Paleomagnetic studies of Hercynian dyke provinces in the Western Mediterranean: Quantification and tectonic implications of crustal block rotations

西地中海海西岩脉省的古地磁研究：地壳块旋转的量化和构造意义

• 批准号: 239681660
• 负责人: Professor Dr. Valerian Bachtadse
• 金额: --
• 依托单位: Kompetenzbereich Mikrobiom Biotechnologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/239681660?language=en
• 关键词: Paleomagnetic; studies; Hercynian; dyke; provinces

The pathways of magma ascent through the crust are dominated by the orientation of pre-existing and/or syn-magmatically developed faults and fractures such that the careful analysis of the spatial distribution, geometry and orientation of dyke patterns allows the reconstruction of the tectonic strain field during and after dyke emplacement. In addition, sophisticated geochronolocial methods allow a very precise age estimation of the products of dyke magmatism. Therefore, dyke swarms can be used as both age and large-scale strain markers.In the central and western Mediterranean, dyke swarms, mainly of Early Permian age, are developed in the southern Hercynian belt of Europe, such as the Catalan Coastal Ranges (CCR), Sardinia, Corsica and Sila Grande in southern Italy. Despite their similar radiometric ages and petrological similarities, the dykes are variably oriented. The proposed tectonic evolution of the dyke patterns in in the above mentioned areas is probably related to the dismemberment of the southern Hercynian belt in the central Mediterranean. Thus, the dyke provinces here can be used for gaining new insights in the detailed tectonic history of the area.Previous paleomagnetic studies on three dyke provinces on Sardinia suggest the breakup of the island in at least three parts and rotations of those parts about vertical axes relative to each other. Ongoing paleomagnetic measurements on samples from the dyke province in the Catalan Coastal Ranges add to this picture. These measurements are embedded in an interdisciplinary study involving measurements of anisotropy of magnetic susceptibiliy (AMS) and Ar/Ar dating.The submitted project aims at incorporating paleomagnetic data from the Sila Grande dyke province in order to better understand the interactions of crustal thinning towards the end of the Hercynian orogeny and the onset of transtension in the southern Hercynian belt.

岩浆在地壳中上升的路径受控于先前存在和(或)同岩浆发育的断裂和断裂的方向，因此仔细分析岩墙的空间分布、几何形状和方向可以重建岩墙侵位过程中和之后的构造应变场。此外，复杂的地质年代学方法可以非常准确地估计岩脉岩浆作用的产物的年龄。地中海中西部的岩墙群主要发育在欧洲南部的海西带，如加泰罗尼亚海岸山脉、撒丁岛、科西嘉岛和意大利南部的Sila Grande。尽管它们的放射性年龄和岩石学相似，但它们的方向是不同的。上述地区岩墙格局的构造演化可能与地中海中部南海西带的解体有关。因此，这里的堤防省可以用来获得对该地区详细构造史的新见解。以前对撒丁岛上三个堤防省的古地磁学研究表明，该岛至少分成三部分，这些部分围绕彼此的垂直轴旋转。对加泰罗尼亚海岸山脉堤防地区的样品进行的正在进行的古地磁测量增加了这一画面。这些测量被嵌入到一项跨学科研究中，该研究涉及磁化率各向异性(AMS)的测量和Ar/Ar测年。提交的项目旨在纳入Sila Grande岩墙省的古地磁数据，以便更好地了解海西造山运动结束时地壳减薄与海西南部带开始伸展的相互作用。