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

与大洋板块边界一般是狭窄的变形区相比，大陆板块边界似乎是一个广泛的区域，具有复杂的和知之甚少的运动学。这些“扩散板块边界”内的地壳块体运动导致边界区内相当小规模的岩石圈变形，而主要板块表现得更加刚性。结果是由各种活动断层分隔的相互作用的岩石的复杂变形模式。为了研究边界带变形的动力学意义，我们建议墨西哥（巴哈）的下加利福尼亚半岛作为一个理想的目标，并提出了详细的古地磁研究。到目前为止，在下加利福尼亚，尽管它位于一个主要的活动扭张带，但几乎没有针对垂直轴旋转的古地磁工作。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25百万年的火山岩和沉积岩。位于断层速率已在地质和第四纪时间尺度上定义的地区。通过对古地磁偏角的分析以及与北美和下加利福尼亚稳定地区同时代数据的比较，我们将能够评估该地区的长期运动学特征以及东部加州湾断裂的影响。这些调查的结果将与全球定位系统的大地测量结果进行比较，目的是评估从古地磁研究中推断出的长期运动是否与从全球定位系统数据中得出的当前变形模式一致，以及是否有可能进行时间上的向后推断。预计在项目期间将获得的新的古地磁数据将在确定下加利福尼亚的地球动力学演变时提供重要参数，并对扩散板块边界内的运动学提供新的认识。

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.