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Chuangu Dai, Geological Survey of Guizhou Province, China (China)
Min Wang, Geological Survey of Guizhou Province, China (China)
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Based on detail analyses of stratigraphy, sedimentary facies, magmatism, and structural patterns of the East Guizhou, the tectonic evolution history of the eastern Guizhou is suggested as following: (1) from the Wuling to the Caledonian Cycles, the transformation from oceanic to continental environment completed; then the Yanshanian and Himalayan Cycles activation were intra-continent. The transformation occurred via a B-type subduction, while A-type collision resulted in the intra-continent activations.
During the transformation, the tectonic location of the eastern Guizhou migrated from the inner belt to the outer belt of the Jiangnan orogen. A foreland basin formed during the Yanshanian in the eastern Guizhou, which evolved into an intra-plate uplift part of the Yangtz Plate by the Himalayan activation. Obviously, both the geologic features and tectonic evolution of the eastern Guizhou were greatly affected by the evolution of the Jiangnan orogen.
Accordingly, a new tectonic division schedule for the eastern Guizhou is proposed as below. The first-level tectonic unit, the Jiangnan orogen is bounded northerly by the Shizong-Songtao-Chili-Jiujiang belt and southerly by the Shaoxin-Pingxiang-Beihai fault system. It is bracketed by the Yangtz (Northwest) and the Cathisian (Southeast) blocks. The Jiangnan orogen can be subdivided into three sub-units: northern, middle, and southern sub-units respectively. The southern boundary of the northern sub-unit is the Shizong-Songtao-Chili-Jiujiang belt, between the Shizong-Songtao-Chili-Jiujiang belt and the Luocheng-Longshen-Taojiang-Jingdezhen is the middle sub-unit; and south of the Luocheng-Longshen-Taojiang-Jingdezhen belt belongs to the southern sub-unit, where the Qiandong-Xiangxi and Nanning-Changsha blocks are enclosed. The three sub-units correspond to the three stages of activation, i.g., the Wuling, the Caledonian, and the Yanshanian respectively. In conclusion, the Jiangnan orogen is a composite one formed by multi-stages orogenesis.
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