STRUCTURE OF GABBRO-ANORTHOSITE MASSIFS OF THE UKRAINIAN SHIELD ACCORDING TO GEOPHYSICAL DATA

Three-dimensional gravitational modeling of the Gorodishchensky and Smeleyansky gabbro-anorthosite massifs, located in the central part of the Korsun-Navomirgorod pluton (Ukrainian Shield), has been carried out. A three-dimensional model of the upper crust of the study area was created using maps of the anomalous gravity field at a scale of 1:200,000, considering the results of detailed seismic surveys using reflected wave method and CDP method (common depth point method). Differences in the structure of the intrusive complex were reflected in seismic wave fields, allowing the boundaries of the entire intrusion to be identified. Three-dimensional gravitational modeling was performed to separate rocks of the main composition and rapakivi granites, differing in density, using computer technology for automated interpretation of geophysical data based on the method of optimization. During the iterative process, three different functionals were calculated. It was proved that the joint use of these functionals reduces the amount of noise in the input data. Three-dimensional gravitational modeling allowed for the identification and delineation of the gabbro-anorthosite bodies in the upper part of the cross-section, with a maximum depth of up to 4-5 km. The constructed model, taking into account all available prior information about the density and geometric parameters of anomalous objects, can be used to obtain reliable geological information about the structure of the Gorodishchensky and Smeleyansky gabbro-anorthosite massifs.