Study And Application Of Local Gravity Anomaly Extraction Based On Wavelet Transform

Gravity anomaly separation is an important step in processing gravity data. If we can accurately extract the local anomalies which caused by the geological structure(or orebody) we are searching for, then we can get twice the result with half the effort in the data processing and the interpretation to next step and improve the accuracy of interpretation. Wavelet transform is a popular method in recent years, which is widely used in various fields. This paper introduces the principle of wavelet transform and multi-resolution analysis which are realized through iterative extraction of signal in different frequency by using Mallat algorithm. In this way, we can finally get each order details and approximation signal to describe each frequency of the abnormal component. Using wavelet multi-resolution analysis can use the characteristics of local anomalies and regional anomaly in the frequency domain. In the high frequency segment, highlight the details and at low frequency, highlight the trend. This paper introduces a set of gravitational density model and calculated its gravity anomaly data. By multi-resolution analysis theory, the two-dimensional gravity anomaly are separated and extract, which verifies the effect of several commonly used wavelets in local gravity anomaly extraction. Local anomalies are got in subtracting regional anomaly that using wavelet approximation from Bouguer gravity anomaly data. In this paper, through comparing the trend surface method and multi-resolution analysis and referring to the newest achievement in research of wavelets transform, wen can come to the conclusion that wavelet multi-resolution analysis has advantages in gravity anomaly identification in different depth. Then we apply the method of wavelet multi-resolution analysis in the Bouguer gravity anomaly data which is collected in Sichuan copper mine and Tibet chromite work area. With its results, we pull out the target area.Results show the validity of analyses which is basically consistent with the borehole data...