Pub Date : 2023-04-21DOI: 10.1130/abs/2022am-382433
Loc Luong, D. Cadol, Susan Bilek, J. M. Mclaughlin, J. Laronne
The transport of sediment is one of the fundamental geomorphic processes governing the evolution of landscapes. Reliable sediment flux forecasts are necessary for a variety of applications such as sedimentation engineering, river restoration, and flood risk mitigation. Quantifying bedload driven by flood events in ephemeral channels is notoriously difficult because of the scarcity, irregular nature, and high intensity of flash floods. Seismic methods appear to be a promising tool to characterize such fluvial processes, as they continuously record the ground motions caused by bedload and water movement while located outside of the active channel. We evaluated the performance of the physics-based model estimates of bedload fluxes developed by Tsai et al. (2012) by comparison to continuous monitoring of bedload measurements. The model establishes a mathematical relationship for the power spectral density (PSD) of the Rayleigh waves produced by vertically impulsive impacts from saltating particles based on the rate of impacts of fluvial sediment for a given bedload flux and grain size distribution. As a test of this model, we collected seismic data during flow events and compared the seismically-estimated bedload flux with high-precision bedload flux observations. These data derive from a multi-year campaign of monitoring an ephemeral, sand-and-gravel bedded channel reach of the Arroyo de los Pinos, central New Mexico, USA. Based on seismic data analysis, we find that bedload transport correlates to signals in the 30-80 Hz frequency range, whereas rainfall correlates to signals above 100 Hz. Inverting seismic data for bedload fluxes using the vertical impact model results in overestimates of the observed bedload flux by ~2 orders of magnitude. We investigate three hypotheses that may explain this discrepancy. First, the process of rolling and/or sliding particles, as opposed to saltating particles, may be the predominant cause of model discrepancy. Rolling particles are perhaps a very significant contributor to bedload at this study site. Second, the fine-grained alluvial characteristics of this riverbed, as contrasted to a rigid bedrock substratum used in the model, lead to significant attenuation of seismic energy as a result of the inelastic impact of bedload particles. Third, the bedload impact frequency model may not fully depict the impact of particles onto the riverbed in this environment. By thoroughly examining bedload transport mechanisms and considering alternative impulse functions for seismic noise generation, we intend to construct a new physics-based model within the framework of the existing models to quantify bedload transport in the ephemeral environment.
{"title":"QUANTIFYING BEDLOAD TRANSPORT IN EPHEMERAL CHANNELS USING SEISMIC METHODS","authors":"Loc Luong, D. Cadol, Susan Bilek, J. M. Mclaughlin, J. Laronne","doi":"10.1130/abs/2022am-382433","DOIUrl":"https://doi.org/10.1130/abs/2022am-382433","url":null,"abstract":"The transport of sediment is one of the fundamental geomorphic processes governing the evolution of landscapes. Reliable sediment flux forecasts are necessary for a variety of applications such as sedimentation engineering, river restoration, and flood risk mitigation. Quantifying bedload driven by flood events in ephemeral channels is notoriously difficult because of the scarcity, irregular nature, and high intensity of flash floods. Seismic methods appear to be a promising tool to characterize such fluvial processes, as they continuously record the ground motions caused by bedload and water movement while located outside of the active channel. We evaluated the performance of the physics-based model estimates of bedload fluxes developed by Tsai et al. (2012) by comparison to continuous monitoring of bedload measurements. The model establishes a mathematical relationship for the power spectral density (PSD) of the Rayleigh waves produced by vertically impulsive impacts from saltating particles based on the rate of impacts of fluvial sediment for a given bedload flux and grain size distribution. As a test of this model, we collected seismic data during flow events and compared the seismically-estimated bedload flux with high-precision bedload flux observations. These data derive from a multi-year campaign of monitoring an ephemeral, sand-and-gravel bedded channel reach of the Arroyo de los Pinos, central New Mexico, USA. Based on seismic data analysis, we find that bedload transport correlates to signals in the 30-80 Hz frequency range, whereas rainfall correlates to signals above 100 Hz. Inverting seismic data for bedload fluxes using the vertical impact model results in overestimates of the observed bedload flux by ~2 orders of magnitude. We investigate three hypotheses that may explain this discrepancy. First, the process of rolling and/or sliding particles, as opposed to saltating particles, may be the predominant cause of model discrepancy. Rolling particles are perhaps a very significant contributor to bedload at this study site. Second, the fine-grained alluvial characteristics of this riverbed, as contrasted to a rigid bedrock substratum used in the model, lead to significant attenuation of seismic energy as a result of the inelastic impact of bedload particles. Third, the bedload impact frequency model may not fully depict the impact of particles onto the riverbed in this environment. By thoroughly examining bedload transport mechanisms and considering alternative impulse functions for seismic noise generation, we intend to construct a new physics-based model within the framework of the existing models to quantify bedload transport in the ephemeral environment.","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83901539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-01DOI: 10.1130/abs/2022nc-374851
A. Stigall
{"title":"A REVIEW OF THE LATE ORDOVICIAN (KATIAN) RICHMONDIAN INVASION OF EASTERN LAURENTIA : WHAT I’VE LEARNED IN THE 25 YEARS SINCE STIG BERGSTRÖM FIRST INTRODUCED ME TO THESE ROCKS","authors":"A. Stigall","doi":"10.1130/abs/2022nc-374851","DOIUrl":"https://doi.org/10.1130/abs/2022nc-374851","url":null,"abstract":"","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86560728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-16DOI: 10.1130/abs/2022am-379803
E. Austin, A. Mychajliw
Documenting how ecosystems responded to climate change in the past can inform models for the future relevant to conservation decision-making. Packrat middens, or giant nests consisting of gathered plant material made by rodents of the genus Neotoma, represent one of the best data sources for understanding how plant communities change over time. These nests can be preserved for thousands of years, spanning episodes of glacial-interglacial variation, such as the Pleistocene-Holocene transition, or more recent fluctuations, such as the Little Ice Age and Medieval Warm Period. We used the USGS-NOAA paleoclimate open-access database to develop spatiotemporal reconstructions of plant species in Southern California, incorporating more than 242 individual middens with a total of 193 available radiocarbon dates spanning around 44,493 years cal BP. As a result, 374 plant species were identified within the SoCal middens, with Joshua Tree (Yucca brevifolia), Joint Pine (Ephedra species), and California Juniper (Juniperus californica) being the most abundant. We then applied these data to reconstruct past vegetation communities and contextualize a recently discovered asphaltic midden recovered from the La Brea Tar Pits (Los Angeles, California). The La Brea midden represents both the oldest and most coastal midden in our dataset in California and contains vegetation spanning Marine Isotope Stages 2-3. Ultimately, this research allows us to paint a picture of changing vegetation over time as a baseline for palaeoecological food web studies and can be compared with present day packrat nests found in this urban biodiversity hotspot. These data will be curated through the Conservation Paleobiology Network’s urban vegetation working group (based in Los Angeles, California) and made available for use by conservation and management projects throughout the region. With this information, CPN can implement habitat restoration projects in SoCal.
{"title":"UNDERSTANDING PALEOCLIMATE THROUGH SOUTHERN CALIFORNIA'S PACKRAT MIDDENS","authors":"E. Austin, A. Mychajliw","doi":"10.1130/abs/2022am-379803","DOIUrl":"https://doi.org/10.1130/abs/2022am-379803","url":null,"abstract":"Documenting how ecosystems responded to climate change in the past can inform models for the future relevant to conservation decision-making. Packrat middens, or giant nests consisting of gathered plant material made by rodents of the genus Neotoma, represent one of the best data sources for understanding how plant communities change over time. These nests can be preserved for thousands of years, spanning episodes of glacial-interglacial variation, such as the Pleistocene-Holocene transition, or more recent fluctuations, such as the Little Ice Age and Medieval Warm Period. We used the USGS-NOAA paleoclimate open-access database to develop spatiotemporal reconstructions of plant species in Southern California, incorporating more than 242 individual middens with a total of 193 available radiocarbon dates spanning around 44,493 years cal BP. As a result, 374 plant species were identified within the SoCal middens, with Joshua Tree (Yucca brevifolia), Joint Pine (Ephedra species), and California Juniper (Juniperus californica) being the most abundant. We then applied these data to reconstruct past vegetation communities and contextualize a recently discovered asphaltic midden recovered from the La Brea Tar Pits (Los Angeles, California). The La Brea midden represents both the oldest and most coastal midden in our dataset in California and contains vegetation spanning Marine Isotope Stages 2-3. Ultimately, this research allows us to paint a picture of changing vegetation over time as a baseline for palaeoecological food web studies and can be compared with present day packrat nests found in this urban biodiversity hotspot. These data will be curated through the Conservation Paleobiology Network’s urban vegetation working group (based in Los Angeles, California) and made available for use by conservation and management projects throughout the region. With this information, CPN can implement habitat restoration projects in SoCal.","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81745223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-01DOI: 10.1130/abs/2022am-380130
Kassandra O. Lindsey, Lauren Broes
{"title":"GEOCHRONOLOGY AND GEOMORPHIC MAPPING TO ESTIMATE DEBRIS-FLOW DEPOSITIONAL AGES AND RECURRENCE INTERVALS ALONG STATE HIGHWAY 145 AND 62, SAN MIGUEL COUNTY, COLORADO","authors":"Kassandra O. Lindsey, Lauren Broes","doi":"10.1130/abs/2022am-380130","DOIUrl":"https://doi.org/10.1130/abs/2022am-380130","url":null,"abstract":"","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88327406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-31DOI: 10.1130/abs/2022am-378122
D. Malone, M. Sell, Aidan Krieger, D. Malone
Here we present the results of detailed (1:24,000 scale) mapping of the Bald Mountain 7.5 Minute Quadrangle Wyoming, which includes Archean basement rocks of the Laramide Bighorn uplift. These basement rocks are mantled by Paleozoic cratonic strata of the Flathead, Gros Ventre, Gallatin, Bighorn, Madison and Amsden formations. This region was explored for gold associated with the basement rocks, and Th in the basal Flathead sandstone. Isotopic age determinations (LA-ICPMS U-Pb on zircon) of the basement rocks were conducted at the University of Arizona Laserchron Center. Three phases of Archean rocks were defined, all of which range from ∼2880-2890 Ma, and include a prominent, pink, strongly foliated (WNW trending) alkali feldspar granite with pegmatite, a weakly foliated purple granite, and a yellow, poorly exposed adamellite. These rocks were uplifted during the Paleogene Laramide orogeny, and now form a southwest verging breached drape fold over a steeply inclined, basement-cored reverse fault. Dips of footwall strata range from 10–70° to the SW. Hanging wall rocks dip gently to the NE. Quaternary landslide deposits occur along steep slopes in the Gros Ventre Shale and alluvium occurs along the principle streams.
{"title":"GEOLOGIC MAP OF THE BALD MOUNTAIN QUADRANGLE, NORTHERN BIGHORN MOUNTAINS, WYOMING","authors":"D. Malone, M. Sell, Aidan Krieger, D. Malone","doi":"10.1130/abs/2022am-378122","DOIUrl":"https://doi.org/10.1130/abs/2022am-378122","url":null,"abstract":"Here we present the results of detailed (1:24,000 scale) mapping of the Bald Mountain 7.5 Minute Quadrangle Wyoming, which includes Archean basement rocks of the Laramide Bighorn uplift. These basement rocks are mantled by Paleozoic cratonic strata of the Flathead, Gros Ventre, Gallatin, Bighorn, Madison and Amsden formations. This region was explored for gold associated with the basement rocks, and Th in the basal Flathead sandstone. Isotopic age determinations (LA-ICPMS U-Pb on zircon) of the basement rocks were conducted at the University of Arizona Laserchron Center. Three phases of Archean rocks were defined, all of which range from ∼2880-2890 Ma, and include a prominent, pink, strongly foliated (WNW trending) alkali feldspar granite with pegmatite, a weakly foliated purple granite, and a yellow, poorly exposed adamellite. These rocks were uplifted during the Paleogene Laramide orogeny, and now form a southwest verging breached drape fold over a steeply inclined, basement-cored reverse fault. Dips of footwall strata range from 10–70° to the SW. Hanging wall rocks dip gently to the NE. Quaternary landslide deposits occur along steep slopes in the Gros Ventre Shale and alluvium occurs along the principle streams.","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74067709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1130/abs/2023se-385291
S. Carmichael, Lilith Hazzard, A. Dombrowski, A. Munkhjargal, J. Waters, P. Königshof, S. Gonchigdorj
{"title":"FLUID ALTERATION OF THE FAMENNIAN HUSHOOT SHIVEETIIN GOL SECTION (BARUUNHUURAI TERRANE, MONGOLIA) PRESERVED IN TITANIA MINERALS: HOW DOES THIS AFFECT GEOCHEMICAL FINGERPRINTING OF SHALLOW WATERS?","authors":"S. Carmichael, Lilith Hazzard, A. Dombrowski, A. Munkhjargal, J. Waters, P. Königshof, S. Gonchigdorj","doi":"10.1130/abs/2023se-385291","DOIUrl":"https://doi.org/10.1130/abs/2023se-385291","url":null,"abstract":"","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75833192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1130/abs/2023se-385745
Matthew Smart, G. Filippelli, W. Gilhooly, K. Ozaki, Chris Reinhard, J. Marshall, J. Whiteside
{"title":"LINKING LAND PLANTS TO DEVONIAN MARINE ANOXIC EVENTS: INTEGRATING NUTRIENT RECORDS AND BIOGEOCHEMICAL MODELING","authors":"Matthew Smart, G. Filippelli, W. Gilhooly, K. Ozaki, Chris Reinhard, J. Marshall, J. Whiteside","doi":"10.1130/abs/2023se-385745","DOIUrl":"https://doi.org/10.1130/abs/2023se-385745","url":null,"abstract":"","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74662243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1130/abs/2023se-385734
I. Yasar, B. Miller, W. Hames
{"title":"POLYMETAMORPHIC EVOLUTION OF THE WESTERN BLUE RIDGE TERRANE THROUGH ACADIAN AND ALLEGHANIAN OROGENIES","authors":"I. Yasar, B. Miller, W. Hames","doi":"10.1130/abs/2023se-385734","DOIUrl":"https://doi.org/10.1130/abs/2023se-385734","url":null,"abstract":"","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75360212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1130/abs/2023se-386116
Rebekah Nicholas, D. Vesper, Autum R. Downey, I. Padilla
{"title":"RELATIONSHIPS BETWEEN METAL CHEMISTRY, CARBON CONTENT, AND PARTICLE SIZE IN CLASTIC CAVE SEDIMENTS","authors":"Rebekah Nicholas, D. Vesper, Autum R. Downey, I. Padilla","doi":"10.1130/abs/2023se-386116","DOIUrl":"https://doi.org/10.1130/abs/2023se-386116","url":null,"abstract":"","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78695955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1130/abs/2023se-385928
Robby Morrow, C. Wilson, Mason L. Payeur
{"title":"GEOCHEMISTRY OF CAROLINA TERRANE METAVOLCANICS AND ASSOCIATED INTRUSIVE ROCKS OF THE RED HILL AND EDGEFIELD 7.5-MINUTE QUADRANGLES, EDGEFIELD COUNTY, SOUTH CAROLINA","authors":"Robby Morrow, C. Wilson, Mason L. Payeur","doi":"10.1130/abs/2023se-385928","DOIUrl":"https://doi.org/10.1130/abs/2023se-385928","url":null,"abstract":"","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78923583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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