Analysis of New Drill Core Samples from within the ChicxclubImpact Basin

对 ChicxclubImpact 盆地内新钻芯样本的分析

• 批准号: 9418652
• 负责人: Virgil Sharpton
• 金额: --
• 依托单位: Lunar and Planetary Institute
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-09-15 至 1998-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9418652&HistoricalAwards=false
• 关键词: Analysis; New; Drill; Core; Samples

9418652 Sharpton Recent analyses of drill core samples and geophysical data have demonstrated that the buried Chicxulub structure in northern Yucatan is the site of a major asteroid or comet strike 65 million years ago at the time of the Cretaceous-Tertiary (KT) mass extinctions. The crater produced by this event is believed to be between 165 km and 280 km in diameter. As such, it is one of the largest impact structures recognized on Earth and its study offers important contributions to the understanding of large-body impact and to disciplines ranging from research of carbonate platforms to the evolution of the continental crust. Universidad Nacional Autonoma de Mexico (UNAM) has undertaken a shallow drilling program to recover continuous core samples of the basin fill deposits and underlying impact breccias. More than 1000 m of core have been recovered from five wells located along the flanks of the basin. These samples will permit a more precise estimate of the size and shape of the basin, and will constrain the rate and nature of its infilling through the Cenozoic. Samples of the underlying breccias are critical for estimating the types and proportions of rocks involved in this impact event and evaluating its environmental effects. These samples also provide an important resource for additional investigations and will be available to the international science community. This project focuses on two scientific goals: (1) Derive the basic Cenozoic stratigraphic and paleoenvironmental framework for the Chicxulub basin based on these new core samples, augmenting the existing information in Pemex cores and well logs. This information will provide important new insights into the shape of the Chicxulub basin and the geological and paleontological evolution of the southern Gulf of Mexico and Yucatan Platform. (2) Evaluate impact breccias from two core localities in terms of lithological characteristics, depths, evidence of reworking, et c. Each of these sites corresponds to a proposed basin rim location. Consequently, how deep these breccias are located below the present surface and what they are composed of will provide tests for current basin models including size and shape of the final basin and the original excavation crater. These breccias will also aid in constraining the proportions of target materials excavated and heated in the Chicxulub impact event and help constrain the magnitudes of potential killing mechanisms such as ocean acidification, global cooling, or greenhouse warming due to vaporization of sulfates or carbonates. ***

9418652夏普顿最近对岩芯样本和地球物理数据的分析表明，尤卡坦半岛北方的埋藏希克苏鲁布结构是6500万年前在第三纪-第三纪大规模碰撞时一颗主要小行星或彗星撞击的地点。据信，这一事件产生的陨石坑直径在165公里至280公里之间。因此，它是地球上公认的最大的撞击结构之一，对它的研究为了解大型天体撞击以及从碳酸盐台地研究到大陆地壳演化等学科作出了重要贡献。墨西哥国立自治大学（UNAM）已经开展了一项浅层钻探计划，以恢复盆地填充沉积物和下伏冲击角砾岩的连续岩心样品。已从沿着盆地两侧的五口威尔斯井中采出超过1000米的岩心。这些样品将允许更精确地估计盆地的大小和形状，并将限制其在新生代的填充速率和性质。下面的角砾岩样本对于估计这次撞击事件中所涉及的岩石的类型和比例以及评估其环境影响至关重要。这些样本还为进一步调查提供了重要资源，并将提供给国际科学界。该项目主要有两个科学目标：（1）根据这些新的岩心样品，补充Pemex岩心和测井资料，建立希克苏鲁布盆地新生代地层和古环境的基本框架。这些信息将为了解希克苏鲁布盆地的形状以及墨西哥湾南部和尤卡坦地台的地质和古生物演化提供重要的新见解。(2)根据岩性特征、深度、改造证据等，评价两个核心地点的冲击角砾岩。这些地点中的每一个都对应于拟议的盆地边缘位置。因此，这些角砾岩位于目前地表以下的深度以及它们的组成将为当前盆地模型提供测试，包括最终盆地和原始挖掘火山口的大小和形状。这些角砾岩还将有助于限制在希克苏鲁布撞击事件中挖掘和加热的目标物质的比例，并有助于限制潜在的杀伤机制的程度，如海洋酸化、全球变冷或由于硫酸盐或碳酸盐的蒸发而导致的温室效应。***