下扬子苏南地区重磁场特征与上地壳层带构造的初步研究

A PRELIMINARY APPROACH TO THE CHARACTERISTICS OF GRAVITY AND MAGNETIC FIELDS AND THE UPPER CRUSTAL LAYERED STRUCTURES IN THE AREA OF THE SOUTH JIANGSU,THE LOWER YANGTZE PARAPLATFORM

本文通过对下扬子苏南区重磁资料的计算机处理结果,结合其他有关资料,提出了该区重磁场若干特征及其反映的上地壳层带构造特点的初步认识:1.重磁场表现的一系列正负相间的异常条带,沿不同走向的重磁异常梯度带,异常轴向的突然改变、扭曲等特征,说明该区发育了数条北东向及北北东向复式背、向斜褶皱带以及北东向,近东西向,北北东向,北西向四组不同构造旋回期形成的断裂构造带;2.从重磁场强度分布、物性特征揭示与褶皱、断裂构造带伴生发育了不同层位、不同深度、不同走向的逆冲推覆构造及局部滑脱构造;3.全区上地壳显示三层特点:即基底构造层、含油气构造层、披覆构造层。

Based on the data and information derived from gravity and magnetic investigations in the South Jiangsu with computer processings and combined with relative geological studies, it is suggest ed that the characteristics of the gravity and magnetic fields and the upper crustal layered structures show as follows: 1. A series of interval positive and negative abnormal zones of gravity and magnetic fields, ab normal gravity and magnetic gradients distributed along various trends,and abrupt changing and contortion of axial abnormalies have suggested that a number of NE, NNE composite anticline and syn cline-folding belts and NE, near-NW, NNE and NW four groups of structures formed in the various periods have developed in the area of the South Jiangsu. 2. the distribution of gravity and magnetic field intensity and their physical characteristics re veal that the overthrust in various trends and regional decollements developed in different levels and depths accompanied with foldings and fault structures in the area. 3. The upper crust of the area is characterized by three layered structures i. e. the layer of basement structures, the layer of petroliferous structures and the layer of draping structures.