Cenozoic Tectonic Uplift And Sedimentary Evolution Of The Tiklik Area, Western Kunlun Orogen

The Tiklik area is located in the northwest of the Tibetan Plateau, and belongs to a part of the Western Kunlun orogen. Studies of the Cenozoic evolution in this area will provide more valuable information for the Cenozoic orogenic processes of the Western Kunlun orogen, as well as the evolution of the SW Tarim basin and uplift of the Tibetan Plateau. With the geologic researches had been doing many geological studies, however, there are so many cognitions need to unify and so many geologic problems need to do further research, such as, uplift process, structural deformation, structural evolution, sedimentary evolution and basin-mountain coupling, et al. Based on the theory of the basin-mountain coupling and thrust fold, this paper carried the field geologic investigation, the explanation of CEMP profiles and seismic profiles, paleocurrent analysis, clastic rock characteristic analysis, fission track thermochronology analysis, and grain size analysis, this paper focuses on the Cenozoic tectonic uplift, structural deformation in the piedmont of the Tiklik and evolution of the SW Tarim basin, and following implication have been achieved.The first raw structural belt-Fusha-Keliyang structutal belt is a damaged anticline which is cut though by a strike-slip reverse fault, and the high-angle faults and its branches in the central is a dextral strike-slip reverse fault zone. The result suggests that the Fusha-Keliyang structural belt had undergone two different kinds of deformations since Cenozoic. The first stage was the contraction deformation, and the Fusha-Keliyang anticline belt which belongs to the Cenozoic thrust belt in front of the Western Kunlun orogen was formed, and the Fusha-Keliyang anticline belt was composed of two anticlines which the western anticline and eastern anticline were superposed near the KD 1 well. The second stage was a strike-slip deformation, and a high angle dextral strike-slip reverse fault cut through the anticline, which destroyed and divided the anticline into a number of blocks. The dextral strike-slip reverse fault was developed in the core of the anticline in the western part which resulted the western anticline into several fault blocks, but it was developed in the north rim of the anticline and the core of the anticline was reserved in the eastern part, resulting in obvious differences in the two anticlines.Apatite fission track data in this paper indicate that the Tiklik had undergone at least three-stage cooling exhumation history since Cenozoic:(1) the rapid uplift and cooling stage in 16-13Ma, then the erosion rates are between 0.167-1.375mm/yr; (2) slower uplift and ersion in 13-5Ma, erosion rates are between 0.094～0.143mm/yr; (3) again fast uplift and cooling since 5Ma, erosion rates are more than 0.3mm/yr, and the maximum can reach 0.88mm/yr.Based on the field investigation and grain size analysis of the Keliyang area, this paper discussed the Cenozoic evolution of SW Tarim basin. Experienced several transgressions and regressions in Paleogene, a series of marine sediments such as gypsum, shelly limestone, gypsum-containing mudstone are deposited in the Keliyang area, indicating that the basin is a cratonic basin in this stage. With the Tarim sea regressed in Oligocene, the sedimentary environment changed from shallow marine facies to fluvial facies, marking the initiation of the foreland basin development. The lake sediments in Middle Miocene suggested that the Keliyang area was located in the foredeep of the foreland basin, and the basin is starved basin in this stage. The sedimentary environment had changed from a relatively calm fluvial environment to alluvial fan environments since the late Miocene, indicated that foreland basin was destroyed, and hence formed present structural framework.Through geological field work, petrography of sandstone and grain size analysis, it can conclude that tectonic activity is weak in basin, where develop lake facies to lake delta facies during the deposition of the Keziluoyi Formaiton (after early Miocene). The depositional environment has changed from delta plain to fan middle subfaices during the deposition of Atux Formation. Then during the deposition of Xiyu Formaition, conglomerates settle in east part of basin, forming present structural framework.Apatite fission track data, sedimentary record and structural deformation indicate tha the uplift process of the Tiklik have experienced five phases since Cenozoic:(1) the stable phase in Paleocene- Late Oligocene (65-25Ma); (2) faster uplift and exhumation in late Ologocene-early and middle Miocene (25-16Ma); (3) rapid uplift and coling stage in early and middle Miocene -middle Miocene (16-13Ma); (4) slow uplift and exhumation stage in middle Miocene -early Pliocene (13-5Ma); (5) strong uplift in Pliocene (5Ma).