasts are a mixture of extrabasinal granitic and metamorphic quartzite, and intrabasinal porphyritic basaltic andesite, dacite, and basalt from the western Cascades and Columbia River Basalts. Troutdale terrace gravels grade northward into contemporaneous volcanic pebble and cobble gravel terrace deposits produced along the ancestral Cowlitz River that are dominantly composed of porphyritic andesite gravel and volcanic sand from the western Cascades. Lower terraces along the Cowlitz River were deposited by the late Pleistocene Missoula Floods. All of these unconsolidated to semiconsolidated gravels and sands are prone to landslides, and the Aldercrest-Banyon landslide, the second worst landslide disaster in American history, occurred in the Troutdale Formation gravels. After eruption of the Grays River Volcanics and deposition of the Cowlitz Formation, the forearc underwent a period of transtension in the late-middle Eocene related to magmatic upwelling and reorganization of the subducting Farallon Plate. This event produced a northwest-trending set of oblique slip normal faults, along which Grays River dikes intruded. Starting in the early Miocene the region underwent a transpressional event, reactivating many of the northwest-trending faults, and producing the Columbia Heights Anticline, Hazel Dell Syncline, the Coal Creek Fault, and the Kelso Fault Zone. The paleotopography resulting from this event was stream eroded to a nearly flat plain before emplacement of the Columbia River Basalts, which are nearly horizontal today. Continued offset along the northwest-trending fault set has also offset the Columbia River Basalts. Continued oblique slip post-Miocene broad arching of the Coast Range and downcutting by the Columbia and Cowlitz Rivers has resulted in Pliocene and Pleistocene terraces, and produced an east-west fault set that offsets all earlier structural features. Title: Stratigraphy and sedimentology of the middle eocene Cowlitz Formation and adjacent sedimentary and volcanic units in the Longview-Kelso area, southwest Washington Author: McCutcheon, Mark S. Geologic mapping of the Longview-Kelso area and the measurement and description of a composite 650-meter thick stratigraphic section of the Cowlitz Formation (Tc) in Coal Creek using bio-, magneto-, litho-, and sequence stratigraphy reveals a complex interplay of Cowlitz micaceous, lithic arkosic shelf to tidal/estuarine to delta plain facies associations, and Grays River basalt lava flows and interbedded basalt volcaniclastics from nearby Grays River eruptive centers (e.g., Mt. Solo and Rocky Point). The lower 100 meters of the Coal Creek section (informal unit 1, Chron 18r) consists of micaceous, lithic arkosic sandstone and siltstone and minor coals, was deposited as part of a highstand system tract (HST) at the base of 3rd order cycle number 3. This unit consists of four dominantly tidal shoaling-upward arkosic sandstone parasequences reflecting upper shoreface to delta plain depositional environments. The overlying unit 2 (Chron 18n) is defined by abundant Grays River basalt volcaniclastic interbeds that intertongue with Cowlitz lithic arkoses. This unit represents the latter part of 3rd order cycle 3, and consists of mostly fining- and thinning-upward parasequences of middle shoreface to delta plain successions of an aggradational to transgressive parasequence set. Near the top of unit 2 is a maximum marine flooding surface depositing lower shoreface lithic arkosic sandstone to shelf siltstones over upper shoreface micaceous lithic arkose. Unit 3 comprises 3rd order cycle 4 (Chron 17r), a lowstand system tract, and consists of 6 mostly fining- and thinning-upward parasequences of lower shoreface to delta plain facies associations. A parasequence or erosional boundary at the base of unit 5 (Chron 17r) consists of submarine channel-fill scoured into underlying micaceous siltstones, produced during a lowstand system tract (LST) of 3rd order cycle 5. This deep marine channel-fill sequence is overlain by thinlybedded to laminated overbank distal turbidites and hemipelagic siltstones that define the top of the Coal Creek section. These 5 informal units in Coal Creek lithologically and chronologically correlate to 5 similar informal units defined by Payne (1998) in the type section of Cowlitz Formation in Olequa Creek near Vader -30 km to the north. Middle Eocene Grays River Volcanics of the study area are mapped as two separate units: a lower unit over 150 meters thick in places, consisting of subaerial basaltic flows and invasive flows (Tgvl), intrusions (Tgvis and Tgvid), and volcaniclastics (Tgvsl); and an upper unit consisting of commonly mollusk-bearing, shallow marine basaltic sedimentary interbeds that intertongue with the Cowlitz Formation (Tgvs2), particularly Cowlitz unit 2 of the Coal Creek section. These volcaniclastic deposits are intrabasinal, derived from volcanic highlands to the west and northwest, and local phreatomagmatic tuff cones. The lower Grays River volcaniclastic unit typically overlies Grays River flows in the study area and is divided into 5 informal facies. Geochemically, Grays River flows in the study area fall within normal parameters (3 to 4% TiO2 and high iron tholeiitic basalts). However, basalt flows and bedded scoriaceous breccias near Rocky Point are anomalously low in TiO2 and are considered in this study to be a separate volcanic subunit (Rocky Point Basalts), time equivalent to and interfingering with Grays River lavas, but may represent mixing with shallower western Cascade calc-alkaline magma. Over 60 younger Grays River dikes intrude the Cowlitz Formation in Coal Creek. A dike low in the Coal Creek section is dated at 40 ± 0.36 Ma, and an invasive flow at Mt. Solo is dated at 36.98 ±.78 Ma. Volcanics capping the hills east of the Cowlitz River are chemically distinct as slightly younger western Cascade basaltic andesite flows, and two dikes east of the river are chemically distinct as western Cascade andesite. Overlying Grays River Volcanics and Cowlitz Formation in much of the study area, are clayey and commonly tuffaceous siltstones and silty sandstones, possibly of the late Eocene-early Oligocene Toutle Formation, a new unit to this area. The Toutle Formation is a mixture of wave and stream reworked micaceous and arkosic Cowlitz Formation and fresh silicic pyroclastic ash and pumice from the active western Cascade arc. An angular unconformity separates the Paleogene Grays River Volcanics, Cowlitz Formation, and Toutle Formation from the early to middle Miocene Columbia River Basalt Group. Based on lithology, geochemistry, stratigraphic relationships, and magnetic polarity, 6 individual Columbia River Basalt flows have been mapped in this study. The three lower Grande Ronde flows are of normal polarity and Ortley low MgO chemical composition. The lowermost flow (N2 Ortley #1) is absent in the Columbia Heights area, low MgO, about 10 meters thick and consists of pillow-palagonite sequences in the upper quarry on Mt. Solo. Aphyric N2 Ortley flow #2 is over 35 meters thick with well-developed upper and lower colonnade, and of intermediate MgO. N2 Ortley flow #3 is pillow-palagonite in the Storedahl Quarry and low MgO. A -4-meter thick tuffaceous overbank siltstone and basalt conglomeratic channel interbed separates the three low MgO Ortley flows from the overlying high MgO N2 Grande Ronde Sentinel Bluffs flow. A single exposure of well-developed large colonnade with sparse 1 cm labradorite laths, and reddish oxidized soil, defines the N Sand Hollow flow of the Frenchman Springs Member of the Wanapum Formation. The overlying Pomona Member is mapped based on previous work by other authors. Pliocene gravels and arkosic sand of the Troutdale Formation form upland terrace deposits up to 100 meters thick in southern parts of the study area, and represent the uplifted paleo-thalweg and overbank flood deposits of the downcutting, antecedent ancestral Columbia River. Well-rounded clasts are a mixture of extrabasinal granitic and metamorphic quartzite, and intrabasinal porphyritic basaltic andesite, dacite, and basalt from the western Cascades and Columbia River Basalts. Troutdale terrace gravels grade northward into contemporaneous volcanic pebble and cobble gravel terrace deposits produced along the ancestral Cowlitz River that are dominantly composed of porphyritic andesite gravel and volcanic sand from the western Cascades. Lower terraces along the Cowlitz River were deposited by the late Pleistocene Missoula Floods. All of these unconsolidated to semiconsolidated gravels and sands are prone to landslides, and the Aldercrest-Banyon landslide, the second worst landslide disaster in American history, occurred in the Troutdale Formation gravels. After eruption of the Grays River Volcanics and deposition of the Cowlitz Formation, the forearc underwent a period of transtension in the late-middle Eocene related to magmatic upwelling and reorganization of the subducting Farallon Plate. This event produced a northwest-trending set of oblique slip normal faults, along which Grays River dikes intruded. Starting in the early Miocene the region underwent a transpressional event, reactivating many of the northwest-trending faults, and producing the Columbia Heights Anticline, Hazel Dell Syncline, the Coal Creek Fault, and the Kelso Fault Zone. The paleotopography resulting from this event was stream eroded to a nearly flat plain before emplacement of the Columbia River Basalts, which are nearly horizontal today. Continued offset along the northwest-trending fault set has also offset the Columbia River Basalts. Continued oblique slip post-Miocene broad arching of the Coast Range and downcutting by the Columbia and Cowlitz Rivers has resulted in Pliocene and Pleistocene terraces, and produced an east-west fault set that offsets all earlier structural features. Close