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Calcareous nannofossil assemblages were investigated across the Oceanic Anoxic Event (OAE) at the Cenomanian/Turonian Boundary (CTB) in a section from the Western Interior Basin and a borehole from the New Jersey coastal plain. The objective was to determine the surface-water response to environmental perturbations during the OAE. A decrease in surface water fertility at the two localities is suggested by an increase in relative abundances of taxa with oligotrophic affinities and a concomitant decrease in taxa with mesotrophic or eutrophic affinities. Oligotrophy and anoxia at both localities are likely responses to increased water-column stratification associated with the incursion of warmer waters from lower latitudes. [ABSTRACT FROM AUTHOR]

Presents a reply relating to the article `High-Resolutions Records of the Late Paleocene Thermal Maximum and Circum-Caribbean volcanism: Is There a Causal Link?' Discussion on the late Paleocene thermal maximum in the Caribbean; Reference to the carbon isotope excursion; Decrease of CaCO3 in deep sea.

To fully assess the resilience and recovery of life in response to the Cretaceous–Paleogene (K-Pg) boundary mass extinction ~ 66 million years ago, it is paramount to understand biodiversity prior to the Chicxulub impact event. The peak ring of the Chicxulub impact structure offshore the Yucatán Peninsula (México) was recently drilled and extracted a ~ 100 m thick impact-generated, melt-bearing, polymict breccia (crater suevite), which preserved carbonate clasts with common biogenic structures. We pieced this information to reproduce for the first time the macrobenthic tracemaker community and marine paleoenvironment prior to a large impact event at the crater area by combining paleoichnology with micropaleontology. A variable macrobenthic tracemaker community was present prior to the impact (Cenomanian–Maastrichtian), which included soft bodied organisms such as annelids, crustaceans and bivalves, mainly colonizing softgrounds in marine oxygenated, nutrient rich, conditions. Trace fossil assemblage from these upper Cretaceous core lithologies, with dominant Planolites and frequent Chondrites, corresponds well with that in the overlying post-impact Paleogene sediments. This reveals that the K-Pg impact event had no significant effects (i.e., extinction) on the composition of the macroinvertebrate tracemaker community in the Chicxulub region. [ABSTRACT FROM AUTHOR]

Lithified marine sediments are not equitably distributed through time, raising the possibility that lithification masks biological signals when data from unlithified and lithified sediments are compared or combined. Using mollusk-dominated assemblages from the early Cenozoic of the Gulf Coastal Plain, we find that lithification conceals small taxa, decreases taxonomic resolution, and exacerbates the undersampling of rare taxa. Lithified assemblages appear less diverse and have less even abundance distributions than coeval unlithified samples. These limitations cannot be overcome by standardization procedures, nor are they likely to be circumvented by collecting larger samples. The effects of this bias, however, can be mitigated by restricting analyses to a single lithification state or to specific size classes. Since lithification selectively obscures small taxa, the magnitude of this bias will be most severe when organisms are particularly small, such as in the aftermath of mass extinctions. In the study area, lithification artificially protracts the recovery period following the Cretaceous-Paleogene mass extinction by ~7 m.y. [ABSTRACT FROM AUTHOR]

Oceanic Anoxic Event 2 (OAE2; ~94.5 Ma) occurred in the latest Cenomanian and represents a perturbation to the global carbon cycle. The event is geochemically recorded in shales and limestones of the Western Interior Basin of North America and is additionally marked by foraminiferal bio-events (e.g., turnovers, extinctions). These bio-events are attributed to changing paleoceanographic conditions and circulation patterns in the Western Interior Seaway related to the onset of OAE2. Here we investigate the paleoenvironment near the southwestern edge of the seaway during OAE2 by integrating microfossil and geochemical records from the lower beds of the Tokay Tongue (Mancos Shale) at Carthage, New Mexico, USA. We demonstrate that this locality represents an expanded section of OAE2 based on temporal constraints from carbon isotope chemostratigraphy and the occurrence of regional marker ash-fall deposits (bentonites), limestones and other carbonate-rich beds. Prior to the onset of OAE2, a unique assemblage of benthic foraminiferal morphologies suggests the presence of a distinct water mass in the southwestern part of the seaway compared to coeval neritic and distal sites. Microfossil assemblages record the Benthonic Zone, a typical OAE2 bio-event, with some distinctions. The event is still identifiable and thereby useful in marking the earliest stages of OAE2. Early in OAE2, calcareous nannofossil and foraminiferal assemblages indicate intervals of high productivity. The dominance of biserial planktic foraminifera (Planoheterohelix spp.) suggests the development of photic zone euxinia with intensification of OAE2. During OAE2, epifaunal trochospiral benthic foraminifera (Gavelinella dakotaensis) suggest intervals of improved conditions related to food availability and seafloor ventilation. Later, as increased surface water productivity and subsequent food availability prevailed at the seafloor through the end of the OAE2 interval, benthic foraminifera were abundant and assemblages were dominated by infaunal, low oxygen tolerant species (Neobulimina albertensis), suggesting prevailing dysoxia. We attribute differences in the expression of bio-events and foraminiferal community composition at Carthage to the influence of freshwater runoff from the western margin that drove high-productivity conditions throughout OAE2. [ABSTRACT FROM AUTHOR]

Abstract: The mid-Pliocene was an interval of subtle reorganisation within the nannoplankton community, including the prominent and biostratigraphically important last occurrences of Sphenolithus abies and Reticulofenestra pseudoumbilicus. The transition is part of the Pliocene to Recent ‘attrition’ of nannofossil species that resulted from changes in the distribution of trophic resources, and deep-water and surface-water current systems, likely associated with the initiation of Northern Hemisphere glaciation. The extinctions of Sphenolithus abies and Reticulofenestra pseudoumbilicus were analysed in detail at ODP Sites 659, 662, and 926 in the equatorial and subequatorial Atlantic. These taxa show significantly different patterns of duration and timing of decline based on high-resolution abundance records and calibration with oxygen isotope stratigraphy. The initiation of abundance decline between 3.71 and 3.67 Ma and the extinction of S. abies between 3.56 and 3.52 Ma are diachronous. This extinction may have been a response to the intensification of glacial intervals at this time. In contrast, the last occurrence of R. pseudoumbilicus at 3.81–3.82 Ma appears to be a valid example of biostratigraphic (although not necessarily biological) synchrony in the fossil record. Direct environmental forcing is not attributable for the extinction of R. pseudoumbilicus; however, indirect physical and/or biological environmental stress may explain the observed patterns. [Copyright &y& Elsevier]

The strontium isotope ratios ([sup 87]Sr/[sup 86]Sr) of marine barite microcrystals separated from Cretaceous sedimentary deposits from Ocean Drilling Program and Deep Sea Drilling Project sites from the Pacific and Indian Oceans have been compared to the composite Sr isotope curve of McArthur et al. The barite in these cores accurately recorded the seawater [sup 87]Sr/[sup 86]Sr ratio, thereby reaffirming the composite Cretaceous strontium curve. Moreover, marine barite is a more reliable recorder of [sup 87]Sr/[sup 86]Sr than is carbonate in sedimentary deposits with high clay content, thereby providing an opportunity for Sr isotope stratigraphy and dating in carbonate-poor or diagenetically altered sections. We have used the barite-derived Sr isotope record to refine the biostratigraphic age models of the sites investigated. [ABSTRACT FROM AUTHOR]

The article informs about Probing the hydrothermal system of the Chicxulub peak-ring crater and multiring basin. Topics discusserd include information on International Ocean Discovery Program (IODP) and International Continental Scientific Drilling Program (ICDP) Expedition; and chemical and mineral alteration in the Chicxulub crater was previously detected within a few centimeter-size rock fragments from a petroleum exploration borehole.

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. [ABSTRACT FROM AUTHOR]

The cause of the end-Cretaceous mass extinction is vigorously debated, owing to the occurrence of a very large bolide impact and flood basalt volcanism near the boundary. Disentangling their relative importance is complicated by uncertainty regarding kill mechanisms and the relative timing of volcanogenic outgassing, impact, and extinction. We used carbon cycle modeling and paleotemperature records to constrain the timing of volcanogenic outgassing. We found support for major outgassing beginning and ending distinctly before the impact, with only the impact coinciding with mass extinction and biologically amplified carbon cycle change. Our models show that these extinction-related carbon cycle changes would have allowed the ocean to absorb massive amounts of carbon dioxide, thus limiting the global warming otherwise expected from postextinction volcanism. [ABSTRACT FROM AUTHOR]

Abstract Planktonic foraminiferal assemblages in two cores from Maryland and New Jersey show evidence for significant changes in surface ocean habitats on the continental shelf during the Paleocene-Eocene Thermal Maximum (PETM). At both sites, significant assemblage shifts occur immediately before the onset of the event. These changes include the appearance of abundant triserial/biserial species as well as rare excursion taxa, which are limited to the interval of the carbon isotope excursion at deep-sea sites. The assemblage shifts signal the development of new habitats immediately prior to the onset of the PETM, likely involving warming, surface ocean acidification, increased stratification and oligotrophy. A sharp increase in diversity at the onset of the event is interpreted as a further increase in stratification and warming, as well as increased water depth and more eutrophic conditions. Finally, we observe variant morphologies of several planktonic foraminifera, which may also signal the response of the assemblage to environmental perturbation. Highlights • Planktonic foraminiferal assemblage shifts occur before and during the onset of the PETM on the Coastal Plain • "Excursion" species Acarinina sibaiyaensis appears on the Atlantic Coastal Plain prior to the CIE • Observations of variant morphologies may signal environmental perturbation on the coastal plain [ABSTRACT FROM AUTHOR]

Geologically abrupt carbon perturbations such as the Palaeocene–Eocene Thermal Maximum (PETM, approx. 56 Ma) are the closest geological points of comparison to current anthropogenic carbon emissions. Associated with the rapid carbon release during this event are profound environmental changes in the oceans including warming, deoxygenation and acidification. To evaluate the global extent of surface ocean acidification during the PETM, we present a compilation of new and published surface ocean carbonate chemistry and pH reconstructions from various palaeoceanographic settings. We use boron to calcium ratios (B/Ca) and boron isotopes (δ11B) in surface- and thermocline-dwelling planktonic foraminifera to reconstruct ocean carbonate chemistry and pH. Our records exhibit a B/Ca reduction of 30–40% and a δ11B decline of 1.0–1.2‰ coeval with the carbon isotope excursion. The tight coupling between boron proxies and carbon isotope records is consistent with the interpretation that oceanic absorption of the carbon released at the onset of the PETM resulted in widespread surface ocean acidification. The remarkable similarity among records from different ocean regions suggests that the degree of ocean carbonate change was globally near uniform. We attribute the global extent of surface ocean acidification to elevated atmospheric carbon dioxide levels during the main phase of the PETM. [ABSTRACT FROM AUTHOR]

The Salamanca Formation of the San Jorge Basin (Patagonia, Argentina) preserves critical records of Southern Hemisphere Paleo cene biotas, but its age remains poorly resolved, with estimates ranging from Late Cretaceous to middle Paleocene. We report a multi-disciplinary geochronologic study of the Salamanca Formation and overlying Río Chico Group in the western part of the basin . New constraints include (1) an 40Ar/39Ar age determination of 67.31 ±0.55 Ma from a basalt fl ow underlying the Salamanca Formation, (2) micropaleontological results indicating an early Danian age for the base of the Salamanca Formation, (3) laser ablation HR-MC-ICP-MS (high resolutionmulti collector-inductively coupled plasmamass spectrometry) U-Pb ages and a highresolution TIMS (thermal ionization mass spectrometry) age of 61.984 ±0.041(0.074) [0.100] Ma for zircons from volcanic ash beds in the Peñas Coloradas Formation (Río Chico Group), and (4) paleomagnetic results indicating that the Salamanca Formation in this area is entirely of normal polarity, with reversals occurring in the Río Chico Group. Placing these new age constraints in the context of a sequence stratigraphic model for the basin, we correlate the Salamanca Formation in the study area to Chrons C29n and C28n, with the Banco Negro Inferior (BNI), a mature widespread fossiliferous paleosol unit at the top of the Salamanca Formation, corresponding to the top of Chron C28n. The diverse paleo botanical assemblages from this area are here assigned to C28n (64.67- 63.49 Ma), 2-3 million years older than previously thought, adding to growing evidence for rapid Southern Hemisphere fl oral recovery after the Cretaceous-Paleogene extinction. Important Peligran and "Carodnia" zone vertebrate fossil assemblages from coastal BNI and Peñas Coloradas exposures are likely older than previously thought and correlate to the early Torrejonian and early Tiffanian North American Land Mammal Ages, respectively. [ABSTRACT FROM AUTHOR]

The Cretaceous-Paleogene boundary ∼65.5 million years ago marks one of the three largest mass extinctions in the past 500 million years. The extinction event coincided with a large asteroid impact at Chicxulub, Mexico, and occurred within the time of Deccan flood basalt volcanism in India. Here, we synthesize records of the global stratigraphy across this boundary to assess the proposed causes of the mass extinction. Notably, a single ejecta-rich deposit compositionally linked to the Chicxulub impact is globally distributed at the Cretaceous-Paleogene boundary. The temporal match between the ejecta layer and the onset of the extinctions and the agreement of ecological patterns in the fossil record with modeled environmental perturbations (for example, darkness and cooling) lead us to conclude that the Chicxulub impact triggered the mass extinction. [ABSTRACT FROM AUTHOR]

The Paleocene-Eocene Thermal Maximum (PETM, ∼55 million years ago) was an interval of global warming and ocean acidification attributed to rapid release and oxidation of buried carbon. We show that the onset of the PETM coincided with a prominent increase in the origination and extinction of calcareous phytoplankton. Yet major perturbation of the surface-water saturation state across the PETM was not detrimental to the survival of most calcareous nannoplankton taxa and did not impart a calcification or ecological bias to the pattern of evolutionary turnover. Instead, the rate of environmental change appears to have driven turnover, preferentially affecting rare taxa living close to their viable limits. [ABSTRACT FROM AUTHOR]

The Paleocene-Eocene Thermal Maximum (PETM) has been attributed to a rapid rise in greenhouse gas levels. If so, warming should have occurred at all latitudes, although amplified toward the poles. Existing records reveal an increase in high-latitude sea surface temperatures (SSTs) (8° to 10°C) and in bottom water temperatures (4° to 5°C). To date, however, the character of the tropical SST response during this event remains unconstrained. Here we address this deficiency by using paired oxygen isotope and minor element (magnesium/calcium) ratios of planktonic foraminifera from a tropical Pacific core to estimate changes in SST. Using mixed-layer foraminifera, we found that the combined proxies imply a 4° to 5°C rise in Pacific SST during the PETM. These results would necessitate a rise in atmospheric pCO[sub2] to levels three to four times as high as those estimated for the late Paleocene. [ABSTRACT FROM AUTHOR]

The Chicxulub impact led to the formation of a ~ 200-km wide by ~1-km deep crater on México's Yucatán Peninsula. Over a period of hours after the impact the ocean re-entered and covered the impact basin beneath several hundred meters of water. A suite of impactites were deposited across the crater during crater formation, and by the resurge, tsunami and seiche events that followed. International Ocean Discovery Program/International Continental Scientific Drilling Program Expedition 364 drilled into the peak ring of the Chicxulub crater, and recovered ~130 m of impact deposits and a 75-cm thick, fine-grained, carbonate-rich "Transitional Unit", above which normal marine sedimentation resumed. Here, we describe the results of analyses of the uppermost impact breccia (suevite) and the Transitional Unit, which suggests a gradual waning of energy recorded by this local K-Pg boundary sequence. The dominant depositional motif in the upper suevite and the Transitional Unit is of rapid sedimentation characterized by graded bedding, local cross bedding, and evidence of oscillatory currents. The lower Transitional Unit records the change from deposition of dominantly sand-sized to mainly silt to clay sized material with impact debris that decreases in both grain size and abundance upward. The middle part of the Transitional Unit is interrupted by a 20 cm thick soft sediment slump overlain by graded and oscillatory current cross-laminated beds. The uppermost Transitional Unit is also soft sediment deformed, contains trace fossils, and an increasing abundance of planktic foraminifer and calcareous nannoplankton survivors. The Transitional Unit, as with similar deposits in other marine target impact craters, records the final phases of impact-related sedimentation prior to resumption of normal marine conditions. Petrographic and stable isotopic analyses of carbon from organic matter provide insight into post-impact processes. δ13C org values are between terrestrial and marine end members with fluctuations of 1–3‰. Timing of deposition of the Transitional Unit is complicated to ascertain. The repetitive normally graded laminae, both below and above the soft sediment deformed interval, record rapid deposition from currents driven by tsunami and seiches, processes that likely operated for weeks to potentially years post-impact due to subsequent continental margin collapse events. Highly siderophile element-enrichment at the top of the unit is likely from fine-grained ejecta that circulated in the atmosphere for several years prior to settling. The Transitional Unit is thus an exquisite record of the final phases of impact-related sedimentation related to one of the most consequential events in Earth history. [ABSTRACT FROM AUTHOR]

Cretaceous oceanic anoxic events (OAEs) were periods of geologically short (<1 million years) global change characterized by elevated temperatures, changes in ocean biogeochemistry, ecological turnover, and the global-scale deposition of black shales. After decades of OAE research, the intensity and spatiotemporal heterogeneity of ocean anoxia and its direct effects on marine ecology remain areas of active study. We present high-resolution organic geochemical and foraminiferal records from the western margin of the Western Interior Seaway (WIS) during the Cenomanian-Turonian Oceanic Anoxic Event 2 (OAE2, ~94 Ma) that indicate reorganization of a neritic ecosystem in response to sea-level rise, and dynamic changes in redox conditions that were likely driven by enhanced marine productivity. A significant transgression prior to OAE2 decreased terrestrial organic matter input and led to enhanced productivity, anoxic bottom waters and sediments, and episodic photic zone euxinia. During the middle of OAE2, further enhanced productivity led to the " Heterohelix shift" in planktic foraminifera, the " Gavelinella acme" in benthic foraminifera, and deoxygenation in sediments, bottom waters, and the upper water column. The combined use of high-temporal resolution algal, bacterial, and terrestrial biomarkers, in addition to foraminiferal records, demonstrates the sensitivity of marine autotrophic and heterotrophic communities to sea-level rise and variable water column oxygenation in marginal marine settings during hyperthermal events. Furthermore, our results reveal the temporal and spatial heterogeneity of anoxia during OAE2 in the WIS. This study highlights widespread shallow marine feedbacks during global change that may affect neritic ecosystems under future warming scenarios. • Marine productivity and anoxia/euxinia was enhanced by transgressions. • Algal, bacterial, and foraminiferal assemblages changed with anoxia/euxinia. • First direct comparison of foraminiferal and biomarker records during OAE2 in WIS. [ABSTRACT FROM AUTHOR]

A response by authors P. Schulte et al. to letters to the editor about their article “The Chicxulub Asteroid Impact and Mass Extinction at the Cretaceous-Paleogene Boundary,” in the March 5, 2010 issue is presented.

The chronology of the Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma) remains disputed, hampering complete understanding of the possible trigger mechanisms of this event. Here we present an astrochronology for the PETM carbon isotope excursion from Howards Tract, Maryland a paleoshelf environment, on the mid-Atlantic Coastal Plain. Statistical evaluation of variations in calcium content and magnetic susceptibility indicates astronomical forcing was involved and the PETM onset lasted about 6 kyr. The astrochronology and Earth system modeling suggest that the PETM onset occurred at an extreme in precession during a maximum in eccentricity, thus favoring high temperatures, indicating that astronomical forcing could have played a role in triggering the event. Ca content data on the paleo-shelf, along with other marine records, support the notion that a carbonate saturation overshoot followed global ocean acidification during the PETM., (© 2022. The Author(s).)

The Paleocene-Eocene Thermal Maximum (PETM) is recognized by a major negative carbon isotope (δ 13 C) excursion (CIE) signifying an injection of isotopically light carbon into exogenic reservoirs, the mass, source, and tempo of which continue to be debated. Evidence of a transient precursor carbon release(s) has been identified in a few localities, although it remains equivocal whether there is a global signal. Here, we present foraminiferal δ 13 C records from a marine continental margin section, which reveal a 1.0 to 1.5‰ negative pre-onset excursion (POE), and concomitant rise in sea surface temperature of at least 2°C and a decline in ocean pH. The recovery of both δ 13 C and pH before the CIE onset and apparent absence of a POE in deep-sea records suggests a rapid (< ocean mixing time scales) carbon release, followed by recovery driven by deep-sea mixing. Carbon released during the POE is therefore likely more similar to ongoing anthropogenic emissions in mass and rate than the main CIE.

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., (Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

An asteroid impact in the Yucatán Peninsula set off a sequence of events that led to the Cretaceous-Paleogene (K-Pg) mass extinction of 76% species, including the nonavian dinosaurs. The impact hit a carbonate platform and released sulfate aerosols and dust into Earth's upper atmosphere, which cooled and darkened the planet-a scenario known as an impact winter. Organic burn markers are observed in K-Pg boundary records globally, but their source is debated. If some were derived from sedimentary carbon, and not solely wildfires, it implies soot from the target rock also contributed to the impact winter. Characteristics of polycyclic aromatic hydrocarbons (PAHs) in the Chicxulub crater sediments and at two deep ocean sites indicate a fossil carbon source that experienced rapid heating, consistent with organic matter ejected during the formation of the crater. Furthermore, PAH size distributions proximal and distal to the crater indicate the ejected carbon was dispersed globally by atmospheric processes. Molecular and charcoal evidence indicates wildfires were also present but more delayed and protracted and likely played a less acute role in biotic extinctions than previously suggested. Based on stratigraphy near the crater, between 7.5 × 10 14 and 2.5 × 10 15 g of black carbon was released from the target and ejected into the atmosphere, where it circulated the globe within a few hours. This carbon, together with sulfate aerosols and dust, initiated an impact winter and global darkening that curtailed photosynthesis and is widely considered to have caused the K-Pg mass extinction., Competing Interests: The authors declare no competing interest.

Migration is an integral feature of modern mysticete whale ecology, and the demands of migration may have played a key role in shaping mysticete evolutionary history. Constraining when migration became established and assessing how it has changed through time may yield valuable insight into the evolution of mysticete whales and the oceans in which they lived. However, there are currently few data which directly assess prehistoric mysticete migrations. Here we show that calcite δ 18 O profiles of two species of modern whale barnacles (coronulids) accurately reflect the known migration routes of their host whales. We then analyze well-preserved fossil coronulids from three different locations along the eastern Pacific coast, finding that δ 18 O profiles from these fossils exhibit trends and ranges similar to modern specimens. Our results demonstrate that migration is an ancient behavior within the humpback and gray whale lineages and that multiple Pleistocene populations were undertaking migrations of an extent similar to those of the present day., Competing Interests: The authors declare no conflict of interest.

The Cretaceous/Palaeogene mass extinction eradicated 76% of species on Earth 1,2 . It was caused by the impact of an asteroid 3,4 on the Yucatán carbonate platform in the southern Gulf of Mexico 66 million years ago 5 , forming the Chicxulub impact crater 6,7 . After the mass extinction, the recovery of the global marine ecosystem-measured as primary productivity-was geographically heterogeneous 8 ; export production in the Gulf of Mexico and North Atlantic-western Tethys was slower than in most other regions 8-11 , taking 300 thousand years (kyr) to return to levels similar to those of the Late Cretaceous period. Delayed recovery of marine productivity closer to the crater implies an impact-related environmental control, such as toxic metal poisoning 12 , on recovery times. If no such geographic pattern exists, the best explanation for the observed heterogeneity is a combination of ecological factors-trophic interactions 13 , species incumbency and competitive exclusion by opportunists 14 -and 'chance' 8,15,16 . The question of whether the post-impact recovery of marine productivity was delayed closer to the crater has a bearing on the predictability of future patterns of recovery in anthropogenically perturbed ecosystems. If there is a relationship between the distance from the impact and the recovery of marine productivity, we would expect recovery rates to be slowest in the crater itself. Here we present a record of foraminifera, calcareous nannoplankton, trace fossils and elemental abundance data from within the Chicxulub crater, dated to approximately the first 200 kyr of the Palaeocene. We show that life reappeared in the basin just years after the impact and a high-productivity ecosystem was established within 30 kyr, which indicates that proximity to the impact did not delay recovery and that there was therefore no impact-related environmental control on recovery. Ecological processes probably controlled the recovery of productivity after the Cretaceous/Palaeogene mass extinction and are therefore likely to be important for the response of the ocean ecosystem to other rapid extinction events.