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

与通常是狭窄变形带的海洋板块边界相比，大陆板块边界似乎是具有复杂和鲜为人知的运动学的广泛区域。在这些“扩散板块边界”内，地壳块体的运动导致边界带内相当小规模的岩石圈变形，而主要板块表现出更多的刚性。其结果是由各种活动断裂隔开的相互作用的地体的复杂变形模式。为了研究边界带形变的动力学意义，我们建议将墨西哥下加利福尼亚半岛(BAJA)作为理想的目标，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一个主要的活动伸展带，但针对垂直轴旋转的古地磁工作还很少。为了解决这个问题，计划使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。位于地质和第四纪时间尺度上已确定断裂率的地区。对古地磁偏角的分析以及与北美和下加利福尼亚州稳定地区的同时代数据的比较，将使我们能够评估该地区的长期运动学和加利福尼亚州海湾向东倾斜裂谷的影响。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，目的是评估从古地磁学研究得出的长期运动是否与根据GPS数据得出的当前形变模式相一致，以及是否有可能进行时间倒推。预计在项目期间将提供的新的古地磁数据将在确定下加利福尼亚州的地球动力学演化时提供重要参数，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.