A 3-D wavelet-based fusion technique for integrated interpretation of various physical-property models inversed from gravity and magnetic data

2015 ◽  
Author(s):  
Lianghui Guo* ◽  
Xiaohong Meng ◽  
Junjie Zhou ◽  
Yuanjie Li
Keyword(s):  
Physical Property ◽  
Magnetic Data ◽  
Fusion Technique ◽  
Gravity And Magnetic ◽  
Integrated Interpretation ◽  
Gravity And Magnetic Data

Joint inversion of gravity and magnetic data for two-layer models

Geophysics ◽  
2006 ◽  
Vol 71 (3) ◽  
pp. L35-L42 ◽  
Author(s):  
Mark Pilkington
Keyword(s):  
Least Squares ◽  
Joint Inversion ◽  
Physical Property ◽  
Magnetic Data ◽  
Model Parameters ◽  
Constant Density ◽  
Central Uplift ◽  
Gravity And Magnetic ◽  
Damped Least Squares ◽  
Gravity And Magnetic Data

Gravity and magnetic data are inverted jointly in terms of a model consisting of an interface separating two layers having a constant density and magnetization contrast. A damped least-squares inversion is used to determine the topography of the interface. The inversion requires knowledge of the physical property contrasts across the interface and its average depth. Since the relationship between model parameters and data is weakly nonlinear, a constant damped least-squares inverse is used during the iterative solution search. The effect of this inverse is closely related to a downward continuation of the field to the average interface depth. The method is used to map the base of the Sept-Iles mafic intrusion, Quebec, Canada, and the shape of the central uplift at the Chicxulub impact crater, Yucatan, Mexico. At Sept-Iles, the intrusion reaches a thickness of [Formula: see text], coincident with the maximum gravity anomaly, south of the intrusion center. At Chicxulub, the top of the central uplift is modeled to be [Formula: see text] deep and has a single peak form.

scholarly journals The geophysical signature of Oyut deposits, Oyu Tolgoi, Mongolia

2021 ◽  
Vol 26 (52) ◽  
pp. 80-96
Author(s):  
Erdene Batbaatar ◽  
Munkhjargal Todbileg ◽  
Otgonbayar Sansar ◽  
Baatar Bataa
Keyword(s):  
Gravity Data ◽  
Porphyry Copper ◽  
Mineral Deposits ◽  
Magnetic Data ◽  
The South ◽  
Porphyry Cu ◽  
Gravity And Magnetic ◽  
Integrated Interpretation ◽  
Ground Magnetic ◽  
Gravity And Magnetic Data

The well-known Oyu Tolgoi Cu-Au group deposits can be divided into three main deposits: Hugo Dummett deposit (Hugo North and Hugo South), Oyut deposits (South Oyu, Southwest Oyu and Central Oyu), and Heruga deposit in the south. These deposits sit along 26 km long, north-northeast trending belt termed as the Oyu Tolgoi trend. This paper reviews investigations on geophysical signatures of the South Oyu, Southwest Oyu and Central Oyu deposits and compares geophysical models of the mineral deposits with their lithology, alteration, mineralization, and structures. A variety of datasets including induced polarization, ground magnetic, gravity survey are used in the study and generated inversion products of ground magnetic and gravity data with integrated interpretation. Typical responses from the Oyut deposits are: up to 0.1 mGal positive gravity anomaly above background, 100–200 nT low or high magnetic anomaly compared to background depending on the geological situations, and from 12 mV/V to 30 mV/V chargeability anomalies and low resistivity signatures from 100 ohm.m to 400 ohm.m. The interpreted geological-geophysical models of porphyry Cu-Au deposits presents in this study have emphasis on integrated interpretation of geophysical techniques, and inversions of gravity and magnetic data in gold rich porphyry copper system.

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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