Proximal Carbonate Ejecta From the Cretaceous-Tertiary Chicxulub Impact Crater: 87Sr/86Sr Chronology, Ballistic Sedimentation, and Diagenetic Alteration

9909560 Fouke在白垩纪-第三纪（KT）边界的大型天体撞击，目标是覆盖尤卡坦半岛结晶基底的3公里碳酸盐台地。 本研究试图通过分析希克苏鲁布陨石坑附近沉积的弹道喷射碳酸盐沉积物，重建KT撞击的沉积物输运动力学和地球化学。 这些矿床的年龄、来源、搬运机制和沉积后蚀变将根据伯利兹阿尔比恩岛的一个暴露良好的台地顶部剖面进行重建。 还将对墨西哥平台边缘El Guay剖面的被解释为撞击成因的增生火山砾进行分析，将使用阴极发光（CL）岩相学、元素和同位素地球化学（大块岩石和微量样品）以及定量水-岩相互作用模型来确定这些撞击成因沉积物的成因。 初步分析已经确定了几个CL-不同的结晶特征的火山砾和角砾岩块，这将提供重要的新的限制蒸汽云沉积机制和地球化学。 将进行试验，以确定通过KT边界的全球海水87 Sr/86 Sr标准曲线（0.7077至0.7079）的对称趋势是否可用于确定：（1）原始沉积组分（角砾岩块、火山砾、骨架材料、海相胶结物）的沉积年龄，以及（2）碰撞玻璃的同沉积或沉积后早期事件

9909560FoukeA large-body impact at the Cretaceous-Tertiary (KT) boundary targeted 3 km of carbonate platform covering crystalline basement on the Yucatan peninsula. This study seeks to reconstruct the sediment transport dynamics and geochemistry of the KT impact by analyzing ballistically ejected carbonate sediments deposited close to the Chicxulub crater. The age, source, transport mechanisms, and post-depositional alteration of these deposits will be reconstructed from a well-exposed platform top section at Albion Island, Belize. Accretionary lapilli interpreted to be of impact origin will also be analyzed from the platform margin El Guay section in Mexico, The genesis of these impact-derived sediments will be determined using cathodolumineseence (CL) petrography, elemental and isotopic geochemistry (bulk rock and microsamples), and quantitative water-rock interaction modeling. Preliminary analyses have identified several CL-distinct crystalline features in the lapilli and breccia blocks that will provide important new constraints on vapor cloud sedimentary mechanisms and geochemistry. Tests will be conducted to determine whether symmetrical trends in global seawater 87sr/86 Sr standard curve (0.7077 to 0.7079) through the KT boundary can be used to determine: (1) the depositional age of original sedimentary components (breccia blocks, lapilli, skeletal material, marine cements), and (2) syndepositional or early post-depositional events of impact glass