Relative Roles of Late Cretaceous-Early Tertiary Versus Middle Tertiary Extension in Southeastern California and Southwestern Arizona

Palona、Orocopia和Rand片岩是加利福尼亚南部和亚利桑那州西南部的晚白垩世-早第三纪俯冲带岩石。根据一种模型，这些岩石位于北美西部中生代弧下，沿着文森特-巧克力山逆冲构造，起源于低角度、向东倾斜的俯冲。因此，该模型暗示了从上到西的运动感。然而，许多研究表明，在断层的许多暴露处，顶部向东运动，由于俯冲作用，这将改变俯冲极性，并给Loramide构造带来一些几何问题。最近的研究表明，许多这些“错误方向”的动力学指标可能是由于逆冲表面后来的正常断裂重新激活所致。本项目将关注这种可能的重新激活，并尝试确定运动的日期。成功的结果将有助于最终解决北美西南缘白垩纪构造几何的主要争议之一，并阐明更年轻的伸展事件。

9626589 Jacobson The Palona, Orocopia and Rand Schists are Late Cretaceous-early Tertiary subduction zone rocks in southern California and southwestern most Arizona. These rocks were emplaced beneath the mesozoic arc of western North America along the vicent-chocolate mountain thrust, according to one model, originating during low-angle, east-dipping subduction. Thus the model implies top to the west sense of movement. However, many studies have documented top to the east movement on many exposures of the fault, which due to subduction, would reverse subduction polarity and create several geometric problems for Loramide tectonics. Recent work has indicated that many of these "wrong way" kinetic indicators may be due to later, normal faulting reactivation of the thrust surface. This project will focus on this possible reactivation and will attempt to date the movement. Successful results will help finally resolve one of the main controversies of the Cretaceous tectonic geometry of the southwest margin of North America, and illuminate the younger extensional event.