断裂构造精细解释技术——三方向小子域滤波

针对利用重磁场资料解决地质构造的精细划分和解释问题，提出三方向小子域滤波方法. 根据直立岩脉重力异常曲线特征和DCT理论，分析了直立岩脉重力异常π/２相位偏移技术，给出了突出三方向直立岩脉特征的平面重力异常及其π/2相移的DCT转换的理论公式. 模型实验证实，经过坐标变换后的偏移结果，其异常梯度最大值的水平位置与铅垂台阶断面在地面上的投影位置相一致；利用传统的小子域滤波分别检测每个方向偏移处理结果中的梯级带，突出三方向的异常分界特征，从而实现三方向小子域滤波的数值计算. 在应用中表明，传统的小子域滤波只能识别出黑龙江虎林盆地11条断裂带，而三方向小子域滤波法检测出33条断裂，这说明三方向小子域滤波法大大增强了对平面断裂水平位置信息的识别.

A technique for elaborate explanation of faulted structures: three-directional small subdomain filtering

In order to resolve the elaborate explanation problem of geologic structure using the data of gravity and magnetic field, the paper proposes a method of tree-directional small subdomain filtering based on DCT. We analyze the offset technique, in which the phase of gravity anomalies of vertical dike is displaced by π/2, and deduce theoretical formulas, in which the planar gravity anomalies characterizing a vertical dike are highlighted using the DCT method to make their phases transform π/2. It is shown in model experiments that the planar location of the greatest gradient of the displacement result after coordinate transformation is the same as the projective location of the vertical step. Using the conventional method of small subdomain filtering to check gravity gradient zones in offset processing results of each direction and to stand out boundary characteristic of three directional anomalies, so the numerical calculation of three-directional small subdomain filtering can be achieved. In the application, the conventional small subdomain filtering can only discern 11 fractures, but the three-directional samall subdonmain filtering discerns 33 fractures in Hulin basin of Heilongjiang. It is shown that the technique of three-directional small subdonmain filtering can identify more information for horizontal location of planar fault structures.