Paläomagnetische Quantifizierung neogener Blockrotationen an einer aktiven, transtensionalen Plattengrenze, Baja California, Mexiko

与通常是狭窄变形区域的海洋板块边界相比，大陆板块边界看起来是广泛的区域，其运动学复杂且知之甚少。这些“扩散板块边界”内的地壳块体运动会导致边界区域内的岩石圈发生相当小规模的变形，而主板则表现得更加坚硬。结果是被各种活动断层分隔开的相互作用地体的复杂变形模式。为了研究边界带变形的动态影响，我们建议将墨西哥下加利福尼亚半岛（Baja）作为理想目标，并提出详细的古地磁研究。到目前为止，尽管下加利福尼亚州位于主要的活跃张紧带，但针对垂直轴旋转的古地磁工作还很少进行。为了解决这个问题，计划利用经典的古地磁方法来研究年龄从0到25m.y的火山岩和沉积岩。位于断层率已在地质和第四纪时间尺度上定义的地区。对古地磁偏角的分析以及与来自北美和下加利福尼亚州稳定地区的同期数据的比较将使我们能够评估该地区的长期运动学以及加利福尼亚湾东部倾斜裂谷的影响。这些调查的结果将与全球定位系统（GPS）的大地测量结果进行比较，目的是评估古地磁研究推导出的长期运动是否与GPS数据导出的当前变形模式一致，并且可以在时间上向后推断。项目期间预计将获得的新古地磁数据将为定义下加利福尼亚州的地球动力学演化提供重要参数，并为扩散板块边界内的运动学提供新的线索。

Compared to oceanic plate boundaries which are generally narrow zones of deformation, continental plate boundaries appear as widespread areas with complex and poorly understood kinematics. Motion of crustal blocks within these “diffuse plate boundaries” causes rather small-scale lithospheric deformation within the boundary zone, while the main plates behave more rigid. Complex deformation patterns of interacting terranes separated by a variety of active faults are the consequence. To study the dynamic implications of boundary zone deformation we suggest the Baja California peninsula, Mexico (Baja), as an ideal target and propose a detailed paleomagnetic study. Up to now, little paleomagnetic work directed toward vertical axis rotations has been done in Baja California, despite its location in a major active transtensional zone. To address this problem, it is planned to use classical paleomagnetic methods to study volcanic and sedimentary rocks ranging in age from 0 to 25m.y. located in areas where the faulting rates have been defined on geologic and Quaternary time scales. The analysis of paleomagnetic declinations and comparison to coeval data from North America and stable areas of Baja California will allow us to evaluate the long-term kinematics of the region and the effects of oblique-rifting in the Gulf of California to the east. The results of these investigations will be compared to geodetic measurements from Global Positioning System (GPS) with the aim to assess whether long-term motion deduced from paleomagnetic studies is coherent with the current deformation patterns derived from GPS data and extrapolation backward in time is possible. The new paleomagnetic data to be expected during the duration of the project will provide important parameters when defining the geodynamic evolution of Baja California and shed new light on the kinematics within a diffuse plate boundary.