CAREER: The Quest for Precision in Stratigraphy: Extending Neogene-Scale Resolution into the Paleozoic

职业：对地层学精度的追求：将新近纪尺度的分辨率扩展到古生代

• 批准号: 1455030
• 负责人: Bradley Cramer
• 金额: $ 70.5万
• 依托单位: University of Iowa
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-01 至 2022-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1455030&HistoricalAwards=false
• 关键词: CAREER; Quest; Precision; Stratigraphy; Extending

CAREER: The Quest for Precision in Stratigraphy: Extending Neogene-Scale Resolution into the PaleozoicBradley Cramer, University of IowaEAR-1455030The biological, chemical, and environmental history of the Earth is recorded in the rock record of strata exposed at and below the surface. One of the most critical components to the ability to read this history of past changes to the Earth is the ability to determine the precise order of events (chronostratigraphy) as well as the precise timing and duration of these events (geochronometry/geochronology). In order to be able to determine the exact cause-and-effect sequences of events that produced prior biological, chemical, and environmental change, one must be able to first provide very fine controls on the precise order of events as well as the precise timing and duration of events. Such precise control is commonly available when studying events in the comparatively recent history of the Earth. For example, temporal and stratigraphic control in the order of a few thousand years or less is common when working on more recent events, but such control for the much older portions of Earth history are generally unavailable. As a general rule, the ability to determine the order of events and their timing and duration gets worse the farther back in time one looks. Therefore, when studying events that are hundreds of millions of years old, resolution is typically plus/minus tens to hundreds of thousands of years, or worse. This is a critical roadblock to determining the natural limits of variability and operational feedbacks within the ocean-atmosphere-biosphere global climate system during ancient global change events. The Paleozoic Era (541 Ma to 252 Ma) contains many of the largest biogeochemical perturbations in Earth history, and one small slice of the Paleozoic Era is the objective of this CAREER award in an effort to demonstrate that Neogene-scale resolution of the rock record of biogeochemical events is possible in deep time. This study will help to establish an unparalleled level of chronostratigraphic and geochronologic detail to provide a framework for high-resolution evaluation of global triggers, feedbacks, and ultimately, the mechanisms responsible for two major biogeochemical events that took place during the Wenlock Epoch of the Silurian Period (431 Ma to 427 Ma). The research conducted by this study will include unprecedented detail of the early Sheinwoodian (Ireviken) and Homerian (Mulde) biogeochemical events that had major impacts on the global biosphere (extinction events) as well as the global carbon cycle. This study will utilize fully integrated high-resolution event stratigraphy (HiRES) that will include biostratigraphy (conodonts, chitinozoans), stable isotope chemostratigraphy (carbon and oxygen), sequence stratigraphy, radioisotope geochronometry (U-Pb zircons), and XRF elemental data to dramatically improve the calibration of the Silurian time scale and the ability to globally correlate Wenlock strata and events, as well as to evaluate several existing models of Silurian global change and the nature of the Paleozoic Earth-Life system.

事业：追求地层学的精确度：将新近纪尺度的分辨率扩展到古生代EAR-1455030爱荷华大学的布拉德利·克雷默地球的生物、化学和环境历史被记录在暴露在地表和地表以下的地层的岩石记录中。阅读地球过去变化历史的能力最关键的组成部分之一是能够确定事件的准确顺序(年代地层学)以及这些事件的准确时间和持续时间(地质计时学/地质年代学)。为了能够确定导致先前生物、化学和环境变化的事件的确切因果序列，必须首先能够对事件的准确顺序以及事件的准确时间和持续时间提供非常精细的控制。在研究相对较近的地球历史上发生的事件时，这种精确的控制是常见的。例如，在研究较新的事件时，几千年或更短时间内的时间和地层控制是常见的，但对地球历史上更古老的部分通常不能进行这种控制。一般来说，确定事件顺序及其时间和持续时间的能力随着时间追溯到更远而变得更差。因此，在研究数亿年前的事件时，分辨率通常是正负数万年或更差。这是在古老的全球变化事件期间确定海洋-大气-生物圈全球气候系统内的可变性和业务反馈的自然限度的关键障碍。古生代(541 Ma至252 Ma)包含了地球历史上许多最大的生物地球化学扰动，古生代的一小部分是这一职业奖的目标，以努力证明在深部对生物地球化学事件的岩石记录进行新近纪尺度的分辨是可能的。这项研究将有助于建立无与伦比的年代地层和地质年代学细节，为高分辨率地评价全球触发、反馈以及最终导致志留纪文洛克时期(431 Ma至427 Ma)两个主要生物地球化学事件的机制提供一个框架。这项研究进行的研究将包括对全球生物圈(灭绝事件)和全球碳循环产生重大影响的早期SheinWooddian(Ireviken)和Hmer ian(Mulde)生物地球化学事件的前所未有的详细信息。这项研究将利用完全集成的高分辨率事件地层学(HIRES)，其中将包括生物地层学(牙形刺、几丁虫)、稳定同位素化学地层学(碳和氧)、层序地层学、放射性同位素测时(U-铅锆石)和XRF元素数据，以显著改进志留纪时间尺度的校准和全球文洛克地层和事件的对比能力，并评估志留纪全球变化的几种现有模型和古生代地球-生命系统的性质。