COLLABORATIVE RESEARCH: Organic Carbon Burial, Anoxia, and Ecological-Evolutionary Events in the Appalachian Basin During the Middle and Late Devonian (Givetian-Famennian)

合作研究：阿巴拉契亚盆地中、晚泥盆世（吉维田-法门纪）有机碳埋藏、缺氧和生态演化事件

• 批准号: 9725803
• 负责人: Carlton Brett
• 金额: $ 2.21万
• 依托单位: University of Rochester
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-01-01 至 1999-03-02
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9725803&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; Organic; Carbon; Burial

9725803 Brett The widespread but episodic deposition of organic carbon-rich facies (ORF) in marine basins during Earth history has been recognized as an important problem in the geological sciences. Water column stratification and consequent anoxia has commonly been the favored hypothesis to account for ancient ORF deposition, but in recent years alternate hypotheses have emerged that highlight the importance of coupled biogeochemical and sedimentological processes (e.g., high productivity, stratigraphic condensation), and even suggest that water column anoxia may not have been as prevalent as once thought. Yet oxygen deficiency, whether as a cause or consequence of organic carbon burial, has been postulated as a potential driving force for evolutionary change and extinction during the Phanerozoic. For example, it was recently implicated as a possible cause of overturn events punctuating distinct Silurian and Devonian benthic faunas of the Appalachian basin. These benthic faunas are termed ecological-evolutionary subunits, the pattern of punctuational change at the community level is called coordinated stasis has rapidly become a forefront of research in evolutionary paleoecology, very few studies have integrated analyses of faunal changes with independent assessments of coeval environmental change, and none have focused on the role of redox dynamics. What are the spatial and temporal relationships between organic matter burial events and oxygen deficiency? How does oxygen depletion relate to evolutionary change within a community, a basin, or an ecosystem? This proposal outlines a plan to re-evaluate hypotheses for the origin of ORF deposits in the Middle to Late Devonian Appalachian basin (late Eifelian through early Famennian), and to use the data collected for this purpose to investigate the causes of faunal stasis and overturn. A preliminary data set of geochemical analyses from core samples has been generated (Fig.3, Table 2) that illustrates why previous hypotheses for the o rigin of ORF in the Appalachian basin need to be updated. This data set has provided a foundation for the development of working hypotheses relating OFR deposition and coordinated stasis, as well as a trial for selection of the best paleoenvironmental parameters to employ in the study. The two year project will focus on two cores from west central New York that will be analyzed for sedimentologic and ichnologic trends and sampled for geochemical analyses. Three types of geochemical data sensitive to redox dynamics will be collected (carbon isotopes; abundance of C, Fe, S, and P; and concentration of trace metals), and the results will be compared to a compilation of published and unpublished data on macrofaunal trends within and around the Appalachian basin. Tests for the statistical covariance of redox sensitive proxies and faunas will allow the fundamental hypothesis, that oxygen depletion controls faunal turnover, to be confirmed or refuted. Alternate mechanisms, such as species-area effects related to relative sea level changes, will also be considered. In recent years the importance of changes in ocean circulation and biogeochemistry to past global change have been increasingly recognized. The results of this study will provide a major contribution to the understanding of organic carbon accumulation processes in the evolution of epicontinental foreland basins, and of the relationship between carbon cycling, redox history, and ecological-evolutionary events in the rock record.

小行星9725803 在地球历史时期，海相盆地中普遍存在的富有机碳相（ORF）沉积是地质科学中的一个重要问题。 水柱分层和随后的缺氧通常是解释古代ORF沉积的有利假设，但近年来出现了替代假设，强调了耦合地球化学和沉积学过程的重要性（例如，高生产力，地层浓缩），甚至表明水柱缺氧可能并不像以前认为的那样普遍。 然而，无论是作为有机碳埋藏的原因还是结果，缺氧都被假定为中生代进化变化和灭绝的潜在驱动力。 例如，它最近被认为是阿巴拉契亚盆地志留纪和泥盆纪底栖动物群发生倾覆事件的可能原因。 这些底栖动物群被称为生态-进化亚基，在群落水平上的间断变化模式被称为协调停滞，已迅速成为进化古生态学研究的前沿，很少有研究将动物群变化的分析与同时代环境变化的独立评估相结合，没有一项研究关注氧化还原动力学的作用。 有机质埋藏事件与缺氧之间的时空关系是什么？ 在一个群落、一个盆地或一个生态系统中，氧气消耗与进化变化有什么关系？ 该提案概述了一个计划，重新评估假设的起源ORF存款中晚泥盆世阿巴拉契亚盆地（晚Eifelian通过早期法门），并使用为此目的收集的数据，调查动物区系停滞和推翻的原因。 一个初步的数据集的地球化学分析，从核心样品已经产生（图3，表2），说明为什么以前的假设origin的ORF在阿巴拉契亚盆地需要更新。 这一数据集提供了一个基础，为发展有关OFR沉积和协调停滞的工作假设，以及在研究中采用的最佳古环境参数的选择试验。 这个为期两年的项目将集中在纽约中西部的两个岩心上，将对这两个岩心进行沉积学和遗迹学趋势分析，并取样进行地球化学分析。 将收集对氧化还原动力学敏感的三种类型的地球化学数据（碳同位素; C、Fe、S和P的丰度;以及微量金属的浓度），并将结果与已发表和未发表的大型动物趋势数据汇编进行比较阿巴拉契亚盆地内和周围。 氧化还原敏感的代理和动物群的统计协方差的测试将允许的基本假设，即氧气消耗控制动物的营业额，被证实或反驳。 还将考虑其他机制，例如与相对海平面变化有关的物种-面积效应。 近年来，人们越来越认识到海洋环流和海洋地球化学变化对过去全球变化的重要性。 这项研究的结果将提供一个重大贡献的理解有机碳积累过程中的陆表海前陆盆地的演化，和碳循环，氧化还原历史和生态演化事件之间的关系在岩石记录。