Anatexis in Himalayan crust: Evidence from geochemical and chronological investigations of Higher Himalayan Crystallines |
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| Authors: | Email author" target="_blank">Xiaosong?YangEmail author Zhenmin?Jin Jin?Ma |
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| Institution: | 1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China
2. Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China |
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| Abstract: | Migmatization in Higher Himalayan Crystallines (HHC) results from anatexis. The widely distributed migmatites in HHC are an important clue to investigate the relationship be- tween anatexis and the origins of Higher Himalayan leucogranites (HHL), and to understand the effect of anatexis on crustal evolution during the post-collision period. We studied in detail the chemical features of three basic constituent parts of the migmatites, i.e. leucosome, mesosome and melanosome, and determined the K-Ar ages of leucosomes. Our studies indicate that type-I leucosome is the product of crystallization of melt generated by partial melting of mesosome at source region, but type-II leucosome and HHL probably underwent crystallization differentiation of plagioclase during melt aggregation and migration. The age of 22.67 Ma of Type-I leucosome, which is a little older than the beginning of MCT movement, indicates that anatexis may have played an important role in the formation of MCT. That the ages of type-II leucosome (ranging from 14.82 to 18.37 Ma) are consistent with that of HHL provides new chronological evidence for the relationship between migmatization and HHL. We obtained a very young age of 6.23 Ma of Type-II leucosome that provides new time constraint on magma activity in the central segment of Higher Himalayas. |
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| Keywords: | Higher Himalayan Crystallines migmatite anatexis leucosome K-Ar age |
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