International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

GRANITIC PEBBLES IN UPPER CRETACEOUS RED CONGLOMERATES OF THE HAŢEG BASIN (SOUTHERN CARPATHIANS, ROMANIA): GEOCHEMISTRY AND PROVENANCE AS CLUES IN A TECTONIC CONTROVERSY

Pages: 389 - 395

Authors: TUDOR BERZA

Abstract: The Southern Carpathians (Romania) represent a segment of the Alpine belt of Europe where Cretaceous collision generating nappe stacking was followed by normal faulting leading to core complex formation and exhumation of the lower (Danubian) nappe system, in a process of orogen-parallel extension. There is a controversy on the timing of the normal faulting: latest Cretaceous versus Eocene. One of the reasons for the Cretaceous option rests on the consideration of the basement of the Danubian nappes from the Retezat Mountains as the source area for granite and gneiss pebbles in Upper Maastrichtian-Paleogene(?) red conglomerates of the Haţeg Basin. Zircon fission-track ages around 80 Ma of granitic pebbles from these red conglomerates have been previously used to date the start of the exhumation and erosion of Danubian nappes since the Late Cretaceous, assuming their provenance from the southerly located Retezat pluton. But the major and trace element composition of a granite pebble, from the same outcrop at Clopotiva, shows K, Na, Rb and Th excess and Ca, Fe and Sr deficit, precluding its origin from this major Danubian granitoid pluton. This leaves room for an Eocene to Early Oligocene start for the exhumation of the Danubian nappes.

Keywords: Southern Carpathians, Hateg Basin, Maastrichtian conglomerates, Danubian granitoids, basement exhumation, pebbles

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