Collaborative Research: Post-Impact Studies of the Chesapeake Bay Impact Structure: Quantifying Continental Margin Evolution

这个项目将扩展CD资助的早期工作，包括美国中大西洋边缘的地层学分析。为了从地层记录中提取全球海平面变化，并评估海平面上升、构造沉降和沉积物输入对被动大陆边缘沉积的作用，PIS参与了对这一被动边缘进行取心、测井和地震剖面的长期项目。这一努力最终形成了过去1亿年的海平面估计，主要是通过对新泽西州陆上钻孔的回溯研究得出的。切萨皮克湾撞击结构(CBIS)最近由美国地质调查局(USGS)钻探(在火山口内钻了5个岩心孔)。私人投资机构(以光盘资助)参与了记录钻孔，并可接触岩心进行分析。PIS将评估对地壳下沉的重大影响的地球动力学效应，以及全球海平面和区域构造变化在塑造边缘地层记录方面的相对作用。将陨石坑内5个岩心孔的反剥离结果(考虑了沉积物加载、压实、古水深度和盆地下沉的影响)与以前分析过的陨石坑外岩心孔进行比较，将使它们能够量化构造和全球海平面的影响。这些比较将提供一个自然实验，量化撞击产生的容纳性与“正常”热挠曲下沉、海平面和沉积物供应对被动大陆边缘演化的相对影响。该项目特别侧重于影响的短期和长期构造后果、东海岸新生代地层的改进以及始新世后地区和全球海平面曲线的改善。该项目还将检查撞击后立即沉积的沉积物的氧和碳同位素组成，以寻找与撞击造成的气候影响有关的同位素漂移。

0606693MillerThis project will extend earlier work funded by CD involving the analysis of stratigraphy on the US Mid-Atlantic Margin. The PIs have been involved in a long term project of coring, logging, and seismic profiling of this passive margin in order to extract global sea-level change from the stratigraphic record and evaluate the role of eustasy, tectonic subsidence, and sediment input on passive continental margin sedimentation. This effort has culminated in the development of a eustatic estimate for the past 100 million years derived largely from backstripping studies of New Jersey onshore boreholes. The Chesapeake Bay Impact Structure (CBIS) has recently been drilled by the USGS (5 coreholes drilled within the crater). The PIs were involved (with CD funding) in logging the holes and have access to the cores for analysis. The PIs will evaluate the geodynamic effects of a large impact on crustal subsidence and the relative roles of global sea-level and regional tectonic changes on molding the stratigraphic record of the margin. Comparison of backstripping (accounting for the effects of sediment loading, compaction, paleowater depth, and basin subsidence) results from the 5 coreholes in the crater with previously analyzed coreholes outside the crater will allow them to quantify the effects of tectonics and global sea level. These comparisons will provide a natural experiment quantifying the relative effects of impact-generated accommodation versus "normal" thermo-flexural subsidence, sea-level, and sediment supply on the evolution of a passive continental margin. The project specifically focuses on short and long term tectonic consequences of impact, refinement of Cenozoic stratigraphy for the east coast, and improvement of the regional and global sea level curve for post-Eocene time. The project will also examine the oxygen and carbon isotopic composition of sediments deposited immediately after the impact in order to look for isotopic excursions associated with climatic effects caused by the impact.