ALBERT

Description: 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.

Description: The updated geological and potential fields data on the East European Platform margin in SE Poland confirm the existence of several regional units differing in Ediacaran to Silurian development: the Upper Silesian Block, Ma[l]opolska Block and [L]ysogory Block. All the blocks are characterized by a distinct crustal structure seen in Vp velocity models obtained from the seismic refraction data of the CELEBRATION 2000 Programme. The first two units are interpreted as exotic terranes initially derived from Avalonia-type crust and ultimately accreted before the late Early Devonian. The [L]ysogory Block is probably a proximal terrane displaced dextrally along the Baltica margin. The sutures between the terranes do not precisely match lateral gradients in Vp models. This is partly explained by a limited resolution of refraction seismic data (20 km wide interpretative window). Most of the difference is related, however, to a post-accretionary tectonism, mainly Variscan transtension-transpression. The latter processes took advantage of lithospheric memory recorded earlier as zones of rheological weakness along the former suture zones. The course of the East European Platform margin (= Teisseyre-Tornquist Zone) corresponds most likely to the Nowe Miasto-Zawichost Fault marking the NE boundary of the proximal [L]ysogory Terrane.

Description: This paper describes the results of seismic refraction investigations of the upper crustal structure in the area of Deception Island, West Antarctica, which were made during the Polish Antarctic Geodynamical Expeditions in 1979-80 and 1987-88. In the caldera and immediate vicinity of Deception Island a layer of unconsolidated and poorly consolidated young sediments of 1.9–2.2 km s−1 P-wave velocity was found. Velocities of 4.1–4.3 km s−1 were found in the depth interval from 0.6–1.3 to about 3 km. Lateral differences in upper crustal structure between the south-eastern and western sectors were identified. In the region between Deception and Livingston islands an inclined boundary with a velocity of about 6.1 km s−1 occurs. A deep fault zone dividing crustal blocks beneath Deception Island is associated with a prominent volcanic line within Bransfield Strait extending between Deception and Bridgeman islands.

Description: The updated geological and potential fields data on the East European Platform margin in SE Poland confirm the existence of several regional units differing in Ediacaran to Silurian development: the Upper Silesian Block, Małopolska Block and Łysogóry Block. All the blocks are characterized by a distinct crustal structure seen in Vp velocity models obtained from the seismic refraction data of the CELEBRATION 2000 Programme. The first two units are interpreted as exotic terranes initially derived from Avalonia-type crust and ultimately accreted before the late Early Devonian. The Łysogóry Block is probably a proximal terrane displaced dextrally along the Baltica margin. The sutures between the terranes do not precisely match lateral gradients in Vp models. This is partly explained by a limited resolution of refraction seismic data (20 km wide interpretative window). Most of the difference is related, however, to a post-accretionary tectonism, mainly Variscan transtension–transpression. The latter processes took advantage of lithospheric memory recorded earlier as zones of rheological weakness along the former suture zones. The course of the East European Platform margin (= Teisseyre–Tornquist Zone) corresponds most likely to the Nowe Miasto–Zawichost Fault marking the NE boundary of the proximal Łysogóry Terrane.