Abstract The inversion of a sedimentary basin could be associated with compressional reactivation of basin-forming normal faults, upwards movement of the basement blocks and partial or complete erosion of its sedimentary infill. Basin inversion might be also related to whole-basin uplift that is not linked to the reactivation of basement faults, and results in the development of regional stratigraphic gaps and unconformities. Both types of basin inversion have been documented in SE Poland using seismic data. Regional NW–SE seismic profiles illustrate earliest Late Jurassic (earliest Oxfordian) and earliest Late Cretaceous (Cenomanian) regional unconformities related to regional basin-scale uplifts in the SE segment of the Polish Basin. Late Cretaceous (Turonian?–Maastrichtian) progressive uplift of the Mid-Polish Swell has been documented along the NE border zone of this regional anticlinal structure. The Upper Cretaceous inversion-related sedimentary succession is characterized by an overall progradational character directed from the SW towards the NE. Buried contourite drifts that were detected within the Upper Cretaceous succession using seismic data indicate the existence of contour currents encircling inversion-related intrabasinal morphological barriers. A new tectonic scenario of the Mesozoic evolution of SE Poland would have a significant impact on the modelling of tectonic subsidence and the history of petroleum systems.

Abstract The IGUANES cruise took place in May 2013 on the R/V L’Atalante along the Demerara passive transform margin off French Guiana and Surinam. Seismic, multibeam and chirp acquisitions were made. Piston cores were collected for pore geochemistry and sedimentology. A mooring was deployed on the sea-bottom for 10 months (temperature, salinity, turbidity and current measurements). This new dataset highlights the lateral variability of the 350 km-long Guiana–Surinam transform margin due to the presence of a releasing bend between two transform segments. The adjacent Demerara Plateau is affected by a 350 km-long giant slide complex. This complex initiated in Cretaceous times and was regularly reactivated until recent times. Since the Miocene, contourite processes seem to be active due to the onset of the North Atlantic Deep Water (NADW) bottom current. A main NADW water vein flows towards SE, eroding slide headscarps and allowing the deposition of contourite drifts. Numerous depressions looking like comet tails or comet scours record this flow. Some of those were interpreted before the cruise as active pockmarks. Pore geochemistry and core analysis do not show any evidence of present-day gas seepage.

Abstract Predicting potential sandstone reservoir character of deep-water sedimentation units in the postrift subsurface section of the Morocco Atlantic coast is problematic as there are only a few deep wells in the area. Two key control points for uppermost Jurassic to Lower Cretaceous deposition in this area are the Deep Sea Drilling Project (DSDP) Leg 41, Site 370 (1975), and DSDP Leg 50 Site 416 (1976) cores. Sites 370 and 416 are located approximately 150 kilometers from the coast of Morocco, and are in 4,200 m of water, at the base of the continental slope. Sedimentologic characterization of cored strata in the 1978 and 1980 DSDP volumes is generalized, and only a few restricted intervals are described in detail. This study presents results from a new lithologic description of 440 meters of conventional core from Sites 370 and 416. Strata range from Tithonian to Albian in age. Claystone and siltstone are the dominant lithofacies and comprise 91% of the cores. The cores also contain 6.8% sandstone, 1.7% fine-textured carbonate, and 0.6% carbonate grainstone. The focus here is on the sandstone and grainstone. Sandstone beds are either Bouma turbidites (26.4%) or contourites (73.6%). Sandstone turbidite beds range from centimeter to several decimeters thick, and are not preferentially distributed within the Mesozoic section. Contourite beds are ≤4 cm. Carbonate grainstones occur in Valanginian to Aptian strata. They were deposited as calciturbidites, and contain platform derived carbonate grains. The presence of numerous turbidite beds (>200) distributed throughout the Tithonian to Albian strata suggests the repeated occurrence of throughgoing turbidite fairways on the Morocco Atlantic slope.