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

墨西哥下加利福尼亚州活跃转张板块边界新近纪地块旋转的古地磁定量

• 批准号: 37108510
• 负责人: Professor Dr. Valerian Bachtadse
• 金额: --
• 依托单位: Sektion Geophysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2010-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/37108510?language=en
• 关键词: Pal; omagnetische; Quantifizierung; neogener; Blockrotationen

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.

与海洋板块边界通常是狭窄的变形带相比，大陆板块边界是一个广泛的区域，其运动学复杂且鲜为人知。地壳块体在这些“扩散板块边界”内的运动导致边界带内相当小范围的岩石圈变形，而主板块表现得更为刚性。其结果是被各种活动断层分隔的相互作用的地体形成了复杂的变形模式。为了研究边界带变形的动力学意义，我们建议墨西哥下加利福尼亚半岛（Baja）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，尽管下加利福尼亚州位于一个主要的活动张拉带，但针对垂直轴旋转的古地磁工作很少。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的火山岩和沉积岩。位于断裂速率已在地质和第四纪时间尺度上确定的地区。对古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以东的斜裂作用。这些研究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研究推断出的长期运动是否与从GPS数据得出的当前变形模式一致，并可能进行向后的时间外推。在项目进行期间，预计将获得的新的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。