| 试论横断山区印支旋回的构造特征 |
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| DISCUSSION ON INDOSINIAN CYCLE IN THE HENGDUANSHAN REGION (TRANSECT MOUNTAINS) |
| The greatest Indosinian fold region in the world was formed during the Indosinian Cycle in Southwestern Asia.The Triassic System is widely distributed in the Transverse Mountains and varies in sedimentational types. The related formations form three fold belts, i. e., the Jinshanjian-Yuanjiang, the Yu-shu-Yidun and the Ganze-Yajiang belts. They constitute one of the best regions for studying the tectonic evolution of Indosinian Cycle.According to the features of the sedimentary formations and tectonic movements, we divide them into three types.1. Jinshanjian-Yuanjiang type. It is considered to be of eugeosynclinal nature characterized by the presence of oceanic crust and formed during permian to Carnic.2. Yushu-Yidun type. It is also referred to an eugeosynclinal type, characterized by Island-Arc features and formed from the beginning of Early Triassic to the Early Noric stage.3. Ganze-Yajiang type : Being referred to the miogeosynclinal type, it is characterized by epicontinental formation which were formed from early Middle Triassic to the end of the Late Triassic.Therefore, the rocks of these fold belts were formed, one after another, from west to east, during that time of Permian to Early Middle Triassic and they were consolidated during the tectonic movements of Late Triassic.Indosinian Cycle is the main perion for the geosynclinal development in the Transverse Mountains. The said geosynclinal development can be divided into six stage: the Carboniferous or Precarboniferous--the Consolidated stage of the continental crust;the Permian--the Disintegrating stageof the Continental Crust; the Early to Middle Triassic--the stage of Oceanic Crust spreading; the Late Triassic--the Stage of Subduction; and the Jurassic-Cretaceous to Cenozoic--the Stage of Compression to intensive Compression.Indosinian Cycle contains the spreading and subduction period in the tectonic development.In the western districts of the Transverse Mountains, such as Tengchong-Baoshan, Dengqen-Zogang and Angqian-Qamdo regions, a large number of the Lower Triassic beds are absent and there is an unconformity between the Lower and Middle Triassic.In the southeastern districts which belong to the Yangtze Paraplatform.the main regression began at Early Triassic.All the above facts were related to the intensive spreading of the three Indosinian geosynclines. In the Late Triassic there occurred subduction along the Jinshajiang-Red River Deep Fracture and in the west of it (such as near Jomda) was formed the Island-Arc of the Carnic age.Other subductions occurred along the Ganze-Litang Deep Fracture while in the districts further west these formed the Yushu-Yidun Island-Arc of the Noric Stage.In some districts in the back arc region, such as the Dengqen-Zogong and Angqian-Qamdo etc., there existed two unconformities, one was between the Early and the Late Noric and the other between the Noric and Carnic. They were related to the two subductions above-mentioned. |
| CHEN Bing-wei,AI Chang-xing.1983.DISCUSSION ON INDOSINIAN CYCLE IN THE HENGDUANSHAN REGION (TRANSECT MOUNTAINS)[J].Acta Geoscientica Sinica,5(3):25-40. |
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