An offshore-onland transect across the NE Black Sea (Crimean margin): evidence of Cenozoic two-stage compression

Abstract

In the tectonic evolution of the Black Sea (BS) there are several unsolved questions: 1) the timing of the BS opening and 2) the timing of the Cenozoic shortening of the northern margin of the Eastern BS (EBS) basin. Mainly, the age-frame of the main compressional deformations is assumed as Oligo-Miocene, related to the Greater Caucasus (GC) basin inversion. The Crimean Mountains (CM) is one of the key areas to fix the tectonic evolution of the BS therefore, we focus on an integrated onshore/offshore transect from the Eastern CM to the Sorokin trough (north of EBS). We used newly collected stratigraphic and structural data from the Eastern CM, and a new interpretation of multichannel seismic lines. We define 1) the seismic stratigraphy and constrain the relative chronology of deformations, 2) the age of seismic units by correlation of the seismic data with the Subbotina-403 well log, and 3) we construct an on-and-off shore transect of the Eastern CM - North of the EBS region. Our results evidence a polyphased compression: 1) during Paleocene-Earliest Eocene and 2) the one starting during the Oligocene-Miocene. Normal faults appeared to be related to flexural bending, instead of evidencing the EBS Cretaceous rifting.