重力异常三维反演——视密度成像方法技术的应用

3D INVERSION OF GRAVITY ANOMALY∶AN APPLICATION OF THE APPARENT DENSITY IMAGERY TECHNOLOGY

将起伏地形上测量的重力异常,延拓至平均水平面;对平面上的重力场进行不同深度层源的切割分离;再将各层的重力场向下延拓至相应的深度,并反演出该深度层的密度结构。以此得到的密度,反映该深度层密度的近似分布,故称为视密度成像。在重力场的曲面向下延拓过程中,采用了新的延拓方法———迭代法,延拓深度大,延拓过程稳定;且不需解线性代数方程组,避开了制约三维反演实用化的计算时间的瓶颈问题。在主频1.73 GHz的微机上,完成71×81数据点反演的计算时间为10 s。以新疆一个地区的实例说明这种方法的反演效果。

The continuation of the observed gravity anomaly on an undulate terrain to the mean horizontal plane is carried out. Then the gravity field on this plane is separated by cutting the method into several fields caused by strata at different depths. Gravity fields resulting from different strata are downward continued to the corresponding depths, and the density of the strata is inversed. The density obtained by this method is the approximate density contribution of the strata, and is called apparent density imagery. In downward continuation of the gravity field, a new continuation method, i.e. , iteration approach, is used. The process of continuation is stable and has a relatively great depth of continuation. This continuation technology does not need to solve linear algebraic equation system and can overcome the computation time bottleneck which hinders the application of 3D inversion to practice. For a data set of 71 × 81 points, it takes 10s for 3D inversion on a 1.73 GHz PC. A real case in a certain area of Xinjiang is presented to demonstrate the effect of applying this method to inversion.