Abstract
Obtaining horizontal edges and the buried depths of geological bodies, using potential field tensor data directly is an outstanding question. The largest eigenvalue of the structure tensor is one of the commonly used edge detectors for delineating the horizontal edges without depth information of the potential field tensor data. In this study, we presented a normalized largest eigenvalue of structure tensor method based on the normalized downward continuation (NDC) to invert the source location parameters without any priori information. To improve the stability and accuracy of the NDC calculation, the Chebyshev–Pade´ approximation downward continuation method was introduced to obtain the potential field data on different depth levels. The new approach was tested on various models data with and without noise, which validated that it can simultaneously obtain the horizontal edges and the buried depths of the geological bodies. The satisfactory results demonstrated that the normalized largest eigenvalue of structure tensor can describe the locations of geological sources and decrease the noise interference magnified by the downward continuation. Finally, the method was applied to the gravity data over the Humble salt dome in USA, and the near-bottom magnetic data over the Southwest Indian Ridge. The results show a good correspondence to the results of previous work.
Highlights
The source parameters estimation of potential field tensor data is an important part for geological interpretation, which can provide the horizontal position and the buried depth of the geological bodies as an a priori information for potential field inversion (Li and Oldenburg 1998)
The normalized full gradient (NFG) method proposed by the Russian Geophysical School (Elysseieva and Pašteka 2009, 2019) can be directly used to obtain
Based on the generalized normalized downward continuation (NDC) method, some authors have applied it on the local wavenumber (Ma et al 2014), total horizontal derivatives (Li et al 2014), directional analytic signals (Zhou 2015) and directional total horizontal derivatives (Zhou et al 2017) to obtain the horizontal edges and the buried depth simultaneously
Summary
The source parameters estimation of potential field tensor data is an important part for geological interpretation, which can provide the horizontal position and the buried depth of the geological bodies as an a priori information for potential field inversion (Li and Oldenburg 1998). The residual noise of the potential field gradient data at different depths can be further removed by the Gaussian envelop when using the NDC of the largest eigenvalue of structure tensor to estimate the geology source. 3. alculate potential field gradient data at the different depth levels by using the Chebyshev–Padeapproximation downward continuation method. All of their maximum values (the white dot) can display the edge position and the center depth of the prism at 10 m. The black rectangle are the locations of the prisms in the horizontal plan, and the white line is the cross section for Fig. 7
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