青藏高原东缘地壳密度结构及其地球动力学意义  

CRUSTAL DENSITY STRUCTURE OF THE EASTERN TIBETAN PLATEAU AND ITS GEODYNAMIC IMPLICATIONS

作　　者：李丹丹[1,2] 唐新功 熊治涛[1,3] LI Dan-dan;TANG Xin-gong;XIONG Zhi-tao(Key Laboratory of Exploration Technologies for Oil and Gas Resources of MOE,Yangtze University,Wuhan 430100,China;Chinese Antarctic Center of Surveying and Mapping,Wuhan University,Wuhan 430079,China;Department of Earth and Space Sciences,Southern University of Science and Technology,Shenzhen 518055,China)

机构地区：[1]长江大学,“油气资源与勘探技术”教育部重点实验室,武汉430100 [2]武汉大学,中国南极测绘研究中心,武汉430079 [3]南方科技大学,地球与空间科学系,深圳518055

出　　处：《地震地质》2023年第4期936-951,共16页Seismology and Geology

基　　金：国家自然科学基金(42274087,41874119,42174083)资助

摘　　要：青藏高原东缘是高原物质向E及SE扩展的重要通道,掌握青藏高原东缘的地壳密度结构对研究青藏高原的隆升、变形机制具有重要意义。文中在前人研究成果的基础上,选取了地面实测的9条交叉的重力测线数据,以深地震反射剖面为约束,采用人机交互模式反演得到了青藏高原东缘地下的二维密度结构,并通过克里金插值法获取了三维密度结果。反演结果表明,青藏高原东缘地区具有巨厚的地壳,莫霍面埋深最深约为61km,而四川盆地的莫霍面埋深约为42km,以龙门山-安宁河-小金河断裂为界,两侧形成了莫霍面深度变化梯度带;从反演得到的沉积层厚度来看,沉积层在青藏高原东缘几个块体内呈现中心普遍厚度较大、边缘厚度较薄的特点。结合该地区的地震空间分布特征分析,青藏高原东缘的莫霍面和沉积层厚度分布与该地区的地震分布均具有很强的相关性,这对未来地震预测也具有重要的参考价值。The continuous collision and convergence between the Indian and Eurasian plates have caused strong uplift and deformation within the Tibetan plateau and the surrounding areas.The eastern Tibetan plateau,as an important channel for the eastward and south-eastward expansion of plateau materials,is an critical area for understanding the interaction between the Tibetan plateau and the eastern tectonic blocks and for understanding the eastward escape of plateau deep materials,which is of great significance for studying the uplift and deformation mechanism of the Tibetan plateau.A large number of studies on the eastern Tibetan plateau have provided an important basis for revealing the uplift mechanism of this region.However,its complex geology makes it difficult in understanding the uplift mechanism from the single geophysical interpretation.The gravity field reflects the density properties of the subsurface material,and can be related to the wave velocity properties of the seismic data by certain translation relationships.In addition,gravity data can improve the crustal model of the area not adequately covered by seismic data,which can not only provide the three-dimensional crustal density structure of the area,but also reflect the relationship between the spatial distribution of earthquakes and the crustal structure from a gravity perspective.In this paper,based on the previous research results,we selected field survey gravity data of nine intersecting lines and used the deep seismic reflection as the constraint to invert the density interface depth distribution of each line by using human-computer interaction mode,and then used the kriging interpolation method to obtain the three-dimensional Moho depth and basement depth in the area,and then we obtained the sediment thickness by analyzing the difference between the topography and the basement depth.The inversion results show that the overall trend of Moho depth is deep in the west and shallow in the east,with the deepest depth in the west being 61km and the shallowe

关 键 词：青藏高原东缘 地壳密度结构 莫霍面 沉积层厚度 

分 类 号：P315.2[天文地球—地震学]