Seismic imaging and attribute analysis of Chicxulub Crater central sector, Yucatán Platform, Gulf of Mexico

Chicxulub Crater, formed ~66Ma ago by an asteroid impact on the southern Gulf of Mexico, is the best preserved of the three large multi-ring basins in the terrestrial record. The crater structure is characterized by a semi-circular concentric ring pattern, marking the crater basin, peak ring, terrace zone and basement uplift. Analysis of a grid of 19 seismic reflection profiles using seismic attributes, marker horizons, contour surfaces and 3-D views is used to investigate the stratigraphy of the central zone. We used interactive software and routine applications to map the impact breccias, breccia-carbonate contact and post-impact carbonates. Four horizons marked by high-amplitude reflectors representing high-impedance contrasts were identified and laterally correlated in the seismic images. Complex trace attribute analysis was applied for petrophysical characterization. Surface contour maps of base and top of stratigraphic packages were constructed, which mapped the impactites and post- and pre-impact carbonate stratigraphy. Basin floor, marked by the contact between the impact breccias and overlying carbonates is shown by laterally discontinuous high-amplitude reflectors. Discontinuous scattered reflectors interpreted as the upper breccias beneath the crater floor, have an average thickness of ~300msm. The Paleogene sedimentary units are characterized by multiple reflectors with lateral continuity, which contrast with the seismic response of underlying breccias. The basal Paleocene sediments follow the basin floor relief. Upwards in the section, the carbonate strata are characterized by horizontal reflectors, which are interrupted by a regional unconformity. Onlap/downlap packages over the unconformity record a period of sea level change

Seismic imaging and attribute analysis of Chicxulub Crater central sector, Yucatán Platform, Gulf of Mexico

Chicxulub Crater, formed ~66Ma ago by an asteroid impact on the southern Gulf of Mexico, is the best preserved of the three large multi-ring basins in the terrestrial record. The crater structure is characterized by a semi-circular concentric ring pattern, marking the crater basin, peak ring, terrace zone and basement uplift. Analysis of a grid of 19 seismic reflection profiles using seismic attributes, marker horizons, contour surfaces and 3-D views is used to investigate the stratigraphy of the central zone. We used interactive software and routine applications to map the impact breccias, breccia-carbonate contact and post-impact carbonates. Four horizons marked by high-amplitude reflectors representing high-impedance contrasts were identified and laterally correlated in the seismic  images. Complex trace attribute analysis was applied for petrophysical characterization. Surface contour maps of base and top of stratigraphic packages were constructed, which mapped the impactites and post- and pre-impact carbonate stratigraphy. Basin floor, marked by the contact between the impact breccias and overlying carbonates is shown by laterally discontinuous high-amplitude reflectors. Discontinuous scattered reflectors interpreted as the upper breccias beneath the crater floor, have an average thickness of ~300msm. The Paleogene sedimentary units are characterized by multiple reflectors with lateral continuity, which contrast with the seismic response of underlying breccias. The basal Paleocene sediments follow the basin floor relief. Upwards in the section, the carbonate strata are characterized by horizontal reflectors, which are interrupted by a regional unconformity. Onlap/downlap packages over the unconformity record a period of sea level change

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Seismic imaging and attribute analysis of Chicxulub Crater central sector, Yucatán Platform, Gulf of Mexico

Chicxulub Crater, formed ~66Ma ago by an asteroid impact on the southern Gulf of Mexico, is the best preserved of the three large multi-ring basins in the terrestrial record. The crater structure is characterized by a semi-circular concentric ring pattern, marking the crater basin, peak ring, terrace zone and basement uplift. Analysis of a grid of 19 seismic reflection profiles using seismic attributes, marker horizons, contour surfaces and 3-D views is used to investigate the stratigraphy of the central zone. We used interactive software and routine applications to map the impact breccias, breccia-carbonate contact and post-impact carbonates. Four horizons marked by high-amplitude reflectors representing high-impedance contrasts were identified and laterally correlated in the seismic images. Complex trace attribute analysis was applied for petrophysical characterization. Surface contour maps of base and top of stratigraphic packages were constructed, which mapped the impactites and post- and pre-impact carbonate stratigraphy. Basin floor, marked by the contact between the impact breccias and overlying carbonates is shown by laterally discontinuous high-amplitude reflectors. Discontinuous scattered reflectors interpreted as the upper breccias beneath the crater floor, have an average thickness of ~300msm. The Paleogene sedimentary units are characterized by multiple reflectors with lateral continuity, which contrast with the seismic response of underlying breccias. The basal Paleocene sediments follow the basin floor relief. Upwards in the section, the carbonate strata are characterized by horizontal reflectors, which are interrupted by a regional unconformity. Onlap/downlap packages over the unconformity record a period of sea level change

Distribution des sédiments sur la marge du golfe de Tehuantepec (Pacifique Oriental). Exemple d'interaction tectonique-eustatisme

During the PROGEMA I cruise which took place on the south-western Pacific coast of Mexico (between 14 degrees and 16 degrees N, 92 degrees and 96 degrees W), 3.5 kHz echo-sounding profiles, surface samples and cores as well as hydrological and oxygen minimum measurements down to 2250 m water depth were made in the Gulf of Tehuantepec. Chemical, sedimentological, mineralogical, X-ray and BEM analyses of waters, core and surface samples provided new data which permit a better knowledge of the Gulf of Tehuantepec margin, where tectonic activity is due to an active subduction. On the shelf of the gulf, the distribution pattern of quaternary deposits is affected by a double tectonic forcing and by eustatic oscillations of the sea level. The first tectonic control is linked to the existence of north-south tectonic troughs in the Tehuantepec Isthmus, in which the atmospheric circulation between the Gulfs of Mexico and Tehuantepec is accelerated by the Venturi effect. The resulting winds, called "Tehuanos", play an important role in the forcing of surface circulation in the Gulf of Tehuantepec, inducing a deviation of the general circulation and thus forcing the distribution pattern of terrigenous sediment supply according to two physiographically and mineralogically distinct provinces, inherited from the past tectonic evolution, which are separated by the Tehuantepec axis. - A southeastern province related to the Caribbean Plate and fed by: (1) the rivers draining the Chiapas Massif; and (2) the Costa-Rica Current driving tropical and subtropical waters from Central America. - A northwestern province part of the North American Plate and fed by: (1) the Rio Tehuantepec which drains the Sierra de Oaxaca; and (2) the Californian Current. The second tectonic control is linked to the tectonic structure of the margin influenced by: - shallow banks where the products of a present-day phosphatogenesis are concentrated because they are swept by upwellings. The latter are reinforced because the banks are situated south of the wind corridor; - tectonic depressions acting as sediment traps; - numerous canyons cutting the slope along brittle accidents, driving weak turbidity currents but which play an important role in the forcing of upwelling currents. Antarctic diatoms are found which are conveyed by the deep circulation from the South-Eastern Pacific and provide evidence that Antarctic Cold Water masses (AABW) rise towards the shelf. The influence of eustatism is attested by the presence on the shelf of the Gulf of Tehuantepec of three paleoshorelines at 40, 75 and 130 m water depth, linked to the Wurmian sea level and to the postglacial sea level rise as on many passive margins.Lors de la mission PROGEMA I conduite dans le golfe de Tehuantepec, des profils 3,5 kHz, de nombreux prélèvements de sédiments, des mesures hydrologiques et d'oxygène minimum jusqu'à une profondeur de 2250 m, ont été réalisés. Leurs études fournissent des données nouvelles pour la connaissance de cette marge active. Ces données montrent que la distribution des dépôts du Quaternaire à ce niveau de la marge subit un double forçage tectonique et un forçage eustatique. Le premier impact de la tectonique est lié à l'existence, dans l'isthme de Tehuantepec, de couloirs tectoniques Nord-Sud dans lesquels la circulation atmosphérique engendre des vents appelés « Tehuanos å. En interférant avec la circulation générale, ces vents répartissent les apports terrigènes selon deux provinces physiographiques et minéralogiques distinctes de part et d'autre de leur axe : • -|une province sud-orientale (plaque Caraïbe), alimentée depuis le Massif de Chiapas et parcourue par les masses d'eau tropicales et subtropicales véhiculées par le courant du Costa-Rica; • -|une province nord-occidentale (plaque Nord Américaine), alimentée depuis la Sierra de Oaxaca et atteinte par le courant de Californie. Le second effet de la tectonique est dû à la présence: • -|de hauts-fonds sur lesquels se concentrent les produits d'une phosphatogénèse actuelle associée aux upwellings forcés par l'action des « Tehuanos å ; • -|de dépressions d'origine tectonique qui constituent des pièges à sédiments; • -|de nombreux canyons guidés par des accidents tectoniques qui drainent de faibles écoulements turbiditiques et canalisent les courants d'upwelling amenant sur la plate-forme des diatomées australes. L'influence de l'eustatisme se traduit, sur la plate-forme par la présence à −40m, −75m et − 130m, de trois niveaux de stationnement marin que l'on peut lier au niveau marin würmien et à la remontée postglaciaire

Relaciones tectónicas en la margen continental al sur del Golfo de México y cinemática del manto: morfología-basamento-bloques corticales sobre la placa

The inferences of the geological history of the sedimentary basins in Mexico have been limited by the paradigm of basements which are at the access levels where borehole capacity allows to reach, to oil drilling systems. However, mapping and relief itself, of oceanic and continental basements complex convey and additional history: they explain the troughs and hales for the sedimentary fill, as a result of kinematics, fracture and deformation of crustal blocks on top of oceanic and continental plates. With the inverted "Bouguer Anomaly" data, integrated with other previous geological and geophysical data, and its assembling on a southern portion of the Gulf of Mexico, the Ocean-Continent Transitional Zone was computed in marine surroundings of Veracruz.Tabasco States. In the region other tectonophysical features associated to the continental margin kinematics in a crustal scale of the top of two or more subplates, are discussed. The high "Macizo de Veracruz" (for Veracruz Massif, i.e.missinterpreted "Macizo del Golfo") bounds in yuxtaposition against the continent, the Gulf oceanic subplate which occupies the dislodged space that the Yucatan Continental subplate and others, left in the Gulf's interior. If the "Macizo del Golfo" ever existed, this was the Yucatan continental plate, which above sea level eroded and supplied detritaldepositsto the west when passing next to Veracruz Basin

Seismic stratigraphic evidence of a pre-impact basin in the Yucatán Platform: morphology of the Chicxulub crater and K/Pg boundary deposits

Fifty-four 2D seismic profiles and 13 boreholes were used to describe pre-impact and post-impact deposits in the Yucatán Shelf. Previous work has identified a pre-impact basin in the northwest portion of the Chicxulub structure. The geometry of seismic reflectors associated with the Mesozoic Era shows that this pre-impact depression, here named Yucatán Trough, extends from the southern part of the Yucatán Peninsula to the northern face of the Campeche Escarpment. Stratigraphic data from boreholes of the Yucatán Platform suggest that the main sedimentary fills of the Yucatán Trough are a thin series of Upper Jurassic-Lower Cretaceous red beds, followed by the evaporite-dominated Lower Cretaceous and the carbonate-dominated Upper Cretaceous sedimentary successions. The mapping of the Cretaceous-Paleogene (K/Pg) deposits allowed us to observe the morphology of the Yucatán Shelf by the time of the Chicxulub impact event. The two-way seismic time K/Pg deposits map in conjunction with the free-air gravity anomaly map of the northern Yucatán Block reveals that, before the impact, the carbonate platform was divided into two blocks by a ~ 95–205 km wide and ~ 470-km long trough-shaped depression, probably a rift-basin with a north-south orientation, in which the central structure of Chicxulub impact crater is contained. The seismic reflectors overlying the top of the K/Pg deposits show that, during the Cenozoic Era, both the Yucatán Trough and impact basin were filled by progradational sequences which flattened the surface completely until the current block of the Yucatán Platform was configured. [Display omitted] •A new seismic dataset combined with borehole and gravity data allowed us to define the morphology of a pre-impact basin within the Yucatán Platform.•A ~95-205-km wide and ~470-km long trough-shaped low topographic feature divides the Yucatán Platform into two blocks.•The pre-existing basin, here named Yucatán Trough, is north-south oriented and contains the Chicxulub crater structure.•Deposits that filled the Yucatán Trough during the Mesozoic are mainly Lower to Upper Cretaceous evaporites and carbonates.•The Yucatán Trough is probably a rift basin induced by the Jurassic counterclockwise rotation of the Yucatán Block

Geodinámica holocénica y reciente del sistema fluvio-deltáico Grijalva-Usumacinta, suroeste del Golfo de México

The Coastal Plain al southwestern Gulf of Mexico, since Quaternary to Recent, resulted from the supply of terrigenous sediments, due lo denudation of the outcropping rocks of the Sierra Madre del Sur and also becausetheefficiency of the transport, dispersion and deposition of the coastal process by means of littoralcurrents, waves, tides, eolian, and washovers. Moreover, the continental and marine conditions were favorable during the late Holocene (5600 years) to depositextensiveprogradingterrigenous sediments toward the Gulf of Mexico, developed by berms and beach-ridge deposits with arate of northernprocreation about 6 to 10 meters/year. The coastal plain suffered a tectonic reactivation and as consequence the holocenicsedimentary deposits moved 7.5 km northwestern along a fault transcurrent system with a rate of 4 m/year; then, the fluvial, deltaic fronts were exposed to the action of the erosional coastal processes. Contemporaneously to thistectonicdisplacements, eastern block moved along the Xicalango-Fault lo the southeast and the stratigraphicsequence al Punta Xicalango al the eastern portion of the studiedarea,resulted from the sediments derived from the denudationof the fluvial-deltaic front al western side of the studiedarea. The complex-deltaic front, is undergoingerosion today at rate of 3 to 4meters/year, same speed as such of that of the tectonic displacements occurredduringHolocene; also erosion occurs dueto the scarcity of sand and becamethepresence of anticyclonic ring marinecurrent transporting the sedimentsnorthwestern and also, because the collision of a loop current anticyclonic ring against the continental shelf-slope, which also transport the sediments along the coastal zone of the western Gulf of Mexico; moreover, maybe erosion occurs because global climate changes. Therefore, under the actual sedimentary and marine hydrodynamics, possibility is low that Grijalva-Usumacinta fluvial-deltaic complex system progrades northern