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The Cenomanian–Turonian succession of southern Mexico is characterized by an abrupt change from shallow marine to pelagic facies. The drowning of the platform coincides with the widely documented Cenomanian–Turonian Oceanic Anoxic Event (CTOAE). A proper understanding of the drowning event and the effects of the OAE requires, as an essential first step, the construction of a detailed stratigraphic framework. This has been achieved and utilizes sedimentological data as well as a combination of benthic and planktonic biostratigraphic schemes.Deposition of the Cenomanian–Turonian sedimentary rocks of the Guerrero–Morelos basin was controlled by tectonic and oceanographic factors resulting in depositional environments ranging from a semi-restricted shelf, ramp, pelagic and prodelta deposits. Facies analysis indicates that shallow marine limestones of the Morelos Formation (lower-upper Cenomanian) were deposited in intertidal–shallow supratidal and subtidal environments in a semi-restricted shelf. Peloidal-bioclastic packstone–wackestones with minor grainstones are the predominant texture of these rocks. Abundant large benthic foraminifers, calcareous algae (dasycladacean) and mollusks (gastropods and rudists) characterize the fossil assemblage.The Cuautla Formation (uppermost Cenomanian–Turonian) represents sedimentation on a low-energy, wave-dominated, carbonate ramp. The inner ramp accumulated bioclastic banks and shoals composed of peloidal-benthic foraminifer-grainstone, calcareous red and green algae, rudists and minor solitary corals. The middle ramp is represented by nodular packstones with a diverse assemblage of echinoderms, green and red algae, bryozoan, rudists, solitary corals, roveacrinids, calcisphaerulids, and non-keeled planktonic foraminifers. The outer ramp is dominated by argillaceous wackestone–packstone characterized by calcisphaerulids, roveacrinids, and non-keeled planktonic foraminifers. An increase in terrigenous-clastic material towards the eastern part of the area indicates progradation of a deltaic system while the Mexcala Formation (uppermost Cenomanian–Turonian) was deposited in a pelagic setting.The drowning of the platform is at the contact between the Morelos and Cuautla or Mexcala formations and is dated as latest Cenomanian. The drowning is a hiatus in most sections and it began before the end of the Cenomanian by a minimum of 150 ky if the top of the Morelos is not eroded. [Copyright &y& Elsevier]

Detailed stratigraphic and facies analyses were conducted and combined with seismic facies and 3D seismic‐derived plan view images to interpret the depositional environments, processes and depositional elements during the Miocene for an area located in the southern Gulf of Mexico. The results showed that deposition during the Miocene mainly occurred in a slope setting, with bathymetric changes associated with highs and mini‐basins related to salt features. From the sedimentological interpretation, 13 sedimentary facies were identified. The abundant lithofacies were structureless (massive) sandstone and massive mudstone. Ripple‐ , parallel and cross‐laminated sandstone and siltstone were found in minor proportions. The main depositional processes were related to turbidity currents, including high‐density and low‐density currents; debris flows (mud flows and grain flows) were of secondary importance, as was deposition from fallout of suspended hemipelagic mud particles. The vertical and lateral distributions of facies revealed seven facies associations linked to depositional environments. These facies associations were the building blocks that were used to characterize the depositional elements recognized on seismic data. The main depositional elements identified were mass‐transport complexes, submarine channels, and frontal splays. Finally, interpretations from different data sets enabled the conclusion that, during the Miocene in this area were submarine fans deposited on an irregular paleotopography, with topographic lows and highs controlled by salt tectonics. [ABSTRACT FROM AUTHOR]

This study focuses on the interpretation of stratigraphic sequences through the integration of biostratigraphic, well log and 3D seismic data. Sequence analysis is used to identify significant surfaces, systems tracts, and sequences for the Miocene succession. The depositional systems in this area are dominantly represented by submarine fans deposited on the slope and the basin floor. The main depositional elements that characterize these depositional settings are channel systems (channel-fills, channel-levee systems), frontal splays, frontal splay complexes, lobes of debrites and mass-transport complexes. Five genetic sequences were identified and eleven stratigraphic surfaces interpreted and correlated through the study area. The Oligocene-lower Miocene, lower Miocene and middle Miocene sequences were deposited in bathyal water depths, whereas the upper Miocene sequences (Tortonian and Messinian) were deposited in bathyal and outer neritic water depths. The bulk of the Miocene succession, from the older to younger deposits consists of mass-transport deposits (Oligocene-lower Miocene); mass transport deposits and turbidite deposits (lower Miocene); debrite deposits and turbidite deposits (middle Miocene); and debrite deposits, turbidite deposits and pelagic and hemipelagic sediments (upper Miocene). Cycles of sedimentation are delineated by regionally extensive maximum flooding surfaces within condensed sections of hemipelagic mudstone which represent starved basin floors. These condensed sections are markers for regional correlation, and the maximum flooding surfaces, which they include, are the key surfaces for the construction of the Miocene stratigraphic framework. The falling-stage system tract forms the bulk of the Miocene sequences. Individual sequence geometry and thickness were controlled largely by salt evacuation and large-scale sedimentation patterns. For the upper Miocene, the older sequence (Tortonian) includes sandy deposits, whereas the overlying younger sequence (Messinian) includes sandy facies at the base and muddy facies at the top; this trend reflects the change from slope to shelf settings. [ABSTRACT FROM AUTHOR]

Abstract In the southern Gulf of Mexico, deepwater sediments were affected during deposition by contractional and extensional deformation events and halokinesis. The Miocene reservoirs in this area were deposited in slope and basinal settings during the falling-stage systems tracts and the lowstand systems tracts, where channel and frontal splay depositional elements were the most important. The integration of the structural analysis with seismic data, seismic attributes and isochron maps allows us to evaluate how the deformational events (especially the contractional event D3) controlled the distribution of sediments and the external geometry of their deposits. This interplay between deformation and sedimentation mainly occurred in two ways. First, the structural elements modified the paleobathymetry of the basin and created an accommodation space for clastic deposition. Second, the structural features controlled the entry of sediments. During the Oligocene and early Miocene, the depocenters were bounded by diapirs, salt sheets and structural highs formed by older salt anticlines. On the other hand, for the middle Miocene, the depocenters were controlled by the presence of folds in the southern part of the study area and by shortened diapirs and salt sheets in the periphery. The formation of these depocenters provided the accommodation space for sediment deposition; as a result, during the early and middle Miocene, the frontal splays were confined to these depocenters. At the end of the middle Miocene, these depocenters were filled, and channel levee systems and frontal splay complexes predominated. Finally, during the late Miocene, the depocenters formation was controlled by the extensional event, which provided the accommodation space for sediment deposition in half-grabens, where frontal splays complexes and channel levee systems were the most important depositional elements. All of these structural elements had significant implications for the architecture and internal organization of the turbidite systems. Highlights • Reservoirs were deposited in the slope during the falling-stage and lowstand systems tracts. • Structural elements modified the paleotopography of the basin creating accommodation space. • Structural elements controlled the entry of sediments. • Deformation events had implications in the architecture and organization of turbidites. [ABSTRACT FROM AUTHOR]