From the early stages of exploration to prospect evaluation, integrated gravity and magnetic interpretations contribute to more effective exploration. Such interpretations aid in preplanning seismic surveys and serve as an independent check on seismic interpretations in difficult areas. They also provide the basis for an integrated approach to determination of density, verification of basement, information on fault offsets, and much more.
Gravity and magnetics complement seismic and offer an independent source of information on subsurface geology. When integrated into seismic interpretations, gravity and magnetic information can improve geologic understanding and reduce exploration risk. EDCON-PRJ offers custom interpretations using gravity, seismic, well log and geologic data in addition to aeromagnetics.
THE ROLE OF AEROMAGNETIC DATA IN EXPLORATION
Aeromagnetic data reflect the varying rock types in the crust. Quantitative interpretations of aeromagnetic data, integrated with the known surface geology, can delineate many structures and plutons that control the location of mineralization. Major, deep-seated structures are often manifested in the magnetic data by alignments of magnetic discontinuities. Plutons, particularly those of Tertiary age, frequently exhibit prominent magnetic anomalies. As a general principal, low-level surveys are more influenced by variations in near-surface rocks, and higher-level surveys “look” deeper, i.e. they map changes in rock-types at greater depth.
Regional Aeromagnetic Surveys –
- Best for mapping major regional structures, delineating large intrusive complexes and volcanic fields
- Suited for identifying areas on a district scale
Detailed, Low-level Surveys –
- Best for mapping shallow subsurface features including faults, intrusives, dikes, skarn zones, and sometimes alteration
- When used with other geological, geochemical, and geophysical data, can provide valuable assistance in spotting drill holes
- Often useful in delineating pediments and estimating depth of cover.
EDCON-PRJ has been providing integrated geological-geophysical interpretations to the mineral exploration industry for decades. The geophysical analysis is quantitative, provided that profile data are available. Causative sources are delineated, and depths, magnetic susceptibilities, densities, and geometry are estimated. Structural elements, faults, lineaments, and magnetic discontinuities are identified. The geophysical analysis is then integrated with the geologic data base, including radiometric age dates on plutons, volcanic rocks, and mineralization, to put the geophysical interpretation into a geologic context. Finally, the interpretation results are related to known mineral occurrences to identify the geological-geophysical parameters that appear to control the location of the mineral occurrences.
EDCON-PRJ performs confidential interpretations either in its own office or in the customer’s office.