A 3-D gravity modeling of the crustal structure of the Dnieper-Donets Basin and Donbas. I. Sediments
© T.P. Yegorova, 2000
For the purpose of construction the thre dimensional model for the part of the Dnieper-Donets Basin, including Dnieper graben and Donbas, a gravity modelling of the sedimentary cover of the region has been carried out. The main approach of the utilized 3-D modelling is multivariate gravity analysis by use of back-stripping analysis. Two general models of the sedimentary cover are considered: 1) in four - layers approximation with constant average density in the layers and 2) with exponential density increase with depth in the upper layer (up to 6 km) and constant density in the lower layer. The residual field, obtained by subtraction of the calculated effect of sediments from the observed field reveals an intensive positive anomaly along the basin axis with an amplitude increasing in south-eastern direction according to the increase of thickness of the sedimentary cover. The residual gravity anomaly is due to dense mafic and ultramafic rocks intruded into the crust along the basin axis as a result of Late-Paleozoic rifting. For the first time this high-density domain, previously obtained for the crystalline crust below the Dnieper graben, has been traced beneath the transition zone from Dnieper graben to Donbas and Donbas itself.