改进的倾斜角法在位场场源边界识别中的应用

位场场源边界识别是位场数据分析解释中的重点内容之一。相邻异常源由于场的叠加而难以区分,尤其是对于叠加异常中不同深度的场源边界的识别。倾斜角法是位场数据处理中常用的边界增强方法之一,能有效突出低振幅、短波长的异常特征。本文基于倾斜角法定义了新的位场边界探测方法,该方法利用倾斜角方程中位场二阶垂直导数与垂向导数水平导数之比进行计算,能有效区分相邻异常源产生的叠加异常,突出叠加异常中不同深度场源的边界特征。通过综合模型和实测数据,并与现有的基于导数的位场边界探测方法进行比较,评价了该方法的应用效果。结果表明,该方法对场源深度的变化不太敏感,它可以更准确地确定场源边界,区分相邻异常源的叠加异常,尤其对密集型组合地质构造的识别有较好的效果,即使是在场源埋深较大情况下,也能突出叠加异常中不太明显的微弱变化的线性异常特征,以及弱异常源的形态特征,可为精细研究局部地质构造提供技术支持。

Application of the improved tilt angle method to source edge detection of the potential field

Source edge recognition is a key and difficult issue in data analysis and interpretation of the potential field. It is difficult to distinguish adjacent anomalous sources because of their field superposition, especially for the edge detection of field sources with different depths in superimposed anomalies. In this paper, a new potential field edge detection method is proposed based on the tilt angle method. This method calculates the ratio of the second-order vertical derivative of the potential field to the horizontal derivative in the tilt angle equation. It can effectively distinguish the superimposed anomalies generated by adjacent anomalous sources and highlight the boundary characteristics of sources at varied depths in superimposed anomalies. The new method is tested and the application effect is evaluated on synthetic models and measured data from eastern Tianshan by comparing with the existing derivative-based potential field edge detection method. The results show that the new method is not sensitive to the depth variation of field sources, and able to conduct more accurate estimation of field source edges and separation of superimposed anomalies from adjacent anomalous sources, especially for the identification of dense combined geological structures. Even for deep-buried field sources, this method can highlight the lineation and shape of weak anomalous sources that are not so evident in superimposed anomalies. This method thus can provide technical support for fine study of local geological structures.