Abstract:There exist different view points about the deformation characteristics of the Indosinian Movement during late Middle Triassic in south China. Someones emphasize on the importance of the Indosinian Movement or consider that the NNEtrending folds in Late Paleozoic cover were formed in the movement, while others hold that the movement was weak and the NNEtrending folds were formed in Yanshanian Movement, or later. Therefore the writers studied emphatically on the lineament trend of Indosinian Movement in southeastern Hunan, and ensured NNEtrending of the lineament which indicated regional NWW compression. The studies on the Late Triassic—Jurassic rudimental basins in Sandou of Zixin, Yaogangxian of Yizhang and Shatian of Guidong show that the unconformity surface under early Yanshanian tectonic layer incised the NNEtrending folds in Upper Paleozoic. Rotating the unconformity surface to horizontal along the trending direction, writers recovered the NNEtrending of the Upper Paleozoic layers and structural lineament. There exist rapid variation of layers under the unconformity surface along E—W direction. The facts indicate that the lineament trend of Indosinian Movement in southeastern Hunan was NNE rather than E—W, and accordingly the regional compressional stess was NWW rather than S—N. The dynamic mechanism of the Indosinian Movement in southeastern Hunan can be related with the intracontinental subduction—convergence between the Yangtze and Cathaysia block. Combining regional data, writers consider that the tectonic settings and regimes of Indosinian Movement in different areas of South China were different.
