PETROLOGICAL AND GEOCHEMICAL DATA CONCERNING THE MANTLE BENEATH THE PERSANI MOUNTAINS QUATERNARY BASALT AREA, RUMANIA

Abstract

The peridotite xenoliths from the Quaternary continental trachybasalts of Persani Mountains originate in an anhydrous spinel lherzolitic mantle, the Mg# value of which is of 91.3. It presents a porphyroblastic texture. The geochemical characteristics are close to those of the mantle beneath the Dreiser Weither (Germany) volcanic area. During the Tertiary and Quaternary periods the mantle underwent deformation (Fig. 1) and recrystallization (Fig. 2) phenomena along some shear zones, determined by two trans-crustal fracture systems, that led to the cratonization of the Persani Mountains area, and affected the mantle beneath it, also. Thus, there were set up the PT conditions for the mantle partial melting at a rate of ca. 4%, from which the trachybasaltic magma resulted at a depth of about 225 km.