Studies on the uplift, denudation and cooling history of the Himalayan range and associated changes in monsoon

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Chronological and petrological studies on sillimanite-kyanite grade metamorphic rocks of the lower part of the Higher Himalayan Crystallines and the Main Central Thrust zone at the frontal part of nappe in Dhankuta area, eastern Nepal revealed that they were formed under condition of 11 kb/720 centigrade and 8 kb/580 centigrade, respectively. Their P/T condition are as same as those of the metamorphic rocks distributed 100 km to the north of nappe front. It suggests that the metamorphic belt was nearly horizontal and its northern end had constituted the middle crust of Tibet after delamination of subducted Indian upper crust.Heavy mineral analysis of the foreland basin sediments, Dumri Formation, clarified that preceding of the emplacement of higher-grade metamorphic nappe during 15-10 Ma, lower-grade metamorphic rocks of the Kathmandu nappe exhumed and eroded during 20-16 Ma.