Cambrian magmatism in the Vlahina Mt. (SW Bulgaria) – correlation with the Vertiskos Unit (Serbo-Macedonian Massif)

Abstract

The Rhodope massif and the Kraishte Zone are parts of the Internal Balkanides separated by Gabrovdol detachment. In the most southwestern part of Bulgaria one of the units of the Serbo-Macedonian Massif (the western part of the Rhodope Massif) the Vertiskos Unit crops out. Part of this unit represented by metagabbro-metadiorites is exposed in an area of about 60 km2 in the central part of the Vlahina Mountain. These rocks are metamorphosed at lower amphibolite facies conditions (T = 630–670 °C and P = 0.85–1.05 GPa). LA-ICP-MS U-Pb dating of zircons display concordant age of these rocks of 541±2.6 Ma. The petrological and isotopic investigations show significant differences with the rocks of the Vertiskos Unit and allow us to assign these rocks to the basement of the Kraishte zone (Struma Unit).