Formation of central uplift structures in large, complex impact craters: Mechanical importance of pseudotachylitic breccia zones and prominent dislocations in the development of the Vredefort Dome, South Africa

大型复杂撞击坑中中央隆起结构的形成：假速岩角砾岩带和南非弗里德堡圆顶发育过程中显着位错的机械重要性

• 批准号: 30307603
• 负责人: Professor Dr. Wolf Uwe Reimold
• 金额: --
• 依托单位: Museum für Naturkunde - Leibniz-Institut für Evolutions- und Biodiversitätsforschung (MfN)
• 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 2011-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/30307603?language=en
• 关键词: Formation; central; uplift; structures; large

Despite the fact that large meteorite impact belongs to the least understood processes in planetary geology, detailed structural studies of terrestrial impact structures, let alone of large complex ones, are still in their infancy. Considerable uncertainty centres around the formation of central uplifts, more specifically, the (1) geometric and kinematic significance of prominent dislocations, (2) the temporal and mechanical relationships between continuous and discontinuous deformation and (3) the mechanical role of voluminous pseudotachylitic breccia bodies in this process. These issues are addressed in a combined field-structural, laboratory and 3D geometric restoration analysis using the Vredefort Dome, a deeply eroded relic of a central uplift and best preserved natural laboratory on Earth for such study. The study will also test whether shock-induced melt, i.e., pseudotachylitic breccia, was transported from highpressure to low-pressure sites during formation of the central uplift, und thus pertains directly to solving the pseudotachylite controversy . Structural analyses proposed herein are intimately linked with the petrographic and geochemical and analyses of pseudotachylitic breccia delineated in the companion proposal by Prof. U. Reimold.

尽管大型陨石撞击属于行星地质学中最不为人所知的过程，但对地球撞击结构的详细结构研究，更不用说大型复杂撞击结构的研究，仍处于起步阶段。相当大的不确定性集中在中央隆起的形成上，更具体地说，（1）突出位错的几何和运动学意义，（2）连续和不连续变形之间的时间和力学关系，以及（3）大量假速岩角砾岩体的力学作用在这个过程中。这些问题通过结合现场结构、实验室和 3D 几何恢复分析来解决，其中使用 Vredefort 圆顶，这是一个被深度侵蚀的中央隆起遗迹，也是地球上用于此类研究的保存最完好的自然实验室。该研究还将测试在中央隆起形成过程中，冲击引起的熔融（即假速石角砾岩）是否从高压部位迁移到低压地点，从而直接关系到解决假速石争议。本文提出的结构分析与 U. Reimold 教授的同伴提案中描述的假速岩角砾岩的岩相学和地球化学分析密切相关。