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

[0606705]这个项目将扩展由美国环境规划署资助的早期工作，包括分析美国中大西洋边缘的地层学。为了从地层记录中提取全球海平面变化，并评估海浮、构造沉降和沉积物输入对被动大陆边缘沉积的作用，pi参与了对被动大陆边缘的取心、测井和地震剖面的长期项目。这一努力的最终结果是，根据对新泽西州陆上钻孔的回溯研究，得出了过去1亿年的波动估计。切萨皮克湾撞击构造（CBIS）最近由美国地质勘探局钻探（在火山口内钻了5个岩心孔）。pi（在CD的资助下）参与了孔的记录，并可以访问岩心进行分析。pi将评估对地壳沉降的巨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对塑造边缘地层记录的相对作用。将陨石坑内5个岩心孔的反剥离（考虑沉积物负荷、压实、古水深和盆地沉降的影响）结果与先前分析过的陨石坑外岩心孔进行比较，将使他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，量化冲击产生的调节与“正常”热弯曲沉降、海平面和沉积物供应对被动大陆边缘演化的相对影响。该项目特别关注影响的短期和长期构造后果，改进东海岸新生代地层，改善区域和全球后始新世海平面曲线。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，以寻找与撞击引起的气候影响有关的同位素漂移。

0606705KominzThis 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.