Orogen-parallel extension in the Southern Carpathians

Abstract

A structural study, including a kinematic analysis based on sense of shear criteria recorded in fault rocks, is combined with fission-track dating. A two-stage Alpine tectonic evolution is proposed for the major tectonic units which constitute the Southern Carpathians of the Parang mountains area. Upper Cretaceous top-to-the-SSE nappe stacking was followed by WSW–ENE orogen-parallel extension in the Eocene. Top-to-the-ENE shearing in lower greenschist-facies mylonites from the eastern part of the Danubian window (Parang mountains) is associated with a low-angle detachment at the base of the brittlely deformed Getic nappe (the Getic detachment). Below the dome-shaped Getic detachment, east-dipping at the eastern termination of the Danubian window, the Danubian units were rapidly exhumed. Hence, the eastern part of the Danubian window represents a greenschist-facies core complex. As a working hypothesis, it is proposed that this orogen-parallel stretch was originally N–S-oriented and that it formed when the Rhodopean fragment (which includes the Getic and Supragetic nappes) moved northward into an oceanic embayment, past the western margin of Moesia. This Eocene extension was part of a process of oroclinal bending in the area of the Southern Carpathians and their continuation into the Balkan mountains. Extension was followed by about 50° clockwise rotation of the Southern Carpathians, associated with dextral wrenching along the northern boundary of Moesia and compression in the Moldavides of the Eastern Carpathians.