The first stripped gravity map of the Turčianska Kotlina Basin

Abstract

During the last years, many new results related to the thickness of the sedimentaryfill and other geophysical and geological constrains on the structure of the TurˇcianskaKotlina Basin have been obtained. It allowed us to calculate the first, original strippedgravity map in this basin. To obtain this map the 3D gravity effect of the basin sedimentaryfill had to be calculated. The gravity effect of the sediments was determined for twodifferent 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 exponentiallyfrom 2.00 g cm−3 on the surface up to 2.67 g cm−3 on the pre-Tertiary basement. On themaps of the calculated gravity effects it can be observed that the maximum amplitudesreach about -12 mGal. The gravity effect is larger in the case when the densities of thesedimentary fill vary exponentially. After subtraction of the gravity effects from the mapof complete Bouguer gravity map, the resultant stripped gravity maps were defined. Thedetailed analysis of these maps indicates that the northern part of the pre-Tertiary basementof the basin could be built mostly by the Mesozoic rocks, which belong to the Hronicand Fatric units. The structure of the basement in the southern part of the basin seemsto be more complicated. This feature probably reflects a presence of Neogene volcanitesin the basin basement belonging to the Kremnick´e vrchy Mts. The picture of the gravityfield in the stripped gravity map predicts that the Paleogene sediments probably do notbuild the sedimentary fill in the southern part of the basin.