Drilling The Cretaceous/Paleogene Boundary in NJ: Testing the Relationship of Geochemical Anomalies to Event Beds

最近一次标志着白垩纪/古近纪（K/P）边界的大灭绝事件发生在6500万年前，导致90%的海洋浮游生物和恐龙灭绝。 这次灭绝与一颗大的小行星的撞击有关（阿尔瓦雷斯假说），该小行星被追踪到尤卡坦半岛（墨西哥的希克苏鲁布）。 但最近在德克萨斯州和新泽西的研究对希克苏鲁布撞击是白垩纪末杀手的范式提出了质疑。 据报道，希克苏鲁布撞击球粒位于德克萨斯州布拉索斯的边界以下，在新泽西露头（Pinna层）白垩纪菊石和软体动物化石的显著保存层的底部出现Ir异常。相比之下，以前的研究大陆动力学/大洋钻探计划腿174 AX陆上新泽西岩心孔和DSDP/ODP深海岩心孔表明，有一个小球层与海洋浮游生物的灭绝被解释为海啸的粘土碎屑层覆盖。 露头和地下钻探表明，新泽西沿海平原是恢复完整和保存完好的K/P边界剖面的绝佳地点。PI将在新泽西（马纳斯泉河、蒙茅斯堡和克罗斯维克斯河）的露头顶部钻取三个紧密间隔的浅孔（50-70英尺）钻孔断面，这些钻孔断面将提供保存完好的材料，其上级于露头断面，用于古生物学和地球化学分析。 他们还将详细分析安提阿教堂，AL和Brazos，TX岩心孔。 他们的工作假设是，有一个影响与一个Ir异常和一个小球层，这是直接联系到大规模灭绝事件和灭绝事件是没有因果关系的主要气候或海平面变化的100 kyr到百万年的规模。 他们的假设预测，在要进行密集采样的剖面中，只会发现一个原地球粒层和一个Ir异常。

The most recent mass extinction event that marks the Cretaceous/Paleogene (K/P) boundary occurred at 65 million years ago, resulted in the extinction of 90% of marine plankton and the dinosaurs. This extinction has been linked to the impact of a large asteroid (the Alvarez hypothesis) that has been traced to the Yucatan peninsula (Chicxulub, Mexico). However, recent studies in Texas and New Jersey have questioned the paradigm that the Chicxulub impact was the killer at the end of the Cretaceous. The Chicxulub impact spherules are reported below the boundary at Brazos, TX and an Ir anomaly occurs at the base of a layer of remarkable preservation of Cretaceous ammonites and mollusk fossils in New Jersey outcrops (the Pinna bed). In contrast, previous studies of Continental Dynamics/Ocean Drilling Program Leg 174AX onshore New Jersey coreholes and DSDP/ODP deep-sea coreholes suggest that there is one spherule layer associated with the extinction of the marine plankton overlain by a clay clast layer interpreted as a tsunamite. Outcrop and subsurface drilling has shown that the New Jersey coastal plain is an excellent location to recover complete and well-preserved K/P boundary sections. PIs will drill three closely spaced drilling transects of shallow (50-70 ft) holes on top of outcrops in New Jersey (Manasquan River, Fort Monmouth, and Crosswicks Creek) that will provide well-preserved material that is superior to outcrop sections for paleontological and geochemical analyses. They will also analyze in detail the Antioch Church, AL and Brazos, TX coreholes. Their working hypotheses are that there was one impact associated with one Ir anomaly and one spherule layer that was directly linked to the mass extinction event and that the extinction event was not causally related to major climatic or sea-level changes on the 100 kyr to million-year scale. Their hypotheses predict finding only one in situ spherule layer and one Ir anomaly in the sections to be intensely sampled.