Cretaceous–Neogene tectonic evolution of the northern margin of the Black Sea from seismic reflection data and tectonic subsidence analysis

Abstract

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.

Kinematics of back‐arc inversion of the Western Black Sea Basin

“…Wide open anticlines or smaller-scale folds formed along the same type of highangle reverse faults with reduced offsets activated earlier during the Oligocene -early Miocene [Afanasenkov et al, 2007;Khriachtchevskaia et al, 2010].…”

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

“…There is also good evidence of a compressional regime in this area in the Eocene (cf. Khriachtchevskaia et al 2010;Sheremet et al 2016a) in contiguous offshore regions, although they indicate that the most intense period of shortening began later. Significant volcanic activity also occurs in the Eocene in the study area, as reported by Sahakyan et al (2016) in the Lesser Caucasus and Hippolyte et al (2015) in the eastern Pontides.…”

Sedimentary basin tectonics from the Black Sea and Caucasus to the Arabian Platform: introduction

“…The onset of inversion tectonics is fairly precisely dated by structural relationships seen in seismic data on the northern margin of the Black Sea as late Middle Eocene (Khriachtchevskaia et al 2010), following a period of relative quiescence. However, extension following Late Cretaceous obduction processes on the SE margin of the TASA block in SE Turkey and on the Arabian Plate continued until the Middle Eocene possibly due to roll-back of the slab related to the southern Neotethys Oceanic .…”

“…The extensional events, including the formation of the Black Sea basin, that took place mainly during middle-Late Cretaceous times (Bergerat et al 2010;Kaymakci et al 2010;Khriachtchevskaia et al 2010;Konerding et al 2010) were replaced as subduction terminated in the northern Neotethys and collision of the intervening continental terranes began, leading to inversion tectonics throughout the circum-Black Sea area. The onset of inversion tectonics is fairly precisely dated by structural relationships seen in seismic data on the northern margin of the Black Sea as late Middle Eocene (Khriachtchevskaia et al 2010), following a period of relative quiescence.…”

“…Inversion tectonics in the immediate Black Sea area ended by the Middle to Late Miocene (Khriachtchevskaia et al;Konerding et al 2010), as indicated by evidence of renewed extensional tectonic activity in the western Black Sea area (Konerding et al 2010).…”