The Internal Stratigraphy of K/T Boundary Sediments and Implications for their Provenance

K/T边界沉积物的内部地层学及其物源意义

• 批准号: 9206520
• 负责人: William Boynton
• 金额: $ 11.52万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-07-15 至 1995-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9206520&HistoricalAwards=false
• 关键词: Internal; Stratigraphy; Boundary; Sediments; Implications

This study will examine the stratigraphy of Cretaceous/Tertiary boundary sediments deposited in the proto- Caribbean region to determine their provenance, the way in which they were transported, and how local conditions may have influenced their deposition. In particular, we will determine the size distribution of impact melt spherules, both as a function of stratigraphic height and with distance from their source; determine the compositions of impact melt spherule glasses, whether they vary with stratigraphic height or with distance from their source, and infer their provenance based on their compositions; determine the distribution of shocked mineral phases (such as quartz, feldspar, and spinel) with stratigraphic height and infer their provenance; use this information to determine criteria which can be used to assess whether a deposit of boundary sediments is undisturbed or has been reworked; and determine the overall thicknesses of undisturbed boundary sediments. These observations of boundary sediments will be coupled with theoretical calculations of ejecta transport. The combined studies should identify the approximate location of the source crater and the lithologies of the target material, both of which should determine whether the Chicxulub structure, which we have proposed to be the location of a terminal Cretaceous impact, is a viable candidate. The study should also have wide application to the deposition of ejecta from large (100 km) craters, a subject which is poorly understood at the present time.

这项研究将研究沉积在原加勒比地区的白垩纪/第三纪边界沉积物的地层学，以确定它们的来源、它们的运输方式以及当地条件如何影响它们的沉积。 特别是，我们将确定冲击熔体球粒的尺寸分布，作为地层高度和距源头距离的函数；确定冲击熔融球状玻璃的成分，无论它们是否随地层高度或距其来源的距离而变化，并根据其成分推断其来源；确定冲击矿物相（例如石英、长石和尖晶石）随地层高度的分布并推断其来源； 利用这一信息来确定可用于评估边界沉积物沉积物是否未受干扰或已被改造的标准；并确定未受干扰的边界沉积物的总体厚度。 这些边界沉积物的观测将与喷射物传输的理论计算相结合。 综合研究应确定源陨石坑的大致位置和目标材料的岩性，两者应确定希克苏鲁伯结构（我们提出的白垩纪末期撞击位置）是否是可行的候选者。 这项研究还应该广泛应用于大型（100公里）陨石坑喷射物的沉积，而目前人们对此知之甚少。