THE EVOLUTION OF THE NEOGENE VOLCANISM IN THE APUSENI MOUNTAINS (ROMANIA) - CONSTRAINTS FROM NEW K-AR DATA

New K-Ar data from the Apuseni Mountains Neogene volcanic area are pre sented. When combined with geological and magnetic polarity data, the new data clarify the duration and evolution of this volcanic area. The y show that the Neogene volcanic activity took place during the Late B adenian-Pannonian (15-7 Ma). The beginning of calc-alkaline andesitic volcanism (around 15-13 Ma) had an explosive character giving a widesp read volcano-sedimentary formation. The volcanic activity reached the paroxysm during the Sarmatian (13.5-11 Ma), when thick lava flows and large volcanic structures were emplaced. This activity decreased in th e Pannonian (10-7 Ma) and was restricted to the central and northeaste rn parts of the studied area. In the central part, the volcanic activi ty slopped in the Early Pannonian (10 Ma), while in the northeastern p art it lasted until the Late Pannonian (7 Ma). The volcanic products a re covered by pure sedimentary formations in only a few parts of the a rea. During all this time, tectonic activity played an important role in the basin's development and volcanic processes.