Cooling history and tectonic exhumation stages of the south-central Tibetan Plateau (China): Constrained by 40Ar/39Ar and apatite fission track thermochronology

Between the Qiangtang Block and Yalung-Zangpo Suture Zone in the south-central Tibetan Plateau, the following geological units and suture zones have been identified from south to north: the Gangdese Granitic Belt, the Lhasa Block, the Nyainqentanghla Shear Zone, the Dangxiong-Sangxiong Tectono-granitic Belt and the Bangong-Nujiang Suture Zone. To better constrain the tectonic evolution and cooling histories of these units 40Ar/Ar-49 muscovite, biotite and K-feldspar, as well as apatite fission track dating and thermochronological analysis have been carried out. The analytical results indicate that the south-central Tibetan Plateau, with the exception of the Nyainqentanghla Shear Zone, provides a record of three cooling stages at 165-150, 130-110 and similar to 45-35 Ma. Fission-track data modelling also indicates that the stages of cooling were different in the different tectonic belts or blocks. Very different cooling phases occurred in the south-central Tibetan Plateau, compared with southern Tibet, as well as along the Yalung-Zangpo Suture Zone. There is no thermochronological evidence to indicate that the south-central part of Tibetan Plateau was influenced by the underthrusting of Indian Plate. The three-stage cooling history and the stages of tectonic exhumation were controlled completely by the closure of the Bangong-Nujiang Suture Zone along its eastern segment during Middle-Late Jurassic (165-150 Ma) and its western segment in the Early-Late Cretaceous (130-110 Ma), as well as by the collision between the Indian and Asian plates in the Paleogene (45-35 Ma). (c) 2005 Elsevier Ltd. All rights reserved. Between the Qiangtang Block and Yalung-Zangpo Suture Zone in the south-central Tibetan Plateau, the following geological units and suture zones have been identified from south to north: the Gangdese Granitic Belt, the Lhasa Block, the Nyainqentanghla Shear Zone, the Dangxiong-Sangxiong Tectono-granitic Belt and the Bangong-Nujiang Suture Zone. To better constrain the tectonic evolution and cooling histories of these units 40Ar/Ar-49 muscovite, biotite and K-feldspar, as well as apatite fission track dating and thermochronological analysis have been carried out. The analytical results indicate that the south-central Tibetan Plateau, with the exception of the Nyainqentanghla Shear Zone, provides a record of three cooling stages at 165-150, 130-110 and similar to 45-35 Ma. Fission-track data modelling also indicates that the stages of cooling were different in the different tectonic belts or blocks. Very different cooling phases occurred in the south-central Tibetan Plateau, compared with southern Tibet, as well as along the Yalung-Zangpo Suture Zone. There is no thermochronological evidence to indicate that the south-central part of Tibetan Plateau was influenced by the underthrusting of Indian Plate. The three-stage cooling history and the stages of tectonic exhumation were controlled completely by the closure of the Bangong-Nujiang Suture Zone along its eastern segment during Middle-Late Jurassic (165-150 Ma) and its western segment in the Early-Late Cretaceous (130-110 Ma), as well as by the collision between the Indian and Asian plates in the Paleogene (45-35 Ma). (c) 2005 Elsevier Ltd. All rights reserved.