摘要
青藏高原北部青海省境内跨越四个一级板块构造单元、四个二级板块构造单元和九个三级板块构造单元。通过对重力、航磁、低频地震反射和大地电磁测深等地球物理资料的分析,总结出一级板块构造单元边界断裂即岩石圈断裂的地球物理标志及三级板块构造单元的地球物理场特征。利用地球物理资料建立了地壳重力模型。地壳表面被断裂切割成若干断块,且由地表往深部分若干物性层,据此建立变密度层块地壳结构模型,用以解析板块所涉岩石圈结构特征。地壳巨厚并且壳内存在低阻层是青藏高原板块构造的特征之一。其低阻层呈水平层状时为稳定的刚性地块,对应板块构造单元为隆起区;当低阻层呈波状起伏时为不稳定的柔性地块,对应板块构造单元为海盆区。
Qinghai part of north Qinghal-Xizang plateau crosses four First-Grtade plateteetonic units, four Second-Grade platetectonic units and nine Third-Grade platetectonic units. By analysing the geophysical data such as gravity,aeromagnetic survey,low frequency earthquake reflection,telluric electromagnetic sounding,and so on,the geophysical mark of the margin fractures of First-Grade platetectonic units,that is,lithospheric fractures and geophysical field features of Third-Grade platetectonic units have been summarized in this article. Crustel gravity model has been set up on the geophysical data. Crustal surface has been cut into several faultblocks by fractures which can be divided into a few physical beds from the surface to the depth,so that the crustal structural model of variable density M-blocks has been put forward to interpret the lithospheric structural features connecting with platetectonics. One of platetectonic characters of Qinghai-Xizang(Tibet)plateau is that there are hugely thick crust and low resistance hed in the crust. When the low resistance bed is horizontal,the crustal block is stead and hard with the platetectonic unit being uprised area. When the low resistance bed is undulation,the crustal block is unsteady and weak with the platetectonic unit being sea-basin area.
关键词
板块
构造
地球物理
青藏高原
Northe Qinghai-Xizang(Tibet) plateau
low frequency earthquake reflection
telluric electromagnetic sounding
