Geochemical characters of the granites in the North Lancangjiang granitic belt and its tectonic implication
Paleotethyan granites are well developed in eastern Tibet,such as the Jiangda-Weixi granitic belt related to the Jinshajiang suture,the Yidun granitic belt related to the Ganzi-Litang suture belt.But as part of the main Paleotethyan suture,the North Lancangjiang granitic belt is not well studied.Here we provide petrologic and geochemical feathers of the rocks in this belt to disclose its tectonic implication.The zircon ages of the granite rocks are clustered around 217±1 Ma;mean εHf(t)value is around-13.5 with mean TDM2 age around 2.1 Ga;and mean εNd(t)value is around-12.0 with mean TDM2 age around 2.0 Ga.Isotope and geochemical data show that the rocks are derived from middle or upper crust with ancient lower crustal material contamination,and emplaced in continental collision environment.The case suggests eastward subduction of the oceanic lithosphere beneath the Lanping-Simao massif and subsequence collision during the paleo-Tethyan evolution.The discovery of the granite in Weixi area further suggests the North Lancangjiang granitic belt spans over 700 km in eastern Tibet.The granitic belt from Leiwuqi country,through Jitang and Yanjing towns in Changdu City,then passing Meili Snow Mountain,finally reached the Biluo Snow Mountain of Weixi Country.The petrologic,geochronological and geochemical data in this paper provide new data for the correlation between Longmu co-Shuanghu suture belt and Changning-Menglian suture belt.
North Lancangjiang granitic beltBiluo Snow Mountain granitePaleotethyan sutureGeochemical characteristicsS-type granite
万方数据
维普
