Late Ordovician Epeiric Sea Circulation, Environmental Change, and Biotic Turnover: Model and Data Synthesis

晚奥陶世表海环流、环境变化和生物周转：模型和数据综合

• 批准号: 0106737
• 负责人: Mark Patzkowsky
• 金额: $ 18万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2005-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0106737&HistoricalAwards=false
• 关键词: Late; Ordovician; Epeiric; Sea; Circulation

ABSTRACTLate Ordovician Epeiric Sea Circulation, Environmental Change, and Biotic Turnover: Model and Data SynthesisOne of the most difficult problems facing the earth science community today is identifying the ultimate causes of extinction and migration in the history of life. In the sedimentary record, biotic change such as extinction is often linked to evidence of environmental change, however the processes underlying environmental change are often complex and poorly understood. Numerical models of physical systems that are tested against the sedimentary record provide a means by which the ultimate causes for bioevents can be investigated. We propose to use a numerical model of ocean circulation to determine the ultimate causes for an extinction event in the Late Ordovician of North America.This study has two main components. In the first component we hypothesize that rapid shifts in environmental conditions linked to extinction during the Late Ordovician of North America were caused by changes in bathymetry, paleogeography, and precipitation associated with mountain building. We will model ocean circulation for two time intervals that span the abrupt shift in environmental conditions and related extinction event. We will test the validity of the model results against the distribution of sedimentary indicators of oceanographic conditions. In the second component of the study we will investigate the relative importance of single variables like changes in sea level, paleogeography, bathymetry, and precipitation in producing rapid oceanographic shifts in the epeiric seas that may have caused significant extinction of species. In investigating the ultimate causes of extinction, modeling has the advantage that single variables can be isolated and their effects on the system evaluated. We will identify plausible causes of the extinction event by determining how well the model results match the spatial and temporal faunal changes. By gaining insight into the causes of rapid oceanographic changes in these epeiric seas, this study has broad implications for understanding environmental change and extinction during any time in Earth's history when epeiric seas were important components of marine ecosystems.

摘要晚奥陶纪表海环流、环境变化和生物周转：模型和数据综合当今地球科学界面临的最困难的问题之一是确定生命历史上灭绝和迁移的最终原因。 在沉积记录中，灭绝等生物变化通常与环境变化的证据联系在一起，但环境变化的过程往往很复杂且人们知之甚少。 根据沉积记录进行测试的物理系统数值模型提供了一种研究生物事件最终原因的方法。 我们建议使用海洋环流数值模型来确定北美晚奥陶世灭绝事件的最终原因。这项研究有两个主要组成部分。 在第一部分中，我们假设北美晚奥陶世期间与灭绝相关的环境条件的快速变化是由测深、古地理和与造山相关的降水的变化引起的。 我们将对跨越环境条件突变和相关灭绝事件的两个时间间隔的海洋环流进行建模。 我们将根据海洋条件沉积指标的分布来测试模型结果的有效性。 在研究的第二部分中，我们将研究海平面、古地理、测深和降水等单一变量的相对重要性，这些变量在表海中产生快速的海洋学变化，这些变化可能导致物种的严重灭绝。 在研究灭绝的最终原因时，建模的优点是可以隔离单个变量并评估它们对系统的影响。 我们将通过确定模型结果与空间和时间动物区系变化的匹配程度来确定灭绝事件的可能原因。 通过深入了解这些表层海洋快速海洋变化的原因，这项研究对于理解地球历史上表海是海洋生态系统重要组成部分的任何时期的环境变化和灭绝具有广泛的意义。