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• 1. [Article] ENVIRONMENTAL HISTORY OF ESTUARINE DISSOLVED OXYGEN INFERRED FROM TRACE-METAL GEOCHEMISTRY AND ORGANIC MATTER

  Environmental history recorded in sediments can reconstruct estuarine water quality metrics, such as dissolved oxygen, through the use of geochemical and biological proxies. I collected sediment cores ...

  Citation × Citation Citation Abstract Copy Title: ENVIRONMENTAL HISTORY OF ESTUARINE DISSOLVED OXYGEN INFERRED FROM TRACE-METAL GEOCHEMISTRY AND ORGANIC MATTER Author: Johnson, Geoffrey Year: 2017 Environmental history recorded in sediments can reconstruct estuarine water quality metrics, such as dissolved oxygen, through the use of geochemical and biological proxies. I collected sediment cores from two locations in the Coos Bay Estuary, at South Slough and Haynes Inlet, spanning from ~1680 AD to the present. To address the historical record of water column oxygen in the estuary I measured a suite of geochemical proxies including organic matter, magnetic susceptibility, and redox-sensitive metals to calibrate against a detailed 15-year record of dissolved oxygen. High visual correlation of these proxies and recent water quality supports the interpretation of long-term water quality from sediment cores. Finally, my semi-quantitative analysis describes a complex history where potential low water quality has increased at South Slough, while decreasing or staying stable at Haynes inlet over the last 300 years, though erosion indicators profoundly increase at both sites across the Euro-Amercian settlement horizon. This history was explained in terms of changing land use (logging, splash dams) effects on erosion and organic matter loading, oceanic vs terrestrial water sources, and the role of the dredged Coos Bay channel affecting the replenishment of estuary water. Title: ENVIRONMENTAL HISTORY OF ESTUARINE DISSOLVED OXYGEN INFERRED FROM TRACE-METAL GEOCHEMISTRY AND ORGANIC MATTER Author: Johnson, Geoffrey Year: 2017 Environmental history recorded in sediments can reconstruct estuarine water quality metrics, such as dissolved oxygen, through the use of geochemical and biological proxies. I collected sediment cores from two locations in the Coos Bay Estuary, at South Slough and Haynes Inlet, spanning from ~1680 AD to the present. To address the historical record of water column oxygen in the estuary I measured a suite of geochemical proxies including organic matter, magnetic susceptibility, and redox-sensitive metals to calibrate against a detailed 15-year record of dissolved oxygen. High visual correlation of these proxies and recent water quality supports the interpretation of long-term water quality from sediment cores. Finally, my semi-quantitative analysis describes a complex history where potential low water quality has increased at South Slough, while decreasing or staying stable at Haynes inlet over the last 300 years, though erosion indicators profoundly increase at both sites across the Euro-Amercian settlement horizon. This history was explained in terms of changing land use (logging, splash dams) effects on erosion and organic matter loading, oceanic vs terrestrial water sources, and the role of the dredged Coos Bay channel affecting the replenishment of estuary water. Close

• 2. [Article] Exploring, Exploiting and Evolving Diversity of Aquatic Ecosystem Models: a Community Perspective

  Here, we present a community perspective on how to explore, exploit and evolve the diversity in aquatic ecosystem models. These models play an important role in understanding the functioning of aquatic ...

  Citation × Citation Citation Abstract Copy Title: Exploring, Exploiting and Evolving Diversity of Aquatic Ecosystem Models: a Community Perspective Author: Janssen, Annette B.G., Arhonditsis, George B., Beusen, Arthur, Bolding, Karsten, Bruce, Louise, Bruggeman, Jorn, Couture, Raoul-Marie, Downing, Andrea S., Elliott, J. Alex, Frassl, Marieke A., Gal, Gideon, Gerla, Daan J., Hipsey, Matthew R., Hu, Fenjuan, Ives, Stephen C., Janse, Jan H., Jeppesen, Erik, Jöhnk, Klaus D., Kneis, David, Kong, Xiangzhen, Kuiper, Jan J., Lehmann, Moritz K., Lemmen, Carsten, Özkundakci, Deniz, Petzoldt, Thomas, Rinke, Karsten, Robson, Barbara J., Sachse, René, Schep, Sebastiaan A., Schmid, Martin, Scholten, Huub, Teurlincx, Sven, Trolle, Dennis, Troost, Tineke A., Van Dam, Anne A., Van Gerven, Luuk P.A., Weijerman, Mariska, Wells, Scott A., Mooij, Wolf M. Year: 2015 Here, we present a community perspective on how to explore, exploit and evolve the diversity in aquatic ecosystem models. These models play an important role in understanding the functioning of aquatic ecosystems, filling in observation gaps and developing effective strategies for water quality management. In this spirit, numerous models have been developed since the 1970s. We set off to explore model diversity by making an inventory among 42 aquatic ecosystem modellers, by categorizing the resulting set of models and by analysing them for diversity. We then focus on how to exploit model diversity by comparing and combining different aspects of existing models. Finally, we discuss how model diversity came about in the past and could evolve in the future. Throughout our study, we use analogies from biodiversity research to analyse and interpret model diversity. We recommend to make models publicly available through open-source policies, to standardize documentation and technical implementation of models, and to compare models through ensemble modelling and interdisciplinary approaches. We end with our perspective on how the field of aquatic ecosystem modelling might develop in the next 5–10 years. To strive for clarity and to improve readability for non-modellers, we include a glossary. Title: Exploring, Exploiting and Evolving Diversity of Aquatic Ecosystem Models: a Community Perspective Author: Janssen, Annette B.G., Arhonditsis, George B., Beusen, Arthur, Bolding, Karsten, Bruce, Louise, Bruggeman, Jorn, Couture, Raoul-Marie, Downing, Andrea S., Elliott, J. Alex, Frassl, Marieke A., Gal, Gideon, Gerla, Daan J., Hipsey, Matthew R., Hu, Fenjuan, Ives, Stephen C., Janse, Jan H., Jeppesen, Erik, Jöhnk, Klaus D., Kneis, David, Kong, Xiangzhen, Kuiper, Jan J., Lehmann, Moritz K., Lemmen, Carsten, Özkundakci, Deniz, Petzoldt, Thomas, Rinke, Karsten, Robson, Barbara J., Sachse, René, Schep, Sebastiaan A., Schmid, Martin, Scholten, Huub, Teurlincx, Sven, Trolle, Dennis, Troost, Tineke A., Van Dam, Anne A., Van Gerven, Luuk P.A., Weijerman, Mariska, Wells, Scott A., Mooij, Wolf M. Year: 2015 Here, we present a community perspective on how to explore, exploit and evolve the diversity in aquatic ecosystem models. These models play an important role in understanding the functioning of aquatic ecosystems, filling in observation gaps and developing effective strategies for water quality management. In this spirit, numerous models have been developed since the 1970s. We set off to explore model diversity by making an inventory among 42 aquatic ecosystem modellers, by categorizing the resulting set of models and by analysing them for diversity. We then focus on how to exploit model diversity by comparing and combining different aspects of existing models. Finally, we discuss how model diversity came about in the past and could evolve in the future. Throughout our study, we use analogies from biodiversity research to analyse and interpret model diversity. We recommend to make models publicly available through open-source policies, to standardize documentation and technical implementation of models, and to compare models through ensemble modelling and interdisciplinary approaches. We end with our perspective on how the field of aquatic ecosystem modelling might develop in the next 5–10 years. To strive for clarity and to improve readability for non-modellers, we include a glossary. Close

• 3. [Article] Geochemistry of Plutonic Rocks of the Western Cascades, Washington & Oregon : Relationship to Crustal Segmentation and Ore Genesis

  The volcanic (~45-10 Ma) and plutonic rocks (~37-12 Ma) comprising the Western Cascades extend from northernmost California to southern British Columbia and are ancestral to modern arc magmatism. The ancestral ...

  Citation × Citation Citation Abstract Copy Title: Geochemistry of Plutonic Rocks of the Western Cascades, Washington & Oregon : Relationship to Crustal Segmentation and Ore Genesis Author: Utevsky, Elinor S. The volcanic (~45-10 Ma) and plutonic rocks (~37-12 Ma) comprising the Western Cascades extend from northernmost California to southern British Columbia and are ancestral to modern arc magmatism. The ancestral arc hosts a series of small plutons that are locally associated with porphyry (Cu-Mo) and epithermal (Au) ore deposits. Three crustal segments identified by Schmidt et al. (2008, 2013) in the modern arc are potentially reflected in the geochemistry of the ancestral Cascades as well: Paleozoic-Mesozoic accreted terranes, metamorphic rocks, and granites to the north; thin Paleocene Siletzia oceanic crust of the Columbia Embayment in the center; and Paleozoic-Mesozoic ultramafic sheets and marine arc-related volcanic and sedimentary rocks of the Klamath Terrane to the south. Therefore, the Western Cascades of Washington and Oregon provide a field laboratory to examine the chemical compositions and ages of granitoid intrusions associated with a variety of magmatic-hydrothermal ore deposits, and to compare the compositions with the along-arc variation of the age, composition and thickness of the underlying crust. The majority of the 15 new zircon U-Pb ages reported in this study are 27 to 12 Ma with the exception of the ~37 Ma Snoqualmie North Fork intrusions of central WA. A total of 610 zircons were analyzed, of which 118 have ages older than the main population and are considered to be xenocrystic or inherited. The north segment contains the oldest (up to 67 Ma) and most continuous inherited population. The absence of inherited grains older than 67 Ma suggests that neither the North Fork nor White River districts overlie old crystalline crust, but instead overlie Paleocene-Eocene volcanics that are the likely source of inherited zircons. Districts of the Columbia segment have sparse inherited zircon populations (n = 38 of 350 total), ranging from 54 to 20 Ma. The dearth of inherited zircons in the center of the arc suggests limited contamination by a source no older than 55 Ma, likely the dominant Eocene sources of detrital zircon found within the Tyee Formation. Districts overlying the Klamath Terrane have slightly more substantial inherited zircon populations than districts overlying Siletzia but still decidedly few inherited grains (a total of 25 out of 85 grains analyzed, ranging from 44 to 19 Ma); these grains are likely sourced from similar contaminants to those underlying the central segment of the arc, instead of from accreted Mesozoic rocks of the Klamath Terrane. The hypabyssal plutonic rocks represent a small area (~1%) of exposures in the Western Cascades, and range in composition from diorites to granodiorites and minor granite. Fe-Ti oxides, where preserved, include magnetite and ilmenite in proportion of ~2:1, and together with presence of hornblende and biotite are suggestive of modest oxidation states of ~ ΔNNO of 0 to 1 (Carmichael & Nicholls, 1967). Abundant hornblende is observed in 31 of 36 available petrographic sections. Ba/Nb values are not obviously correlated with SiO₂ content from any given district, but tend to increase at any given SiO₂ content from north to south. Th/Ta ratios notably increase with SiO₂, and are lowest in the mid-latitude districts (North Santiam, Detroit Dam, Quartzville, and Blue River). While increased slab fluid could increase Ba relative to Nb, the greater abundance of Ba, Th, and Th/Ta southward at given SiO₂ are more consistent with an increased role of crustal contamination. Dy/Yb ratios decrease with increasing SiO₂ contents with the exception of the North Fork District. V/Sc ratios decrease with increasing SiO₂ with the exception of samples of the Spirit Lake Pluton, and slightly increase from south to north at any given SiO₂ content. Zircons in the Western Cascades plutonic rocks have characteristically large negative Eu anomalies (Eu/Eu* < 0.5) and small positive Ce anomalies, correlated with relatively reduced oxidation states and low water contents, even when directly associated with moderately economic porphyry Cu deposits. Although these magmas are sufficiently water-rich to abundantly crystallize and fractionate amphibole (at least 3 wt. % H₂O), it is evident that plagioclase likely crystallized early and was not suppressed by high water contents (> 3 wt. % H₂O). There is no evidence that Western Cascade magmas were strongly oxidized (> NNO +1). Although crustal thickness is poorly constrained in the north and south segments, it is evidently variable along-arc (and may thicken slightly to the south), but is likely relatively thin. I therefore suggest that crustal thickness and lithology substantially control ore potential within the Western Cascade Arc. Title: Geochemistry of Plutonic Rocks of the Western Cascades, Washington & Oregon : Relationship to Crustal Segmentation and Ore Genesis Author: Utevsky, Elinor S. The volcanic (~45-10 Ma) and plutonic rocks (~37-12 Ma) comprising the Western Cascades extend from northernmost California to southern British Columbia and are ancestral to modern arc magmatism. The ancestral arc hosts a series of small plutons that are locally associated with porphyry (Cu-Mo) and epithermal (Au) ore deposits. Three crustal segments identified by Schmidt et al. (2008, 2013) in the modern arc are potentially reflected in the geochemistry of the ancestral Cascades as well: Paleozoic-Mesozoic accreted terranes, metamorphic rocks, and granites to the north; thin Paleocene Siletzia oceanic crust of the Columbia Embayment in the center; and Paleozoic-Mesozoic ultramafic sheets and marine arc-related volcanic and sedimentary rocks of the Klamath Terrane to the south. Therefore, the Western Cascades of Washington and Oregon provide a field laboratory to examine the chemical compositions and ages of granitoid intrusions associated with a variety of magmatic-hydrothermal ore deposits, and to compare the compositions with the along-arc variation of the age, composition and thickness of the underlying crust. The majority of the 15 new zircon U-Pb ages reported in this study are 27 to 12 Ma with the exception of the ~37 Ma Snoqualmie North Fork intrusions of central WA. A total of 610 zircons were analyzed, of which 118 have ages older than the main population and are considered to be xenocrystic or inherited. The north segment contains the oldest (up to 67 Ma) and most continuous inherited population. The absence of inherited grains older than 67 Ma suggests that neither the North Fork nor White River districts overlie old crystalline crust, but instead overlie Paleocene-Eocene volcanics that are the likely source of inherited zircons. Districts of the Columbia segment have sparse inherited zircon populations (n = 38 of 350 total), ranging from 54 to 20 Ma. The dearth of inherited zircons in the center of the arc suggests limited contamination by a source no older than 55 Ma, likely the dominant Eocene sources of detrital zircon found within the Tyee Formation. Districts overlying the Klamath Terrane have slightly more substantial inherited zircon populations than districts overlying Siletzia but still decidedly few inherited grains (a total of 25 out of 85 grains analyzed, ranging from 44 to 19 Ma); these grains are likely sourced from similar contaminants to those underlying the central segment of the arc, instead of from accreted Mesozoic rocks of the Klamath Terrane. The hypabyssal plutonic rocks represent a small area (~1%) of exposures in the Western Cascades, and range in composition from diorites to granodiorites and minor granite. Fe-Ti oxides, where preserved, include magnetite and ilmenite in proportion of ~2:1, and together with presence of hornblende and biotite are suggestive of modest oxidation states of ~ ΔNNO of 0 to 1 (Carmichael & Nicholls, 1967). Abundant hornblende is observed in 31 of 36 available petrographic sections. Ba/Nb values are not obviously correlated with SiO₂ content from any given district, but tend to increase at any given SiO₂ content from north to south. Th/Ta ratios notably increase with SiO₂, and are lowest in the mid-latitude districts (North Santiam, Detroit Dam, Quartzville, and Blue River). While increased slab fluid could increase Ba relative to Nb, the greater abundance of Ba, Th, and Th/Ta southward at given SiO₂ are more consistent with an increased role of crustal contamination. Dy/Yb ratios decrease with increasing SiO₂ contents with the exception of the North Fork District. V/Sc ratios decrease with increasing SiO₂ with the exception of samples of the Spirit Lake Pluton, and slightly increase from south to north at any given SiO₂ content. Zircons in the Western Cascades plutonic rocks have characteristically large negative Eu anomalies (Eu/Eu* < 0.5) and small positive Ce anomalies, correlated with relatively reduced oxidation states and low water contents, even when directly associated with moderately economic porphyry Cu deposits. Although these magmas are sufficiently water-rich to abundantly crystallize and fractionate amphibole (at least 3 wt. % H₂O), it is evident that plagioclase likely crystallized early and was not suppressed by high water contents (> 3 wt. % H₂O). There is no evidence that Western Cascade magmas were strongly oxidized (> NNO +1). Although crustal thickness is poorly constrained in the north and south segments, it is evidently variable along-arc (and may thicken slightly to the south), but is likely relatively thin. I therefore suggest that crustal thickness and lithology substantially control ore potential within the Western Cascade Arc. Close