The first stripped gravity map of the Turčianska Kotlina Basin

Abstract

During the last years, many new results related to the thickness of the sedimentary fill and other geophysical and geological constrains on the structure of the Turˇcianska Kotlina Basin have been obtained. It allowed us to calculate the first, original stripped gravity map in this basin. To obtain this map the 3D gravity effect of the basin sedimentary fill had to be calculated. The gravity effect of the sediments was determined for two different density conditions. Firstly, the average density of the sediments was constant (2.45 g cm−3). Secondly, we supposed that the density of sediments varies exponentially from 2.00 g cm−3 on the surface up to 2.67 g cm−3 on the pre-Tertiary basement. On the maps of the calculated gravity effects it can be observed that the maximum amplitudes reach about -12 mGal. The gravity effect is larger in the case when the densities of the sedimentary fill vary exponentially. After subtraction of the gravity effects from the map of complete Bouguer gravity map, the resultant stripped gravity maps were defined. The detailed analysis of these maps indicates that the northern part of the pre-Tertiary basement of the basin could be built mostly by the Mesozoic rocks, which belong to the Hronic and Fatric units. The structure of the basement in the southern part of the basin seems to be more complicated. This feature probably reflects a presence of Neogene volcanites in the basin basement belonging to the Kremnick´e vrchy Mts. The picture of the gravity field in the stripped gravity map predicts that the Paleogene sediments probably do not build the sedimentary fill in the southern part of the basin.