ALBERT

Description: The Black Sea is generally thought to be a back-arc basin with active extension (rifting) beginning in late Early Cretaceous times - although some fundamental issues such as the presence or absence of a related magmatic arc and the orientation of the related, driving, subduction zone remain vaguely defined at best. However, as shown here, the regional structure of the Black Sea is consistent with that predicted by geodynamic models of modern back-arc basin formation, in which extension is driven by slab roll-back. This includes an asymmetric distribution of horst and graben structures in the back-arc basin, the distribution and spacing of which is related to the strength of the underlying lithosphere, which forms the hanging wall of the subduction zone. By analogy, the intrabasinal structure of the Black Sea as a whole is explicable as the consequence of a single phase of asymmetric back-arc basin formation, not two separate phases independently responsible for its western and eastern segments, and its underlying lithosphere is rheologically strong, as predicted by recent models of Precambrian Europe and present-day tomography.

Description: Three fundamental stages of the Cretaceous-Neogene tectonic evolution of the Odessa Shelf and Azov Sea (northern margins of western and eastern Black Sea basins, respectively) have been documented from the analysis of reinterpreted regional seismic profiling and one-dimensional (1-D) subsidence analysis of 49 wells, for which the stratigraphic interpretation was recently revised. (1) An initial active rifting stage began within the Early Cretaceous (not later than Aptian-Albian times) and continued until the end of the Santonian in the Late Cretaceous (c. 128-83 Ma). A system of half-grabens with mainly south-dipping normal faults developed on the Odessa Shelf at this time. The most profound faulting, accompanied by volcanic activity, occurred in the NE-SW orientated Karkinit-Gubkin rift basin at the boundary between the Eastern European and Scythian platforms. The footwalls of half-grabens were exposed above sea level and subject to erosion at this time. Active extensional processes affected the western part of Azov Sea and, while the onset and cessation of these cannot be tightly constrained, they are compatible with the well constrained results from the Odessa Shelf. (2) The second tectonic stage is one of passive post-rift thermal subsidence that lasted from the Campanian (Late Cretaceous) until the end of the Middle Eocene (83-38.6 Ma). (3) The third stage of basin evolution is one of inversion tectonics in a compressional setting. Discrete inversion events occurred at the end of the Middle Eocene, during the Late Eocene, during the Early Miocene and at Middle Miocene times (c. 38.6 Ma, c. 35.4 Ma, c. 16.3 Ma, c. 10.4 Ma, respectively) and typical inversion structures developed on the Odessa Shelf, some parts of which were uplifted and significantly eroded (down to the Lower Cretaceous succession). The southern part of the Azov Sea, opening into the northernmost eastern Black Sea basin, subsided rapidly during this time; thereafter, until the Quaternary, rapid subsidence was limited to its southeastern part, which was incorporated into the Indolo-Kuban foreland basin of the Greater Caucasus orogen.

Description: The Palaeozoic to recent evolution of the Tethys system gave way to the largest mountain chain of the world extending from the Atlantic to Pacific oceans - the Alpine-Himalayan Mountain chain, which is still developing as a result of collision and northwards convergence of continental blocks including Apulia in the west, the Afro-Arabian Plate in the middle and the Indian Plate in the east. This Special Publication addresses the main problems of the middle part of this system incorporating the Balkans, Black Sea and Greater Caucasus in the north and the Afro-Arabian Plate in the south. Since the Early Mesozoic a number of small to large scale oceanic basins opened and closed as the intervening continental fragments drifted northwards and diachronously collided with and accreted to the southern margin of the Eurasian Plate. Despite the remarkable consequences of this, in terms of subduction, obduction and orogenic processes, little is known about the timing and palaeogeographic evolution of the region. This includes the amounts of shortening and interplay between synconvergent extension and compression, development of magmatic arc and arc-related basins and the timing and mechanism of their deformation. The chapters presented in this Special Publication present new information that help to fill some of the gaps of the puzzle.