Uppermost Maastrichtian Research Articles

Upper Campanian–Maastrichtian chronostratigraphy of the Skælskør‐1 core, Denmark: correlation at the basinal and global scale and implications for changes in sea‐surface temperatures

The lithostratigraphy, calcareous nannofossil biostratigraphy, carbon- and oxygen-isotope stratigraphy and gamma-ray profile are presented for the Skaelskor-1 core, eastern Denmark. The correlation of carbon isotopes to Gubbio (Italy) and ODP Site 762C (Indian Ocean) provides the chronostratigrahical framework of the core through a tie to magnetostratigraphy. Two new carbon-isotope excursions are defined for the uppermost Maastrichtian of the core and prove useful for long-distance correlation. Twenty stratigraphic tie-points are used for correlation of the upper Campanian–Maastrichtian interval by combining carbon-isotope and gamma-ray variations. Significant dissimilarities in the gamma-ray profiles of the Danish Basin cores preclude the sole use of this tool for basin-scale correlations. Bulk oxygen-isotopes and semi-quantitative abundance changes in the warm-water calcareous nannofossil Watznaueria barnesiae and the cool-water Kamptnerius magnificus highlight the following past changes in sea-surface temperatures (SSTs): relatively warm late Campanian SSTs, cooling across the Campanian–Maastrichtian boundary and through the early Maastrichtian, warming across the early–late Maastrichtian transition, cooling in the late Maastrichtian, intense warming in the latest Maastrichtian chron C29r, followed by a very short episode of cooling immediately before the Cretaceous–Palaeogene boundary. The late Campanian–Maastrichtian evolution in sea water temperatures inferred from the Danish Basin is similar to that delineated at tropical latitude oceanic sites.

Late Cretaceous-Early Paleogene (Turonian? to early Danian) planktic foraminifera from DSDP site 356: a biostratigraphic reappraisal

Biostratigraphic results obtained with a systematic study of the planktic foraminiferal assemblages recovered from Upper Cretaceous-Lower Paleogene strata (Turonian? to early Danian in age) of Deep Sea Drilling Program (DSDP) Site 356, Sao Paulo Plateau, are presented and discussed herein. Fifty-nine planktic foraminiferal species were identifi ed within the studied interval, enabling the identifi cation of 11 planktic foraminiferal zones (Turonian? to early Danian in age): Marginotruncana schneegansi, Dicarinella concavata, Dicarinella asymetrica, Globotruncanita elevata, Contusotruncana plummerae, Radotruncana calcarata, Globotruncanella havanensis, Pseudoguembelina palpebra, Abathomphalus mayaroensis, Pseudoguembelina hariaensis and Pα. An unconformity spanning at least 0.96 Ma could also be suggested within core 31 (Maastrichtian in age), due to the absence of the Racemiguembelina fructicosa Interval Zone from the studied section. High sedimentation rates were estimated within the Santonian (Dicarinella asymentrica Total-range Zone) and the uppermost Maastrichtian (Pseudoguembelina hariaensis Interval Zone) of DSDP site 356, while lower and more constant values were suggested for the Campanian-lower Maastrichtian interval (Globotruncanita elevata Partial-range Zone to Pseudoguembelina palpebra Interval Zone). The reliability in identifying the Contusotruncana plummerae Interval Zone (Campanian in age) in Cretaceous sections of the South Atlantic Ocean is confi rmed herein.

PHENOTYPIC PLASTICITY, SPECIATION, AND PHYLOGENY IN EARLY DANIAN PLANKTIC FORAMINIFERA

Research Article| April 01, 2014 PHENOTYPIC PLASTICITY, SPECIATION, AND PHYLOGENY IN EARLY DANIAN PLANKTIC FORAMINIFERA Eduardo A. M. Koutsoukos Eduardo A. M. Koutsoukos Geologie-Paläontologie Institut für Geowissenschaften, Universität Heidelberg, Im Neuenheimer Feld 234, DE-69120 Heidelberg, Germany. E-mail: ekoutsoukos@gmail.com Search for other works by this author on: GSW Google Scholar Author and Article Information Eduardo A. M. Koutsoukos Geologie-Paläontologie Institut für Geowissenschaften, Universität Heidelberg, Im Neuenheimer Feld 234, DE-69120 Heidelberg, Germany. E-mail: ekoutsoukos@gmail.com Publisher: Cushman Foundation for Foraminiferal Research Received: 20 Mar 2013 Accepted: 10 Dec 2013 First Online: 13 Jul 2017 Online ISSN: 1943-264X Print ISSN: 0096-1191 © 2014 Cushman Foundation for Foraminiferal Research Journal of Foraminiferal Research (2014) 44 (2): 109–142. https://doi.org/10.2113/gsjfr.44.2.109 Article history Received: 20 Mar 2013 Accepted: 10 Dec 2013 First Online: 13 Jul 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Eduardo A. M. Koutsoukos; PHENOTYPIC PLASTICITY, SPECIATION, AND PHYLOGENY IN EARLY DANIAN PLANKTIC FORAMINIFERA. Journal of Foraminiferal Research 2014;; 44 (2): 109–142. doi: https://doi.org/10.2113/gsjfr.44.2.109 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyJournal of Foraminiferal Research Search Advanced Search Abstract A piston core drilled at a water depth of 2809 m off Rio de Janeiro, southeastern Brazil, recovered a 1.83-m thick section of unconsolidated muddy sediments, representing a complete stratigraphic succession across the Cretaceous–Paleogene (K/Pg) boundary. The sediments yielded abundant, strikingly pristine tests of planktic and benthic foraminifera, unaffected by diagenetic alteration or recrystallization.The sedimentary record ranges from the uppermost Maastrichtian (P. hantkeninoides Zone) to the lower Danian (zones P0–P1c), spanning a time interval of about 3–4 Myr through the K/Pg transition. A detailed taxonomic appraisal of the recovered planktic foraminiferal assemblages is presented, together with an evaluation of lineage relationships, phylogenetic trends, and the sequence of evolutionary events that took place among the Globigerinina at the beginning of the Cenozoic.The numerous recent taxonomic studies of Danian planktic foraminifera notwithstanding, the significance of phenotypic varieties has never been assessed in a paleoecological context. Whereas the cancellate-walled, low trochospiral, large-sized Praemurica (Truncorotaloididae) and Parasubbotina and Subbotina (Globigerinidae) lineages evidently underwent rapid speciation over a relatively narrow phenotypic range, the small-sized Praemurica, the distinctly elevated trochoid Eoglobigerina (Globigerinidae), the Parvulorugoglobigerina, and the coiled to elongate morphotypes of the Guembelitria and Woodringina (all members of the family Guembelitriidae) and Chiloguembelina (Chiloguembelinidae) lineages show phenotypic plasticity over a much broader range. This dichotomy correlates with inferred differences in life-history parameters among these planktic taxa, including pelagic-dwelling preferences, related to reproductive and feeding strategies and to water-mass trophic levels.Two new early Danian planktic foraminiferal species are established herein: Praemurica nikolasi n. sp., the earliest recorded Truncorotaloididae and cancellate species, likely evolved directly from Hedbergella monmouthensis near the base of Zone P0 and probably giving rise to all subsequent cancellate lineages of the early Danian; and Globoconusa victori n. sp., evolved from Globoconusa daubjergensis within Zone P1c. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Cretaceous-Paleogene Dinoflagellate Biostratigraphy and the Age of the Clayton Formation, Southeastern Missouri, USA

Sedimentary deposits in Stoddard County, southeastern Missouri, reveal a K-Pg transition sequence represented by the uppermost Maastrichtian Owl Creek Formation and the Paleocene Clayton Formation. The Clayton Formation is characterized by a basal fossiliferous coquinite that contains reworked late Maastrichtian macrofossils. Dinoflagellate biostratigraphy is used to determine the age of the coquinite layer and specifically whether or not it is an end-K tsunamite deposit resulting from the Chicxulub impact event. Results indicate a mixed assemblage of late Maastrichtian and early Danian dinocysts within the basal coquinite of the Clayton Formation. Maastrichtian dinocyst taxa identified are Riculacysta amplexa, Pierceites pentagonus, Phelodinium tricuspe and Dinogymnium sp. and dinocysts utilized as global indicators of the basal Danian, also present in the coquinite, consist of Senoniasphaera inornata, Carpatella cornuta, Damassadinium californicum, and Lanternosphaeridium reinhardtii. A gray mud occurring above the coquinite in the middle of the Clayton Formation contains the mid-Danian dinoflagellate Senegalinium iterlaaense. Collectively, these data suggest that the coquinite was deposited well after the K-Pg event but before the middle Danian. The mixed assemblage of Late Cretaceous and Paleocene dinocysts preserved in the coquinite weakens the hypothesis that it is an end-K tsunamite deposit and suggests instead that it may result from a long-term transgressive lag. We also extend the stratigraphic range of the Paleocene Senegalinium simplex downward into the uppermost Maastrichtian.

Paleoclimate estimates and fire ecology immediately prior to the end-Cretaceous mass extinction in the Frenchman Formation (66 Ma), Saskatchewan, Canada

The fossil-rich deposits of the uppermost Maastrichtian (66Ma) Frenchman Formation of southern Saskatchewan, Canada provide a detailed, continuous record of terrestrial ecosystem dynamics during the last half-million years leading up to the end-Cretaceous mass extinction. Paleoenvironmental interpretations for the Frenchman Formation are here refined by the first absolute paleoclimate estimates for the Late Cretaceous of Saskatchewan, and by the placement of these climate estimates within a North American context. Climate estimates were calculated using Leaf Margin Analysis and the Climate Leaf Analysis Multivariate Program (CLAMP), derived from two independent plant macrofossil assemblages collected from the Frenchman Formation. Climate parameter estimates indicate that the Maastrichtian climate of southern Saskatchewan was subtropical to warm-temperate, with mean annual temperatures between 12°C and 14°C, and with marked seasonality. These results are comparable with estimates derived from other late Campanian and Maastrichtian paleofloras in the Western Interior Basin, although small variations among coeval localities were noted or determined. Overall, the plant fossil assemblages from the two study localities support the paleoenvironmental interpretation of the Frenchman Formation as a swampy to lowland forest system with canopy-forming deciduous conifers and a diverse, angiosperm-dominated mid-canopy and understory. An unexpected, marked disparity in plant diversity was found between the two paleofloras, despite the plant assemblages returning similar paleoclimate parameter estimates. Abundant in situ inertinite (fossil charcoal) deposits were found in association with the less diverse paleofloral site, which contained only angiosperm fossils. Inertinite was absent from the deposits containing the more diverse paleoflora, which contained a different composition of angiosperm and gymnosperm fossils. Fire is known to be a prevalent feature of Late Cretaceous deposits worldwide, and modern angiosperm plants typically are the first to recover following fire disturbances. We suggest that the two Frenchman Formation paleofloras represent different stages of secondary ecological succession following a disturbance by fire. The identification of fire ecology in the fossil record may have important implications for understanding biodiversity patterns on small spatial and temporal scales immediately prior to the Cretaceous mass extinction.

The Last Pterosaurs: First Record from the Uppermost Maastrichtian of the Tremp Syncline (Northern Spain)

Abstract:Pterosaur bones are for the first time reported from the Tremp Syncline (Spain) and the southern Pyrenees. They come from the Torrebilles‐2 site (Isona, Lleida Province) in the upper Maastrichtian part of the Tremp Formation, which falls within the C29r magnetochron. Fragmentary long bones are referred to the Pterosauria based on their cortical thinness, micro‐architecture, and histological features. They belong to very large to possibly giant individuals. The most complete specimen is possibly a partial right femur. The review of the Maastrichtian pterosaur record shows that only a few specimens can be referred to the C29r (which contains the K/Pg boundary). The identification of fragmentary remains could improve our knowledge about the abundance and distribution of these flying sauropsids just before the end‐Cretaceous mass extinction.

A Cretaceous–Palaeogene boundary geological site, revealed by planktic foraminifera and dinoflagellate cysts, at Ouled Haddou, eastern external Rif Chain, Morocco

Planktic foraminifera and organic-walled dinoflagellate cyst investigations in the Ouled Haddou outcrop (eastern external Rif Belt) in northern Morocco, revealed a continuous sedimentation and a complete record of the Cretaceous–Palaeogene (K–Pg) transition. Both planktic foraminifera and dinoflagellate cyst assemblages observed in the studied Maastrichtian–Danian boundary interval are diverse and well-preserved and contain numerous chronostratigraphically significant bio-events that have allowed a high resolution biostratigraphic analysis, based on the first and last occurrences of index species and also on the massive disappearance and abundance changes of different taxa. Planktic foraminifera allow correlation of the studied interval with the uppermost Maastrichtian Abathomphalus mayaroensis Zone and the lower Danian Guembelitria cretacea, Parvularugoglobigerina eugubina, Parasubbotina pseudobulloides and Subbotina triloculinoides zones. A mass extinction of planktic foraminifera is observed at the end of the Abathomphalus mayaroensis Zone. This mass extinction is followed by three renewal steps of planktic foraminifera in the basal Danian. The Cretaceous–Palaeogene boundary is placed just above the mass extinction of Globotruncanids and Heterohelicids and below the first appearences of earliest Danian markers genera Globoconusa, and Parvularugoglobigerina.According to dinoflagellate cysts, the recognition of the latest Maastrichtian and earliest Danian is based on global bio-events, including the first occurrence of the latest Maastrichtian species Disphaerogena carposphaeropsis, Glaphyrocysta perforata, and Manumiella seelandica, the latest Maastrichtian acme of Manumiella seelandica, and the first occurrence of the earliest Danian markers Carpatella cornuta, Damassadinium californicum and Senoniasphaera inornata. The dinoflagellate Damassadinium californicum Zone characterizing the Danian in the Northern Hemisphere is recognized in this section. The Cretaceous–Palaeogene boundary is placed, at the same position determined by Planktic foraminifera, immediately above the acme of Manumiella seelandica and the last appearance of few Cretaceous taxa such as Dinogymnium spp. and Alisogymnium euclaense, and directly below the first occurrences of Carpatella cornuta, Damassadinium californicum and Senoniasphaera inornata. However, in contrast to calcareous planktic foraminifera, dinoflagellate cysts did not undergo a mass extinction at the K–Pg boundary, but shows important changes in the relative abundances of different species or groups of morphologically related species.Both planktic foraminifera and dinoflagellate cyst assemblages suggest deposition in subtropical to warm temperate province, but in an austere sea environments under a regressive regime during the uppermost Maastrichtian and open sea environments under a transgressive regime during the lower Danian. Dinoflagellate cysts indicate relatively stable warm conditions during the upper Maastrichtian, followed successively by cooler conditions in the uppermost Maastrichtian and at the K–Pg boundary, a gradual warming alternated by 3 rapid successive cooling pulses in the lower most Danian, and then a gradual returning to relatively warm conditions.The Ouled Haddou section needs to be preserved as a geoheritage site, because it is the sole Moroccan section with a good quality and an easy access, and hosts a complete registration of the Cretaceous–Palaeogene boundary transition.

Calcareous nannofossil assemblage changes and stable isotope data from Maastrichtian to Selandian in the Akveren Formation, Western Black Sea, Turkey

This study is based on calcerous nannofossil assemblages changes and fluctutions of stable carbon and oxygen isotopes was collected clayey limestones, limestones, and marls in the Maastrichtian to Selandian from Akveren Formation (Western Black Sea). As the relative abundances of species of Micula spp, Watznauera barnesiae, and Arkhangelskiella cymbiformis, which tolerated changes of temperature and nutrition, carbon and oxygen isotopes compositions, and low species richness imply strong diagenesis effect at the Maastrichtian, there is no important diagenesis effect at Paleocene. Just after the Cretaceous/Tertiary (K-Pg) boundary, Thoracosphaera spp. and Braarudosphaera bigelowi were dominant species; Danian is characterized by Thoracosphaera, Ericsonia ovalis, Cruciplacolithus spp., Coccolithus pelagicus, and Ericsonia subpertusa. Generally, the nutrition productivity is good–moderate in Lower Maastrichtian, and decreasing carbon isotope values during the Uppermost Maastrichtian shows the presence of oligotrophic environmental conditions suitable with global nutrition crises before the K-Pg boundary and diagenesis in study area. Throughout the Danian, mesotrophic–oligotrophic environmental conditions dominate; however, the decrease in nutrition before Selandian represents oligotrophic environmental conditions. The increasing nutrition at Selandian is related to the change in the environmental conditions.

The Last Cretaceous Ammonites in Latin America

Sections yielding late Maastrichtian ammonite assemblages are rare in Latin America and precise biostratigraphic correlation with European type sections remains difficult. In all, the extinction pattern of ammonites appears to differ between sites in southern high latitudes and those in the tropics to subtropics. In austral sections of Chile, and possibly also in southern Argentina, diverse assemblages range throughout most of the substage and then show a gradual decline prior to the Cretaceous—Paleogene (K—Pg) boundary. Further north, in northeast Brazil, only two genera (Diplomoceras, Pachydiscus) range into the uppermost Maastrichtian, but disappear within the last 0.3 Ma of the Cretaceous. In tropical sections of Columbia and Mexico, the decline of ammonites started earlier and Sphenodiscus is the last ammonite known to occur in the late Maastrichtian. In all sections revised here the disappearance of ammonites was completed prior to the end of the Maastrichtian and was thus independent of the asteroi...

Three new species of dinoflagellate cyst from Cretaceous–Paleogene (K-Pg) boundary sections at mid-Waipara River and Fairfield Quarry, South Island, New Zealand

A palynological investigation of marine uppermost Maastrichtian to lower Paleocene strata in two New Zealand sections, mid-Waipara River and Fairfield Quarry, revealed well-preserved dinoflagellate cyst assemblages including three new dinoflagellate cyst species. A formal description of the new dinoflagellate cyst species are presented here. Furthermore a variation of Carpatella cornuta, named C. aff. cornuta is discussed. In the mid-Waipara River section the ranges of the new species Adnatosphaeridium regulatum sp. nov., Alterbidinium mcmillanii sp. nov. and Canningia fairfieldensis sp. nov. are calibrated directly with other microfossil groups including foraminifera, radiolarian and terrestrially derived spores and pollen. The last occurrence of Adnatosphaeridium regulatum sp. nov. is within the lowermost Danian foraminiferal zone Pα and this event is recorded in sections located in several New Zealand sedimentary basins. Alterbidinium mcmillanii sp. nov. has a very restricted range within the latest Maastrichtian to basal Danian with its last occurrence within foraminferal zone P0. Canningia fairfieldensis sp. nov. has so far only been recorded in lower Danian strata and occurs within the foraminiferal zones Pα to P1c and radiolarian zones RP1?–RP2. A morphological variation of Carpatella cornuta named Carpatella aff. cornuta is only observed in a very narrow interval across the Cretaceous–Paleogene (K-Pg) boundary in the mid-Waipara River section. Based on comparison with other New Zealand K-Pg boundary sections, A. mcmillanii sp. nov. and C. fairfieldensis sp. nov. seem to have a palaeoenvironmental affinity for shallow marine to inner neritic depositional environments.

Planktonic foraminiferal and calcareous nannofossil biostratigraphy and magnetostratigraphy of the uppermost Campanian and Maastrichtian at Zumaia, northern Spain

The well-exposed and continuous uppermost Cretaceous in the coastal section of Zumaia (northern Spain) crops out as cyclic, deep-water, hemipelagic carbonate-rich sediments of significant geological interest. We present a new, high-resolution calibration of planktonic foraminiferal and calcareous nannofossil biostratigraphic datums, alongside new magnetostratigraphy. Six planktonic foraminiferal zones (Rugoglobigerina rotundata to Pseudoguembelina hariaensis) and nine nannofossil (sub)zones (UC15eTP? to UC20dTP) have been identified, encompassing the uppermost Campanian through uppermost Maastrichtian. Magnetostratigraphic data were obtained from the lower half of the section, where chrons C31r and C31n have been identified; the lithological nature of the upper part of the section provided spurious palaeomagnetic results. According to these data, the Campanian/Maastrichtian (C/M) boundary lies in Chron C31r at Zumaia. Differences between the planktonic foraminiferal and nannofossil datums at Zumaia and those from the Tercis boundary stratotype section (France) suggest that the biostratigraphic criteria used to identify the C/M boundary are problematic. We propose, therefore, two alternative, key biostratigraphic datums with which to determine the stratigraphic position of this boundary: the stratigraphic base occurrence datum (BO) of the planktonic foraminifer Pseudoguembelina palpebra and the top occurrence datum (TO) of the nannofossil Broinsonia parca subsp. constricta. The C31r/C31n magnetic polarity reversal, and the BOs of the planktonic foraminifer Racemiguembelina fructicosa and the nannofossil Lithraphidites quadratus are events that may prove useful in formally defining the lower/upper Maastrichtian boundary.

Palynostratigraphy of the Cretaceous–lower Palaeogene sedimentary succession in the Kangerlussuaq Basin, southern East Greenland

A new palynological event biostratigraphy for the Cretaceous–lower Palaeogene succession in the Kangerlussuaq Basin, onshore southern East Greenland is presented. Sixty-three biostratigraphical marker events are recognised, based on the first and last occurrences of dinoflagellate cysts and pollen from eleven key outcrop sections through the Sorgenfri, Christian IV, Sediment Bjerge and Vandfaldsdalen Formations of the Kangerdlugssuaq and Blosseville Groups. The palynological events are correlated with published event stratigraphies and with palynological zonations from North–East Greenland, West Greenland, North America, the North Sea and the Faroe–Shetland Basin. The palynological records date the Sorgenfri Formation as middle Albian to Coniacian or ?early Santonian, the Christian IV Formation as ?late Campanian to late Maastrichtian and the Sediment Bjerge Formation as late Danian to late Selandian. The biostratigraphic ranges of dinoflagellate cysts, pollen and macrofossils around the lower to upper Maastrichtian boundary are discussed and correlated.The palynological records and recent isotopic dating results (40Ar/39Ar) of volcanic rocks indicate that the youngest sediments of the Vandfaldsdalen Formation are of Thanetian or early Ypresian age. The study documents two major hiatuses in the area: the boundary between the Sorgenfri and Christian IV Formations spans the ?upper Coniacian–Santonian and Campanian, whilst the unconformity between the Christian IV and Sediment Bjerge Formations possibly spans the uppermost Maastrichtian and the lower Danian, indicating that the Cretaceous–Palaeogene boundary is represented by a major unconformity, as recognised widely around the northern North Atlantic.

Planktonic foraminiferal biostratigraphy of the upper Cretaceous to mid-Paleocene of the Dababiya Quarry Corehole, Upper Nile Valley, Egypt

Biostratigraphic studies of planktonic foraminifera on the Dababiya Quarry corehole suggest an eight-fold zonal subdivision of the lower (Dakhla Shale,Danian) and middle (uppermost Dakhla and Tarawan Chalk) Paleocene. Preliminary studies of the basal part of the hole (~137–140 m) and the uppermost Cretaceous (~80–81 m) indicate the presence of the lower Maastrichtian Globotruncana aegyptiaca and upper Maastrichtian Pseudoguembina palpebra Zones, respectively. It would appear that there is a short hiatus at the Cretaceous/Paleocene boundary (denoted by the P. palpebra/Parvulorugoglobigerina eugubina zonal boundary and apparent absence of the (uppermost Maastrichtian) Pseudoguembelina hantkeninoides Zone and the (basal Danian) Guembelitria cretacea (P0) Zone, which may be due to syn-sedimentary tectonic and/or inadequate sampling density. The Danian/Selandian (D/S) boundary is placed at the boundary between the Igorina albeari/Praemurica carinata (=lower part of Zone P3b) Zone and the Ig. albeari (=upper part of Zone P3b) Zone at a distinct phosphatic bed tentatively correlated with the Qreiya Bed (in the Qreiya section) and the “Neo-Duwi Event" at 44.5m. This bed is marked by the gradual disappearance of praemuricid taxa in general and the lowest occurrence of P. carinata in particular.

Food supply to the seafloor in the Pacific Ocean after the Cretaceous/Paleogene boundary event

Deep-sea benthic foraminifera show important but transient assemblage changes at the Cretaceous/Paleogene (K/Pg) boundary, when many biota suffered severe extinction. We quantitatively analyzed benthic foraminiferal assemblages from lower bathyal–upper abyssal (1500–2000 m) northwest Pacific ODP Site 1210 (Shatsky Rise) and compared the results with published data on assemblages at lower bathyal (~ 1500 m) Pacific DSDP Site 465 (Hess Rise) to gain insight in paleoecological and paleoenvironmental changes at that time. At both sites, diversity and heterogeneity rapidly decreased across the K/Pg boundary, then recovered. Species assemblages at both sites show a similar pattern of turnover from the uppermost Maastrichtian into the lowermost Danian: 1) The relative abundance of buliminids (indicative of a generally high food supply) increases towards the uppermost Cretaceous, and peaks rapidly just above the K/Pg boundary, coeval with a peak in benthic foraminiferal accumulation rate (BFAR), a proxy for food supply. 2) A peak in relative abundance of Stensioeina beccariiformis, a cosmopolitan form generally more common at the middle than at the lower bathyal sites, occurs just above the buliminid peak. 3) The relative abundance of Nuttallides truempyi, a more oligotrophic form, decreases at the boundary, then increases above the peak in Stensioeina beccariiformis. The food supply to the deep sea in the Pacific Ocean thus apparently increased rather than decreased in the earliest Danian. The low benthic diversity during a time of high food supply indicates a stressed environment. This stress might have been caused by reorganization of the planktic ecosystem: primary producer niches vacated by the mass extinction of calcifying nannoplankton may have been rapidly (<10 kyr) filled by other, possibly opportunistic, primary producers, leading to delivery of another type of food, and/or irregular food delivery through a succession of opportunistic blooms. The deep-sea benthic foraminiferal data thus are in strong disagreement with the widely accepted hypothesis that the global deep-sea floor became severely food-depleted following the K/Pg extinction due to the mass extinction of primary producers (“Strangelove Ocean Model”) or to the collapse of the biotic pump (“Living Ocean Model”).

Recovery of the deep-sea floor after the Cretaceous−Paleogene boundary event: The benthic foraminiferal record in the Basque–Cantabrian basin and in South-eastern Spain

A detailed analysis of the Upper Cretaceous and lower Paleogene benthic foraminiferal assemblages (> 63 μm) from the middle bathyal Loya section (Basque–Cantabrian Basin, Southwestern France) has been carried out. The benthic foraminiferal and palaeoenvironmental turnover across the K/Pg boundary at Loya has been compared to that observed in the nearby Bidart section. Both sections exhibit mesotrophic conditions in the uppermost Maastrichtian, and a drastic decrease in the nutrient supply to the sea floor in coincidence with the K/Pg boundary. Moreover, a faunal recovery of the assemblages is observed through the lowermost Danian. The pattern of faunal and palaeoenvironmental recovery in the Basque–Cantabrian Basin has been compared to that observed in the middle bathyal Agost and Caravaca sections (South-eastern Spain), where a similar decrease in the food supply to the sea floor is observed in coincidence with the K/Pg boundary. However, whereas low oxygen conditions have been recorded in the lowermost Danian in these two sections, no evidence for oxygen deficiency has been found in the Basque–Cantabrian Basin, thus pointing to the regional – and not global – nature of low oxygen conditions following the K/Pg boundary event. Benthic foraminifera from the G. cretacea Biozone suggest environmental instability in the Basque–Cantabrian Basin and in Southeastern Spain. Such environmental stress has been related not only to the collapse of the food web due to the extinction of calcareous primary producers, but also to a rapidly changing food supply driven by phytoplankton blooms. Although stabilization of the ecosystems in surface waters probably occurred towards the upper part of the G. cretacea Biozone, data available from the Ps. pseudobulloides Biozone at Bidart and Agost indicate that food supply to the benthos had not completely recovered, at least, 200 kyr after the K/Pg boundary.

The response of benthic foraminifera to the K–Pg boundary biotic crisis at Elles (northwestern Tunisia)

The high-resolution quantitative study of benthic foraminifera from the Elles section (NW Tunisia) that contains one of the most complete Cretaceous–Paleogene (K–Pg) boundary transition and spans about 357 kyr provides detailed data on the palaeoenvironmental turnover across the K–Pg boundary. Benthic foraminifera indicate outer neritic-uppermost bathyal depths without perceivable bathymetrical changes throughout. Uppermost Maastrichtian assemblages are well preserved and highly diversified, indicating stable environment and mesotrophic to weakly eutrophic conditions during the latest Cretaceous. Benthic foraminifera underwent a major faunal turnover in coincidence with the K–Pg boundary, where a dramatic and sudden decrease in the percentage of both infaunal morphogroups and buliminids, as well as in diversity, heterogeneity, and genus and species richness of the assemblages, are recorded indicating overall oligotrophic conditions. Benthic foraminifera do not show significant extinction at the end of the Cretaceous, with only about 3% of the species clearly becoming extinct together with the temporary disappearance of some taxa. A stepped pattern of faunal recovery and restructuring is recognizable during the lowermost Danian reflecting the gradual restabilization of the environmental conditions after the K–Pg boundary event. The nature and the abundance of food supply to the sea floor conditioned the faunal turnover in the earliest Paleogene which reflects not only a sudden collapse of the food web due to the extinction of calcareous primary producers, but also a major, rapid change in composition and abundance of food supply just after the K–Pg boundary. Short-term blooms of some opportunistic species within the G. cretacea Zone and the lowermost part of the Ps. pseudobulloides Zone would reflect instability in the benthic assemblages that might be related to the transfer to the sea floor of food supply not easily used by the benthos through short-term, large blooms or changes in abundance of opportunistic, various phytoplankton groups. The major environmental instability at the sea floor that just follows the K–Pg boundary event may have been thus related to changes in the phytoplankton composition and abundance and would have taken place over a period of about 25 kyr. Benthic foraminiferal assemblages appear to stabilize in the lowermost part of Zone Ps. pseudobulloides (∼ 65 kyr after the K–Pg boundary event). The sea floor ecosystem, at least at outer neritic-uppermost bathyal depths, may have recovered over a considerably shorter period than commonly suggested, even if the food delivery to the sea floor had not fully recovered the pre-K–Pg levels as indicated by the lower percentages of infaunal morphogroups and buliminids. This would be also in agreement with the rapid recovery of terrestrial ecosystems following the biotic crisis at the K–Pg boundary. The drastic change of benthic foraminiferal assemblages coincident with the K–Pg boundary at Elles and their staggered reorganization during the lowermost Paleogene are largely compatible with the catastrophic effects of a huge asteroid impact on Earth at the K–Pg boundary that severely destabilized the oceanic phytoplankton-based food web.

Stevns Klint, Denmark: Uppermost Maastrichtian chalk, Cretaceous–Tertiary boundary, and lower Danian bryozoan mound complex

Stevns Klint is a 14.5 km long coastal cliff south of Copenhagen, Denmark. It is a classical Cretaceous–Tertiary boundary locality and constitutes the type locality of the Danian Stage together with the nearby Faxe quarry. The irregular coastal topography, the presence of numerous old quarries in the upper, Danian part of the cliff section, and the inaccessibility of parts of the coast makes it difficult to construct an exact geological profile of the whole length of the cliff. Until now the only profile is a fine engraved pen drawing from a boat by Puggaard in 1853. We present a new profile of the cliff constructed on the basis of multi-model photogrammetric mapping of a long series of overlapping photographs taken from a small airplane. This was supplemented by photography and observations from a boat and from the beach. The exposed succession is about 45 m thick and is subdivided into a series of new lithostratigraphic units. It shows the stratigraphic evolution from the uppermost Maastrichtian, across the Cretaceous–Tertiary boundary and into the lower Danian. The position of the boundary varies from about 5 m below to about 30 m above present day sea level. The irregular relief has been interpreted as due to Paleogene folding but it actually represents a depositional sea-floor topography. The lower part of the succession comprises about 25 m of upper Maastrichtian benthos-rich chalk of the newSigerslev Member showing irregular low-amplitude mounded bedding outlined by thin layers of nodular flint, passing upward into benthos-poor, gently wavy to almost horizontally bedded chalk poor in flint. The member is capped by a double incipient hardground and a prominent marker band of nodular flint, occurring 30–50 cm beneath the upper hardground can be followed along the length of the cliff. The upper hardground is overlain by uppermost Maastrichtian bryozoan chalk wackestone deposited in low asymmetrical mounds of the new Højerup Member. It is 4–5 m thick in the southern part of the cliff, thins gradually to the north, and has wedged out almost completely at the northern end of the cliff. The new Sigerslev and Højerup Members form the top part of the Maastrichtian Tor Formation in the Stevns Klint area. It is overlain by the new lowermost Danian Fiskeler Member (P0 foraminifer Zone) which drapes the troughs between the mound crests and wedges out gradually towards the margins of the troughs. It is generally about 5–10 cm thick and passes gradually upwards into the strongly burrowed new Cerithium Limestone Member (Pα–P1a Zones), which is up to 60 cm thick. The Fiskeler and Cerithium Limestone Members form the new Rødvig Formation. An erosional hardground surface truncates the top of the Cerithium Limestone Member and the intervening crests of the uppermost Maastrichtian mounds of the Højerup Member. The surface is overlain by lower Danian bryozoan packstone–rudstone mound complexes (foraminifer zones P1b–P1c , local coccolith zones 2–3, Nannoplankton Zones D2–D3). The internal architecture of the mounds is outlined by thick black flint layers and the mounded bryozoan limestone belongs to the new Korsnæb Member of the new Stevns Klint Formation. Up to 20 m of bryozoan limestone are preserved beneath the Quaternary deposits, forming the top of the cliff succession. The new photogrammetric profile may serve as an excursion guide, as a basis for detailed sedimentological study, and for biostratigraphical, geochemical and palaeomagnetic sampling. Finally, it illustrates the geometry, dimensions and architecture of one of the finest carbonate mound complexes known.

Ostracodes bathyaux du Crétacé terminal – Éocène moyen en Atlantique tropical (Plateau de Demerara, Leg 207)

Ostracode faunal assemblages which lived in bathyal environments are analysed from uppermost Maastrichtian – middle Eocene sediments of sites 1260 and 1261, drilled on the distal margin of Demerara, off Surinam (Leg 207, western tropical Atlantic). As for numerous other groups, the Cretaceous/Tertiary mass extinction event led to the disappearance of numerous bathyal ostracode species and it was followed by a very slow recovery during the Palaeocene. It appears that this extinction event was more devastating for detritus-feeder ostracode species than for filter or silt-eater groups, which crossed the K/T boundary without any or little morphological change. This extinction selectivity may be explained by the drop in productivity of surface waters which took place at the K/T boundary. Finally, psychrospheric ostracode species were encountered in Middle Eocene sediments, confirming thus the general cooling of deep oceanic realm recognised in general for this time interval.

Dinoflagellate and foraminiferal biostratigraphy of the Gurpi Formation (upper Santonian–upper Maastrichtian), Zagros Mountains, Iran

A rich dinoflagellate cyst assemblage has been recovered from an outcrop of the Gurpi Formation, the hydrocarbon source rock in the South Iranian Basin. Key dinoflagellates recorded in the section studied provide a means of correlation with zonation schemes for Australasia and north-west Europe. These include Eucladinium kaikourense, Nelsoniella aceras, Odontochitina spp., Cannosphaeropsis utinensis, Palaeocystodinium denticulatum and Dinogymnium spp. The assemblage points to a late Santonian–late Maastrichtian age for the Gurpi Formation. Dinoflagellate and planktonic foraminiferal evidence indicates the presence of a hiatus spanning the uppermost Maastrichtian to at least the lowermost Danian at the base of a glaucony-rich layer separating the Gurpi Formation from the overlying Pabdeh Formation. Palynofacies and lithofacies profiles suggest that the sediments were deposited in an open, relatively deep marine outer ramp environment belonging to ramp facies 8 and 9.

The Cretaceous-Paleogene boundary at the Poty section, NE Brazil: foraminiferal record and sequence of events - a review

The Poty Quarry, near Recife, Pernambuco, in northeastern Brazil, is presently the best exposed marine Cretaceous-Paleogene (K/Pg) boundary section known in southern low-latitude regions, spanning the uppermost Maastrichtian, Plummerita hantkeninoides Zone, to Danian, Pα, P1a/P1b and P2 zones. It provides evidence for a possible extraterrestrial bolide impact which occurred in the earliest Danian, corresponding to near or at the boundary between the Pα and P1a foraminiferal zones (c. 100,000 to 200,000 years after the K/Pg transition). The dating of the possible impact-triggered tsunami beds at Poty suggests a secondary K/Pg boundary event, perhaps part of multiple impacts during a few hundred thousand years around the transition.