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Wu L.,Zhejiang University | Wu L.,Research Center for Structures in Oil and Gas Bearing Basins | Gong Q.,BGP Inc. | Qin S.,BGP Inc.
Acta Petrologica Sinica | Year: 2013

The active left-lateral Altyn Tagh Fault (ATF) defines the tectonic northern edge of the Tibetan Plateau, and is one of the largest and most important faults worldwide. The fast slip along the fault is regarded as one of the major ways to absorb the India-Tibet convergence. However, when did Cenozoic left-slip on the ATF initiate remains a subject of hot debate possibly due to the complexity of the fault itself. In this paper, we focus on the various geological responses to the left-slip on the fault, and figure out their formation time which is helpful in understanding the timing of left-slip along the ATF. They are: (1) provenance change in western Qaidam Basin; (2) Late Cenozoic flexural SE Tarim Basin; (3) NE-SW directed upper-crustal shortening in NE Tibetan Plateau; (4) strike-slip related basins and (5) the linear mountain along the ATF. The result shows that these slip-related phenomena all formed after Mid-Miocene (ca. 15 ±2Ma), which we accordingly interpret as the initial time of left-slip along the ATF. We also analyze the possible reason for the discrepancy between Cenozoic long-term slip rates and reported Quaternary slip rates along the ATF, and discuss the ways how the activities of the ATF formed the Altyn Mountain and controlled the Mid-Miocene tectonic reorganization in NE Tibetan Plateau. Source


Chen X.,Zhejiang University | Chen H.,Zhejiang University | Cheng X.,Zhejiang University | Shen Z.,Research Center for Structures in Oil and Gas Bearing Basins | Lin X.,Research Center for Structures in Oil and Gas Bearing Basins
Tectonophysics | Year: 2015

The geology of Tian Shan provides an excellent example for understanding the intracontinental orogeny in the context of Indian-Eurasian convergence. Previous studies leave much space in basinfill deposition process to be assessed in the regions west to the Talas-Fergana fault (TFF). We improve the understanding by conducting new investigations on sedimentology and magnetostratigraphy in the Tierekesazi section of the foreland region of south West Tian Shan. Four lithofacies have been identified, (i) marine lithofacies from the Aertashi to Bashibulake Formations, (ii) lacustrine to fluvial (plain) lithofacies from the Keziluoyi to the middle Pakabulake Formations, (iii) alluvial sand-gravel sheet lithofacies in the upper Pakabulake Formation, and (iv) conglomerate lithofacies from the Atushi to Xiyu Formations. Magnetostratigraphic analysis, accompanied with biostratigraphic correlation, indicates that four lithofacies cover age intervals of ca. 65. Ma to 34. Ma, ca. 22.1. Ma to 12. Ma, 12. Ma to 5.2. Ma, and 5.2. Ma to approximately present (?), with the sediment accumulation rates increasing from ca. 2.4/3.3-3.5 (compacted/decompacted) cm/ka in the lithofacies (i), to 12.3/16-17. cm/ka in the lithofacies (ii), to 16.3/19.5-20.6. cm/ka in the lithofacies (iii), and finally to >. 22.8/>. 22.8. cm/ka in the lithofacies (iv). These results suggest three episodes of sedimentary events.Combined with previous results, these episodes of sedimentary events are attributed to tectonic activities that are widespread along south Tian Shan. We speculate that the Oligo-Miocene boundary event more directly and likely marks the initial underthrusting of the Tarim block beneath the south Tian Shan. The mid-Miocene and Mio-Pliocene boundary events, although approximately synchronous between the regions east and west to the TFF, have different structural expressions in the two regions. Such difference is proposed to cause the dextral slipping of the TFF, and more fundamentally, likely be driven by the northward indentation of the Pamir at this time. © 2015. Source


Xiao A.,Zhejiang University | Xiao A.,Research Center for Structures in Oil and Gas Bearing Basins | Wu L.,Zhejiang University | Wu L.,Research Center for Structures in Oil and Gas Bearing Basins | And 2 more authors.
Acta Petrologica Sinica | Year: 2013

The active Altyn Tagh Fault in northern Tibetan Plateau is one of the largest and most significant linear structures in the world, and its Cenozoic activity is the important constraint on the growth mechanism of the Tibetan Plateau. In this paper, we illustrate that the Altyn Tagh Fault was dominated by basal shear during Late Eocene-Middle Miocene but by large-scale left-slip movement since then based on comprehensive analysis on uplifts of different trending in the Altyn Mountain and reported materials. We study systematically on the distribution, geometry and timing of the EW- and NW-trending fault systems inside the Qaidam Basin, and find that they are completely different fault systems forming in different time, different areas and controlled by different factors, showing a perfect coupling with the two-stage movement of the Cenozoic Altyn Tagh Fault. We also discover that height and width of the Altyn Mountain culminated in Mid-Miocene and then decreased according to the sedimentary and structural characteristics in NW Qaidam Basin, which can be well explained by the transition from basal shear to left-slip of the Altyn Tagh Fault. Source


Lou Q.Q.,Third Geological Group of Zhejiang Province | Lou Q.Q.,Zhejiang University | Xiao A.C.,Zhejiang University | Xiao A.C.,Research Center for Structures in Oil and Gas Bearing Basins | And 3 more authors.
Yanshi Xuebao/Acta Petrologica Sinica | Year: 2016

Depressions with terrestrial sediments is a unique and very important kind of sedimentary basins on earth, which usually develops by differential subsidence within Craton and /or thermal subsidence in the late stage of rift basin. In this paper, based on the characteristics of this type of basin, we put forward a method and workflow on basin Prototype reconstruction using a comprehensive analysis of sedimentary facies, isomaps of remnant thickness, regional cross-sections and related balance sections. The method and workflow include restoring the original boundaries of the basin using residual sedimentary facies, the original shapes during different stages using balanced cross-sections, and the original sediment thickness using relevant exploratory well data and balanced cross-sections. By this method we can research the basin prototype within the original shape of basin, which eliminates the effect of later tectonic alteration. We analyzed the Cenozoic Prototype of the Qaidam Basin in northern Tibetan Plateau based on the above workflow. The result shows that the change of sedimentary patterns of the Qaidam Basin over time was closed related to the activities of the Altyn Tagh Fault. Source


Wu L.,Zhejiang University | Wu L.,Research Center for Structures in Oil and Gas Bearing Basins | Xiao A.,Zhejiang University | Xiao A.,Research Center for Structures in Oil and Gas Bearing Basins | And 10 more authors.
Cretaceous Research | Year: 2011

Formation of Mesozoic western China, which was dominated by tectonic amalgamation along its southern margin and associated intracontinental tectonisms, holds a key for interpreting the succedent Cenozoic evolution. This paper presents new data including lithology, sedimentary facies, stratigraphic contact, seismic interpretation and paleo-structures within the Upper Jurassic-Lower Cretaceous strata in the northern Qaidam Basin, NW China. These data all account for a contractional tectonic deformation in the earliest Cretaceous. The South Qilian Shan, according to the sedimentary features and provenance analysis, reactivated and exhumated during the deformation, controlling the deposition of the Lower Cretaceous sequences. A simplified model for the Late Jurassic-Early Cretaceous paleogeography and tectonics of the northern Qaidam Basin is accordingly proposed. The results also support a ∼25° clockwise rotation of the Qaidam Basin since the Early Cretaceous and a more accurate Mesozoic evolution process for the basin. This earliest Cretaceous deformation, associated with the reactivation of the South Qilian Shan at the time, are part of the intracontinental tectonisms in central Asia during the Mesozoic, and probably driven by both the closure of the Mongol-Okhostk Ocean to the north and the collision of the Lhasa and the Qiangtang blocks to the south. © 2011 Elsevier Ltd. Source

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