Petrology and SHRIMP U-Pb zircon chronol- ogy are reported for the dacite of the Sangxiu Formation in the central segment of Tethyan Himalaya to the southeast of Yangzuoyong Co. Twenty-one measured zircon grains from ...Petrology and SHRIMP U-Pb zircon chronol- ogy are reported for the dacite of the Sangxiu Formation in the central segment of Tethyan Himalaya to the southeast of Yangzuoyong Co. Twenty-one measured zircon grains from a dacite sample of the Sangxiu Formation can be divided into two groups, which include long columnar magmatic zircons of 133±3.0 Ma, representing the age of volcanism in the Sangxiu Formation, and inherited zircons consisting of core and overgrowth rim, in which ages of the three cores are 2244±16, 1153±33 and 492±25 Ma respectively; and the age of one overgrowth rim is 132.7±5.2 Ma. These ages are con- sidered to represent the remelting of accretionary crust at different periods resulting from the volcanism of Sangxiu Formation. These volcanic rocks in the Sangxiu Formation, for which age is close to that of Bunbury basalt in south- western margin of Australia, and older than that of Rajma- hal basalt in northeastern India, maybe considered as the products of early activity of the hotspot represented by the Rajmahal basalt.展开更多
基金This study was financially supported by the National Key stone Basic Research Program of China(Grant No.2002CB412609)the Integrated Study of Basic Geology in the Blank Area of Southem Tibetan Plateau(Grant No.200313000025)the Key Laboratory of Lithospheric Tectonics and Exploration,China University of Geosciences,Ministry of Education,China(Grant No.2003004).
文摘Petrology and SHRIMP U-Pb zircon chronol- ogy are reported for the dacite of the Sangxiu Formation in the central segment of Tethyan Himalaya to the southeast of Yangzuoyong Co. Twenty-one measured zircon grains from a dacite sample of the Sangxiu Formation can be divided into two groups, which include long columnar magmatic zircons of 133±3.0 Ma, representing the age of volcanism in the Sangxiu Formation, and inherited zircons consisting of core and overgrowth rim, in which ages of the three cores are 2244±16, 1153±33 and 492±25 Ma respectively; and the age of one overgrowth rim is 132.7±5.2 Ma. These ages are con- sidered to represent the remelting of accretionary crust at different periods resulting from the volcanism of Sangxiu Formation. These volcanic rocks in the Sangxiu Formation, for which age is close to that of Bunbury basalt in south- western margin of Australia, and older than that of Rajma- hal basalt in northeastern India, maybe considered as the products of early activity of the hotspot represented by the Rajmahal basalt.
