摘要
The Ordos Block is a critical component of the North China Craton(NCC),which is located at the northeastern edge of the Tibetan Plateau.Over the years,it has undergone complex tectonic evolution due to the influence of multiple factors,such as the India–Eurasia plate collision,the subduction of the Pacific Plate,and the southward movement of the Siberian Plate.To investigate the crustal structure and dynamic evolution of the northern margin of the Ordos Block,this study employs joint inversion of receiver functions and gravity data and then integrates results from geology,geophysics,and geodesy.The overall results indicate that the crustal thickness shows a thickening trend from south to north.The generally high Poisson’s ratio suggests that the crust is rich in silica or subjected to high crustal stress.Furthermore,the common conversion point(CCP)stacking results identify distinct layering in the subsurface structure of the northern margin,including the Conrad discontinuity and low-velocity zones,thus reflecting its complex deep structure.Driven by the eastward growth of the Tibetan Plateau and the northwestward subduction of the Pacific Plate,the block rotates counterclockwise,playing a significant role in the formation of surrounding rift basins.The abovementioned findings emphasize the influence of surrounding tectonic activities on the crustal structure and dynamics of the northern margin of the Ordos Block,thus highlighting the potential for strong earthquakes in the region.
鄂尔多斯块体是华北克拉通的关键组成部分,位于青藏高原东北缘,经历了复杂的构造演化,受印度-欧亚板块碰撞、太平洋板块俯冲和西伯利亚板块南移等多重因素的影响。本研究利用接收函数和重力联合反演方法,结合地质学、地球物理学和大地测量学等多研究成果,对鄂尔多斯块体北缘的地壳结构和动力学演化进行了研究。研究结果表明,地壳厚度呈现由南向北增厚的趋势,且普遍的泊松比值较高,表明地壳富含硅质成分或存在较高的地壳应力。共转换点叠加结果识别出北缘地下结构的明显分层,包括康拉德界面和低速带,反映了其复杂的深部构造。此外,受青藏高原东向生长和太平洋板块西北向俯冲的驱动,地块逆时针旋转,对周围裂谷盆地的形成起着重要作用。这些现象强调了周边构造活动对鄂尔多斯块体北缘地壳结构和动力学的影响,突出了该地区发生强震的可能性。
基金
funded by the Earthquake Agency of Inner Mongolia Autonomous Region Director's Fund Project(Grant No.2023QN13)
the Natural Science Foundation of Inner Mongolia Autonomous Region(Grant No.2024MS0421)
the Inner Mongolia Autonomous Region Science and Technology Plan(Grant No.2023YFSH0004).
