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

职业：地层学中对精确性的追求：将新第三纪尺度的分辨率扩展到古生代布拉德利·克莱默，爱荷华大学-1455030地球的生物、化学和环境历史记录在地表和地表以下暴露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确定事件的精确顺序（年代地层学）以及这些事件的精确时间和持续时间（地质年代学/地质年代学）。 为了能够确定产生先前生物、化学和环境变化的事件的确切因果顺序，人们必须首先能够对事件的精确顺序以及事件的精确时间和持续时间进行非常精细的控制。这种精确的控制在研究地球相对较近的历史事件时是常见的。例如，在研究更近的事件时，时间和地层控制在几千年或更短的数量级上是常见的，但对于地球历史上更古老的部分，这种控制通常是不可用的。一般来说，人们越是追溯过去，就越难判断事件的顺序、时间和持续时间。因此，当研究数亿年前的事件时，分辨率通常是正负几十万年或更糟。这是一个关键的障碍，以确定自然限制的变化和业务反馈的海洋-大气-生物圈全球气候系统在古代全球变化事件。古生代（541 Ma至252 Ma）包含了地球历史上许多最大的地球化学扰动，古生代的一小部分是这个CAREER奖的目标，旨在证明在深时间内对岩石记录的地球化学事件的新近纪尺度分辨率是可能的。这项研究将有助于建立一个无与伦比的年代地层学和地质年代学的细节水平，提供一个高分辨率的全球触发器，反馈，并最终的机制，负责两个主要的地球化学事件，发生在志留纪文洛克时代（431马至427马）的评估框架。这项研究将包括对全球生物圈（灭绝事件）以及全球碳循环产生重大影响的早期Sheinwoodian（Ireviken）和Homerian（Mulde）地球化学事件的前所未有的细节。这项研究将利用包括生物地层学在内的完全集成的高分辨率事件地层学（HiRES（牙形石，几丁虫），稳定同位素化学地层学（碳氧），层序地层学，放射性同位素地质年代学（U-Pb锆石）和XRF元素数据，以显着提高志留纪时间尺度的校准和全球关联温洛克地层和事件的能力，以及评估几个现有的志留纪全球变化模型和古生代地球生命系统的性质。

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.