The Yardoi gneiss dome is located to the easternmost of the North Himalayan Gneiss Dome (NHGD),southern Tibet. It consists of metapelite,garnet amphibolite,granite and leucogranite,and is a key subject to constrain th...The Yardoi gneiss dome is located to the easternmost of the North Himalayan Gneiss Dome (NHGD),southern Tibet. It consists of metapelite,garnet amphibolite,granite and leucogranite,and is a key subject to constrain the formation and tectonic evolution of NHGD. SHRIMP zircon U/Pb data on the leucogranite yield an age of 35.3±1.1 Ma,which is substantially older than that of the similar leu-cogranites to the west. Sr and Nd isotope systematics indicate that this leucogranite was derived from partial melting of the mixed garnet amphibolite and metapelite. Our data suggest that (1) during the early stage of Himalayan magmatism,amphibolite dehydration melting overwhelmed that of the metapelite; and (2) such a melting at middle-lower crust might be a major factor that initiated the movement along the Southern Tibetan Detachment System (STDS).展开更多
基金Supported by National Natural Science Foundation of China (Grant No.40673027)the Outlay Research Fund of Chinese Academy of Geological Sciences (Grant No.20071120101125)the Hundred Talent Program of Chinese Academy of Sciences
文摘The Yardoi gneiss dome is located to the easternmost of the North Himalayan Gneiss Dome (NHGD),southern Tibet. It consists of metapelite,garnet amphibolite,granite and leucogranite,and is a key subject to constrain the formation and tectonic evolution of NHGD. SHRIMP zircon U/Pb data on the leucogranite yield an age of 35.3±1.1 Ma,which is substantially older than that of the similar leu-cogranites to the west. Sr and Nd isotope systematics indicate that this leucogranite was derived from partial melting of the mixed garnet amphibolite and metapelite. Our data suggest that (1) during the early stage of Himalayan magmatism,amphibolite dehydration melting overwhelmed that of the metapelite; and (2) such a melting at middle-lower crust might be a major factor that initiated the movement along the Southern Tibetan Detachment System (STDS).
