First mineral chemistry data on the exotic igneous clasts from the Cretaceous successions of the Moldavides (Eastern Carpathians, Romania) insights into magma evolution and geotectonic settings.

Abstract

Igneous (granites, granodiorites and rhyolites) clasts of exotic (i.e. non-Carpathian) origin, can be found in the Cretaceous successions of the Moldavide flysch of the Eastern Carpathians. These clasts, with the age of ca. 600 Ma, are attributed to a presumed ridge located in the flysch basin in the Early to Late Cretaceous period, to the Cuman Cordillera. Here, we present for the first time mineral chemistry data on these exotic igneous clasts, using the information in the present paper to discuss the geotectonic setting and P-T conditions during the formation of the igneous rocks that made up the basement of the disappeared paleorelief known as Cuman Cordillera. Selected samples of intrusive rocks were investigated by means of optical microscopy and electron microscopy. Biotite, feldspar and amphibole chemistry data were used for thermobarometry, indicating crystallization temperature at ca. 730-780°C and depth of magma emplacement around 10 km, within a possible range of 5-15 km. Biotite chemistry favors magma generation in convergent plate margins geotectonic setting.