利用△T异常反演居里面深度的一种新方法

A new method for Curie interface depth inversion using △T anomaly

利用△T异常反演居里面深度的方法分为两个步骤：第一步，用多次插值切割法从总异常中分离出由居里面起伏引起的△T异常;第二步，用二维单一磁性界面深度的非线性反演的样条函数法对由居里面起伏引起的△T异常进行反演得到居里面深度。关于二维单一磁性界面深度的非线性反演的样条函数法，其例表明：它适用于剩磁与感磁方向不一致的情形;可通过对△T异常作报幅谱分析确定最佳反演点距;非线性反演优于线性反演;迭代是单调收敛的;界面基准理深取得不准时，反演结果只产生有限的误差。用△T异常反演居里面深度的方法对较复杂的模型进行试算取得了较好的效果。南海沿10°N纬线剖面的居里面深度反演实例表明：居里面深度比英霍面深度浅一些，二者的起伏形态有一定的一致性;海盆区的居里面最浅;陆坡区和岛坡区的居里面较陡;大陆和陆架区及岛派和场架区的居里面较平坦且最深。

The method for Curie interface depth inversion using aT anomaly includes two steps: (1) △T anomaly that results from Curie interface undulation is separated out from total anomaly by using multi-interpolation cutting method, and (2) inversion of △T anomaly is made to obtain Curie interface depth by taking spline function method for non1inear inversion of 2-D single magnetic interface depth. Spline function method for nonlinear inversion of 2-D single magnetic interface depth is suitable to the case where residual magnetism and induced magnetism have different directions respectively. The optimal inversion interval can be determined by doing an amplitude spectrum analysis of △T anomaly. Nonlinear inversion is better than linear inversion. Iteration is monotonously convergent. Inversion result only has some errors when datum interface depth is inaccurate.The method for Curie interface inversion using △T anomaly has been applied to the computation of complicated model to bring good result. The depth inversion of Curie interface along 10°N latitude section in South China Sea came to the following conclusions:·Curie interface depth is more shallow than Moho depth, but their undulation shapes are coincident in some degree.· The Curie interface under sea basin area is the most shallow one of all.· The Curie interface under continental slope or island slope is quite steep.· The Curie interfaces under continent, continental shelf, island arc and island shelf are quite flat but the deepest.