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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. 

Abstract The Loop Current is a key component of global circulation via the northward transport of warm, salty water, and an important influence on Gulf of Mexico hydrography. Understanding how the Loop Current will respond to ongoing anthropogenic warming is critically important, but the history of the Loop Current is poorly known. Here, we present the results of a high resolution (3–8 m) multichannel seismic survey of pelagic carbonate sediment drifts on the eastern Campeche Bank associated with the Loop Current. We identify three seismic megasequences: Megasequence A is a Lower Cretaceous carbonate platform, Megasequence B comprises Cretaceous to lower Cenozoic pelagic carbonates with weak/no contour current flow, and Megasequence C comprises a series of large (100s of m thick) contourite drifts representing the inception and history of the Loop Current. The base of the contourites is marked by a regionally mappable unconformity eroding underling strata, sometimes incising hundreds of meters. The drifts contain a succession of sequence sets separated from each other by regional unconformities and comprising plastered drifts and massive mounded drifts, which characterize modern deposition with active moats on the seafloor. A lack of sediment cores in the study area precludes age determination of these drifts, except for the youngest (Late Pleistocene). Comparison to legacy seismic lines across Deep Sea Drilling Project Site 95, outside our study area, implies that the base of Megasequence C is Oligocene in age, and that the Loop Current developed during the global reorganization of ocean circulation around the Eocene‐Oligocene Transition. 

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. 

Abstract Recent changes in US oceanographic assets are impacting scientists' ability to access seafloor and sub‐seafloor materials and thus constraining progress on science critical for societal needs. Here we identify national infrastructure needs to address critical science questions. This commentary reports on community‐driven discussions that took place during the 3‐dayFUTURE of US Seafloor Sampling Capabilities 2024 Workshop, which used an “all‐hands‐on‐deck” approach to assess seafloor and sub‐seafloor sampling requirements of a broad range of scientific objectives, focusing on capabilities that could be supported through the US Academic Research Fleet (US‐ARF) now or in the near future. Cross‐cutting issues identified included weight and size limitations in the over‐boarding capabilities of the US‐ARF, a need to access material at depths greater than ∼20 m below the seafloor, sampling capabilities at the full range of ocean depths, technologies required for precise navigation‐guided sampling and drilling, resources to capitalize on the research potential of returned materials, and workforce development. 

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.