K-Ar datings of Neogene-Quaternary calc-alkaline volcanic rocks in Romania

Neogene-Quaternary plate convergence-related calc-alkaline magmatic rocks from Romania have been dated using the K-Ar radiometric technique. The magmatic rocks occur in the East Carpathians and the Apuseni Mts. In the-East Carpathians, the discontinuous magmatic arc is segmented into two main volcanic areas ' Oaq-Gutái (oG) and Cálima-ni-Gurghiu-Harghita (CGH) at the extremities and an intrusive (subvolcanic) segment (Jibles-Toroiaga-Rodna-Bárgau: TTRB) in the middle. According to biostratigraphical data, volcanic activity started in the,Badenián ' but the oldest rocks are dated atL3.4 Ma. The volcanic activity ceased at about 0.2Ma. The range of apparent ages during Pannonian (9-11 Ma) in TTRB is partly coeval with that of OG, reflecting the paroxysm of the magmatic activity. The longest interval of activity was detected in the Gutái Mts. (13.5-6.9 Ma)-. An obvious age progression along the arc was pointed out for CGH volcanic chain, enhanced along the terminal 40 km of South Harghita Mts. (4.3-0.2 Ma). Preliminary data from the Apuseni Mts. suggest he Sarmatian as the main interval for magmatic activity in that region (13.4-12.4 Ma). This study deals with the geochronological interpreta