DOBRE-2 WARR profile: the Earth's upper crust across Crimea between the Azov Massif and the northeastern Black Sea

Abstract

The DOBRE-2 wide-angle reflection and refraction profile was acquired in June 2007 as a direct, southwestwards prolongation of the 1999 DOBREfraction'99 that crossed the Donbas Foldbelt in eastern Ukraine. It crosses the Azov Massif of the East European Craton, the Azov Sea, the Kerch Peninsula (the easternmost part of Crimea) and the northern East Black Sea Basin, thus traversing the entire Crimea–Caucasus compressional zone centred on the Kerch Peninsula. The DOBRE-2 profile recorded a mix of onshore explosive sources as well as airguns at sea. A variety of single-component recorders were used on land and ocean bottom instruments were deployed offshore and recovered by ship. The DOBRE-2 datasets were degraded by a lack of shot-point reversal at the southwestern terminus and by some poor signal registration elsewhere, in particular in the Black Sea. Nevertheless, they allowed a robust velocity model of the upper crust to be constructed along the entire profile as well as through the entire crust beneath the Azov Massif. A less well constrained model was constructed for much of the crust beneath the Azov Sea and the Kerch Peninsula. The results showed that there is a significant change in the upper crustal lithology in the northern Azov Sea, expressed in the near surface as the Main Azov Fault; this boundary can be taken as the boundary between the East European Craton and the Scythian Platform. The upper crustal rocks of the Scythian Platform in this area probably consist of metasedimentary rocks. A narrow unit as shallow as about 5 km and characterized by velocities typical of the crystalline basement bounds the metasedimentary succession on its southern margin and also marks the northern margin of the northern foredeep and the underlying successions of the Crimea–Caucasus compressional zone in the southern part of the Azov Sea. A broader and somewhat deeper basement unit (about 11 km) with an antiformal shape lies beneath the northern East Black Sea Basin and forms the southern margin of the Crimea–Caucasus compressional zone. The depth of the underlying Moho discontinuity increases from 40 km beneath the Azov Massif to 47 km beneath the Crimea–Caucasus compressional zone.

Tectonic Evolution of the Eastern Black Sea and Caucasus: an introduction

“…A local seismic tomography study of this same area centred on the Kerch Peninsula and reported by Gobarenko et al (2015) complements the Starostenko et al (2016) geophysical study. The resulting three-dimensional P-and S-wave velocity models, for an area of c. 200 × 100 km (east-west and north-south, respectively) with a depth of c. 40 km ( Fig.…”

“…Sydorenko et al (2016) report a geological interpretation of a regional seismic reflection profile acquired along the same transect and in association with the DOBRE2 WARR profile (labelled 8 in Fig. 1) reported by Starostenko et al (2016) and the resulting velocity model of the latter is superimposed on the former. The regional basin architecture from the Azov Sea, crossing the Kerch Peninsula into the Black Sea as far south as the eastern Black Sea deep basin, consists of a series of basement structural highs separating a series of sedimentary depocentres and is mainly a consequence of the compressional tectonic regime affecting the area since the Eocene.…”

“…The papers touching on pre-Cretaceous tectonic evolution include overview papers, such as Adamia et al (2015) for the Caucasus domain as seen from Georgia, and papers addressing the eastern Black Sea domain (Nikishin et al 2015b) and its contiguous onshore geology in Crimea (Sheremet et al 2016b), the second of which deals with important issues of Mesozoic stratigraphy. There are also geophysical papers, in particular Starostenko et al (2016), whose authors recognize extensional structures and Late Palaeozoic, PermoTriassic and Jurassic sedimentary basins in an upper crustal velocity model of the Black Sea domain.…”

Exploration Plays in the Caucasus Region

“…Several regional-scale compressional episodes affected the entire Black Sea during the Cenozoic (e.g. Stovba et al 2009). Finally, there are possibly stratigraphic traps within the Miocene-Pliocene sequence outboard from the Tuapse foldbelt (Fig.…”

Geometry and Cenozoic evolution of the Crimean fold-thrust belt from cross-section balancing and kinematic forward modeling

“…According to the DOBRE regional seismic profiles (see Fig. 2, a), the crust below the Crimean peninsula is 40-50 km thick and gradually thins southward [Yegorova, Gobarenko, 2010;Starostenko et al, 2015Starostenko et al, , 2016. The Scythian crystalline basement was drilled to 0,2-2,0 km depth [Muratov, 1960]; the hanging Paleozoic sedimentary rocks -also only known from wells -are 1-5 km thick [Muratov, Sydrenko, 1969].…”