DOBRE-2 WARR profile: the Earth's upper crust across Crimea between the Azov Massif and the northeastern Black Sea
2017
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.
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