Collaborative Research: Testing the Early Late Ordovician Cool Water Hypothesis

合作研究：检验早奥陶世晚期冷水假说

• 批准号: 1323444
• 负责人: Kenneth MacLeod
• 金额: $ 18万
• 依托单位: University of Missouri-Columbia
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-15 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1323444&HistoricalAwards=false
• 关键词: Collaborative; Research; Testing; Early; Late

Collaborative Research: Testing the Early Late Ordovician Cool Water Hypothesisby Achim Herrmann, Louisiana State UniversityKenneth MacLeod, University of MissouriStephen Leslie, James Madison UniversityEAR-1324954, -1323444, -1324577ABSTRACTThe Late Ordovician glaciation (LOG) is associated with the second largest mass extinction event of the Phanerozoic. It marks the end of the global warm conditions of the early Paleozoic that lasted ~150my and occurred under elevated pCO2 conditions. Considerable doubt has recently been raised with regard to the duration of the LOG, its potential driving mechanisms, and pre-glacial, long-term temperature variations. For instance approximately 15 Ma prior to LOG the North American continental plate was situated in tropical to subtropical latitudes, but sedimentological and paleontological evidence suggest a shift from deposition of warm water carbonates to deposition of cool water carbonates. It is not clear whether this sedimentological change reflects global cooling (indicating significant perturbation to the global climate system well before the Late Ordovician glaciation) or physical responses to tectonic activity with no requisite climatic implications. The projects will test competing hypotheses that try to explain this event through an extensive geochemical study. In particular, PIs will use the geochemical archive of conodont apatite (delta18O and epsilonNd) and carbonates (DELTA48, delta18O, and delta13C) to address questions about paleoceanographic conditions during the Early Late Ordovician. They expect that this research will lead 1) to clarification of potential causes for the paleontological/sedimentological changes during this interval, 2) to a better understanding of epicontinental sea circulation and an improved facies model for epicontinental low latitude carbonate platforms (for which no modern-day analogues exist), and 3) to better documentation of the temperature history of the Ordovician greenhouse interval.This research project will have active participation by undergraduate students, graduate students, and a secondary school science teacher. Therefore, the project will not only impact present university students and researchers, it will also impact future generations of students through enhancing an earth science secondary educations teacher¡¦s knowledge base and science curriculum. Data will be contributed to publicly accessible databases making them available for further research and general education in the fields of paleoclimate and paleoceanography.

合作研究：测试晚奥陶世早期冷水假说路易斯安那州立大学阿希姆·赫尔曼肯尼斯·麦克劳德密苏里大学斯蒂芬·莱斯利，詹姆斯·麦迪逊大学EAR-1324954，-1323444，-1324577摘要晚奥陶世冰川(LOG)与显生界第二大物种灭绝事件有关。它标志着早古生代全球暖期的结束，这种暖期持续了约150年，发生在二氧化碳含量升高的条件下。最近，对于原木的持续时间、其潜在的驱动机制以及冰期前的长期温度变化，人们提出了相当大的疑问。例如，在记录之前大约15 Ma，北美大陆板块位于热带到亚热带纬度，但沉积学和古生物证据表明，从温水碳酸盐沉积转变为冷水碳酸盐沉积。目前尚不清楚这种沉积学变化是反映了全球变冷(表明早在晚奥陶世冰川作用之前就对全球气候系统造成了重大扰动)，还是反映了对构造活动的物理反应，而没有必要的气候影响。这些项目将测试相互竞争的假说，这些假说试图通过广泛的地球化学研究来解释这一事件。特别是，PIS将利用牙形刺磷灰石(Delta18O和epsilonND)和碳酸盐(Delta48、Delta18O和Delta13C)的地球化学档案来解决晚奥陶世早期古海洋条件的问题。他们预计，这项研究将导致1)澄清这一时期古生物/沉积学变化的潜在原因，2)更好地了解陆缘海洋环流和改进陆缘低纬碳酸盐台地(目前还没有类似的台地)的相模式，3)更好地记录奥陶纪温室间的温度历史。这项研究项目将得到本科生、研究生和一名中学科学教师的积极参与。因此，该项目不仅将影响目前的大学生和研究人员，还将通过加强地球科学中学教师S的知识基础和科学课程来影响未来的学生。将把数据提供给公众可查阅的数据库，使其可用于古气候和古海洋学领域的进一步研究和一般教育。