Discovery of meridional structures in the western Tarim basin and their implications

The Tarim basin is a rigid block which is situated between the Qinghai-Tibet Plateau and Tianshan orogenic belt.Previous workers found nearly E-W structures and structures parallel to the pe-ripheral orogenic belt in the interior of the basin and intensively studied the characteristics,formation and evolution of these structures.However,they did not find meridional structures.In this study the authors have found meridional structures in the western Tarim basin.They are meridional hinge folds and a fault propagation fold,which mainly formed during the Late Permian.The meridional structures reflect that the Tarim basin had undergone compression from the west in the Late Permian.Under the long-distance ef-fect of collision of the Indian and Eurasian plates,the meridional structures near the Tumxuk fault belt have been activated again since the Palaeogene period.The discovery of the meridional structures is of great significance for hydrocarbon exploration.