Toward a unified model of Altaids geodynamics:Insight from the Palaeozoic polycyclic evolution of West Junggar(NW China)  

作　　者：Flavien CHOULET Michel FAURE Dominique CLUZEL CHEN Yan LIN Wei WANG Bo XU Bei 

机构地区：[1]UMR6249,Chrono-Environnement,CNRS/Universite de Bourgogne Franche-Comte,Besangon,France [2]UMR 7327,Institut des Sciences de la Terre d'Orleans,BRGM/CNRS/Universite d'Orleans,Orleans,France [3]POle Pluridisciplinaire de la Matiere et de l'Environnement,Universite de la Nouvelle Caledonie,Noumea,France [4]Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [5]Department of Earth Science,University of Nanjing,Nanjing 210093,China [6]Key Laboratory of Orogenic Belts and Crustal Evolution,Peking University,Beijing 100871,China

出　　处：《Science China Earth Sciences》2016年第1期25-57,共33页中国科学（地球科学英文版）

基　　金：the National Basic Research Program of China(Grant Nos.2009CB825008&2007CB411301);Chinese National S&T Major Project(Grant No.2008ZX05008);the project‘‘Paleomagnetic study on the tectonic and paleogeographic evolution of northwest of China’’funded by SINOPEC;co-sponsored by the National Natural Science Foundation of China(Grant Nos.40821002&40802043)

摘　　要：The Altaid tectonic collage extends over Central Asia, exposing numerous accretionary orogens that can account for the Palaeozoic continental crust growth. A pluridisciplinary approach, using geochronological, geochemical, structural and palaeomagnetic tools was carried out to unravel the architecture and the evolution of West Junggar （Northwestern China）, a segment of the Altaid Collage. A polycyclic geodynamic evolution is inferred and includes： （1） an Early Palaeozoic cycle, characterized by the closure of two oceanic basins bounded by island-arc systems; （2） an Early Devonian subduction jamming resulting in a minor-scale collision documented by thrusting, syntectonic sedimentation and subsequent crutal thinning associ- ated with alkaline magmatism; （3） a Late Palaeozoic cycle, driven by the evolution of two opposite subduction zones devel- oped upon the Early Palaeozoic basement. Detailed structural analysis and paleomagnetic data provide constraints for the late evolution of Junggar in the frame of the development of the Late Palaeozoic Kazakh orocline, which led to oblique subduction and transpression in the West Junggar accretionary complex. Progressive buckling of the Kazakh orocline further resulted in Late Carboniferous to Permian wrench tectonics, and lateral displacement of lithotectonic units. Block rotations that continued after the Late Triassic are due to diachronous intraplate reactivation. This scenario mirrors the Palaeozoic geodynamics of the Altaid Collage. Multiple Early Palaeozoic collisions of intra-oceanic arcs and micro continents have contributed to the formarion of the Kazakhstan Microconrinent. Since the Late Palaeozoic, subductions formed around this microcontinent and the final oblique closure of oceanic domains resulted in the transcurrent collage of Tarim and Siberia cratons. Palaeozoic strike-slip faults were later reactivated during Mesozoic intracontinental tectonics.The Altaid tectonic collage extends over Central Asia, exposing numerous accretionary orogens that can account for the Palaeozoic continental crust growth. A pluridisciplinary approach, using geochronological, geochemical, structural and palaeomagnetic tools was carried out to unravel the architecture and the evolution of West Junggar(Northwestern China), a segment of the Altaid Collage. A polycyclic geodynamic evolution is inferred and includes:(1) an Early Palaeozoic cycle, characterized by the closure of two oceanic basins bounded by island-arc systems;(2) an Early Devonian subduction jamming resulting in a minor-scale collision documented by thrusting, syntectonic sedimentation and subsequent crutal thinning associated with alkaline magmatism;(3) a Late Palaeozoic cycle, driven by the evolution of two opposite subduction zones developed upon the Early Palaeozoic basement. Detailed structural analysis and paleomagnetic data provide constraints for the late evolution of Junggar in the frame of the development of the Late Palaeozoic Kazakh orocline, which led to oblique subduction and transpression in the West Junggar accretionary complex. Progressive buckling of the Kazakh orocline further resulted in Late Carboniferous to Permian wrench tectonics, and lateral displacement of lithotectonic units. Block rotations that continued after the Late Triassic are due to diachronous intraplate reactivation. This scenario mirrors the Palaeozoic geodynamics of the Altaid Collage. Multiple Early Palaeozoic collisions of intra-oceanic arcs and micro continents have contributed to the formation of the Kazakhstan Microcontinent. Since the Late Palaeozoic, subductions formed around this microcontinent and the final oblique closure of oceanic domains resulted in the transcurrent collage of Tarim and Siberia cratons. Palaeozoic strike-slip faults were later reactivated during Mesozoic intracontinental tectonics.

关 键 词：West Junggar GEODYNAMICS PALEOZOIC PALEOMAGNETISM Crustal growth 

分 类 号：P541[天文地球—构造地质学] P534.4[天文地球—地质学]