3D geologic model of Shizishan ore field constrained by gravity and magnetic interactive modeling: A case history

Geophysics ◽  
2013 ◽  
Vol 78 (1) ◽  
pp. B25-B35 ◽  
Author(s):  
Qingtian Lü ◽  
Guang Qi ◽  
Jiayong Yan
Keyword(s):  
3D Visualization ◽  
Mineral Exploration ◽  
3D Structure ◽  
Spatial Relations ◽  
3D Models ◽  
Magnetic Data ◽  
Gravity And Magnetic ◽  
Geologic Model ◽  
Gravity And Magnetic Data ◽  
Ore District

We performed a study on using an integrated geologic model in mineral exploration at depth. Shizishan ore field, in the western part of the Tongling ore district, Anhui Province in China, is well known for its polymetallic deposits and recent deep discovery of Dongguashan deposit at around 1000-m depth. Understanding the 3D structure and delineating the locations and variations of the intrusions and ore-controlling strata in the study area are essential for selecting deep mineral targets. A pilot 3D geologic model, covering an area of 11 × 16 km and extends to a depth of 3 km, has been constructed by interactive gravity and magnetic inversions to define the geometry, depth, and physical properties of geologic bodies at depths. The 3D visualization of the results assists in understanding the spatial relations between various intrusive units and the ore-bearing strata. The model has confirmed most previous knowledge, but also revealed new features of different folds and intrusions that are important for planning future exploration at large depths. Several deep targets have also been predicted by combining the conceptual mineralization model in the district with the 3D geologic model. Our study demonstrates the potential of using gravity and magnetic data with geologic constraints to build 3D models in structurally complex areas for the purpose of mineral exploration at depth and under cover.

Interpretation of gravity and magnetic data with geological constraints for 3D structure of the Thuringian Basin, Germany

2017 ◽  
Vol 136 ◽  
pp. 35-41 ◽  
Author(s):  
Ilya Prutkin ◽  
Peter Vajda ◽  
Thomas Jahr ◽  
Florian Bleibinhaus ◽  
Pavel Novák ◽  
...  
Keyword(s):  
3D Structure ◽  
Magnetic Data ◽  
Gravity And Magnetic ◽  
Geological Constraints ◽  
Gravity And Magnetic Data

Automatic 3-D interpretation of potential field data using analytic signal derivatives

Geophysics ◽  
1997 ◽  
Vol 62 (1) ◽  
pp. 87-96 ◽  
Author(s):  
Nicole Debeglia ◽  
Jacques Corpel
Keyword(s):  
Signal Amplitude ◽  
Vertical Gradient ◽  
Analytic Signal ◽  
Magnetic Data ◽  
Practical Implementation ◽  
Potential Field Data ◽  
Gravity And Magnetic ◽  
Second Derivatives ◽  
Gravity And Magnetic Data ◽  
Derivatives Of

A new method has been developed for the automatic and general interpretation of gravity and magnetic data. This technique, based on the analysis of 3-D analytic signal derivatives, involves as few assumptions as possible on the magnetization or density properties and on the geometry of the structures. It is therefore particularly well suited to preliminary interpretation and model initialization. Processing the derivatives of the analytic signal amplitude, instead of the original analytic signal amplitude, gives a more efficient separation of anomalies caused by close structures. Moreover, gravity and magnetic data can be taken into account by the same procedure merely through using the gravity vertical gradient. The main advantage of derivatives, however, is that any source geometry can be considered as the sum of only two types of model: contact and thin‐dike models. In a first step, depths are estimated using a double interpretation of the analytic signal amplitude function for these two basic models. Second, the most suitable solution is defined at each estimation location through analysis of the vertical and horizontal gradients. Practical implementation of the method involves accurate frequency‐domain algorithms for computing derivatives with an automatic control of noise effects by appropriate filtering and upward continuation operations. Tests on theoretical magnetic fields give good depth evaluations for derivative orders ranging from 0 to 3. For actual magnetic data with borehole controls, the first and second derivatives seem to provide the most satisfactory depth estimations.

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