天山造山带壳幔结构与陆内变形机制研究进展  

Research progress on seismic structures of crust and mantle beneath Tien Shan and their geodynamic implications

作　　者：张秉峰 鲍学伟 Zhang Bingfeng;Bao Xuewei(Key Laboratory of Geoscience Big Data and Deep Resource of Zhejiang Province,School of Earth Sciences,Zhejiang University,Hangzhou 310027,China)

机构地区：[1]浙江大学地球科学学院浙江省地学大数据与地球深部资源重点实验室,杭州310027

出　　处：《地球与行星物理论评（中英文）》2023年第1期27-43,共17页Reviews of Geophysics and Planetary Physics

基　　金：国家重点研发计划资助项目(2019YFA0708604);国家自然科学基金资助项目(41774045)。

摘　　要：天山作为当今世界上最为典型的陆内造山带,对于其深部结构和新生代构造变形过程的研究一直是地球科学领域的前沿和热点,并已经取得大量成果.本文系统总结了近年来利用地震学方法对天山造山带及其邻区壳幔结构研究的最新进展以及存在的争议.这些研究发现包括地壳厚度、莫霍面形态、地幔转换带厚度、地震波速、Q值结构在内的多结构参数的变化与区内各个大地构造单元的对应性较好,彰显出盆-山深部结构的显著差异.研究区各向异性结构复杂,地壳内部的偏振方向存在明显的横向变化,并在上地幔深度转换为和造山带走向基本一致.另外,在中下地壳和上地幔顶部,天山大部表现为明显的低速异常.以上结果揭示了陆内俯冲和地幔上涌对于塑造现今天山复杂构造格局与地质地貌特征的重要意义.然而,现有研究对于我国新疆境内天山壳幔各向异性、岩石圈底界面以及地幔转换带的分辨率还远远不够,并且对于一些重要的结构参数及其解释尚未达成一致的认识.密集流动地震台阵观测和多种地球物理资料的联合分析是解决这一问题并增进对陆内造山带深部动力学过程认识的有效途径.The mechanisms causing the uplifting of the Tien Shan,one of the largest and most active intracontinental orogenic belts on Earth,have been vigorously debated for decades.Seismic investigation is a fundamental tool used for deep structural exploration and is key to understanding continental geodynamics.As such,in this study,we reviewed the recent research progress on the crustal and upper-mantle structures of the Tien Shan and the remaining controversies.The results showed that the Tien Shan and adjacent basins exhibit contrasting structural and physical properties from the crust down to the upper mantle in various aspects,such as crustal thickness,Moho morphology,mantle transition-zone thickness,seismic velocity,and seismic attenuation.The mountainous areas have complex crustal seismic anisotropy patterns,whereas orogen-parallel anisotropic fabrics dominate at upper mantle depths.Low-velocity anomalies pervasively exist in the mid-lower crust and uppermost mantle of Tien Shan.Taken together,these observations provide evidence of the important roles played by intracontinental subduction and mantle upwelling in Cenozoic orogenesis of the Tien Shan.However,further development of our under standing of the geodynamics in Tien Shan has been hindered by the low imaging resolution of seismic anisotropy,lithosphere-asthenosphere boundary,and mantle transition zone in eastern Tien Shan.And some important geophysical parameters and their implications are still far from being well-understood.Future deployment of dense temporary seismic arrays in the eastern Tien Shan and joint inversion of multiple and complementary geophysical data will considerably increase the resolution of seismic models and ultimately enhance our knowledge of geodynamic evolution in compressional intracontinental orogens.

关 键 词：天山 壳幔结构 各向异性 陆内造山 

分 类 号：P315[天文地球—地震学]