Hydromorphological and hydroclimatic methods were used to reconstruct the former surface runoff from the East European part of the Black Sea drainage basin. Data on the shape and dynamics of the last Fennoscandian ice sheet were used to calculate meltwater supply to the headwaters of the Dnieper River. The channel width and meander wavelength of well-preserved fragments of large paleochannels were measured at 51 locations in the Dnieper and Don River basins (East European Plain), which allowed reconstruction of the former surface runoff of the ancient rivers, as well as the total volume of flow into the Black Sea, using transform functions. Studies of the composition of fossil floras derived from radiocarbon-dated sediments of various origins and ages make it possible to locate their modern region analogues. These analogues provide climatic and hydrological indexes for the Late Pleniglacial and Late Glacial landscapes. Morphological, geological, geochronological, and palynological studies show that the landscape, climatic, and hydrologic history of the region included: (1) a cold and dry interval close to the Last Glacial Maximum characterized by high meteoritic surface runoff supplemented by meltwater flow from ice-dam lakes; (2) a warmer humid interval at the end of the Late Pleniglacial with very high surface runoff and formation of extremely large meandering channels, combined with a short event of substantial inflow from the Caspian Sea; and (3) a period from the Oldest Dryas to the Preboreal of nonsteady surface runoff decrease, and transformation of large meandering channels into smaller ones against the background of climate warming.

Abstract Shale gas is produced from fine-grained siliciclastic sediments that are typically rich in organic carbon. Nearly all shales contain thermal gas generated in situ at mature to overmature levels of thermal alteration, although gas of biogenic origin is also produced from some shales. While shale gas production in the USA began in 1821, it is only in the last few years that it has become widely significant (currently about 8% of the domestic gas). In contrast, European shale gas exploration is still in its infancy. In general, European sedimentary basins offer the best potential for shale gas occurrence because thick, organic matter-rich sediments occur in nearly all Phanerozoic strata. Even so, there is little knowledge about the factors controlling shale gas generation and, more importantly, shale gas production in European basins. These factors are not necessarily the same as those that control commercial shale gas production in the USA. Palaeozoic sediments of Cambrian to Ordovician age are currently being tested for their shale gas potential and productivity in Sweden, as are those of Silurian age in Poland. Moreover, Lower and Upper Carboniferous sedimentary successions from England in the west to Poland in the east probably contain shale gas, but their depth, thickness and thermal maturity may be limiting factors for exploration in continental regions. Lower Carboniferous black shales in the Dniepr–Donets Basin of the Ukraine may also hold a significant potential. Moreover, organic-rich sediments of Oligocene/Miocene age in the Paratethyan Basin may offer shale gas potential, for example in the Pannonian Basin. At present, Upper Jurassic black shales are currently being tested for their shale gas potential in the Vienna Basin. European analogues of known biogenic shale gas systems may occur locally in organic-rich Lower Cretaceous sediments in the North German Basin with gas generation being related to Pleistocene glaciation/deglaciation cycles.

The classic failed continental rift or aulacogen is one that intersects a rifted continental margin at a high angle. Based on recent geological and geophysical studies, we have revisited a classic analogy that was drawn between two major intracratonic rifts, the Southern Oklahoma aulacogen in the southern portion of Laurentia and the Dniepr-Donets aulacogen in the southern portion of Baltica. The Southern Oklahoma aulacogen, also known as the Wichita aulacogen, consists of a linear alignment of extensively inverted rift structures that begins at the rifted margin of Laurentia in northeast Texas and extends northwestward at least to southern Colorado. Deep seismic profiles have revealed the upper crustal structure of this feature, and gravity data provide a regional context for interpreting these results. Velocities low enough to indicate the presence of sedimentary rocks extend to a depth of ∼15 km, and the deepest of these sedimentary layers has been interpreted as rift fill. In addition, the main inversion structure of the Southern Oklahoma aulacogen (Wichita uplift) is underlain by very high-velocity and dense mafic material even at upper crustal depths of ∼5 km. The Dniepr-Donets aulacogen has been cited as a type example of an aulacogen and is clearly a “failed rift” in the sense that it did not itself lead to continental breakup and ocean crust formation. The main feature of the aulacogen is a Late Devonian rift basin overlain by a substantial (but variable) postrift sedimentary sequence that records several extensional or transtensional events and at least one moderate compressional reactivation. Recent deep seismic reflection and refraction surveys resolve the geometry of the sedimentary succession in the Donets segment of the basin, indicating an asymmetric form with a steeper basement surface in the south than in the north and a total sedimentary thickness of ∼20 km. A thick (>10 km) high-velocity (>6.9 km/s) lower crustal body lies beneath the rift basin itself and is offset slightly to the north compared to the main basin depocenter. The Moho displays only slight topography around a depth of 40 km although, based on older deep seismic data, it shallows somewhat under the rift axis in the Dniepr segment to the northwest. Thus, major differences between these two major rifts are the nature of the magmatic modification of the crust and degree of inversion. Both the age of initial rifting and subsequent inversion in the Dniepr-Donets aulacogen are redefined compared to what was thought at the time the original analogy was made with the Southern Oklahoma aulacogen.

Abstract The data from oil-bearing Ukrainian basins outline the tectonic control of overpressure development in areas characterized by recent episodes of folding and active compression (dominantly horizontal stress regime). Based on the data presented, vertical compaction alone is not sufficient to account for the observed overpressure development. Tentatively, tectonic deformation is proposed as the dominant factor for overpressure development in sedimentary layers in recently folded regions. During folding, the opening of fractures results in local density decrease and helps in driving the migrating fluids, i.e., both hydrocarbon and formation waters, in the carrier beds toward the top of the structures. Ductile flow of shaly interbeds toward anticlinal closures can also enhance the sealing capacity of these layers. In the Ukrainian Carpathians and salt domes of the Dniepr-Donetz Basin, direct relationships have been evidenced to link and predict the amount of overpressure as a function of the amplitude of the folds. The use of measurements and of the monitoring of overpressures for evaluating the horizontal stress intensity and for the forecasting of earthquakes is also suggested.