Application of potential geophysical fields in ore deposits: Inverse problem solution under complex conditions and 3-D gravity-magnetic field modeling

Ore deposits usually occur in mountainous conditions characterized by rugged relief, complex and variable geological medium. As a rule, application of various modifications of seismic methods in such conditions is not effective. Rugged relief usually limits using such geophysical methods as induced polarization, mise-al-la-masse, transient electromagnetic field and some other methods associated with employing cumbersome equipment. Among the geophysical methods applied in ore deposits may be distinguished mobile, inexpensive and effective potential geophysical fields: magnetic, gravity, self-potential and temperature. The developed non-conventional interpreting system includes: (1) elimination of various kinds of noise; (2) probabilistic-informational methods for revealing useful information about the hidden targets; (3) quantitative procedures enabling to interpret observed anomalies under complex environments (oblique magnetization [polarization], rugged terrain relief and unknown level of the normal field) and (4) improved 3-D combined modelling of magnetic and gravity fields. Performed analysis permitted to reveal some common peculiarities between the magnetic and other abovementioned potential fields. These common aspects make it possible to apply the quantitative procedures developed in magnetic prospecting to the abovementioned geophysical methods. These procedures (improved modifications of characteristic point, tangent and areal methods) have been successfully tested on models and effectively applied in the real situations (gold, copper, pyrite and polymetallic ores, kimberlite pipes and other economic deposits). Application of these interpretation procedures permits not only to localize buried ore targets under the complex environments, but also to determine definite quantitative parameters of these objects.