Abstract
We have developed a mineral exploration method for the joint inversion of 2D gravity gradiometry and magnetotelluric (MT) data based on data-space and normalized cross-gradient constraints. To accurately explore the underground structure of complex mineral deposits and solve the problems such as the non-uniqueness and inconsistency of the single parameter inversion model, it is now common practice to perform collocated MT and gravity surveys that complement each other in the search. Although conventional joint inversion of MT and gravity using model-space can be diagnostic, we posit that better results can be derived from the joint inversion of the MT and gravity gradiometry data using data-space. Gravity gradiometry data contains more abundant component information than traditional gravity data and can be used to classify the spatial structure and location of underground structures and field sources more accurately and finely, and the data-space method consumes less memory and has a shorter computation time for our particular inversion iteration algorithm. We verify our proposed method with synthetic models. The experimental results prove that our proposed method leads to models with remarkable structural resemblance and improved estimates of electrical resistivity and density and requires shorter computation time and less memory. We also apply the method to field data to test its potential use for subsurface lithofacies discrimination or structural classification. Our results suggest that the imaging method leads to improved characterization of geological targets, which is more conducive to geological interpretation and the exploration of mineral resources.
Highlights
The necessity for the accurate exploration of subsurface structures and conditions are driving the development of various strategies for the joint use of information from multiple geophysical data [1,2,3,4,5,6,7,8,9].Different geophysical data can provide different information on the distribution of subsurface properties, while different geophysical exploration methods have different detection capabilities for underground targets
We present an approach for the joint inversion of magnetotelluric (MT) and gravity gradiometry data based on normalized cross-gradient constraints and data-space
For the joint inversion of gravity gradiometry and controlled-source audio-frequency magnetotelluric (CSAMT) data using the model-space method (Figure 20a,b), the final models of resistivity and density are obtained with data misfit (RMSCSAMT = 1.00, RMSGrad = 0.99)
Summary
The necessity for the accurate exploration of subsurface structures and conditions are driving the development of various strategies for the joint use of information from multiple geophysical data [1,2,3,4,5,6,7,8,9]. Minerals 2019, 9, 541 of different physical properties (e.g., how petrophysical characteristics relate resistivity and seismic velocity in porous media), the coupling inversion of different physical properties was realized [12,13] This method is limited by its difficulty in finding the accurate physical relationships of rock in complex underground areas. We used synthetic models of the subsurface to test the resolution, computational efficiency, and memory usage of the algorithm We applied this approach to the interpretation of geophysical field data collected in a mining study area from Jilin Province, China
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