North-south extension in the Tibetan crust triggered by granite emplacement
North-south extension in the Tibetan crust triggered by granite emplacement
复制标题
DOI：
10.1130/g21806.1
复制
发表时间：
2005-11
期刊：
影响因子：
5.8
通讯作者：
M. Aoya;S. Wallis;K. Terada;Jeffrey Lee;Tetsuo Kawakami;Yu Wang;M. Heizler
中科院分区：
文献类型：
--
作者：
M. Aoya;S. Wallis;K. Terada;Jeffrey Lee;Tetsuo Kawakami;Yu Wang;M. Heizler
结合联合收割机锆石高分辨离子探针U-Pb定年和云母40 Ar-39 Ar坪年龄，结合藏南玛拉山地区的野外地质和地球化学资料，表明该地区北喜马拉雅变质穹隆的变形花岗岩核不是印度基底，而是在喜马拉雅运动期间侵入变形的。显微构造观察表明，在花岗岩侵入和相关变质作用期间，发生了由由顶向南逆冲相关变形向顶向北伸展相关变形的转变。这表明，侵入触发了伸展构造在西藏中地壳到上地壳的开始。预期的正反馈机制之间的减压熔融导致更多的入侵和更多的拉伸变形表明，这种机制可能是重要的区域尺度上。
We combine zircon sensitive high-resolution ion microprobe U-Pb spot dating and mica 4 0 Ar- 3 9 Ar plateau ages with field-geological and geochemical constraints from the Malashan area of Southern Tibet to show that the deformed granite core of the North Himalayan metamorphic domes in this area is not Indian basement, but was intruded and deformed during the Himalayan orogeny. Microstructural observations reveal that a transition from top-to-the-south thrust-related to top-to-the-north extension-related deformation occurred during granite intrusion and related metamorphism. This suggests that intrusion triggered the onset of extensional tectonics in the Tibetan middle to upper crust. Expected positive feedback mechanisms between decompression melting leading to more intrusion and more extensional deformation suggest that this mechanism may have been important on a regional scale.