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Gravity-flow deposits are important hydrocarbon exploration targets in most basins. In this study, an integration of geological, geophysical, and geochemical analysis is used to investigate the gravity-flow deposits and their petroleum prospects in the Oligocene Dongying Formation (E 3 d), Bozhong Subbasin, Bohai Bay Basin. Mass-transport deposits (MTDs) and channel-lobe complexes are the main gravity-flow depositional units. The mass-transport deposits (MTDs) show hummocky and chaotic reflections with poor continuity and variable amplitude. The channels display linear geomorphology with weak root-mean-square (RMS) amplitude, and the lobes are dominated by high-continuous and high-amplitude reflection at the terminal channels. The formation of gravity-flow deposits is primarily controlled by high sedimentation rate during a relative lowstand of lake level. The E 3 d 3 source rock has TOC contents in the range of 0.6–3.1%, Rock-Eval S 2 values in the range of 0.7–19.8 mg HC/g rock, and Hydrogen indices (HI) in the range of 100–600 mg/g TOC. The E 3 d 2 L source rock has TOC contents ranging from 0.5 to 1.9%, Rock-Eval S 2 values from 0.4 to 7.8 mg HC/g rock, and HI from 40 to 480 mg/g TOC. Both E 3 d 3 and E 3 d 2 L source rocks have good hydrocarbon-generation potential. The E 3 d 3 and E 3 d 2 L source rocks have entered the oil-generation peak window with the vitrinite reflectance (R o ) higher than 1.0%. Oils generated from the underlying source rocks shortly migrated to the overlying gravity-flow lithologic traps. The gravity-flow reservoirs could serve as potential and effective hydrocarbon exploration targets. [ABSTRACT FROM AUTHOR]

The ongoing exploration for shale oil and gas has focused sedimentological research on the transport and deposition mechanisms of fine-grained sediments, and more specifically on fine-grained mass-flow deposits. It appears, however, that no easily applicable classification scheme for gravity-flow deposits exists, and that such classifications almost exclusively deal with sandy and coarser sediments. Since the lack of a good classification system for fine-grained gravity flow deposits hampers scientific communication and understanding, we propose a classification scheme on the basis of the mud content in combination with the presumed transport mechanism. This results in twelve types of gravity-flow deposits. In order to show the practical applicability of this classification system, we apply it to the Triassic lacustrine Yanchang Formation in the southern Ordos Basin (China), which contains numerous slumps, debris–flows deposits, turbidites and hyperpycnites. The slumps and debrites occur mostly close to a delta front, and the turbidites and hyperpycnites extend over large areas from the delta slopes into the basin plain. The case study shows that (1) mud cannot only be transported but also deposited under active hydrodynamic conditions; (2) fine-grained gravity-flow constitute a significant part of the lacustrine mudstones and shales; (3) muddy gravity flows are important for the transport and deposition of clastic particles, clay minerals and organic matter, and thus are important mechanisms involved in the generation of hydrocarbons, also largely determining the reservoir capability for unconventional petroleum. [ABSTRACT FROM AUTHOR]

Integrated in the peri-Adriatic domain, the Ionian Basin extended along a NW-SE direction during the Late Cretaceous, limited on its sides by the Apulian and the Kruja platforms. The basinal/slope succession was studied in seven outcrops exposed in the Albanian fold-and-thrust belt. Sedimentological investigations, supported by bio- and chronostratigraphy were performed on calcareous Upper Cretaceous hemipelagites, gravity-flow deposits and slumps. The western part of the basin was studied, revealing a strong influence of the Apulian margin, alternatively shedding sediment basinward, by means of a tectonically controlled edge. The Late Albian to Cenomanian period is characterized by the settling of muddy debrites along the margin. A deep basinal environment characterizes this period which prolongs until the Santonian, with no significant influx of the platform basinward. This sedimentary setting abruptly changed at the end of the Santonian, with an important influx derived from both platforms. Coarsening and thickening upward sequences show a progressive increase in sediment shedding during the Campanian. The Late Campanian-Early Maastrichtian period points out a major change on the resedimentation processes with the settling of several slumped units reworking thick sediment packages. The latter can be traced along the Apulian margin, testifying of instabilities along the edge of Apulia. [ABSTRACT FROM AUTHOR]