Miocene volcanism of the Cserhát Mts (N Hungary): Integrated volcano-tectonic, geochronologic and petrochemical study

Abstract

New K/Ar ages and paleomagnetic data connected with volcano-tectonic observations detected three intermediate (andesitic) and three acidic (dacitic-rhyolitic) magmatic phases. Cserhat magmatic activity occurred between 21-12 Ma. The timing of the initial and final acidic and intermediate phases may be connected with the Matra volcano situated to the east. During the Badenian (15-14 Ma) the volcano-tectonic evolution was relatively independent in the Cserhat Mts. The third acidic and intermediate volcanic phases, which developed in the Lower Sarmatian, show similar features as the final phases of the Matra volcano. Based on the major and trace element geochemistry the acidic rocks result from partial melting of the lower crust. Most of the intermediate volcanic rocks were generated from a rather homogeneous fluid-modified source (lithospheric), as triggered by an important heat transfer event. Initial melts sometimes experienced mixing or contamination in the lower or upper crust. This was a period of stro...