High-resolution chemostratigraphy of Maastrichtian/Paleocene transition in Texas, USA, and Brazil

德克萨斯州、美国和巴西马斯特里赫特阶/古新世过渡的高分辨率化学地层学

• 批准号: 24165427
• 负责人: Professorin Dr. Doris Stüben
• 金额: --
• 依托单位: Institut für Angewandte Geowissenschaften (AGW)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2010-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/24165427?language=en
• 关键词: resolution; chemostratigraphy; Maastrichtian; Paleocene; transition

The ICDP drilling of the Chicxulub crater on Yucatan and K-T outcrop studies throughout NE Mexico have revealed stratigraphic, geochemical, mineralogical, paleomagnetic and paleontological evidences that this impact predates the K-T boundary by about 300,000 years and hence could not have been responsible for the end-Cretaceous mass extinction as commonly believed. The major purpose of this project is to contribute by means of geochemical methods on newly sampled and cored material in Brazos and Brasil to the solution of the current controversy over the age of the Chicxulub impact and its relationship to the K-T boundary mass extinction within an interdisciplinary, international research project. The debate is not a matter of who is right or wrong it is more a matter of tremendous implications that go way beyond the mere age of the Chicxulub impact, with tremendous bearing on the nature and cause(s) of mass extinctions during the Earth´s history. Preliminary results of the first project year combined with a comparative, critical evaluation of the latest literature, seems to reinforce the conclusion that the Chicxulub impact and the biostratigraphic K-T boundary of the sections of Brazos and Brazil are not coincident in time. However, a series of key features are still debatable and must be answered before reached to an irrefutable conclusion. Among others, these include (i) the nature of the “event deposits”, (ii) the deposition time of the sediments intercalated above the “event deposits” and the biostratigraphic K-T boundary, (iii) whether the recently discovered “yellow clay layer” below the event deposits at Brazos corresponds or not to the original Chixculub impact ejecta layer, or (iv) whether the Ir anomaly in sediments of Danian age at Poty Quarry, Brazil is reworked or marks a different, younger impact event. Of further major interest is to clear the possible role of other stress factors than impact (e.g. “super-volcanism”, anoxia) to the end-Cretaceous mass extinction.

尤卡坦半岛Chicxulub陨石坑的ICDP钻探和整个墨西哥东北部的K-T露头研究显示，地层学、地球化学、矿物学、古地磁和古生物学证据表明，这种影响比K-T边界早了大约30万年，因此不可能像人们普遍认为的那样是白垩纪末期大灭绝的原因。该项目的主要目的是通过地球化学方法对布拉索斯和巴西的新采样和岩心材料进行研究，以解决目前关于希克苏鲁伯撞击年龄及其与K-T边界大灭绝之间关系的争议，这是一个跨学科的国际研究项目。这场争论不是谁对谁错的问题，它更多的是一个巨大的影响问题，远远超出了希克苏鲁伯撞击的时代，它对地球历史上大规模物种灭绝的性质和原因有着巨大的影响。第一个项目年度的初步结果与对最新文献的比较、批判性评估相结合，似乎加强了希克苏鲁伯撞击和Brazos和巴西剖面的生物地层K-T边界在时间上并不一致的结论。然而，一系列的关键特征仍然存在争议，在得出无可辩驳的结论之前，必须回答这些问题。其中包括(i)“事件沉积物”的性质，（ii）穿插在“事件沉积物”和生物地层K-T边界之上的沉积物的沉积时间，（iii）最近发现的Brazos事件沉积物下方的“黄粘土层”是否与原始的Chixculub撞击喷射层相对应，或者（iv）巴西Poty Quarry达尼年沉积物中的Ir异常是否被重新加工或标志着不同的，更年轻的撞击事件。进一步的主要兴趣是明确其他压力因素在白垩纪末期大灭绝中的可能作用，而不是影响（例如“超级火山作用”、缺氧）。