中国南海中部和北部的重磁异常特征及其地质解释

本文根据1977—1978年南海中部和北部的重磁测量资料的分析研究,结果表明,从南海北部大陆架至大陆坡直至中央深海盆,布格重力异常值和磁异常值有逐渐增大的趋势;自由空间重力异常值的变化与海底地形的高低变化较一致.决定布格重力异常值区域性变化的主要因素是莫霍面的深浅.决定磁异常值大小的主要因素是基底的岩性.有些断陷区具有高的磁异常值和高的布格重力异常值,推测是因基性或超基性岩浆沿断裂上溢而覆盖于变质岩基底之上或侵入变质岩基底之中引起的.     

LINEAR ISOSTATIC GRAVITY ANOMALIES IN THE SOUTH CHINA SEA

In this paper a model of linear isostatic gravity has been shown in the South China Sea. By means of resolving a stochastic integral equation, a compensating density, which is corresponding to the topographic masses of unit volume, has been established. By calculation, the average depth of the mantle bottom under the South China Sea is 450 km and the depth of one of the interfaces within the layer B is 250 km. The depression areas of the South China Sea are caused by the surplus of the compensation in the depth between 450 and 560 km. The compensating and isostatic gravity anomalies have been resolved, and a geological interpretation has been made.     

南海地区的线性均衡重力异常

本文在南海地区建立一线性重力均衡模型,通过求解随机积分方程的方法,求得一单位体积地形的物质向地球内部的补偿密度分布函数,计算出南海地区上地幔底面的平均深度是450km,它的B层内一个界面深度是250km,南海凹陷下去的原因是补偿南海地区在450—560km深的地方密度的盈余。求得南海地区的补偿重力异常和均衡重力异常,并作出地质解释。