中亚哈萨克斯坦山弯构造形成时限与动力学机制  

Timing and origin of the Kazakhstan Orocline in Central Asia:A preliminary synthesis

作　　者：李鹏飞 LI Pengfei(State Key Laboratory of Isotope Geochemistry/Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;CAS Center for Excellence in Deep Earth Science,Guangzhou 510640,Guangdong,China)

机构地区：[1]中国科学院广州地球化学研究所/同位素地球化学国家重点实验室,广东广州510640 [2]中国科学院深地科学卓越创新中心,广东广州510640

出　　处：《地质通报》2024年第12期2151-2161,共11页Geological Bulletin of China

基　　金：国家自然科学基金项目(批准号:42172237);广东省项目(编号:2019QN01H101)

摘　　要：山弯构造作为造山带尺度的弧形或马蹄形构造,控制着造山带的构造样式、岩浆演化、沉积过程及古地理格局。然而,造山带为何发生大规模弯曲形成山弯构造这一科学问题,目前仍困扰着学术界。哈萨克斯坦山弯构造位于中亚造山带西部,涉及约3000 km俯冲带的大规模弯曲,保存着山弯构造形成过程中俯冲带演化方面的连续地质记录,是认知俯冲增生过程中山弯构造形成机制的天然实验室。本文在系统解析中亚造山带西部已有地质、古地磁资料的基础上,探究了哈萨克斯坦山弯构造形成时限与动力学机制,认为哈萨克斯坦山弯构造于晚泥盆世—早二叠世发生弯曲,并推测其早期阶段约120°的弯曲可能受控于准噶尔洋俯冲体系沿走向的不均匀侧向迁移,类似于现今环太平洋地区弧形俯冲带的形成过程,而晚期阶段约60°的弯曲可能是由于西伯利亚、塔里木、东欧克拉通汇聚导致的进一步弯曲。未来工作中,查明哈萨克斯坦山弯构造转折端的变形构造样式,将有助于理解俯冲带大规模弯曲的应变协调机制;而围绕山弯构造南北两翼(中国西天山、西准噶尔地区)及转折端(哈萨克斯坦巴尔喀什湖地区)开展俯冲带侧向迁移方面的研究工作,实现准噶尔洋俯冲体系的4D精细重建,揭示其与造山带弯曲的时空耦合机制,亦将有助于进一步揭示哈萨克斯山弯构造形成的动力学过程。The orocline,as an orogenic−scale structure,records key information of the orogenic evolution in 4D,and has a fundamental impact on the magmatic,structural,sedimentary evolution of orogenic belts.However,the geodynamic origin of oroclinal bending remains controversial.This paper focuses on the Kazakhstan Orocline in the western Central Asian Orogenic Belt,which is an ideal candidate for studying the mechanism of oroclinal bending in accretionary orogens given its continuous record of plate subduction.The paper reviews available geological and paleomagnetic data around the Kazakhstan Orocline,which allows to conclude that major phase of bending during the Late Devonian to Early Carboniferous was likely driven by along−strike variation in trench migration,similarly as the formation of arcuate subduction systems around the Pacific margin.A later stage of bending during the Late Carboniferous to Permian might be associated with the amalgamation of the Siberian,Tarim and Baltic cratons.To further understand the origin of the Kazakhstan Orocline would benefit from structural constraints around the hinge of the Kazakhstan Orocline,as well as 4D reconstruction of the Junggar subduction system along two limbs of the orocline(West Tianshan and West Junggar in NW China)and around the hinge of the orocline(Balkhash area in Kazakhstan).

关 键 词：中亚造山带 哈萨克斯坦山弯构造 板片后撤 地球动力学 俯冲带 

分 类 号：P534.4[天文地球—古生物学与地层学] P54[天文地球—地质学]