Lu H.,State Key Laboratory of Continental Tectonics and Dynamics |
Lu H.,Chinese Academy of Geological Sciences |
Wang E.,CAS Institute of Geology and Geophysics |
Meng K.,CAS Institute of Geology and Geophysics
Tectonophysics | Year: 2014
Despite receiving considerable attention, the nature and timing of Cenozoic tectonic evolution of the Altyn Tagh Fault (AFT) remain highly debated. Here we conducted detailed magnetostratigraphy and anisotropy of magnetic susceptibility (AMS) studies on the Cenozoic Janggalsay section, southeast Tarim basin. Magnetostratigraphy indicates that the measured Janggalsay section spans a time interval of ~. 22-11. Ma. The magnetic declination data suggest that the Janggalsay site has rotated significantly counterclockwise (17.2°. ±. 8.5°) from ~. 22 to 17-15. Ma, while the rotation has terminated from 17-15 to 11. Ma. The results are consistent with a two-stage tectonic model for the ATF, with a phase of large magnitude strike-slip motion along the ATF from the Oligocene to Middle Miocene and a second phase of lower amounts of strike-slip motion and more widespread contraction since the Middle Miocene. The AMS fabric data and sedimentology of the Janggalsay section likely indicate the rapid rock uplift of the Altyn Tagh Range since 16. Ma. © 2014 Elsevier B.V.
Dong H.,State Key Laboratory of Continental Tectonics and Dynamics |
Xu Z.,Chinese Academy of Geological Sciences
Tectonophysics | Year: 2015
The uplift history and tectonic evolution of the Eastern Himalayan Syntaxis (EHS) have been extensively studied in the last several decades. The Médog shear zone, the eastern boundary of the EHS, has preserved considerable significant information on the structural and tectonic evolution of the EHS. In this study, we report kinematics, fabrics and geochronology data of the Médog shear zone in the EHS. Analyses of the crystallographic preferred orientation (CPO) of quartz (EBSD analysis) demonstrated that there are three major slip systems: (1) basalslip, (2) prism [c] slip, and (3) prismslip. These slip systems are consistent with microstructures of low-temperature shearing, medium-temperature shearing and high-temperature shearing, respectively. Zircons from the two gneiss samples possess inherited magmatic cores and metamorphic overgrown rims, yielding a metamorphic age of 29.4-28.6Ma. It is suggested that the dextral shearing along the Médog shear zone was not earlier than the Early Oligocene. The 40Ar/39Ar analysis indicates that the Médog shear zone experienced three thermo-tectonic events from the Late Oligocene to the Pliocene, e.g., ~23.4Ma, 16.9-12.6Ma and ~5.3Ma. We correlate the Oligocene metamorphic event and the Late Oligocene to the Pliocene multi-stage thermo-tectonic events that resulted from subduction of the northeast corner of the India plate. © 2015.
Chen Z.,China University of Geosciences |
Chen Z.,Beijing University of Technology |
Chen Z.,State Key Laboratory of Continental Tectonics and Dynamics |
Meng X.,China University of Geosciences |
And 3 more authors.
Computers and Geosciences | Year: 2015
We present a fast procedure for the interface inversion of density contrast on the platform of GPU. Firstly, based on the iterative method in spatial domain, we introduce soft constraints by some few control points, making the inversion results closer to reality. In this problem, we assume that the density contrast decays with depth according to a parabolic law. Secondly, in order to meet the interface inversion for a wide range large-scale gravity data, we develop GPU program of the 3D interface inversion of basement relief, and give the corresponding optimization strategies and the speedup tests for the calculation results. We demonstrate the applicability and efficacy of this technique by inverting gravity anomalies caused by a synthetic model of a density interface and a set of real field data. © 2015 Elsevier Ltd.
Li H.,Chinese Academy of Geological Sciences |
Li H.,State Key Laboratory of Continental Tectonics and Dynamics |
Lin W.,Petrochina |
Lu Z.,Chinese Academy of Geological Sciences |
And 2 more authors.
Shiyou Diqiu Wuli Kantan/Oil Geophysical Prospecting | Year: 2015
In order to improve seismic imaging quality, we propose in the paper a method for removing moveouts of azimuth anisotropy based on the difference theory, and put forward formulas for moveout corrections. Test results on both model and real data show that data resolution and signal-to-noise ratio have been significantly improved in both prestack gathers and stack sections. © 2015, Science Press. All right reserved.
Qiao X.,State Key Laboratory of Continental Tectonics and Dynamics |
Qiao X.,Chinese Academy of Geological Sciences |
Guo X.,State Key Laboratory of Continental Tectonics and Dynamics |
Guo X.,Chinese Academy of Geological Sciences
Acta Geologica Sinica | Year: 2013
The early Jurassic soft-sediment deformation occurring within lacustrine sandstone is distributed mainly in the Wuqia region of SW Tianshan Mountains, Xinjiang, western China. Triggered by earthquakes, such deformation was found to occur in three beds overlying the lower Jurassic Kangsu Formation. The main styles of deformation structures comprise load cast, ball-and- pillow, droplet, cusps, homogeneous layer, and liquefied unconformity. The deformation layers reflect a series of three strong earthquakes at the end of early Jurassic in the Wuqia region. The differences of deformation mechanisms undergone might represent the varying magnitudes of the earthquake events. During the early Jurassic, the Wuqia region was located in a pull-apart basin controlled by the significant Talas-Ferghana strike-slip fault in central Asia, which initiated the soft-sediment deformation induced by earthquakes. Our research suggests that the paleoseismic magnitudes could have ranged from Ms 6.5 to 7.