Link between frontal collision and lateral plate extrusion: palaeomagnetic fingerprint in the Tethyan Himalaya

印度-亚洲碰撞是地球上研究大陆碰撞地球动力学演化最壮观的“天然实验室”。该项目涉及印度压头正面碰撞与青藏高原挤压之间的联系。在喜马拉雅西部，古地磁资料很好地反映了斜向弯曲。相反，来自中部的数据和来自东部（不丹）的第一个结果表明古地磁旋转，这与造山带弯曲模型不兼容。可以假设，青藏高原的向东挤压在喜马拉雅地区的长期变形中留下了指纹，形成了一个剪切带，具有强烈的顺时针块体旋转和单个块体之间的左旋走滑断层。该模型将与GPS速度显示的当今运动相匹配。该项目的目的是通过分析特提斯喜马拉雅东部约1000年至2000年的古地磁剩磁来检验剪切带的假设。东经83-89度。将对东西向和南北向剖面进行取样，以获得区域轮换模式。二次磁黄铁矿剩磁将被使用，这在以前的项目中被证明提供了可靠的结果。为了支持对古地磁数据的解释，还进行了地质、年代学和地热测量工作。这一多学科概念是在来自德国、瑞士、奥地利、加拿大、中国和尼泊尔的科学家合作的基础上提出的。

The India-Asia collision is the Earth's most spectacular "natural laboratory" to study the geodynamic evolution of continental collision. The project deals with the link between frontal collision by the Indian indenter and the extrusion of the Tibetan Plateau. In the western part of the Himalaya oroclinal bending is well reflected by palaeomagnetic data. In contrast, data from the central part and a first result from the eastern part (Bhutan) indicate palaeomagnetic rotations, which are not compatible with an oroclinal bending model. It can be hypothesised that eastward extrusion of the Tibetan Plateau left its fingerprint in a long-term deformation of the Himalayan region forming a shear zone with strong clockwise block rotations and sinistral strike-slip faults between individual blocks. This model would match with present-day movements shown by GPS velocities. The proposed project aims at testing the hypothesis of a shear zone by analysing palaeomagnetic remanences in the eastern Tethyan Himalaya between ca. 83-89°E. West-east and south-north sections will be sampled to obtain a regional rotation pattern. Secondary pyrrhotite remanences will be used which proved to provide reliable results during former projects. Geological, geochronological and geothermometric work is involved in order to support the interpretation of the palaeomagnetic data. This multidisciplinary concept is based on a cooperation of scientists from Germany, Switzerland, Austria, Canada, China and Nepal.