[S-MP26] 変形岩・変成岩とテクトニクス

[SMP26-07] The origin of the ultrahigh-pressure Tso Morari Complex, NW Himalaya: Implication for Early Paleozoic rifting

*今山 武志¹、Dutta Dripta²、Yi Keewook³ (1.岡山理科大学フロンティア理工学研究所、2.Department of Earth Sciences, Indian Institute of Technology Kanpur、3.Geochronology Team, Korea Basic Science Institute)

キーワード：ultrahigh-pressure Tso Morari Complex、NW Himalaya、Early Paleozoic rifting

The origins and age distribution of the Himalayan high-pressure (HP) and ultrahigh-pressure (UHP) metamorphic rocks are critical to understand the pre-Himalayan history. Although the protoliths to the UHP Tso Morari eclogites in Ladakh, NW Himalaya are believed to be the Permian Panjal volcanics, the geochronological evidence is absent. Here we show that the protoliths of the UHP Tso Morari Complex formed in a continental rift setting at the Indian margin associated with the northern East Gondwana during Early Paleozoic. Zircon U–Pb ages from eight gneisses and one garnet amphibolite indicate the Early Paleozoic bimodal magmatism of 493–476 Ma. Except for arc-related eclogite found in the Nidar ophiolite, most eclogites and amphibolites exhibit enriched LREEs and high concentrations of incompatible elements. Our findings support the previously reported diversity in the sources and ages of the protoliths of the Himalayan HP–UHP metamorphic rocks along the orogen.