A Paleomagnetic Assessment of Footwall Tilting During Large Magnitude Extensional Deformation: A Case Study of the Miocene South Mountains Metamorphic Core Complex.

许多大规模地壳伸展的地区，如盆地 和美国西部的山脉省，已经暴露出不活跃的支队 断层表面倾角很小（10 °）。 然而，断层面 对当今世界地震的分析表明， 这样浅的倾斜通常不会有地震活动。 因此 许多争议已经出现了原始的倾角这些 错误在他们的开始。 这个项目将测试假设 （1）断层起始于10 °或更小的倾角， 在测试帽方向，（2）他们开始在30 °至60 °倾角 随后被倾斜。 古地磁分析 岩石单位从下盘的一个这样的拆离断层在南 亚利桑那州的山脉将提供测试。 结果会有 对大区域构造演化具有重要意义 延伸的大陆地壳

Many areas of large-scale crustal extension, such as the Basin and Range province of western USA, have exposed inactive detachment fault surfaces with very shallow dips (10o). However, fault-plane analysis of present-day earthquakes worldwide shows that faults with such shallow dips are not usually seismically active. Thus much controversy has arisen over the original angle of dip of these faults at their initiation. This project will test the hypotheses that (1) the faults initiated at dips of 10o or less and remained in t hat orientation, and (2) they initiated at dips of 30o to 60o and were subsequently tilted. Paleomagnetic analysis of selected rock units from the footwall of one such detachment fault in South Mountains, Arizona, will provide the test. The results will have substantial significance for the tectonic evolution of large areas of extended continental crust.