Balanced geological cross-section of the outer ukrainian carpathians along the pancake profile

Abstract

The Outer Ukrainian Carpathians (OUC) are part of the Eastern Carpathians, which is a segment of the European Alpine belt. The OUC is crossed by recently acquired WARR (wideangle reflection and refraction) PANCAKE profile (Starostenko et al., 2013). To study the basin architecture of the OUC along the profile a balanced geological cross-section was onstructed. Reconstruction of the balanced geological cross-section has shown that the present day fold-and-thrust belt of the Outer (Flysch) Carpathians was formed in the Miocene from the deposits of the sedimentary basin∼460km in width. Evolution of the sedimentary basin to the present fold-and-thrust belt 70km in width occurred in two stages, characterized by accelerating the shortening rate of the basin from 11.5km/Ma between∼32 and 22 Ma to 22.5km/Ma between∼22 and 12 Ma. The detachment of the flysch complexes of the OUC occurred on the top of the basement located at a depth of 10−12km. The main phase of Miocene thrusting was followed by significant exhumation and erosion during the period of 12−2 Ma related to isostatic uplift in the OUC, which reached a maximum (up to 7km) in the central nappes (Krosno and Dukla-Chornohora). The collision regime, obviously, followed the subduction one; this could happen approximately at 22 Ma which is evident after changing the shortening rate of the basin.