基于DCT的重力归一化总梯度及相位在识别断裂构造中的研究与应用

Study and application of normalized full gradient of gravity anomalies and phase based on DCT in identifying fracture

区别于传统的别列兹金(V.M.Berezkin)法(即傅立叶级数法)和傅立叶变换法,提出在位场转换时采用离散余弦变换(DCT)计算重力归一化总梯度和归一化相位,并把二者结合起来研究断裂构造。分别研究了比较典型的无限延伸铅垂台阶、有限延伸铅垂台阶和正断层模型的GH场和相位特征,模型实验证实了方法的可行性和有效性。得出了寻找地质体断裂的空间位置和水平尺度的规律:在断裂处GH场有极大值圈闭,相位发生突变;多个断面相位有多个突变,两个突变点之间的水平距离反映地质体的水平尺度;不同深度相位突变点之间的连线大致反映了断裂的倾向。将研究方法应用于兴凯—虎林线剖面异常数据处理中,根据该线GH场和相位特征,划分出13条断裂。

By using DCT to calculate normalized full gradient of gravity anomalies and phase, the authors studied faulted structure in conversion of potentialfield, which is differ from conventional V. M. Brezkin and Fourier transform, and also research GH field and phase characteristic of typical infinite vertical step, finite vertical step and normal fault. The model experiments have proved that DCT is viable and valid. Meanwhile, we gain the rules looking for the. location and horizontal distance of fracture. GH field has max entrap and phase mutation in fracture location, and if structures have several fractures, then phase curves have mutations, and distance of two phase mutations can probably identify horizontal distance of fracture. The line joining the different phase mutations in depth can reflect fracture trend. According to the GH field and its phase curves, 13 fractures were delineated in application of the abnormal data in Xingkai - Hulin profile.