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

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，但对陆地撞击结构的详细结构研究仍处于起步阶段，更不用说大型复杂的结构了。相当大的不确定性集中在中央隆起的形成上，更具体地说，是(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)在这一过程中大量伪膝石角砾岩体的力学作用。这些问题将在现场结构、实验室和三维几何恢复分析中得到解决，使用弗里德堡圆顶，这是一个中央隆起的深度侵蚀遗迹，也是地球上保存最完好的自然实验室进行此类研究。该研究还将检验在中央隆起形成过程中，冲击诱发的熔体即伪水晶石角砾岩是否从高压位置运输到低压位置，从而直接关系到解决伪水晶石争议。本文提出的构造分析与U. Reimold教授的论文中所描述的假角砾岩的岩石学、地球化学和分析密切相关。

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.