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Abstract Until recently, information about the end of the Cretaceous was based upon investigation of global outcrop sections. New subsurface drilling and characterization from well cores and logs in the Gulf of Mexico Basin have greatly illuminated the end Cretaceous event. However, the palaeogeography of the late Maastrichtian just prior to bolide impact is less well understood and is of great importance in terms of modelling the resulting distribution and composition of the Chicxulub impact material, as well as tsunami and seiche wave height. Here, we examine the Maastrichtian strata in the basin, synthesizing lithostratigraphy and chronostratigraphy, tectonic plate reconstructions, global and local sea level history, palaeoclimate and depositional systems. Our new Maastrichtian palaeogeographical reconstruction shows the basin prior to the Chicxulub impact at a time of globally high sea level, with widespread deposition of deepwater chalks and shallow marine carbonates and local siliciclastic shorelines fed by the nascent Cordilleran belt. Stratigraphic correlations of wells and outcrops illustrate the range of palaeoenvironments from coastal plain to deep marine. As much as 610 m (2000 ft) of Maastrichtian and Campanian section is mapped around the basin, reflecting accommodation provided by basin subsidence, salt deflation and palaeophysiography. A large thickness of carbonates accumulated in the basin centre, with steep shoreline to basin gradients particularly in Mexico. At the end of the Cretaceous, carbonate palaeoenvironments probably covered 96% of the Gulf of Mexico Basin, with less than 4% of the area likely occupied by siliciclastic systems, a distribution that evolved from the Early Cretaceous. Our maps thus explain dominance of carbonate breccia and chalks in K–Pg boundary units deposited over the basin sites proximal or distal to the Chicxulub impact crater. This also elucidates the large impedance contrast and high amplitude seismic response of the K–Pg boundary horizon, mappable over vast portions of the basin. 

This data set consists of raw multi-channel seismic reflection (MCS) data in SEG-Y format, collected in July 2022 along the continental slope of the Campeche Bank aboard R/V Justo Sierra. The research objective was to map the detailed stratigraphy of sediment drift deposits to explore the history of the Loop Current and its climatic implications. We used the portable high-resolution seismic acquisition system operated by Scripps Institution of Oceanography, which comprised a source array of two 45 cubic inches G.I. air-guns and a GeoEel streamer with 120 channels at a spacing of 6.25 m. The air-gun array was fired every 12.5 m and was towed at a depth of 3 m. Data was recorded using the Geometrics seismic recording system with sample rate of 0.5 ms and recording length of 4 ms. A 50-ms delay was created during each shot as a buffer between the timing pulse that starts the recording and the trigger pulse that fires the air-guns. A total of 11 seismic lines were acquired including two long strike lines, five dip lines, two tilted dip lines and two short transition lines. The shot spacing was not exactly 12.5 m during the first three lines (1001-1003) due to system glitches, therefore, it is necessary to merge navigation with SEG-Y headers to ensure accurate processing of these lines. Detailed acquisition parameters and cruise incidents are described in the associated documents. Funding for this work was provided through NSF awards OCE-1928888 and OCE-1450528, and CONTEX award 2018-38A. 

Previous ichnological analysis at the Chicxulub impact crater, Yucatán Peninsula, México (International Ocean Discovery Program [IODP]/International Continental Scientific Drilling Program [ICDP] Site M0077), showed a surprisingly rapid initial tracemaker community recovery after the end-Cretaceous (Cretaceous-Paleogene [K-Pg]) mass extinction event. Here, we found that full recovery was also rapid, with the establishment of a well-developed tiered community within ~700 k.y. Several stages of recovery were observed, with distinct phases of stabilization and diversification, ending in the development of a trace fossil assemblage mainly consisting of abundant Zoophycos, Chondrites, and Planolites, assigned to the Zoophycos ichnofacies. The increase in diversity is associated with higher abundance, larger forms, and a deeper and more complex tiering structure. Such rapid recovery suggests that favorable paleoenvironmental conditions were quickly reestablished within the impact basin, enabling colonization of the substrate. Comparison with the end-Permian extinction reveals similarities during recovery, yet postextinction recovery was significantly faster after the K-Pg event. The rapid recovery has significant implications for the evolution of macrobenthic biota after the K-Pg event. Our results have relevance in understanding how communities recovered after the K-Pg impact and how this event differed from other mass extinction events. 

Abstract The Cretaceous-Paleogene (K-Pg; 66 Ma) mass extinction was caused by a bolide impact on the Yucatán platform near modern Chicxulub, Mexico. Calcareous nannoplankton, a dominant group of primary producers, were almost eradicated at this time. Post-impact nannoplankton assemblages from Northern Hemisphere sites were characterized by a short-lived series of high-dominance, low-diversity acmes (“boom-bust” successions), which likely represent an unstable post-impact environment. Although these boom-bust successions are a global signal, the mechanisms that controlled the taxonomic switchovers between acmes are currently unknown. Here, we present detailed analyses of calcareous nannoplankton and planktic foraminiferal assemblages in a new K-Pg section from the peak ring of the Chicxulub crater. We show that although nannoplankton assemblages resemble the typical series of acmes at Tethyan sites, the termination of the “disaster” acme in the crater is delayed by at least 500 k.y. The coincidence between shifts in the dominant planktic foraminiferal trophic group and switchovers in nannoplankton boom-bust taxa suggests that this series of acmes may represent a gradual trend toward oligotrophy driven by the global restoration of biological pump efficiency. Thus, the global diachroneity of boom-bust successions likely reflects the differential pacing of biological pump restoration between oceanic basins and settings. 

Abstract The Chicxulub crater was formed by an asteroid impact at ca. 66 Ma. The impact is considered to have contributed to the end-Cretaceous mass extinction and reduced productivity in the world’s oceans due to a transient cessation of photosynthesis. Here, biomarker profiles extracted from crater core material reveal exceptional insights into the post-impact upheaval and rapid recovery of microbial life. In the immediate hours to days after the impact, ocean resurge flooded the crater and a subsequent tsunami delivered debris from the surrounding carbonate ramp. Deposited material, including biomarkers diagnostic for land plants, cyanobacteria, and photosynthetic sulfur bacteria, appears to have been mobilized by wave energy from coastal microbial mats. As that energy subsided, days to months later, blooms of unicellular cyanobacteria were fueled by terrigenous nutrients. Approximately 200 k.y. later, the nutrient supply waned and the basin returned to oligotrophic conditions, as evident from N2-fixing cyanobacteria biomarkers. At 1 m.y. after impact, the abundance of photosynthetic sulfur bacteria supported the development of water-column photic zone euxinia within the crater. 

The Cretaceous-Paleogene (K-Pg) mass extinction is marked globally by elevated concentrations of iridium, emplaced by a hypervelocity impact event 66 million years ago. Here, we report new data from four independent laboratories that reveal a positive iridium anomaly within the peak-ring sequence of the Chicxulub impact structure, in drill core recovered by IODP-ICDP Expedition 364. The highest concentration of ultrafine meteoritic matter occurs in the post-impact sediments that cover the crater peak ring, just below the lowermost Danian pelagic limestone. Within years to decades after the impact event, this part of the Chicxulub impact basin returned to a relatively low-energy depositional environment, recording in unprecedented detail the recovery of life during the succeeding millennia. The iridium layer provides a key temporal horizon precisely linking Chicxulub to K-Pg boundary sections worldwide.