Heavy mineral distributions of Maastrichtian deposits from the Haţeg basin, South Carpathians: Tectonic and palaeogeographic implications

This study represents the first extensive investigation of source-areas of the Maastrichtian continental deposits of the Haţeg basin using heavy mineral associations. The heavy mineral associations consist of garnet, hematite, magnetite, ilmenite, rutile, staurolite, kyanite, epidote, apatite, titanite, tourmaline and zircon. The general pattern indicates different source areas with contrasting metamorphic grades for the northern and southern parts of the basin. The sediments of the northern and central sectors of the basin show a high proportion of garnet, staurolite and kyanite and a low proportion of epidote, suggesting an amphibolite-facies metamorphic source, which is compatible with the lithology of the Getic upper plate on which the basin formed. The samples with abundant amphibolite-facies heavy mineral components have high proportions of magnetic Fe–Ti-oxides with complex exsolution/intergrowth features. These oxides belong chiefly to the hematite–ilmenite solid-solution series and indicate a high-grade metamorphic and/or igneous source area. In the south, the heavy mineral spectra change to epidote-rich, evidence of exhumation and erosion of the greenschist metamorphic rocks of the Danubian lower plate during updoming and core-complex formation. The study shows that for the northern and central parts of the basin, the Getic plate is the main source for the sediments. During the Maastrichtian time, due to increasing relief in the hinterland and exhumation of the lower plate, the Danubian unit fed the basin, as recorded in the sediments situated along Sibişel and Râul Bărbat valley.