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.

9725803布雷特（Brett）在地球历史上将有机碳富集相（ORF）的广泛但偶发性沉积被认为是地质科学中的重要问题。 水柱分层和随之而来的缺氧通常是偏爱的假设来解释古代ORF的沉积，但是出现了其他假设，突显了耦合生物地球化学和沉积学过程的重要性（例如，高生产率，地层凝结），甚至还没有表现为水柱氧化物的高度可能是预期的。 然而，无论是作为有机碳埋葬的原因或结果，氧缺乏症已被假定是phanerozoic期间进化变化和灭绝的潜在驱动力。 例如，最近被认为是推翻事件的可能原因，即阿巴拉契亚盆地的岛屿上有明显的志留纪和泥盆纪底栖动物群。 这些底栖动物群被称为生态进化亚基，社区层面上的标点变化的模式称为协调的停滞已迅速成为进化古生态学研究的最前沿，很少有研究整合了对夫人的变化的分析，而不是对Coeval环境变化的独立评估，而没有研究的角色，而没有研究的角色。 有机物埋葬事件与氧缺乏之间的空间和时间关系是什么？ 氧耗竭与社区，盆地或生态系统内的进化变化有何关系？ 该提议概述了一个计划，以重新评估泥盆纪阿巴拉契亚盆地中至晚期ORF沉积物的起源（艾弗利安晚期通过早期的Famennian），并将收集的数据用于此目的，以调查动物的停滞和推翻的原因。 已经生成了来自核心样品的地球化学分析的初步数据集（图3，表2），该数据说明了为什么需要更新Appalachian盆地中ORF的O型刚度的先前假设。 该数据集为开发有关R的沉积和协调停滞的工作假设的发展提供了基础，以及选择在研究中使用的最佳古环境参数的试验。 为期两年的项目将重点介绍来自纽约西中部的两个核心，这些核心将分析用于沉积学和进食趋势，并采样以进行地球化学分析。 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；以及痕量金属的浓度），并将结果与​​已发表和未发表的关于Appalachachian盆地周围和未发表的大量趋势的数据进行比较。 氧化还原敏感代理和动物群的统计协方差的测试将允许基本假设，即氧耗尽控制动物更新，可以确认或驳斥。 还将考虑替代机制，例如与相对海平面变化有关的物种面积效应。 近年来，海洋循环和生物地球化学对过去全球变化的重要性越来越多。 这项研究的结果将为了解有机碳积累过程的主要贡献，在岩石盆地的演变中，以及岩石记录中碳循环，氧化还原历史与生态进化事件之间的关系。