Mid-Maastrichtian Event Research Articles

Palaeoenvironmental interpretation and isotope stratigraphy of the Campanian–Danian successions in the Zagros Foreland Basin (Kabir Kuh, Lurestan, Iran)

The successions of the Gurpi Formation and the lower Pabdeh Formation were examined through analyses of lithology, sequence stratigraphy, stable isotope stratigraphy, and ichnofossils in the Jahangir Abad and Abhar sections of the Kabir Kuh anticline within the Lurestan Zone. Stratigraphic correlation with the well-dated Gandab section, located within the same anticline, indicates a late Campanian to early Danian age for these successions. This correlation further confirms the presence of notable carbon isotope excursions associated with the Campanian-Maastrichtian Boundary Event (CMBE) and Mid-Maastrichtian Event (MME). Field observations, along with sedimentological and paleontological analyses, suggest that the Kabir Kuh area was situated within the fore-bulge of the Zagros foreland basin during the Late Cretaceous. Changes in lithology, fossil content, and ichnofacies indicate a significant decrease in water depth at the end of the Campanian and the beginning of the Maastrichtian. This interval contains shallow marine macrofossils, including oysters (mainly Lopha), benthic foraminifers, and fossil debris traces, indicative of a high-energy environment. In contrast, shallow-water facies are not recorded within the middle and late Maastrichtian sequences. These sequences are composed of pelagic mud-dominated facies containing deep-sea ichnofossils, indicating a rapid increase in water-depth during the middle–late Maastrichtian. The observed late Campanian to early Maastrichtian shallowing is associated with the development of the Zagros fore-bulge, while the subsequent deepening and significant sediment deposition during the mid to late Maastrichtian are attributed to the subsidence of the basin. This research re-evaluates and refines the existing sequence stratigraphic and sedimentary models of the Zagros foreland basin, offering new perspectives on its geological evolution.

Reply to Comment on “Multi-proxy record of the mid-Maastrichtian event in the European Chalk Sea: paleoceanographic implications” by Mitchell et al. (2024)

Reply to Comment on “Multi-proxy record of the mid-Maastrichtian event in the European Chalk Sea: paleoceanographic implications” by Mitchell et al. (2024)

Multi-proxy record of the mid-Maastrichtian event in the European Chalk Sea: Paleoceanographic implications

The Cretaceous provides us with an excellent case history of ocean-climate-biota system perturbations. Such perturbations occurred several times during the Cretaceous, such as oceanic anoxic events and the end-Cretaceous mass extinction, which have been the subject of an abundant literature. Other perturbations, such as the mid-Maastrichtian Event (MME) remain poorly understood. The MME was associated with global sea-level rise, changes in climate and deep-water circulation that were accompanied by biotic extinctions including ‘true inoceramids’ and the demise of the Caribbean-Tethyan rudist reef ecosystems. So far, the context and causes behind the MME remain poorly studied. We conducted high-resolution integrated biotic, petrological and geochemical studies in order to fill this knowledge gap. We studied, in particular, carbonate Nd and Os isotopes, whole-rock Hg, C and N content, C and N isotopes in organic matter, S isotopes in carbonate-associated sulfate, along with C and O isotopes in foraminifera from the European Chalk Sea: the Polanówka UW-1 core from Poland and the Stevns-1 core from Denmark. Our data showed that sea-level rise of ∼50–100 m lasted around ∼2 Ma and co-occurred with anomalously high mercury concentration in seawater. Along with previously published data, our results strongly suggest that the MME was driven by intense volcanic–tectonic activity, likely related to the production of vast oceanic plateaus (LIP, Large Igneous Province). The collapse of reef ecosystems could have been the consequence of LIP-related environmental stress factors, including climate warming, presumably caused by emission of greenhouse gases, modification of the oceanic circulation, oceanic acidification and/or toxic metal input. The disappearance of the foraminifer Stensioeina lineage on the European shelf was likely caused by the collapse of primary production triggered by sea-level rise and limited amount of nutrient input. Nd isotopes and foraminiferal assemblages attest for changes in sea-water circulation in the European Shelf and the increasing contribution of North Atlantic water masses.

Radiolarian and planktonic foraminiferal biochronology of the Pano Panagia section, Lefkara Formation (Maastrichtian, Upper Cretaceous), Cyprus

Well-preserved radiolarians were studied from a section of the Lefkara Formation near Pano Panagia Village (southwestern Cyprus) which was previously dated as Upper Cretaceous (Maastrichtian). More than 60 radiolarian species were recovered in this section, including Amphipyndax tylotus Foreman, Archaeodictyomitra lamellicostata (Foreman), Lithomelissa (?) sp. aff. L. (?) hoplites Foreman, Lithomespilus coronatus Squinabol sensu Hollis, 1997, Theocapsomma comys group Foreman. Two radiolarian zones were recognized. The Amphipyndax tylotus Radiolarian Zone is traced within the Maastrichtian part of the studied section. The upper limits of stratigraphic ranges of some genera, e.g., Archaeospongoprunum Pessagno, Crucella Pessagno, Multastrum Vishnevskaya, Patellula Kozlova, Praeconocaryomma Pessagno, Pseudoaulophacus Pessagno, Afens Riedel and Sanfilippo, Archaeodictyomitra Pessagno, Foremanina Empson-Morin and Xitus Pessagno are, therefore, expanded to the Maastrichtian. Planktonic foraminifera were identified, represented by an assemblage with Gansserina gansseri (Bolli), Contusotruncana contusa (Cushman) and Pseudotextularia elegans (Rzehak), which indicate stratigraphic interval from Gansserina gansseri to Pseudoguembelina hariaensis Zones (uppermost Campanian to middle part of upper Maastrichtian). Geochemical data indicate a Mid-Maastrichtian Event with relatively high δ13С value in the lower part of the section and a moderate negative trend of δ13С value towards the upper part of the section.

Foraminifera dissolution phases in the upper cretaceous succession of Jebel Duwi, Egypt

The present work examines the function of differential dissolution in planktic and benthic foraminifera and introduces the major factors that affect dissolution in early Mid-Maastrichtian Event MME and Late Maastrichtian Event LME paleoenvironmental reconstructions. Two observations on foraminifera dissolution in the Dakhla Formation, where planktic foraminifera are more susceptible to dissolution than benthic foraminifera in the Hamama Member of the Jebel Duwi section, Eastern Desert (Egypt). They are characterized by a decline in the planktic/benthic (P/B) ratio and a rise in the agglutinated percentage. The results of those observations are used for revealing foraminiferal dissolution in these two zones (Racemiguembelina fructicosa CF4a and Pseudoguembelina palpebra CF2). During these two zones, there were excessive relative abundances of agglutinated foraminifera, indicating that these two intervals witnessed severe carbonate dissolution. The high total organic carbon (TOC) and low pH due to the presence of a lot of organic matter in the black shale’s of the Dakhla Formation of the upper Maastrichtian age is the explanation for the observed dissolution that has nothing to do with oceanographic or volcanic processes. The presence of pyrite within the black shale interval suggests low oxygen conditions and the potential for meteoric water to react with the pyrite and form sulfuric acid. This acid could dissolve any carbonate material well after the original deposition.

Morphometric changes in two Late Cretaceous calcareous nannofossil lineages support diversification fueled by long-term climate change

Morphometric changes have been investigated in the two groups of calcareous nannofossils, Cribrosphaerella ehrenbergii and Microrhabdulus undosus across the Campanian to Maastrichtian of the Zagros Basin of Iran. Results reveal a common episode of size increase at c. 76 Ma, with a sudden increase in the size of C. ehrenbergii and with the emergence of a newly defined, larger species Microrhabdulus zagrosensis n.sp. An even larger species emerges at c. 69 Ma within the Microrhabdulus lineage, Microrhabdulus sinuosus n.sp. The timing of these size changes and origination events matches global changes in nannoplankton diversity and/or in diversity of other planktonic organisms and marine invertebrates. Comparison with long-term global climate change supports that these two distinct episodes of morphological change coincide respectively with the late Campanian carbon isotope event and acceleration of cooling and with climatic instability across the mid-Maastrichtian event.

Response of the lacustrine flora in East Asia to global climate changes across the K/Pg boundary

The global climate during the latest Cretaceous became variable, with several global warming and cooling trends in a context of a greenhouse Earth. The responses of marine ecosystems to these climate events are relatively well known worldwide; however, lacustrine responses are poorly known due to the less frequent and discontinuous terrestrial fossil records. The relative changes in charophyte diversity in continuous lacustrine sedimentary sequences from two basins in East Asia, i.e., Songliao and Jiaolai, are considered here for the first time to establish their correlation with global climate changes during the Late Cretaceous and K/Pg boundary, compared with the well-studied south European Ibero-Armorican Island. Lacustrine deposits correlated with the Campanian–Maastrichtian Boundary Event (CMBE), related to a long cooling period provided a relatively low diversity in East Asia. In contrast, we detected a diverse charophyte flora in lacustrine deposits correlated with the Mid-Maastrichtian Event (MME) in East Asia in a global warming trend. A higher charophyte diversity was further found in the end-Cretaceous global warming event due to speciation under the background of latest Maastrichtian warming event (LMWE). During the LMWE, Characeae species such as Microchara cristata reduced its size significantly due to environmental stress probably related to the Deccan volcanism. On the other hand, a general tendency of increasing the gyrogonite size in new Characeae taxa has been detected in populations extracted from lower Danian deposits, probably related to stable palaeoenvironmental conditions in a global cooling context. This study represents the first attempt to correlate the response of the charophyte flora to global climate changes in permanent lacustrine systems during the three main Late Cretaceous–early Danian climatic turnovers. • Changes of charophyte flora is a sensitive proxy to record climate changes. • Characeae species reduced their size due to environmental stress. • Increasing size in new Danian Characeae taxa is related to global cooling.

The impact of the Cretaceous–Paleogene (K–Pg) mass extinction event on the global sulfur cycle: Evidence from Seymour Island, Antarctica

The Cretaceous–Paleogene (K–Pg) mass extinction event 66 million years ago led to large changes to the global carbon cycle, primarily via a decrease in primary or export productivity of the oceans. However, the effects of this event and longer-term environmental changes during the Late Cretaceous on the global sulfur cycle are not well understood. We report new carbonate associated sulfate (CAS) sulfur isotope data derived from marine macrofossil shell material from a highly expanded high latitude Maastrichtian to Danian (69–65.5 Ma) succession located on Seymour Island, Antarctica. These data represent the highest resolution seawater sulfate record ever generated for this time interval, and are broadly in agreement with previous low-resolution estimates for the latest Cretaceous and Paleocene. A vigorous assessment of CAS preservation using sulfate oxygen, carbonate carbon and oxygen isotopes and trace element data, suggests factors affecting preservation of primary seawater CAS isotopes in ancient biogenic samples are complex, and not necessarily linked to the preservation of original carbonate mineralogy or chemistry. Primary data indicate a generally stable sulfur cycle in the early-mid Maastrichtian (69 Ma), with some fluctuations that could be related to increased pyrite burial during the ‘mid-Maastrichtian Event’. This is followed by an enigmatic +4‰ increase in δ34SCAS during the late Maastrichtian (68–66 Ma), culminating in a peak in values in the immediate aftermath of the K–Pg extinction which may be related to temporary development of oceanic anoxia in the aftermath of the Chicxulub bolide impact. There is no evidence of the direct influence of Deccan volcanism on the seawater sulfate isotopic record during the late Maastrichtian, nor of a direct influence by the Chicxulub impact itself. During the early Paleocene (magnetochron C29R) a prominent negative excursion in seawater δ34S of 3–4‰ suggests that a global decline in organic carbon burial related to collapse in export productivity, also impacted the sulfur cycle via a significant drop in pyrite burial. Box modelling suggests that to achieve an excursion of this magnitude, pyrite burial must be reduced by >15%, with a possible role for a short term increase in global weathering rates. Recovery of the sulfur cycle to pre-extinction values occurs at the same time (∼320 kyrs) as initial carbon cycle recovery globally. These recoveries are also contemporaneous with an initial increase in local alpha diversity of marine macrofossil faunas, suggesting biosphere-geosphere links during recovery from the mass extinction. Modelling further indicates that concentrations of sulfate in the oceans must have been 2 mM, lower than previous estimates for the Late Cretaceous and Paleocene and an order of magnitude lower than today.

Late Maastrichtian carbon isotope stratigraphy and cyclostratigraphy of the Newfoundland Margin (Site U1403, IODP Leg 342)

Earth’s climate during the Maastrichtian (latest Cretaceous) was punctuated by brief warming and cooling episodes, accompanied by perturbations of the global carbon cycle. Superimposed on a long-term cooling trend, the middle Maastrichtian is characterized by deep-sea warming and relatively high values of stable carbon-isotope ratios, followed by strong climatic variability towards the end of the Cretaceous. A lack of knowledge on the timing of climatic change inhibits our understanding of underlying causal mechanisms. We present an integrated stratigraphy from Integrated Ocean Drilling Program (IODP) Site U1403, providing an expanded deep ocean record from the North Atlantic (Expedition 342, Newfoundland Margin). Distinct sedimentary cyclicity suggests that orbital forcing played a major role in depositional processes, which is confirmed by statistical analyses of high resolution elemental data obtained by X-ray fluorescence (XRF) core scanning. Astronomical calibration reveals that the investigated interval encompasses seven 405-kyr cycles (Ma4051 to Ma4057) and spans the 2.8 Myr directly preceding the Cretaceous/Paleocene (K/Pg) boundary. A high-resolution carbon-isotope record from bulk carbonates allows us to identify global trends in the late Maastrichtian carbon cycle. Low-amplitude variations (up to 0.4‰) in carbon isotopes at Site U1403 match similar scale variability in records from Tethyan and Pacific open-ocean sites. Comparison between Site U1403 and the hemipelagic restricted basin of the Zumaia section (northern Spain), with its own well-established independent cyclostratigraphic framework, is more complex. Whereas the pre-K/Pg oscillations and the negative values of the Mid-Maastrichtian Event (MME) can be readily discerned in both the Zumaia and U1403 records, patterns diverge during a ~ 1 Myr period in the late Maastrichtian (67.8–66.8 Ma), with Site U1403 more reliably reflecting global carbon cycling. Our new carbon isotope record and cyclostratigraphy offer promise for Site U1403 to serve as a future reference section for high-resolution studies of late Maastrichtian paleoclimatic change.

Extinction, dissolution, and possible ocean acidification prior to the Cretaceous/Paleogene (K/Pg) boundary in the tropical Pacific

Biotic perturbations and changes in ocean circulation during the Maastrichtian stage of the latest Cretaceous raise questions about whether the biosphere was preconditioned for the end-Cretaceous mass extinction of calcareous plankton. A brief acme of inoceramid clams at ~71Ma on Shatsky Rise in the tropical North Pacific was followed by their extinction during the “mid-Maastrichtian event” at 70.1Ma associated with an abrupt warming of deep waters. This was later followed by an interval of intense dissolution beginning ~67.8Ma at ODP Site 1209 (2387m). The late Maastrichtian dissolution interval was initially gradual, and is characterized by a low planktic/benthic (P/B) ratio, highly fragmented planktic foraminifera, mostly an absence of larger taxa, low abundances of smaller taxa, extremely low planktic foraminiferal numbers, and low planktic foraminiferal and nannofossil species richness. A partial recovery in carbonate preservation and calcareous plankton simple diversity began ~250kyr prior to the K/Pg boundary associated with the incursion of a younger (more enriched δ13C) deep water mass, although total abundances of planktic foraminifera in the sediment remained a tiny fraction of their earlier Maastrichtian values. A second, brief dissolution event occurred ~200kyr before the boundary evidenced by renewed increase in planktic fragmentation, but without a decrease in P/B ratio. Our data show that changing deep water masses, coupled with reduced productivity and associated decrease in pelagic carbonate flux was responsible for the first ~1.6-Myr dissolution interval, while Deccan Traps volcanism (?) may have caused surface ocean acidification ~200kyr prior to the K/Pg mass extinction event.

Evolution and extinction of Maastrichtian (Late Cretaceous) cephalopods from the López de Bertodano Formation, Seymour Island, Antarctica

One of the most expanded records to contain the final fortunes of ammonoid cephalopods is within the López de Bertodano Formation of Seymour Island, James Ross Basin, Antarctica. Located at ~65° South now, and during the Cretaceous, this sequence is the highest southern latitude onshore outcrop containing the Cretaceous-Paleogene (K–Pg) transition. We present comprehensive new biostratigraphic range data for 14 ammonite and one nautiloid species based on the collection of >700 macrofossils from high-resolution sampling of parallel sedimentary sections, dated Maastrichtian to earliest Danian in age, across southern Seymour Island. We find evidence for only a single, abrupt pulse of cephalopod extinction at the end of the Cretaceous when the final seven ammonite species disappeared, consistent with most evidence globally. In the lead up to the K–Pg extinction in the James Ross Basin, starting during the Campanian, ammonite diversity decreased overall, but the number of endemic taxa belonging to the family Kossmaticeratidae actually increased. This pattern continued into the Maastrichtian and may be facies controlled, linked to changes in sea level and seawater temperature. During the early Maastrichtian, ammonite diversity dropped significantly with only two species recorded from the basal López de Bertodano Formation on Seymour Island. The subsequent diversification of endemic taxa and reappearance of long-ranging, widespread species into the basin resulted in an increase in ammonite diversity and abundance during the mid-Maastrichtian. This was coincident with an apparent period of warming temperatures and sea level rise interpreted from palynology and sedimentology, perhaps reflecting a high latitude expression of the Mid-Maastrichtian Event. Late Maastrichtian diversity levels remained stable despite reported climatic and environmental variation. Ammonite diversity patterns during the Maastrichtian parallel those of microfossil species such as nannofossil and planktonic foraminifera, suggesting that dynamic climatic and environmental changes affected many planktonic and nektonic organisms during the latest Cretaceous. However, we suggest that these perturbations had a minimal effect on overall diversity prior to the catastrophic extinction event at the K–Pg boundary.

Maastrichtian carbon cycle changes and planktonic foraminiferal bioevents at Gebel Matulla, west-central Sinai, Egypt

Comparison between the planktonic foraminiferal bioevents from different palaeolatitudes suggests that the biostratigraphic criteria used to identify the Maastrichtian stage boundaries are problematic. A new high-resolution calibration of planktonic foraminiferal biostratigraphic, carbon-isotope, and sequence-stratigraphic criteria has been recorded for the first time from the Maastrichtian Sudr Formation at Gebel Matulla, west-central Sinai. The sedimentary successions allow the identification of prominent long-term carbon isotope events in the Maastrichtian, namely the negative excursion of the Campanian–Maastrichtian Boundary Event (CMBE), the positive excursion of the mid-Maastrichtian Event (MME), and the decline towards the Cretaceous-Palaeogene transition (KPgE). Termination of these well known δ13C events is associated with unconformities, created by eustatic sea-level changes, although the long duration argues for superimposed local tectonic control.

Campanian‐Maastrichtian ocean circulation in the tropical Pacific

The Pacific Ocean is the largest water body on Earth, and circulation in the Pacific contributed significantly to climate evolution in the latest Cretaceous, the culmination of a period of long‐term cooling. Here, we present new high‐resolution late Campanian to Maastrichtian benthic and planktic foraminiferal stable isotope data and a neodymium (Nd) isotope record obtained from sedimentary ferromanganese oxide coatings of Ocean Drilling Program Hole 1210B from the tropical Pacific Ocean (Shatsky Rise). These new records resolve 13 million years in the latest Cretaceous, providing insights into changes in surface and bottom water temperatures and source regions of deep to intermediate waters covering the carbon isotope excursions of the Campanian‐Maastrichtian Boundary Event (CMBE) and the Mid‐Maastrichtian event (MME). Our new benthic foraminiferal δ18O and Nd isotope records together with published Nd isotope data show markedly parallel trends across the studied interval over a broad range of bathyal to abyssal water depths interpreted to reflect changes in the intensity of deep‐ocean circulation in the tropical Pacific. In particular, we observe a three‐million‐year‐long period of cooler conditions in the early Maastrichtian (72.5 to 69.5 Ma) when a concomitant change toward less radiogenic seawater Nd isotope signatures probably marks a period of enhanced admixture and northward flow of deep waters with Southern Ocean provenance. We suggest this change to have been triggered by intensified formation and convection of deep waters in the high southern latitudes, a process that weakened during the MME (69.5 to 68.5 Ma). The early Maastrichtian cold interval is closely related to the negative and positive carbon isotope trends of the CMBE and MME. The millions‐of‐years long duration of these carbon cycle perturbations suggests a tectonic forcing of climatic cooling, possibly related to changes in ocean basin geometry and bathymetry.

Latest Campanian and Maastrichtian palaeoenvironmental changes: Implications from an epicontinental sea (SE Poland and western Ukraine)

The Maastrichtian was a time of a high variability in the climate/ocean system. Most studies on Maastrichtian palaeoenvironment fluxes have been based on evidence from the open ocean realm or from outcrops in the Tethyan realm. We have investigated epicontinental carbonate-rich sediments of Maastrichtian age of the Lublin-Lviv Syncline (SE Poland and western Ukraine). Our study is focused on the population changes of planktonic foraminifers from 21 Maastrichtian outcrop successions and one borehole section. Quantitative and qualitative studies of planktonic foraminifers show long-term foraminiferal changes that make it possible to reconstruct climatic changes and a sea-level curve for the latest Campanian and Maastrichtian from the high-latitude epicontinental sea. A significant regression is inferred for the latest Campanian and earliest Maastrichtian. The highest sea level is noted in the earliest Late Maastrichtian. It coincides with a migration of the benthic and planktonic foraminiferal fauna that was probably triggered by a cooling episode. The cooler episodes correlated with a eustatic sea-level highstand during that time, suggesting that sea level was the most likely mechanism causing a change of global circulation; this temperature drop could be the cause of the mid-Maastrichtian event.

Global correlation of Upper Campanian - Maastrichtian successions using carbon-isotope stratigraphy: development of a new Maastrichtian timescale

Carbon-isotope stratigraphy has proven to be a powerful tool in the global correlation of Cretaceous successions. Here we present new, high-resolution carbon-isotope records for the Global Boundary Stratotype Section and Point (GSSP) of the Maastrichtian stage at Tercis les Bains (France), the Bottaccione and Contessa sections at Gubbio (Italy), and the coastal sections at Norfolk (UK) to provide a global δ13C correlation between shelf-sea and oceanic sites. The new δ13C records are correlated with δ13C-stratigraphies of the boreal chalk sea (Trunch borehole, Norfolk, UK, Lagerdorf-Kronsmoor-Hemmoor section, northern Germany, Stevns-1 core, Denmark), the tropical Pacific (ODP Hole 1210B, Shatsky Rise) and the South Atlantic and Southern Ocean (DSDP Hole 525A, ODP Hole 690C) by using an assembled Gubbio δ13C record as a reference curve. The global correlation allows the identification of significant high-frequency δ13C variations that occur superimposed on prominent Campanian-Maastrichtian events, namely the Late Campanian Event (LCE), the Campanian-Maastrichtian Boundary Event (CMBE), the mid-Maastrichtian Event (MME), and the Cretaceous-Paleogene transition (KPgE). The carbon-isotope events are correlated with the geomagnetic polarity scale recalculated using the astronomical 40Ar/39Ar calibration of the Fish Canyon sanidine. This technique allows the evaluation of the relative timing of base occurrences of stratigraphic index fossils such as ammonites, planktonic foraminifera and calcareous nannofossils. Furthermore, the Campanian-Maastrichtian boundary, as defined in the stratotype at Tercis, can be precisely positioned relative to carbon-isotope stratigraphy and the geomagnetic polarity timescale. The average value for the age of the Campanian-Maastrichtian boundary is 72.1 ± 0.1 Ma, estimated by three independent approaches that utilize the Fish Canyon sanidine calibration and Option 2 of the Maastrichtian astronomical timescale. The CMBE covers a time span of 2.5 Myr and reflects changes in the global carbon cycle probably related to tectonic process rather than to glacio-eustasy. The duration of the high-frequency δ13C variations instead coincides with the frequency band of long eccentricity, indicative of orbital forcing of changes in climate and the global carbon cycle. © 2012 Gebruder Borntraeger, Stuttgart, Germany.

Cretaceous-Palaeogene ocean and climate change in the subtropical North Atlantic

Abstract Ocean Drilling Program (ODP) Leg 171B recovered continuous sequences that yield evidence for a suite of ‘critical’ events in the Earth’s history. The main events include the late Eocene radiolarian extinction, the late Palaeocene benthic foraminiferal extinction associated with the Late Palaeocene Thermal Maximum (LPTM), the Cretaceous-Palaeogene (K-P) extinction, the mid-Maastrichtian event, and several episodes of sapropel deposition documenting the late Cenomanian, late Albian and early Albian warm periods. A compilation of stable isotope results for foraminifera from Leg 171B sites and previously published records shows a series of large-scale cycles in temperature and δ 13 C trends from Albian to late Eocene time. Evolution of δ 18 O gradients between planktic and benthic foraminifera suggests that the North Atlantic evolved from a circulation system similar to the modern Mediterranean during early Albian time to a more open ocean circulation by late Albian-early Cenomanian time. Sea surface temperatures peaked during the mid-Cretaceous climatic optimum from the Albian-Cenomanian boundary to Coniacian time and then show a tendency to fall off toward the cool climates of the mid-Maastrichtian. The Albian-Coniacian period is characterized by light benthic oxygen isotope values showing generally warm deep waters. Lightest benthic oxygen isotopes occurred around the Cenomanian-Turonian boundary, and suggest middle bathyal waters with temperatures up to 20 °C in the North Atlantic. The disappearance of widespread sapropel deposition in Turonian time suggests that sills separating the North Atlantic from the rest of the global ocean were finally breached to sufficient depth to permit ventilation by deep waters flowing in from elsewhere. The Maastrichtian and Palaeogene records show two intervals of large-scale carbon burial and exhumation in the late Maastrichtian-Danian and late Palaeocene-early Eocene. Carbon burial peaked in early Danian time, perhaps in response to the withdrawal of large epicontinental seas from Europe and North America. Much of the succeeding Danian period was spent unroofing previously deposited carbon and repairing the damage to carbon export systems in the deep ocean caused by the K-P mass extinction. The youngest episode of carbon exhumation coincided with the onset of the early Eocene Warm Period and the LPTM, and has been attributed to the tectonic closure of the eastern Tethys and initiation of the Himalayan Orogeny.