根据重力场研究华南地壳结构

华南与华北重力场相比有明显的差别,前者为很强的负异常,它是由于地壳花岗岩化作用使岩石圈密度减小引起的。在沿海地区布格重力异常与莫霍界面起伏没有相关性,地壳与上地幔密度不均匀对重力场分布起主要作用。华南广泛分布花岗岩类,反映了该区特定的地壳结构。花岗岩出露面积与重力等值线有较密切的对应关系,这对于应用重力定量解释推断花岗岩的地下形状具有有利条件。本文讨论运用重力模型研究华南地壳与上地幔结构和花岗岩的地下形态,并探讨花岗岩的成因及其与矿产的关系。

AN INVESTIGATION INTO THE CRUSTAL STRUCTUREOF SOUTH CHINA IN TERMS OF GRAVITY FIELD

The gravity field of South China is obviously different from that of Nor-th China in that the former is characterized by extremely intense negativeanomalies caused by reduction of the density of the lithosphere as a result ofgranitization of the crust. In coastal areas, the Bouguer gravity anomalies showno correlation with the relief of the Moho, and the inhomogenity of densityof the crust and upper mantle seems to play a dominant role in the distribu-tion of the gravity field. The widespread granitoids in South China reflect aspecial crusta' structure of that region. The exposed areas of granites coincidequite intimately with gravity contours, which makes up a favourable prere-quisite for applying gravity data to the quantitative inference and interpre-tation of the shape of granite body at depth. In this paper, a discussion ismade concerning the application of gravity modelling to the study of the earthcrust, the structure of the upper mantle and the subsurface shape of granitesin South China, with a tentative investigation into the genesis of granite andits relations with mineral resources.