Dual influence of the rejuvenation of Southern Tianshan and Western Kunlun orogen on the Cenozoic structure deformation of Tarim Basin,northwestern China:A superposition deformation model from Bachu Uplift

Based on new high-resolution seismic profiles and existing structural and sedimentary results,a superposition de-formation model for Cenozoic Bachu Uplift of northwestern Tarim Basin,northwestern China is proposed. The model presents the idea that the Bachu Uplift suffered structure superposition deformation under the dual influences of the Cenozoic uplifting of Southern Tianshan and Western Kunlun orogen,northwestern China. In the end of the Eocene (early Himalayan movement),Bachu Uplift started to be formed with the uplifting of Western Kunlun,and extended NNW into the interior of Kalpin Uplift. In the end of the Miocene (middle Himalayan movement),Bachu Uplift suffered not only the NNW structure deformation caused by the Western Kunlun uplifting,but also the NE structure deformation caused by the Southern Tianshan uplifting,and the thrust front fault of Kalpin thrust system related to the Southern Tianshan orogen intrudes southeastward into the hinterland of Bachu Uplift and extends NNE from well Pi1 to Xiaohaizi reservoir and Gudongshan mountain,which resulted in the strata folded and denuded strongly. In the end of the Pliocene (late Himalayan movement),the impact of Southern Tianshan orogen decreased because of the stress released with the breakthrough upward of Kalpin fault extending NE,and Bachu Uplift suffered mainly the structure deformation extending NW-NNW caused by the uplifting of Western Kunlun orogen.

Paleozoic Structural Deformation of Bachu Uplift,Tarim Basin of Northwest China:Implications for Plate Drifting

Based on high-resolution 2D seismic profiles, the Paleozoic structural deformation char- acteristics of Bachu （巴楚） uplift of northwestern Tarim basin, NW China, are exhibited in this article. The deformation happened during three main geological periods： the end of Middle-Late Ordovician （O2-3）, the end of Early-Middle Devonian （D1-2）, and the end of Late Permian （P2）. In the Bachu uplift, there developed a series of NW-trending thrust faults and imbricate structures due to the effect of the NW-SE compression stress towards the end of Middle-Late Ordovician （O2-3） （middle Caledonian movement）, and there developed some NNE-trending thrust faults and fault blocks under the control of the NEE-SWW compression stress at the end of Early-Middle Devonian （D1-2） （early Hercynian movement）. However, at the end of Late Permian （P2） （late Hercynian movement）, some NE-trending thrust faults and associated folds developed as a result of the NE-SW compression stress. The first-stage （O2-3） deformation is obviously more violent than those of the latter two stages （D1-2 and P2）, which implies that the Tarim plate drifted quickly to the north at around the same time basin.