PRELIMINARY GEOCHEMICAL DATA ON VOLCANIC ROCKS FROM THE OLT NAPPE (TRANSYLVANIAN NAPPES, ROMANIA): IMPLICATION FOR THEIR ORIGIN IN THE TRANSYLVANIDES

Abstract

The Transylvanian nappes (Rarau, Haghimas and Olt nappes - Fig. 1a) are interpreted as remnants of the Main Tethyan Suture in the Carpathians. According to some authors (Sandulescu and Russo-Sandulescu, 1981; Sandulescu, 1984; Russo-Sandulescu et al., 1983; Sandulescu in Ichim and Sandulescu, 1997), they consist of various types of sedimentary and Mesozoic magmatic rocks related to the ophiolites of Transylvanides (Fig. 1a), which in turn represent a Tethyan oceanic crust associated to the Vardar Zone (Bortolotti et al., 2002). The nature of volcanics from the Olt nappe (ON) is still poorly constrained. Cioflica et al. (1965) reported the occurrence of sub-alkaline and alkaline volcanics interpreted as evolved magmatic products of a tholeiitic ophiolitic series. Nonetheless the alkaline chemistry of volcanics is not consistent with the interpretation of these rocks as ophiolitic remnants linked with the Transylvanides ophiolites (Sandulescu, 1984; Sandulescu in Ichim and Sandulescu, 1997), since no alkaline rocks are found in these ophiolites. The aim of this paper is thus to present preliminary geochemical data on volcanic rocks from the ON in order to assess their possible genetic relationships with the Transylvanides ophiolites.