Cenozoic faults and faulting phases in the western Tarim Basin (NW China): Effects of the collisions on the southern margin of the Eurasian Plate

摘要

The Bachu Rise in the western Tarim Basin is the fore-bulge of the Kunlun late Cenozoic intra-continental foreland basin system formed under the far-field effect of India-Asia collision. Cenozoic faults and faulting are abnormally developed in the Bachu Rise and its adjacent area. Taking the Niaoshan-Gudongshan area on the southern boundary of the Bachu Rise as the key study area, 5 Cenozoic faulting phases were identified in the Bachu Rise and its adjacent area after careful seismic interpretation. They are end Cretaceous beginning similar to Paleogene (ca. 65 Ma) decollement-thrusting, end Paleogene similar to beginning Neogene (ca. 23 Ma) decollement-thrusting, end Miocene beginning similar to Pliocene (ca <1.5 Ma) basement involved thrusting, rate Pliocene early Pleistocene (ca. 3-2 Ma) normal faulting, middle Pleistocene Holocene (ca. <1.5 Ma) decollement-thrusting and strike-slip faulting. The Middle Cambrian and Paleogene gypsum-salt layers serve as the two main decollement layers in the study area. Thrusting of ca. 65 Ma was under the far-field effect of the collision between Lhasa (part of the Cimmerian Continent) and Asia; and the other 4 Cenozoic faulting phases were all under the far-field effect of the India-Asia collision. The late Cenozoic faulting is characterized by pulse thrust. There is one tectonic pause between each two successive thrust pulses. The compressive tectonic stress is weaker and even evolved into a slight tensional tectonic stress and forms normal fault in the tectonic pauses. (C) 2016 Elsevier Ltd. All rights reserved.