2(1/2)度体组合模型反演三维密度界面

THREE-DIMENSIONAL DENSITY BOUNDARY OBTAINED FROM THE INVERSION OF 2(1/2)-DIMENSIONAL MODEL-COMBINATION

成都地质学院

2(1/2)度体组合模型的重力异常与三度体的重力异常非常接近。根据2(1/2)度倾斜板状体的异常表达式导出的2(1/2)度倾斜物质面的重力异常表达式很简单,在一般情况下物质面的异常与板状体的异常是接近的,相对误差不超过15%。引用2(1/2)度倾斜物质面的重力异常计算式建立了三维密度界面迭代反演方法。该方法归结为求解一个以界面深度修改量为未知向量的线性代数方程组,反复对界面深度进行修正,直到获得满意的结果为止。计算了一个控矿构造实例,取得了较为满意的效果。

The gravity anomaly of 2(1/2)-dimensional combined model is similar to that of 3-dimensional ones. The mathematical expression of gravity anomaly for 2(1/2)-dimensional dipping mass surface derived from that of 2(1/2)-dimensional dipping tabular body is rather simple. In genaral, theshapes of these anomalies are quite close. All their relative errors do not exceed 15%.The iterative inversion approach for defining three-dimensional density boundaries based upon the calculation of gravity anomoly due to 2(1/2)-dimensional dipping mass surface is established. It involves the solution of a linear algebraic equation system with the unknown vectors representing the modified values of boundary depth. By iterative corrections of the boundary depth one can get the satisfactory results.Such kind of calculation is made for an ore-controlling trap and satisfactory result is obtained.