Latest Danian Research Articles

Paleoenvironment, sequence stratigraphy, and sea level change in the upper Maastrichtian–Danian boundary interval in Gabal Aras, east Qena, Nile Valley, Egypt

The Cretaceous–Paleogene (K–Pg) boundary interval at Gabal Aras, Qena region (part of the southern Tethyan margin) was investigated in detail for calcareous nannofossil and foraminiferal (planktonic and benthonic) assemblages to characterize the surface and bottom sea water conditions. The K–Pg boundary is marked by a minor hiatus expressed by the absence of the lowermost Danian P0 and Pα planktonic foraminiferal zones. Benthonic foraminifera assemblages indicate moderately oxygenated bottom sea waters associated with oligo-mesotrophic conditions during early late Maastrichtian, and mesotrophic conditions during the latest Maastrichtian. The benthonic foraminiferal assemblage reflects a decrease in the food supply in the bottom sea water during the early Danian, while well-oxygenated and oligotrophic conditions dominated during late Danian. The late Maastrichtian surface water witnessed a general cooling trend that was interrupted by a warming episode that could correspond to the Late Maastrichtian Warming Event (LMWE). Acme of Thoracosphaera associated with increased abundance of Neobiscutum romeinii were observed within the upper part of NP1 Zone indicating stressful surface water conditions. The increase of the epifaunal foraminiferal taxa and the occurrence of Cruciplacolithus primus throughout NP2 and NP3 zones reflect a progressive return to normal marine conditions. In the framework of sequence stratigraphy, two third-order depositional sequences covering the K–Pg boundary interval were identified, interpreted, and correlated. The obtained sea-level curve was evaluated to assess whether it was controlled by the eustatic sea-level changes, regional tectonics, or both these factors.

Calcareous nannofossil biostratigraphy and paleoenvironmental study along the Upper Maastrichtian- Eocene sequence at Eastern and Western Deserts, Egypt

Biostratigraphy and paleoenvironment of seventy surface samples were studied based on calcareous nannofossils along the Upper Maastrichtian – Eocene sequence at Gebel Duwi and Gebel Ghanima sections, Egypt. This succession includes three rock units, arranged from base to top as follow: Dakhla, Tarawan and Esna formations. Seven calcareous nannofossil biozones have been recorded, arranged as follow: CC 25c, CC 26, NP 2/3, NP 4, NP 5, NP 6 and NP 9b, discussed and compared with their counterpart in and outside Egypt. Four present stage boundaries have been discussed; the Cretaceous/Paleogene boundary, it seems to be incomplete in the Gebel Duwi section due to the absence of the biozone NP 1. The Danian/Selandian boundary, it can be determined in the Gebel Ghanima section based on the FO of Fasciclithus tympaniformis. The Selandian/Thanetian boundary, it was difficult to trace in the Gebel Ghanima section, where the topmost part of Zone NP 6 was missed. The Paleocene/Eocene boundary, it cannot be accurately determined in the Gebel Ghanima section, owing to the presence of a small hiatus represented by the absence of the Subzone NP 9a. There is predominance in assemblages’ taxa and were relatively warm-water temperature during the Late Danian in the Gebel Duwi section and highly warm-water temperature around the Paleocene-Eocene boundary in the Gebel Ghanima section. There are two ecozones have been recognized in our study. In the Gebel Duwi, the sediments of ecozone (A) are deposited in cool-water, and transitional states between eutrophic and oligotrophic environments, while that of ecozone (B) are deposited in warm-water and also transitional states between eutrophic and oligotrophic environments. The sediments of ecozone (B) in the Gebel Ghanima are deposited in warm-water and mainly oligotrophic environments.

On the genus Vanikoropsis Meek, 1876 (Gastropoda, Caenogastropoda) from the Paleocene of Denmark and West Greenland with descriptions of three new species

The predominantly Cretaceous gastropod genus Vanikoropsis Meek, 1876 is represented in the Paleocene of Denmark and West Greenland by four species, of which three are established herein as new, viz. Vanikoropsis mortenseni n. sp., Vanikoropsis (s.l.) jakobseni n. sp. and Vanikoropsis (s.l.) bashforthi n. sp. The Danish species was found in a boulder of Kerteminde Marl (Selandian, middle Paleocene) from Gundstrup, while the species from West Greenland were found in the localities Sonja Lens and Qaarsutjægerdal on the Nuussuaq peninsula (late Danian, early Paleocene). The Danish species extends the stratigraphic range of the genus into the middle Paleocene and supports the affinities of the Kerteminde Marl fauna to the Paleocene fauna of West Greenland.

Dinoflagellate cyst evidence for the age, palaeoenvironment and paleoclimate of a new Cretaceous–Paleogene (K/Pg) boundary section at the Bou Angueur syncline, Middle Atlas, Morocco

In this paper, we present results of a palynological analysis of the phosphate succession from the northern flank of the Bou Angueur syncline in the Middle Atlas (central Morocco). The studied interval yielded a well-preserved and diverse palynological content, dominated by dinoflagellate cysts (dinocysts), allowing a detailed taxonomic study of dinocyst and a new biostratigraphic dating of the section. The studied section is assigned to the upper Maastrichtian–Danian interval. A new, relatively complete K/Pg boundary transition was recognized. The succession at the Bou Angueur syncline was compared to Tethyan K/Pg boundary sections, such as the K/Pg boundary Global Stratotype Section and Point (GSSP) at El Kef (NW Tunisia) and Ouled Hadou section (NE Morocco). The dinocyst marker events used for the identification of the late Maastrichtian include the first occurrences of Cordosphaeridium inodes subsp. inodes, Deflandrea galeata and Glaphyrocysta perforata and those used for the early Danian include the first occurrences of Carpatella cornuta, Cassidium fragile, Danea californica, Lanternosphaeridium reinhardtii and Senoniasphaera inornata.The organic-walled dinocyst-producing dinoflagellates did not undergo the K/Pg mass extinction resulting from a large meteoritic impact. They enable us to interpret the environmental and climatic changes in the earliest Danian, while calcareous microfossils could not, since they are partially or completely extinct. We thus describe seven palynological assemblages, reflecting paleoenvironmental and paleoclimatic changes, inferred from changes in relevant ecological parameters, including changes in the relative abundance of selected dinocyst groups, often used as paleoenvironmental indicators. An inner to middle neritic marine environments alternated with several short phases of more offshore conditions is deduced for the late Maastrichtian and earliest Danian and an open outer neritic marine environment during a transgressive regime in the latest Danian. Several dinocyst events were recognized in the studied interval, among which remarkable blooms of tropical warm-water and high-latitude cold-water dinocyst taxa are interpreted herein as ecological responses, related to global climatic changes, including a global warming episode during the late Maastrichtian and the well-known brief global cooling following the K/Pg boundary Chicxulub impact.

Introducing the Våle Formation in the southern central North Sea Basin, offshore Netherlands

Based on the re-interpretation of well (log) data this study shows that the Vale Formation was deposited over large areas (> 100 km) in the southern central North Sea Basin (offshore Netherlands). Up to now, the Vale Formation (and the lateral equivalent Maureen Formation) were only described in the nearby offshore Denmark, Norway and UK. In the latter areas, the Vale Formation consists of sandstones, marlstones and marly mudstones. The results of this study show that in the northern offshore Netherlands, the lithology of the Vale Formation ranges from marlstones to marly claystones. Biostratigraphic analyses by previous studies on samples within the (newly interpreted) Vale Formation indicate a similar age (latest Danian and Selandian) and depositional environment (open marine) in the offshore Netherlands compared to the areas further north. Well correlation panels indicate that the Vale Formation obtains it highest thicknesses (over 30 m) in the western study area from where it thins (to less than 10 m) and changes its log-signature towards the - tectonically uplifted - Dutch Central Graben in the eastern study area. On top of the Dutch Central Graben, the Vale Formation and overlying claystones locally seals off an oilfield in the underlying chalks.

Calcareous Nannofossil Biostratigraphy of the Paleocene-Lower Eocene Successions in the Farafra Oasis, Western Desert, Egypt

This work deals with a high-resolution analysis of calcareous nannofossil in four exposed Paleocene-Lower Eocene successions in the Farafra Oasis, Western Desert, Egypt in order to detect the different types of stage boundaries and hiatuses. The studied four sections were collected from five localities (Gebel North Gunna, Gebel South Gunna, Ain Ramla, El-Quss Abu Said and Bir Karawin). In the study area, the Paleocene-Lower Eocene succession is made up of four formations, namely Dakhla (at base), Tarawan, Esna and Farafra (at top) that unconformably overlie the Maastrichtian Khoman Formation. The oldest Paleocene calcareous nannofossil Zone (NP 4) is recorded in the Dakhla Formation. It unconformably overlies the latest Maastrichtian Micula prinsii (CC 26b) subzone that is recognized in the uppermost part of the Khoman Formation at North Gunna section. Although Zone NP 4 is successively overlain by the Paleocene-Lower Eocene calcareous nannofossil zones NP 5, NP 6, NP 7/8, NP 9a, NP 9b, NP 10a. These zones are not sequentially recorded in all the studied sections.The Danian/Selandian boundary is traced in the uppermost part of Zone NP 4 at North Gunna and South Gunna sections. At this boundary, a minor hiatus is observed. This is in consistence with the global drop in relative sea level during the Late Danian. A pronounced hiatus is founded slightly after the base of Selandian to the base of the Thanetian at North Gunna and South Gunna sections. In contrast, in the western part of the studied area at Ain Ramla-ElQuss Abu Said section, a conformable relation is recorded at the Selandian/Thanetian boundary where the uppermost part of Zone NP 4 is directly followed by Zones NP 5, NP 6 and NP 7/8. A hiatus between the Paleocene and the Eocene (Thanetian/Ypresian boundary) is observed in the lower part of the Esna Formation at North Gunna section. The nature of the Paleocene/Eocene boundary is not recognized in Ain Ramla-ElQuss Abu Said and South Gunna sections because they are described as composite sections. However, the Ypresian NP 9b subzone is recorded at the base of South Gunna section. Subzone NP 10a is recorded in all the studied sections, which may a response to a relative sea level rise during the Early Eocene time.

Integrated bio- and carbon-isotope stratigraphy of the Upper Cretaceous Gurpi Formation (Iran): A new reference for the eastern Tethys and its implications for large-scale correlation of stage boundaries

A high-resolution stratigraphic analysis of the Upper Cretaceous Gurpi Formation has been undertaken in the Shahneshin section (Zagros Basin, Iran). New results on calcareous nannofossils, planktic foraminifers, dinoflagellate cysts and high-resolution carbon and oxygen stable isotopes form the basis of a reference section for the eastern Tethys that spans the upper Coniacian to the late Danian. Carbon-isotope correlation to Gubbio, Italy and the NW German chalk allows for the identification of many isotopic events as well as for the definition of new events in the Campanian and Maastrichtian. Our results allow for a review of the accurate position of the Coniacian/Santonian, Santonian/Campanian, and Campanian/Maastrichtian stage boundaries relative to carbon isotopes and plankton bioevents. The reliability of Coniacian to Maastrichtian planktic foraminifer, dinoflagellate cysts and calcareous nannofossil biohorizons is assessed.

Micropalaeontological and isotopic analyses of the middle Palaeocene succession at Gebel Nezzi (Luxor, Egypt): Implications for eustatic changes

Gebel Nezzi (Upper Nile Valley, Egypt) was chosen to study the middle Palaeocene planktonic foraminiferans, nannoplankton contents, benthic foraminiferans, and stable isotopes to provide additional information into sea‐level changes. Two negative excursions are recorded that are associated with a sharp change in palaeoenvironmental conditions, representing significant global palaeoceanographic, palaeoclimatic, and eustatic events observed at other sites around the world. They are characterized by a drop in total foraminiferal abundance associated with a drop in the type, species richness, frequency, and diversity of foraminifers. The first negative excursion of −0.6‰ δ13C and −0.5 δ18O occurs during the Late Danian Event (LDE) almost near the upper part of the planktonic foraminiferal P3a Subzone and within the calcareous nannofossil NTp8A Subzone at the top of the lower third of Chron C26r. It is dominated by shallow‐water benthic foraminiferans of the Neoeponides duwi biofacies. The Danian‐Selandian boundary lies directly above the LDE within the top of the nannofossil Zone NP4, and within the planktonic foraminiferal Subzone P3b with significant increases in angular morozovellids associated with the earliest Cenozoic hyperthermals. The second negative excursion of −0.6‰ δ13C and −2.2 δ18O occurs near the top of the Dakhla Formation and is dominated by the benthic foraminiferal Bulimina farafraensis biofacies within the upper part of the calcareous nannofossil NTp9 Subzone and upper part of the planktonic foraminiferal P4a Subzone. These negative excursions associated with a well‐known falling sea level and are an important tool for regional correlation. Fluctuations in the foraminiferal population, benthic biofacies, δ 13C and δ18O isotopes and carbonate content reflect three fourth‐order transgressive–regressive (T–R) sequences response to eustatic changes in the Egyptian stable tectonic shelf.

The Paleogeographic Evolution of the Orthophragminids of the Paleogene

AbstractOrthophragminids are larger benthic foraminifera (LBF) and, together with the nummulitids, were the major rock-forming foraminifera from the middle Paleocene to the late Eocene. Today, porous, LBF-bearing, Paleogene limestones, which occur globally from the Pacific and Atlantic margins of the Americas to the Indo-Pacific, form potentially valuable oil reservoirs, and their biota have formed the basis of the definition of three paleobiogeographic provinces, namely those of the Americas, Tethys, and the Indo-Pacific. The orthophragminids of the western part of the Tethyan Province have been studied extensively, however, the other provinces are less well characterized, and until now the origin and paleogeographic development of this group have not been fully articulated. New material described here allows the clear definition of a fourth, South African paleobiogeographic province, and, when combined with refined biostratigraphic dating based on new material from the Americas, Europe, South Asia and SE Asia, enables their paleogeographic and biostratigraphic evolution to be determined. Critically, the occurrence of cosmopolitan planktonic foraminifera (PF) within LBF assemblages enables the first occurrences of various LBF forms within each province to be dated relative to well-calibrated planktonic zones (PZ). From this, we infer that, like the previously studied lepidocyclinids and nummulitids, the orthophragminids originated in the Americas during the Paleocene, probably between the late Danian (PZ P1c, 63.5 Ma) and the early Selandian (PZ P3a, 61.6 Ma). By the middle Paleocene, the orthophragminids had migrated across the Atlantic to the previously isolated West African coast at the extreme of Tethys, probably during global sea-level low stands at 60.3 Ma and again at 56.4 Ma. Subsequently, the American Province again became isolated. In the Tethys, the orthophragminid migrations followed two paths: northeastward through the Tethyan corridor in the late Paleo-cene (Thanetian), and south in the earliest Eocene (Ypresian) to South Africa. The Tethyan forms evolved during the Eocene into many lineages, which in turn migrated, after a few million years of their first appearances into the Indo-Pacific, where they again became isolated and diversified further. Meanwhile the South African forms remained similar to their American ancestors in both small size and external ornamentation, while their internal evolution closely followed that of Tethys forms, as exhibited by three species of Nemkovella and Discocyclina described here from South Africa (Nemkovella mcmilliana n. sp., Discocyclina davyi n. sp. and D. africana n. sp.).

Encrusting and Boring Barnacles Through the Cretaceous/Paleogene Boundary in Northern Patagonia (Argentina)

Information about barnacles as fossil components of hard substrate communities from middle latitudes in the Southern Hemisphere is scarce. Changes in these barnacle communities during episodes of extinction, such as that which occurred during the Cretaceous/Paleogene (K—Pg) boundary, are almost unknown. We describe encrusting and boring barnacles associated with Maastrichtian and Danian oysters, evaluate the involved taphonomic processes and report changes in their frequencies over time. A total of 1,174 valves belonging to nine oyster species, collected from the Jaguel and Roca formations of the Neuquen Basin, were analyzed. Presence/absence of barnacles or their bioerosional traces were recorded, frequencies of host incrustation and bioerosion were calculated and taphonomic and statistical analyses were performed. The encrusting barnacles identified on the oyster shells were assigned to Verruca rocana and, their traces, to the ichnospecies Centrichnus concentricus Bromley and Martinell. The boring barnacles are represented by traces assigned to the ichnogenus Rogerella. A preliminary taphonomic analysis indicated that late Maastrichtian and early Danian shells presented a fair-poor condition given by abrasion and fragmentation as taphonomic attributes while late Danian shells exhibited mostly good-fair or mixed condition for both attributes. Verruca rocana was not recorded during the late Maastrichtian but high frequencies of encrusted valves did become apparent after the K—Pg boundary. Boring barnacles represented by the trace Rogerella exhibited a decline in abundance during the early Danian but an increase during the late Danian. Both the encrusting and the boring barnacles associated with oysters presented an increase in their frequencies during the late Danian.

Comment on “Danian/Selandian unconformity in the central and southern Western Desert of Egypt” by S. Farouk and A. El-Sorogy [J. Afr. Earth Sci. 103 (2015) 42–53

In their recent paper, Farouk and El-Sorogy (2015) present a reconstruction of the Danian–Selandian relative sea-level changes for the Western Desert of Egypt and an interpretation of eustatic versus tectonic controls on the latter. However, the relative sea-level changes should be distinguished from the shoreline shifts (also for the purposes of inter-regional comparisons). From three alternative global curves, two confirm the authors’ conclusions, although it is questionable whether these curves are suitable for the purposes of such an analysis. It cannot be excluded that the relative sea-level fall in the late Danian was caused by the same regional tectonic uplift that resulted in the hiatus at the Danian/Selandian boundary. More research (including quantitative palaeobathymetric modelling) is necessary to understand the relative importance of the eustatic and tectonic controls on the sea-level changes established in the Western Desert of Egypt.

Unravelling volcanism and impact related environmental change in the latest Maastrichtian and early Danian

Unravelling volcanism and impact related environmental change in the latest Maastrichtian and early Danian

The Late Danian Event at Site 1209: a rapid diversification of calcareous nannofossils

The Late Danian Event at Site 1209: a rapid diversification of calcareous nannofossils

The late Maastrichtian to Late Paleocene tectonic evolution of the southern part of the Roer Valley Graben (Belgium)

AbstractThe late Maastrichtian to Late Paleocene seismostratigraphic record of the Roer Valley Graben provides new data on the timing and dynamics of stress changes related to the intra-plate deformation of northwestern Europe. During the deposition of late Maastrichtian to middle Danian limestones, no severe tectonic movements occurred in the southern part of the Roer Valley Graben. Around the late Danian, a known fundamental change in the European intra-plate stress field initiated an increase in subsidence of the southern part of the Roer Valley Graben. Subsidence along the graben border zone enabled relatively thick accumulations of the latest Danian to mid-Selandian siliciclastics in the intra-graben zone. Subsidence was not bounded by large offsets along faults, but rather by flexuring within and along the borders of the Roer Valley Graben. The intensity of these dynamics diminished after the middle Selandian. Most likely due to inherited intra-basinal structural differences, the northern and southern part of the Roer Valley Graben experienced distinctly different late Maastrichtian to Late Paleocene tectonics.

Calcareous Nannofossil Biostratigraphy and Stage Boundaries of the Santonian-Eocene Successions in Wadi El Mizeira Northeastern Sinai, Egypt

The stratigraphic successions exposed in Wadi El Mizeira have been dated through the analysis of the calcareous nannofossil assemblages. The results of this study indicate that the successions comprise the Santonian-Late Maastrichtian (Sudr Formation), the Paleocene (Esna Formation) and the Early Eocene (Thebes Formation). The following biozones were recognized: Late Santonian, CC16 Zone; Late Santonian/Early Campanian, CC17 Zone; Early Campanian, Aspidolithus parcus Zone (CC18) Zone; Late Maastrichtian, CC25c Zone; Early Paleocene (Late Danian), NP3 Zone and NP4 Zone; Late Paleocene (Thanethian-Selandian), NP5 Zone; Early Eocene, NP9b Zone, NP10a Zone, NP11 Zone, NP12 Zone and NP14 Zone. Several stratigraphic hiatus were recorded in the studied interval including the absence of Cretaceous nannofossil Zones CC19 to CC25b and CC26 as well as the early Paleocene Zones NP1 and NP2 and probably the basal part of Zone NP3, in addition to the absence of the Zones NP6 and NP7/8. These hiatus may be attributed to environmental conditions, structural activity and/or post depositional processes. This work represents the first attempt to evaluate the nannofossil taxa of the Wadi El Mizeira, Northeastern Sinai.

Calcareous nannofossil and foraminiferal bio-events of the Danian-Selandian transition of the Quseir area, northwestern Red Sea margin, Egypt

Integration between calcareous nannofossil and the planktonic foraminifera investigations of two exposed section (Gebel Duwi and Gebel Hamadat) from the Quseir area, northwestern Red Sea margin, Egypt allow to divided the calcareous nannofossil Zone NP4 into NTp6, NTp7A, NTp7B, NTp8A, NTp8B, and NTp8C subzones, which reflects continuous, well preserved, and very diverse calcareous microplankton bio-events across the Danian/Selandian boundary. The Danian/Selandian boundary is bracketed at the base of Subzone NTp8B within P3b Subzone below a level close to a sequences planktonic foraminiferal bioevents from older to younger: LO of Igorina albeari, Morozovella occulsa, M. aequa, M. acuta, M. velascoensis, and Subbotina velascoensis. Small specimens (<125ìm) of Globanomalina pseudomenardii first appear within the upper part of nannofossil NP4 Zone near the base of Selandian that differ from those previously documented. Comparison of the calcareous nannofossil and planktonic foraminiferal bio-events noted in the different paleolatitudes revealed variations in the stratigraphic range across the Danian /Selandian boundary. This variation in the timing of the first appearances of planktonic foraminifera is primarily due to taxonomically different concepts and/or climatic changes in different paleogeographic setting. Astrong drop in the relative sea-level during the late Danian associated with Neoeponides duwi benthic assemblage was identified resulting from eustatic sea level changes.

Clay mineralogy and calcareous nannofossils from Jagüel and Roca formations in the eastern sector of Pellegrini Lake, Neuquen Basin, República Argentina.

This study presents new mineralogical, sedimentological, and micropaleontological data from the Jagüel (Late Maastrichtian-Early Danian) and Roca (Danian) formations, located in the eastern sector of Pellegrini Lake, Río Negro province, República Argentina. According to the physical characteristics and the age of the sediments that conform these formations, two siliciclastic lithofacies and a carbonate one were recognized, they are named: Maastrichtian grayish yellow calcareous mudstones, Danian olive gray calcareous mudstones, and Danian carbonates. The rocks which constitutes siliciclastic lithofacies were classified as allochemical mudstones and the mineralogy is characterized by high proportions of clay minerals and, to a lesser extent, calcite. The clay mineral association is dominated by a random (R0) I/S mixed-layers (70-90% Sm) accompanied by lower proportions of illite and kaolinite. The mineralogy and the microfabric of the mudstones reflect that these sediments have not been affected significantly by diagenesis. Clay minerals would be of detrital origin and the predominance of the highly smectitic I/S along all sections would be associated with an active volcanism coming from the western magmatic arc, located in the Neuquén Basin during the Late Cretaceous and Paleocene. Micropalaeontological analyses confirmed the presence of Cretaceous-Paleogene transition in the Jagüel Formation beds. The calcareous nannofossils allowed to relate changes in the the mineralogical associations along the K/P transition. In this way, it was possible to detect an increase in kaolinite content close to the K/P boundary (>10%), that decreases towards higher positions of the Danian, which could indicate a warmer and wetter climate during this interval, that it would tend to be drier with seasonal conditions in the late Danian. The Maastrichtian calcareous nannofossil assemblages suggest oligotrophic environments and a well stratified photic zone, nevertheless, in some horizons, the nannoflora is abundant with lower richness which would indicate more restricted marine conditions.

A portrait of Late Maastrichtian and Paleocene palynoflora and paleoenvironment in the northern Mississippi Embayment, southeastern Missouri

Upper Cretaceous and lower Paleogene sedimentary rocks in southeastern Missouri record the northwest extension of the Mississippi Embayment, yet very little information exists about them due to rarity of outcrops and borehole material. This has hindered a clearer understanding of the depositional conditions before and after the terminal Cretaceous impact event. Access to freshly excavated sediments of the Owl Creek, Clayton and Porters Creek formations and to material from several US Geological Survey boreholes has provided a wealth of data to study this time interval in the area. In this study, detailed palynomorph and palynofacies data have been used to infer palynostratigraphy and paleovegetation. Characteristics of lithology, ichnofossils, invertebrate fossils, foraminifera and well logs have provided the framework for reconstructing the depositional history. Palynomorphs indicate Late Maastrichtian, Danian and Thanetian–Selandian ages for the Owl Creek, Clayton and Porters Creek formations, respectively. Although the Cretaceous–Paleogene (K–Pg) boundary itself is marked by an unconformity, the basal part of the overlying Clayton Formation was apparently deposited as a single megatsunamite following the Chicxulub impact event. Palynofloras suggest mixed coastal and inland subtropical forest vegetation dominated by angiosperm taxa, although abundant records of gymnosperm pollen production occurred at various times during the deposition of the Porters Creek. While terrestrially derived organic components dominate the four palynofacies assemblages (A–D) identified by cluster analysis, lithologic, ichnofacies, macrofossil and dinoflagellate cysts suggest that assemblages C and D, which are characterized by higher percentages of amorphous organic matter, represent more distal marine depositional environments.

Late Cretaceous—Palaeocene mid-latitude climates: inferences from clay mineralogy of continental-coastal sequences (Tremp-Graus area, southern Pyrenees, N Spain)

AbstractThe origin and distribution of late Maastrichtian–early Palaeocene clay mineral associations were investigated in the Tremp-Graus basin (South Pyrenees, Spain) to assess palaeoclimate changes during that period. The studied succession is made up of expanded continental and transitional terrigeneous and carbonate deposits accumulated in a coastal plain setting. X-ray diffraction, SEM-EDX and TEM-AEM analysis reveal that the main clay components are illite and smectite, but kaolinite, chlorite and illite-smectite mixed layers are present, although irregularly distributed, all of them showing a platy morphology typical of a detrital origin. Persistence of the chemical features of the Al-dioctahedral smectites throughout the whole succession demonstrates the persistence of the same source area during the interval studied. Palygorskite occurs in the late Danian and Selandian, within carbonate tidal flats as sabkha-like facies. In SEM images, the palygorskite displays straight fibre morphologies, both coating and branched curling out, a clear proof of authigenic origin.Physical or chemical weathering (PhW/ChW) determined as illite + chlorite/smectite + kaolinite ratio, smectite/kaolinite ratio and palygorskite distribution have been used as clay proxies for palaeoclimate reconstructions. Such data suggest a shift from temperate subhumid (perennial) conditions in late Maastrichtian times to a warm seasonal climate during early Palaeocene times. This trend, however, was dramatically altered during the late Danian–Selandian interval, when prevailing warm and semi-arid to arid climatic conditions caused intense evaporation and the development of an alkaline environment in which the palygorskite authigenesis took place.The proposed climatic trend partly concurs with that established for earliest Danian time by Domingoet al.(2007), also in the Tremp-Graus basin, from isotopic and geochemical proxies, as well as with the reconstruction of Cojan & Moreau (2006), in which a semiarid Danian phase for the near continental basin of Aix-en-Provence is postulated. However, it is at odds with the notion of a humid Danian state in the Pyrenees, as inferred by Gawendaet al.(1999) from clay mineral proxies of deep marine successions.

New taxa of the Order Discoasterales Hay 1977

Three new genera of coccolithophores are introduced and one genus is emended. Six new species are described. They are part of the so-called first radiation of the fascicultihs that began in the latest Danian and constitute a marker for correlation of the Danian/Selandian boundary.