Development of the continental crust deruced from deep subducted crustal materials

深俯冲地壳物质推导出的大陆地壳的发育

基本信息

批准号：
08454156
负责人：
HIRAJIMA Takao
金额：
$ 4.42万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08454156/
关键词：
UHP rocks exhumation path Su-Lu belt, China Dora Maira massif Sanbagawa belt Development of continent 三波川帯エクロジャイトグラニュライト

项目摘要

In 1996, PCI (High resolution Image capture system) was newly combined to the electron microscope in Kyoto Univ. This new tool improved the quality and precision of micron-scale texture analysis for deeply subducted continental materials. The detail texture analysis was performed for the deeply subducted crustal materials collected from Su-Lu belt, eastern China, Dora Maira massif, western Alps and Sanbagawa belt and it made clear following facts.1) Many UHP rocks in the middle and north parts of the Su-Lu belt experienced a granulite facies overprinting at lower crustal level, and the exhumation path from the upper mantle to the lower crust show an isothermal decompression path. The simple thermal calculation suggests that the UHP rocks should exhumed as a large mass more than 15km in diameter to prevent a loss or addition of heat from the wall rocks, even if it exhumed with fairly rapid speed of l0mm/y. This conclusion gives a strong constraint for the exhumation mechanism of the UHP rocks.2) The texture study of Dora Maira massif suggests that the deformation and accompanied fluid infiltration at upper crust pervasively erase precursor UHP evidence especially in quartz-feldsparthic rock rather than basic rocks.3) Our study and literature compile suggest that the granulite facies overprinting on UHP/HP rocks seems to be a common phenomenon in the continent collision belt and annealing at lower crust could be another candidate for obliterating the precursor UHP evidence. This causes a new problem to reevaluate the thermal history of the granulite region for the comprehensive study of the development of continent.

1996年，PCI（高分辨率图像捕获系统）新组合到京都大学的电子显微镜。该新工具改善了深层俯冲大陆材料的微米级纹理分析的质量和精度。对从Su-Lu带，中国东部，Dora Maira Massif，Western Alps和Sanbagawa带收集的深俯冲的地壳材料进行了细节纹理分析，并遵循事实。 Su-lu带在下层地壳水平上经历了颗粒状的颗粒相，从上地幔到下地壳的发掘路径显示出等温解压缩路径。简单的热计算表明，UHP岩石应作为直径超过15公里的大质量挖掘，以防止壁岩中损失或增加热量，即使它以相当快的L0mm/y速度挖掘出来。该结论对UHP岩石的挖掘机制给出了强烈的限制。2）dora maira massif的质地研究表明，上壳的上皮前体前体的变形和伴随的液体浸润，尤其是在石英 - 富含基本岩石中，而不是基本的岩石，而不是基本的岩石。 .3）我们的研究和文献编译表明，在UHP/HP岩石上覆盖过多的颗粒状相似乎是大陆碰撞带中的常见现象，而在下层地壳上进行退火可能是抑制前体UHP证据的另一个候选者。这导致了一个新问题，以重新评估颗粒状区域的热史，以全面研究大陆的发展。