SOLVING TWO PROBLEMS OF GEODYNAMICS WITH THE GRAVITY STRUCTURE METHOD

S. M. Makeev

Institute of Mining, Geology and Geotechnology of the Siberian Federal University, Krasnoyarsk

The classical theory of the gravity potential and its first-order derivatives does not allow a thorough study of density distribution in complex deformed rocks. The author suggests an original gravity structure method which is based on the morpho-structural approach and can be used to solve two problems of geodynamics: spatial separation of dextral and sinistral shear deformations and revealing of near-shearing areas of tension and compression. The method is based on the analysis of dextral and sinistral shear deformations of specific low-frequency gravity field anomalies (gravitational duplexes), which are assumed to be deformation-driven. It was established that the amplitude of bipolar anomalies of gravitational duplex correspond to the accuracy of current gravity survey. The azimuths, shearing trends, and zones of dynamic influence of two deep faults in the Lower Angara folded zone (southwestern Siberian Platform) were defined. Near-shearing tension and compression areas were discovered, their deformation potential was calculated. The example of the Lower Angara folded zone has shown that the largest gas fields of the region can be spatially correlated with the near-shearing tension zones – rifting zones. Some geological problems were formulated that allow verification of the method suggested.

Key words: gravimetry, geodynamics, gravity structure method in geodynamics, azimuth field dispersion, azimuth-frequency analysis, gravitational duplex, shear deformations, rifting, forecast of hydrocarbon fields.

DOI 10.20403/2078-0575-2016-4-63-74