Pub Date : 2024-01-08DOI: 10.1130/abs/2023am-392842
Lindsi J. Allman, Chelsie N. Bowman, Jiří Frýda, Nevin P. Kozik, Jeremy Owens, Seth Young
The Silurian was marked by repeated extinctions, carbon cycle volatility, and significant intervals of climatic change. The most notable of these events were the Ludfordian Lau/Kozlowskii extinction and associated Mid-Ludfordian Lau carbon isotope excursion, both of which have been linked to a period of global cooling and expanded reducing conditions in the global oceans. Here we present new data that characterize marine paleoredox conditions of the Prague Basin, a peri-Gondwanan terrane. This study utilizes iodine-to-calcium ratios to assess local redox conditions in a shallow water carbonate succession and iron speciation and redox-sensitive trace element concentrations to assess local redox conditions of a deeper water sequence. Consistently low values of I/Ca in the shallow water section suggest either persistent local low oxygen conditions or possibly diagenetic overprinting. Iron speciation data suggest that bottom water redox conditions in the deeper shelf setting were consistently anoxic with possible intermittent euxinia. Concentrations of redox-sensitive trace elements consistently higher than upper continental crust values also indicate persistent reducing conditions in the deeper part of the basin. These local redox proxy data from the Prague Basin, including trends in new pyrite sulfur isotope (δ 34 S pyr ) data, are consistent with findings that expansion of anoxic and/or euxinic oceanic conditions occurred. These data, derived from a mid-paleolatitude marine setting, fill an important gap in our current global dataset from this interval of the late Silurian. Thematic collection: This article is part of the Chemical Evolution of the Mid-Paleozoic Earth System and Biotic Response collection available at: https://www.lyellcollection.org/topic/collections/chemical-evolution-of-the-mid-paleozoic-earth-system Supplementary material: https://doi.org/10.6084/m9.figshare.c.7008107
志留纪的特点是反复的生物灭绝、碳循环的不稳定性以及重大的气候变化时期。其中最显著的事件是卢德福期的刘氏/科兹洛夫斯基灭绝以及与之相关的卢德福期中期的刘氏碳同位素偏移，这两个事件都与全球变冷时期和全球海洋的扩大还原条件有关。在此，我们提供了新的数据，描述了布拉格盆地（近贡瓦南地层）海洋古氧化还原条件的特征。这项研究利用碘钙比来评估浅水碳酸盐层序的局部氧化还原条件，并利用铁离子和对氧化还原敏感的痕量元素浓度来评估深水层序的局部氧化还原条件。浅水区段的 I/Ca 值持续偏低，表明当地存在持续的低氧条件，或者可能存在成岩叠压。铁标本数据表明，深层陆架环境的底水氧化还原条件一直处于缺氧状态，可能存在间歇性缺氧。对氧化还原反应敏感的痕量元素的浓度始终高于大陆地壳上层的数值，这也表明盆地深部的还原条件持续存在。布拉格盆地的这些局部氧化还原代用数据，包括新黄铁矿硫同位素（δ 34 S pyr）数据的趋势，与缺氧和/或缺氧海洋条件扩展的发现是一致的。这些数据来自中白垩世海洋环境，填补了我们目前在晚志留纪这一区间的全球数据集的一个重要空白。 专题集：本文是中古生代地球系统化学演化与生物响应文集的一部分，可从以下网址获取： https://www.lyellcollection.org/topic/collections/chemical-evolution-of-the-mid-paleozoic-earth-system 补充材料： https://doi.org/10.6084/m9.figshare.c.7008107
{"title":"CONSTRAINING REDUCING CONDITIONS IN THE PRAGUE BASIN DURING THE LATE SILURIAN LAU/KOZLOWSKII EXTINCTION EVENT","authors":"Lindsi J. Allman, Chelsie N. Bowman, Jiří Frýda, Nevin P. Kozik, Jeremy Owens, Seth Young","doi":"10.1130/abs/2023am-392842","DOIUrl":"https://doi.org/10.1130/abs/2023am-392842","url":null,"abstract":"\u0000 The Silurian was marked by repeated extinctions, carbon cycle volatility, and significant intervals of climatic change. The most notable of these events were the Ludfordian Lau/Kozlowskii extinction and associated Mid-Ludfordian Lau carbon isotope excursion, both of which have been linked to a period of global cooling and expanded reducing conditions in the global oceans. Here we present new data that characterize marine paleoredox conditions of the Prague Basin, a peri-Gondwanan terrane. This study utilizes iodine-to-calcium ratios to assess local redox conditions in a shallow water carbonate succession and iron speciation and redox-sensitive trace element concentrations to assess local redox conditions of a deeper water sequence. Consistently low values of I/Ca in the shallow water section suggest either persistent local low oxygen conditions or possibly diagenetic overprinting. Iron speciation data suggest that bottom water redox conditions in the deeper shelf setting were consistently anoxic with possible intermittent euxinia. Concentrations of redox-sensitive trace elements consistently higher than upper continental crust values also indicate persistent reducing conditions in the deeper part of the basin. These local redox proxy data from the Prague Basin, including trends in new pyrite sulfur isotope (δ\u0000 34\u0000 S\u0000 pyr\u0000 ) data, are consistent with findings that expansion of anoxic and/or euxinic oceanic conditions occurred. These data, derived from a mid-paleolatitude marine setting, fill an important gap in our current global dataset from this interval of the late Silurian.\u0000 \u0000 \u0000 Thematic collection:\u0000 This article is part of the Chemical Evolution of the Mid-Paleozoic Earth System and Biotic Response collection available at:\u0000 https://www.lyellcollection.org/topic/collections/chemical-evolution-of-the-mid-paleozoic-earth-system\u0000 \u0000 \u0000 Supplementary material:\u0000 https://doi.org/10.6084/m9.figshare.c.7008107\u0000","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":"27 19","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139445188","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 : 2023-08-01DOI: 10.1130/abs/2022am-380336
J. Kasbohm, B. Schoene, S. MacLennan, D. Evans, B. Weiss
While rates of Phanerozoic plate movements and magnetic field reversals have been well studied, little is known about such phenomena on early Earth. The ca. 2.8 – 2.7 Ga Fortescue Group on the Pilbara craton in Western Australia has been recognized as a well-preserved sequence of Archean rift volcanics thought to derive from a flood basalt province, and may have been moving rapidly across the globe at two different intervals in its depositional history. We present the results of a magnetostratigraphic study integrated with high-precision U-Pb ID-TIMS geochronology aiming to quantify rates of cratonic motion and provide a continuous time series for changes in Pilbara paleogeography during these two rapid intervals, at ~2.77 and 2.72 Ga. We provide six new or updated high-quality paleomagnetic poles for inclusion in databases tracking Precambrian cratonic motion. During the craton ’ s largest geographic displacement at ~2.77 Ga, we resolve a minimum drift rate of 23 ± 20 cm/a if there was substantial rotation of the Pilbara craton along with translational motion, and a more rapid minimum estimate of 64 ± 23 cm/a if the motion was dominated by translation; these estimates exceed both Mesoarchean and most modern rates of plate motion. We provide a new high-precision U-Pb zircon age of 2721.23 ± 0.88/0.88/6.9 Ma for the Tumbiana Formation stromatolite colony, which developed as the Pilbara craton drifted from 51.5 ± 7.0 ◦ to 32.1 ± 5.7 ◦ paleolatitude. Although the Fortescue Group has been considered an early prototype of large igneous provinces, it was emplaced over a longer duration than its Phanerozoic counterparts and does not fit at least one definition of a large igneous province (LIP). But as a potential prototype of LIP magmatism, the Fortescue succession chronicles eruptive dynamics, rapid paleogeographic changes, and a series of robustly determined magnetic field reversals during the Neoarchean.
{"title":"PALEOGEOGRAPHY AND HIGH-PRECISION GEOCHRONOLOGY OF THE NEOARCHEAN FORTESCUE GROUP, PILBARA, WESTERN AUSTRALIA","authors":"J. Kasbohm, B. Schoene, S. MacLennan, D. Evans, B. Weiss","doi":"10.1130/abs/2022am-380336","DOIUrl":"https://doi.org/10.1130/abs/2022am-380336","url":null,"abstract":"While rates of Phanerozoic plate movements and magnetic field reversals have been well studied, little is known about such phenomena on early Earth. The ca. 2.8 – 2.7 Ga Fortescue Group on the Pilbara craton in Western Australia has been recognized as a well-preserved sequence of Archean rift volcanics thought to derive from a flood basalt province, and may have been moving rapidly across the globe at two different intervals in its depositional history. We present the results of a magnetostratigraphic study integrated with high-precision U-Pb ID-TIMS geochronology aiming to quantify rates of cratonic motion and provide a continuous time series for changes in Pilbara paleogeography during these two rapid intervals, at ~2.77 and 2.72 Ga. We provide six new or updated high-quality paleomagnetic poles for inclusion in databases tracking Precambrian cratonic motion. During the craton ’ s largest geographic displacement at ~2.77 Ga, we resolve a minimum drift rate of 23 ± 20 cm/a if there was substantial rotation of the Pilbara craton along with translational motion, and a more rapid minimum estimate of 64 ± 23 cm/a if the motion was dominated by translation; these estimates exceed both Mesoarchean and most modern rates of plate motion. We provide a new high-precision U-Pb zircon age of 2721.23 ± 0.88/0.88/6.9 Ma for the Tumbiana Formation stromatolite colony, which developed as the Pilbara craton drifted from 51.5 ± 7.0 ◦ to 32.1 ± 5.7 ◦ paleolatitude. Although the Fortescue Group has been considered an early prototype of large igneous provinces, it was emplaced over a longer duration than its Phanerozoic counterparts and does not fit at least one definition of a large igneous province (LIP). But as a potential prototype of LIP magmatism, the Fortescue succession chronicles eruptive dynamics, rapid paleogeographic changes, and a series of robustly determined magnetic field reversals during the Neoarchean.","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":"94 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83744203","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 : 2023-07-19DOI: 10.1130/abs/2022am-377461
I. Allred, M. Blum, B. Frederick, Abdullah M. Wahbi
Continental-scale recycling of detrital zircon (DZ) grains and associated sediment across North American is not well understood. We trace a through line following the DZ proxy for the detritus originally sourced from Grenville and Appalachian orogens. This paper lays out an antecedent framework for one of the greatest sedimentation episodes of the Phanerozoic: the initial dispersal of Appalachian- and Grenville-age DZ grains to the western passive margin of Laurentia and the subsequent paleodrainage reorganization and sediment remobilization back to the east. The DZ U-Pb signature of the Appalachian-Ouachita orogenic system is dominated by Grenville (ca. 1250–950 Ma) and Appalachian (ca. 500–275 Ma) age groups and dominates the Phanerozoic record of North America. This study juxtaposes Pennsylvanian to modern DZ U-Pb data from across North America and demonstrates a persistent Appalachian signature, including a recycled Appalachian signature across Western North America. Lower Pennsylvanian deposits proximal to the Appalachian orogen are 50%–75% Appalachian- and Grenville-age DZ grains, representing the key component in the primary Appalachian signature. It remains unclear how the Appalachian signal was propagated to the west, but the Appalachian DZ signature was clearly present across the late Paleozoic passive margin of Laurentia and thus antecedent to potential DZ recycling throughout the Mesozoic and Cenozoic Eras. Triassic DZ samples document transcontinental fluvial systems that reached the western Laurentian margin, but subsequent Jurassic-Cretaceous samples indicate drainage reversal due to the rise of the Mesozoic Western Cordillera. A persistent Appalachian signature exists in these western-sourced, eastward-flowing systems—a phenomenon that continues to the present: samples are frequently composed of >40% Appalachian- and Grenville-age DZ. However, none of these systems are interpreted to be sourced by primary Appalachian or Grenville terranes, suggesting a recycled Appalachian signature. The persistent Appalachian signature, originally sourced by the linking of two orogenic terranes, continues to dominate the Phanerozoic record of much of North America to this day.
{"title":"THERE AND BACK AGAIN: RECYCLING OF THE APPALACHIAN SIGNATURE IN DZ U-PB RECORDS OF PHANEROZOIC NORTH AMERICA","authors":"I. Allred, M. Blum, B. Frederick, Abdullah M. Wahbi","doi":"10.1130/abs/2022am-377461","DOIUrl":"https://doi.org/10.1130/abs/2022am-377461","url":null,"abstract":"\u0000 Continental-scale recycling of detrital zircon (DZ) grains and associated sediment across North American is not well understood. We trace a through line following the DZ proxy for the detritus originally sourced from Grenville and Appalachian orogens. This paper lays out an antecedent framework for one of the greatest sedimentation episodes of the Phanerozoic: the initial dispersal of Appalachian- and Grenville-age DZ grains to the western passive margin of Laurentia and the subsequent paleodrainage reorganization and sediment remobilization back to the east. The DZ U-Pb signature of the Appalachian-Ouachita orogenic system is dominated by Grenville (ca. 1250–950 Ma) and Appalachian (ca. 500–275 Ma) age groups and dominates the Phanerozoic record of North America. This study juxtaposes Pennsylvanian to modern DZ U-Pb data from across North America and demonstrates a persistent Appalachian signature, including a recycled Appalachian signature across Western North America. Lower Pennsylvanian deposits proximal to the Appalachian orogen are 50%–75% Appalachian- and Grenville-age DZ grains, representing the key component in the primary Appalachian signature. It remains unclear how the Appalachian signal was propagated to the west, but the Appalachian DZ signature was clearly present across the late Paleozoic passive margin of Laurentia and thus antecedent to potential DZ recycling throughout the Mesozoic and Cenozoic Eras. Triassic DZ samples document transcontinental fluvial systems that reached the western Laurentian margin, but subsequent Jurassic-Cretaceous samples indicate drainage reversal due to the rise of the Mesozoic Western Cordillera. A persistent Appalachian signature exists in these western-sourced, eastward-flowing systems—a phenomenon that continues to the present: samples are frequently composed of >40% Appalachian- and Grenville-age DZ. However, none of these systems are interpreted to be sourced by primary Appalachian or Grenville terranes, suggesting a recycled Appalachian signature. The persistent Appalachian signature, originally sourced by the linking of two orogenic terranes, continues to dominate the Phanerozoic record of much of North America to this day.","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88465240","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 : 2023-07-13DOI: 10.1130/abs/2022nc-375495
Noel J. Hernandez Gomez, Lisette E. Melendez, Whitney A. Lapic, Sarah L. Sheffield, Ronald D. Lewis
Crinoids, the group known today as the sea lilies, were a major constituent of ocean environments from the late Carboniferous (323–299 million years ago). However, crinoid fossil-forming potential is poor, and they typically fell apart quickly after death. This limits our ability to study much about their life histories, including how they would have grown. Through the discovery of an area of exceptional fossil preservation in the Barnsdall Formation of Oklahoma, we have a rare chance to learn about the growth of one of these species of crinoids, Erisocrinus typus. Here we perform a growth analysis of a well-preserved series of fossils and discuss the patterns that it showed from its juvenile stage to adulthood.
{"title":"EXAMINING THE ONTOGENY OF THE PENNSYLVANIAN CLADID CRINOID ERISOCRINUS","authors":"Noel J. Hernandez Gomez, Lisette E. Melendez, Whitney A. Lapic, Sarah L. Sheffield, Ronald D. Lewis","doi":"10.1130/abs/2022nc-375495","DOIUrl":"https://doi.org/10.1130/abs/2022nc-375495","url":null,"abstract":"\u0000 Crinoids, the group known today as the sea lilies, were a major constituent of ocean environments from the late Carboniferous (323–299 million years ago). However, crinoid fossil-forming potential is poor, and they typically fell apart quickly after death. This limits our ability to study much about their life histories, including how they would have grown. Through the discovery of an area of exceptional fossil preservation in the Barnsdall Formation of Oklahoma, we have a rare chance to learn about the growth of one of these species of crinoids, Erisocrinus typus. Here we perform a growth analysis of a well-preserved series of fossils and discuss the patterns that it showed from its juvenile stage to adulthood.","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81926187","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 : 2023-06-28DOI: 10.1130/abs/2022am-380343
R. Martindale, Barbara Sofia Sulbaran Reyes, Sinjini Sinha, North Cooc
{"title":"“REEF SURVIVOR” – A NEW BOARD GAME DESIGNED TO TEACH COLLEGE AND UNIVERSITY UNDERGRADUATE STUDENTS ABOUT REEF ECOLOGY, EVOLUTION, AND EXTINCTION","authors":"R. Martindale, Barbara Sofia Sulbaran Reyes, Sinjini Sinha, North Cooc","doi":"10.1130/abs/2022am-380343","DOIUrl":"https://doi.org/10.1130/abs/2022am-380343","url":null,"abstract":"","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":"116 9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84244251","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 : 2023-06-07DOI: 10.1130/abs/2022am-378572
F. Rengers, L. McGuire, K. Barnhart, A. Youberg, D. Cadol, Alexander N. Gorr, Olivia J. Hoch, Rebecca Beers, J. Kean
Abstract. Debris flows transport large quantities of water and granular material, such as sediment and wood, and this mixture can have devastating effects on life and infrastructure. The proportion of large woody debris (LWD) incorporated into debris flows can be enhanced in forested areas recently burned by wildfire because wood recruitment into channels accelerates in burned forests. In this study, using four small watersheds in the Gila National Forest, New Mexico, which burned in the 2020 Tadpole Fire, we explored new approaches to estimate debris flow velocity based on LWD characteristics and the role of LWD in debris flow volume retention. To understand debris flow volume model predictions, we examined two models for debris flow volume estimation: (1) the current volume prediction model used in US Geological Survey debris flow hazard assessments and (2) a regional model developed to predict the sediment yield associated with debris-laden flows. We found that the regional model better matched the magnitude of the observed sediment at the terminal fan, indicating the utility of regionally calibrated parameters for debris flow volume prediction. However, large wood created sediment storage upstream from the terminal fan, and this volume was of the same magnitude as the total debris flow volume stored at the terminal fans. Using field and lidar data we found that sediment retention by LWD is largely controlled by channel reach slope and a ratio of LWD length to channel width between 0.25 and 1. Finally, we demonstrated a method for estimating debris flow velocity based on estimates of the critical velocity required to break wood, which can be used in future field studies to estimate minimum debris flow velocity values.
{"title":"THE INFLUENCE OF LARGE WOODY DEBRIS ON POST-WILDFIRE DEBRIS-FLOW SEDIMENT STORAGE","authors":"F. Rengers, L. McGuire, K. Barnhart, A. Youberg, D. Cadol, Alexander N. Gorr, Olivia J. Hoch, Rebecca Beers, J. Kean","doi":"10.1130/abs/2022am-378572","DOIUrl":"https://doi.org/10.1130/abs/2022am-378572","url":null,"abstract":"Abstract. Debris flows transport large quantities of water and granular material, such as sediment and wood, and this mixture can have devastating effects on life and infrastructure. The proportion of large woody debris (LWD) incorporated into debris flows can be enhanced in forested areas recently burned by wildfire because wood recruitment into channels accelerates in burned forests. In this study, using four small watersheds in the Gila National Forest, New Mexico, which burned in the 2020 Tadpole Fire, we explored new approaches to estimate debris flow velocity based on LWD characteristics and the role of LWD in debris flow volume retention. To understand debris flow volume model predictions, we examined two models for debris flow volume estimation: (1) the current volume prediction model used in US Geological Survey debris flow hazard assessments and (2) a regional model developed to predict the sediment yield associated with debris-laden flows. We found that the regional model better matched the magnitude of the observed sediment at the terminal fan, indicating the utility of regionally calibrated parameters for debris flow volume prediction. However, large wood created sediment storage upstream from the terminal fan, and this volume was of the same magnitude as the total debris flow volume stored at the terminal fans. Using field and lidar data we found that sediment retention by LWD is largely controlled by channel reach slope and a ratio of LWD length to channel width between 0.25 and 1. Finally, we demonstrated a method for estimating debris flow velocity based on estimates of the critical velocity required to break wood, which can be used in future field studies to estimate minimum debris flow velocity values.\u0000","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":"66 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90500462","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 : 2023-06-01DOI: 10.1130/abs/2022ne-375258
J. Thomka, Lilian K. Gunderson
A large favositid tabulate coral colony from the Middle Devonian Edgecliff Member of the Onondaga Formation, collected from Port Colborne, southernmost Ontario, is described herein because of several noteworthy paleontological features preserved via overgrowth by the coral. The initial substratum colonized and subsequently overgrown by the favositid was a large solitary rugose coral; and outward growth resulted in overgrowth of multiple macrofossils, including relatively long portions of large-diameter (probably camerate) crinoid columns. The crinoid columns, which likely represent portions of robust, recumbent dististelar attachment structures, are otherwise known almost entirely from isolated columnals at the collection locality and similar high-energy biostromal lithofacies in the Edgecliff Member elsewhere. One of the crinoid columns is encrusted by a stenolaemate bryozoan containing several examples of a parasitic bioclaustration structure similar to Catellocaula. Hence, the composite coral-crinoid-bryozoan association contains two forms of bioimmuration: preservation of the relatively intact crinoid columns via overgrowth and eventual incorporation into the base of the tabulate coral and preservation of the outline of the bioclaustrated organism (potentially an ascidian tunicate) via embedment in the bryozoan. This specimen serves as a testament to the diversity of biotic interactions and preservational mechanisms that occurred in Paleozoic carbonate buildups.
{"title":"MULTIPLE FORMS OF BIOIMMURATION IN A CORAL-CRINOID-BRYOZOAN ASSOCIATION FROM THE MIDDLE DEVONIAN ONONDAGA FORMATION OF SOUTHERN ONTARIO","authors":"J. Thomka, Lilian K. Gunderson","doi":"10.1130/abs/2022ne-375258","DOIUrl":"https://doi.org/10.1130/abs/2022ne-375258","url":null,"abstract":"A large favositid tabulate coral colony from the Middle Devonian Edgecliff Member of the Onondaga Formation, collected from Port Colborne, southernmost Ontario, is described herein because of several noteworthy paleontological features preserved via overgrowth by the coral. The initial substratum colonized and subsequently overgrown by the favositid was a large solitary rugose coral; and outward growth resulted in overgrowth of multiple macrofossils, including relatively long portions of large-diameter (probably camerate) crinoid columns. The crinoid columns, which likely represent portions of robust, recumbent dististelar attachment structures, are otherwise known almost entirely from isolated columnals at the collection locality and similar high-energy biostromal lithofacies in the Edgecliff Member elsewhere. One of the crinoid columns is encrusted by a stenolaemate bryozoan containing several examples of a parasitic bioclaustration structure similar to Catellocaula. Hence, the composite coral-crinoid-bryozoan association contains two forms of bioimmuration: preservation of the relatively intact crinoid columns via overgrowth and eventual incorporation into the base of the tabulate coral and preservation of the outline of the bioclaustrated organism (potentially an ascidian tunicate) via embedment in the bryozoan. This specimen serves as a testament to the diversity of biotic interactions and preservational mechanisms that occurred in Paleozoic carbonate buildups.","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":"139 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85591607","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 : 2023-05-01DOI: 10.1130/abs/2022am-383366
B. Kendall, Shuai Yang, Xinze Lu, Xinming Chen, Wang Zheng, J. Owens, Seth A. Young
{"title":"URANIUM AND MOLYBDENUM ISOTOPE EVIDENCE FOR GLOBALLY EXTENSIVE MARINE EUXINIA ON CONTINENTAL MARGINS AND IN EPICONTINENTAL SEAS DURING THE DEVONIAN-CARBONIFEROUS HANGENBERG CRISIS","authors":"B. Kendall, Shuai Yang, Xinze Lu, Xinming Chen, Wang Zheng, J. Owens, Seth A. Young","doi":"10.1130/abs/2022am-383366","DOIUrl":"https://doi.org/10.1130/abs/2022am-383366","url":null,"abstract":"","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80513017","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 : 2023-04-21DOI: 10.1130/abs/2022am-383797
Jennifer Lindline, Megan Begay, Letisha Mailboy
The Upper Pecos Watershed (UPW), part of the Rio Grande Basin, extends from the headwaters of the Pecos River in the Sangre de Cristo Mountains (elevation > 12,000 ft) to its confluences with Cow Creek and El Rito (elevation ~ 6,000 ft). The Upper Pecos River supports recreation, agriculture, cattle grazing, tourism, and other uses. It is one of the most ecologically diverse and culturally significant waters of New Mexico. The UPW, along with nearby regional watersheds, was impacted by the 2022 Hermits Peak/Calf Canyon Fire, the largest wildfire in New Mexico’s history (>340,000 acres). Approximately 40,150 acres burned in the UPW, 34% of which were classified by the USFS Burned Area Emergency Response (BAER) team as high burn severity. Such classification raised concerns for post-fire impacts to water quality from increased river discharge, hillside erosion, and fire sedimentation. We collected weekly in-the-field physical-chemical parameters (conductivity, temperature, dissolved oxygen, and pH) using a YSI 556 Multi Probe and grab water samples for turbidity analysis using a Hach TL2300 turbidimeter throughout Summer 2022 to assess the after-effects of the wildfire. These data were compared to water quality data collected by our team in Summer 2020 and 2021 to determine if and how much the water quality departed from baseline values. From the onset of the monsoon rains (mid-June), ash and floating debris were observed in the stream, along with high turbidity and low dissolved oxygen values both in exceedance of the NMAC 20.6.4.900 water quality threshold (> 10.00 NTU and 6 mg/L respectively). Values of pH ranged between 3.79-7.69 with the lowest values corresponding roughly to high discharge events. Temperature and electrical conductivity met water quality standards for the Upper Pecos River’s high-quality cold-water designation (NMAC 20.6.2). We continue to monitor the river, as water quality in the system sets the basis for the rest of ecosystem health
上佩科斯流域(UPW)是里奥格兰德盆地的一部分，从佩科斯河在Sangre de Cristo山脉的源头(海拔> 12,000英尺)延伸到与Cow Creek和El Rito(海拔~ 6,000英尺)的汇合处。上佩科斯河支持娱乐、农业、放牧、旅游和其他用途。它是新墨西哥州最具生态多样性和文化意义的水域之一。UPW以及附近的区域流域受到2022年隐士峰/小牛峡谷大火的影响，这是新墨西哥州历史上最大的野火(超过34万英亩)。在UPW中烧毁了大约40,150英亩，其中34%被USFS烧毁地区应急响应(BAER)团队列为高烧伤严重程度。这样的分类引起了人们对火灾后河流流量增加、山坡侵蚀和火灾沉积对水质的影响的关注。在整个2022年夏季，我们使用YSI 556 Multi Probe每周收集现场物理化学参数(电导率、温度、溶解氧和pH值)，并使用Hach TL2300浊度计采集水样进行浊度分析，以评估野火的后续影响。将这些数据与我们团队在2020年夏季和2021年夏季收集的水质数据进行比较，以确定水质是否偏离基线值以及偏离基线值的程度。季风降雨开始(6月中旬)，河流中出现了灰渣和浮渣，浊度高，溶解氧低，均超过了NMAC 20.6.4.900水质阈值(分别> 10.00 NTU和6 mg/L)。pH值在3.79-7.69之间，最小值大致对应于高放电事件。温度和电导率符合上佩科斯河高质量冷水指定的水质标准(NMAC 20.6.2)。我们继续监测河流，因为系统中的水质为生态系统的其他健康奠定了基础
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Pub Date : 2023-04-21DOI: 10.1130/abs/2022am-378537
Kambray Townsend, L. Crossey, K. Karlstrom, B. Griego, L. Crowley
{"title":"HYDROCHEMISTRY OF AN ALPINE KARST SYSTEM, NORTHERN NEW MEXICO: LAS HUERTAS","authors":"Kambray Townsend, L. Crossey, K. Karlstrom, B. Griego, L. Crowley","doi":"10.1130/abs/2022am-378537","DOIUrl":"https://doi.org/10.1130/abs/2022am-378537","url":null,"abstract":"","PeriodicalId":12535,"journal":{"name":"Geological Society of America Abstracts with Programs","volume":"51 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80989538","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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