Late Cenomanian–Early Turonian facies development and sea-level changes in the Bodenwöhrer Senke (Danubian Cretaceous Group, Bavaria, Germany)

The Upper Cenomanian–Lower Turonian litho-stratigraphic units of the Danubian Cretaceous Group of the proximal Bodenwöhrer Senke (Regensburg, Eibrunn and Winzerberg formations, the latter consisting of a lower Reinhausen Member and an upper Knollensand Member), have been investigated with a focus on facies analysis and sequence stratigraphy. Analyses of litho-, bio-, and microfacies resulted in the recognition of 12 predominantly marine facies types for the Eibrunn and Winzerberg formations. Petrographic and paleontological properties as well as gradual transitions in the sections suggest that their depositional environment was a texturally graded, predominantly siliciclastic, storm-dominated shelf. The muddy–siliceous facies types FT 1–3 have been deposited below the storm wave-base in an outer shelf setting. Mid-shelf deposits are represented by fine- to medium-grained, bioturbated, partly glauconitic sandstones (FT 4–6). Coarse-grained, gravelly and/or shell-bearing sandstones (FT 7–10) developed in the inner shelf zone. Highly immature, arkosic coarse-grained sandstones and conglomerates (FT 11 and 12) characterize an incised, high-gradient braided river system. The Winzerberg Formation with its general coarsening- and thickening-upward trend reflects a regressive cycle culminating in a subaerial unconformity associated with a coarse-grained, gravelly unit of marine to fluvial origin known as the “Hornsand” which is demonstrably diachronous. The overlying Altenkreith Member of the Roding Formation signifies the onset of a new transgressive cycle in the early Middle Turonian. The sequence stratigraphic analysis suggests that the deposition of the Upper Cenomanian and Lower Turonian strata of the Bodenwöhrer Senke took place in a single cycle of third-order eustatic sea-level change between the major sequence boundaries SB Ce 5 (mid-Late Cenomanian) and SB Tu 1 (Early–Middle Turonian boundary interval). The southeastern part of the Bodenwöhrer Senke was flooded in the mid-Late Cenomanian (Praeactinocamax plenus transgression) and a second transgressive event occurred in the earliest Turonian. In the central and northwestern parts of the Bodenwöhrer Senke, however, the initial transgression occurred during the earliest Turonian, related to pre-transgression topography. Thus, the Regensburg and Eibrunn formations are increasingly condensed here and cannot be separated anymore. Following an earliest Turonian maximum flooding, the Lower Turonian Winzerberg Formation filled the available accommodation space, explaining its constant thickness of 35–40 m across the Bodenwöhrer Senke and excluding tectonic activity during this interval. Rapid sea-level fall at SB Tu 1 terminated this depositional sequence. This study shows that Late Cenomanian–Early Turonian deposition in the Bodenwöhrer Senke was governed by eustatic sea-level changes.     

Late Cretaceous (Cenomanian to Campanian) paleoenvironmental history of the Eastern Canadian margin of the Western Interior Seaway: bonebeds and anoxic events

Upper Cretaceous strata in the Pasquia Hills of the northern Manitoba Escarpment, eastern Saskatchewan, Canada provide a detailed paleoenvironmental and sea-level record of the eastern margin of the Western Interior Seaway. Sediments deposited during the Cenomanian/Turonian Greenhorn marine cycle are dominantly black mudstones deposited in a stratified water column, with bottom-water anoxia recurrently reaching into the photic zone. A middle Cenomanian sea-level lowstand event followed by transgression left a series of bonebeds within the Belle Fourche Member of the Ashville Formation, indicating a sedimentary environment starved of coarse siliciclastics. Maximum sea level resulted in the formation of limestone beds within the Favel Formation, further favoured by reduced terrigenous sediment input compared to the western margin. Limestone sedimentation was followed by a phase of increased freshwater input under lower sea level conditions, and reducing zoo- and phytoplankton diversities. During final Greenhorn regression, eastern Saskatchewan probably turned into a restricted basin severely limiting marine circulation. Poor or absent benthic foraminiferal assemblages and biomarker analysis suggest prevailing watermass stratification throughout the Cenomanian/Turonian transgressive/regressive cycle. This was caused either by a freshwater lid, stratification of Boreal and Tethyan-derived watermasses, or both, to various intensities affected by changing sea level. Basin oxygenation during Niobrara time varies between localities along the eastern margin as documented by presence/absence of benthic and planktic foraminifera.     

西藏南部岗巴地区晚白垩世Cenomanian—Turonian集群灭绝事件后有孔虫动物群的复苏

西藏南部岗巴地区Cenomanian-Turonian界线附近发生过一次与大洋缺氧事件有关的集群灭绝事件。其后,随着海水中溶解氧含量的逐渐增加,海洋中微体古生物,尤其是有孔虫逐渐得到了恢复以至繁盛。从Turonian早期至Santonian晚期,有孔虫动物群的复苏过程经历了三个时期：残存期,复苏期及辐射期,其复苏的型式为渐变式复苏。     

Late Cretaceous sedimentary evolution of a northern sector of the Adriatic Carbonate Platform (Matarsko Podolje,SW Slovenia)

Cretaceous shallow-marine carbonate rocks of SW Slovenia were deposited in the northern part of the Adriatic Carbonate Platform. A 560-m-thick continuous Upper Cenomanian to Santonian carbonate succession has been studied near Hru?ica Village in Matarsko Podolje. With regard to lithological, sedimentological, and stratigraphical characteristics, the succession has been divided into nine lithostratigraphic units, mainly reflecting regressive and transgressive intervals of larger scale. During the latest Cenomanian and Early Turonian, hemipelagic limestones were deposited on top of shallow-marine lagoon and peritidal Upper Cenomanian deposits indicating relative sea-level rise. Subsequently, the deeper marine depositional setting was gradually filled by clinoform bioclastic sand bodies overlain by peritidal and shallow-marine low-energy mainly lagoonal lithofacies. Similar lithofacies of predominately inner ramp/shelf depositional settings prevail over the upper part (i.e., Coniacian to Santonian) of the succession. In the area, the Upper Cetaceous carbonate rocks are separated from the overlying Lower Eocene (Upper Paleocene?) carbonate sequence by regional unconformity denoted by distinct paleokarstic features. On the Adriatic Carbonate Platform the deeper marine carbonate setting, developed at the Cenomanian/Turonian boundary, is usually correlated with OAE2 and related eustatic sea-level rise. Similarly, subsequent reestablished shallow-marine conditions are related to Late Turonian long- and short-term sea-level fall. However, we are suggesting that deeper marine deposits were deposited in a tectonically induced intraplatform basin formed simultaneously with the uplift of the northern and northeastern marginal parts of the Adriatic Carbonate Platform.     

Depositional environments and facies development of the Cenomanian–Turonian Galala and Maghra el Hadida formations of the Southern Galala Plateau (Upper Cretaceous,Eastern Desert,Egypt)

The Cenomanian–Turonian (Upper Cretaceous) Galala and Maghra el Hadida formations of the Southern Galala Plateau in Wadi Araba (northern Eastern Desert, Egypt) represent marine depositional systems developing in response to the early Late Cretaceous transgression at the southern margin of the Neotethyan Ocean in tropical paleolatitudes. A facies analysis (litho-, bio- and microfacies) of these successions shows the presence of 22 facies types (FTs, six are related to the Galala Formation, while the Maghra el Hadida Formation is represented by 16 FTs). The Galala Formation was deposited in a fully marine lagoonal environment developing in response to a latest Middle to early Late Cenomanian transgression. The rich suspension- and deposit-feeding macrobenthos of the Galala Formation indicate meso- to eutrophic (i.e., green water) conditions. The facies types of the uppermost Cenomanian–Turonian Maghra el Hadida Formation suggest deposition on a homoclinal carbonate ramp with sub-environments ranging from deep-subtidal basin to intertidal back-ramp. Major and rapid shifts in depositional environments, related to (relative) sea-level changes, occurred in the mid-Late Cenomanian, the Early–Middle Turonian boundary interval, the middle part of the Middle Turonian and the Middle–Late Turonian boundary interval.     

The demise of the rudist-bearing carbonate platforms at the Cenomanian/Turonian boundary: a global control

The demise of the rudist-bearing carbonate blatforms at the Cenomanian/Turonian boundary is tudied in different ways through examples from the Vestern Mediterranean Province. During the Late Cenonanian, North and South Tethyan carbonate platforms xtened widely and were subjected to different climatic and oceanographic conditions. The onset of the demise of the carbonate platforms occurred during Upper Arphaeocretacea and Helvetica biozone times and was boeval with the Global Oceanic Anoxic Event (OAE₂). A major biologic turnover affected the benthic organisms i.e. rudists and large foraminifera. The rudists underwent a severe extinction event, leading to the disappearance of the dominantly aragonite secreting rudists, while the dominantly calcitic forms were less affected. The major development of the carbonate platforms occurred during the Latest Cenomanian — Earliest Turonian, involving a transgressive highstand system tract and a keep-up carbonate organization. During the Early Turonian the carbonate sedimentation was disturbed; hard-grounds, condensed beds, terrigenous inputs developed and a gap in the carbonate platform deposition occurred. A combination of several sequentially linked factors, could explain the demise of the carbonate platform and the major change on the benthic ecosystem at the Cenomanian-Turonian boundary.     

Entobia exogyrarum (Frič, 1883) from the Upper Cretaceous of the Bohemian Cretaceous Basin

The validity of the little-known ichnospecies Entobia exogyrarum (Fri?) is verified. Shells of an oyster, Rhynchostreon suborbiculatum (Lam.), represent the substrate for the sponge borings. The borings occur in many Upper Cenomanian to Middle Turonian localities of the Bohemian Cretaceous Basin. This study revealed that the sponges attacked shells of living oysters. Entobia exogyrarum (Fri?) also represents one of the shallowest occurrences of Entobia borings in the Upper Cretaceous rocks.     

A Late Cretaceous epeiric carbonate platform: the Haftoman Formation of Central Iran

An integrated study of the litho-, bio-, and microfacies of several sections has greatly improved the knowledge on the stratigraphy and depositional setting of the Coniacian to Campanian Haftoman Formation in the Khur area of the northern Yazd Block, Central Iran. Generally, the Haftoman Formation rests on a major tectonic unconformity and commences with a basal conglomerate followed by up to 900 m of shallow-water carbonates with local red sandstone intercalations. Five different depositional environments (from distal to proximal) characterize the facies associations (FA) of the Haftoman Formation: silty, spiculitic wackestone (proximal basin, FA I), bio-/intraclastic wacke-, pack-, and grainstone (marginal shoals, FA II), bioclastic rud-/float-/boundstone (outer platform, FA III), silty mud-/wackestone (lagoonal inner platform, FA IV), and sandstone/sandy limestone (areas close to the mouth of ephemeral streams, FA V). The litho-, micro-, and biofacies of the Haftoman Formation are typical for an epeiric carbonate platform characterized by an arid climate and lagoonal circulation, resulting in nutrient-poor waters, warm temperatures, and high salinities. The Haftoman Platform was attached to an emergent arid hinterland formed by the Anarak Metamorphic Complex to the west and southwest of the study area. Unconformity-bounded depositional units indicate sea-level changes that may correspond to 400-kyr high-frequency sequences but further studies are needed to fully exploit the potential of sequence stratigraphy for regional and inter-regional correlation of the Haftoman Formation.     

A new species of Nehvizdya (Ginkgoales) from the Lower Cretaceous of the Iberian Ranges (Spain)

A new species of the formerly monospecific genus Nehvizdya Hlustík, Nehvizdya penalveri sp. nov. is described from the Albian of the Escucha Formation (Eastern Iberian Ranges, Teruel, Spain). The type species Nehvizdya obtusa Hlustík was first found in the Lower-Middle Cenomanian Peruc Member of the Peruc-Korycany Formation (Bohemian Massif, Czech Republic). Both taxa closely resemble each other, not only in leaf shape and venation pattern, but also in their epidermal structures and the occurrence of resin bodies. The Spanish species, however, is notable for its marked amphistomatic leaves with stomatal apparatus, which have inner folds inside the stomatal pits. Comparison with Eretmophyllum andegavense Pons et al. from the Cenomanian of the Baugeois Clays (Maine-et-Loire, France) allows us to transfer this species to the genus Nehvizdya Hlustík. The new combination proposed is Nehvizdya andegavense (Pons et al.) comb. nov. A taphonomic analysis in this layer appears to characterise a biocoenosis formed from N. penalveri sp. nov. and Frenelopsis alata (K. Feistmantel) Knoblock. Similar associations have been described in the Czech and French Cenomanian. In all three cases, the associations grew around coastal lagoons and ponds where they formed a shrubby halophyte vegetation.     

Integrated stratigraphy and palaeoenvironment of the Cenomanian-Lower Turonian (Upper Cretaceous) of northern Westphalia, North Germany

Summary The present study provides an integrated stratigraphy of the Lower Cenomanian-Lower Turonian of the northwestern Münsterland Basin, Westphalia. This is important to establish a standard section allowing an interregional correlation as well as an interpretation of single environmental conditions, their changes through time and their geographical extent. Numerous sections have been investigated in northern Westphalia, in addition to data from other profiles in North Germany. Macrofossils and thin-sections have been sampled, stable isotope and gamma ray data have been obtained from a part of the sections. Investigation of the sedimentary sequence is based on a analysis of events. Many events are diachronous, whereas others are difficult to define and do not show a wide geographic distribution. For ecological or sedimentological reasons, correlation is not possible. The discussion of events leads to a compound picture of the evolution of the depositional sequence, allowing the reconstruction of palaeo-environmental changes. Sea-level changes and their influence on the fauna is discussed. During maximal sea-level rising, macrofossils occur more frequently for ecological reasons, however, some macrofossil accumulations are lag deposits. Some biostratigraphical problems find their origin in a tectonic separation leading to different habitats. The local tectonics was caused by the intial phase of transpression of the Osning Zone, that can be traced down to the Lower Cenomanian. A correlation of the Cenomanian-Turonian Boundary Event (CTBE) in Westphalia (Lengerich), Colorado (USA) and England (Eastbourne), is possible due to very dense sampling of carbon-isotopes (δ¹³C). In Westphalia, definition of the stage boundary is possible by correlation of carbon isotope curves only. A sequence from the upper Middle Cenomanian, up to the lower Upper Cenomanian, is investigated concerning the controlling factors of biogenic sedimentation. The cyclicity of lithology is investigated by Fast Fourier Trans-formation. It can be shown that sedimentation is forced by orbital cycles, mainly by the precession cycle of the Milankovitch band (P1 and P2, 18 500 and 22 300 years, respectively). This confirms the primary origin of the marlstone-limestone couplets that are obvious in the field. Calculation of sedimentation rates is based on these data. There is a high variability of sedimentation rates, maybe due to a strong variation of productivity in this epicontinental environment. Dedicated to the memory of Jost Wiedmann (1931–1993)     

Les kystes de dinoflagellés du Crétacé moyen de la marge atlantique brésilienne, le bassin de Santos

Organic dinoflagellate cysts are studied from the sedimentary sequence of hole 1-SPS-14A, drilled during oil exploration in the Santos Basin, Brazilian continental margin. The Ariri and Florianópolis Formations (Transitional sequence) do not contain any dinocysts. The oldest found dinocysts occur at the base of the Drift sequence in sediments, within platform carbonates of the Guarujá Formation. Continuous sea-level rise throughout the late Albian and Cenomanian submerged the carbonate platform with the terrigenous input of the Itanhaém Formation. The transgressive phase reached its peak during the Cenomanian/Turonian transition. Pelites were deposited during oceanic anoxic event (OAE-2), consisting the lower part of the Itajaí-Açu Formation. Normal oceanic conditions re-established in the late Turonian. The Brazilian dinocyst assemblage has tethyan affinities. Some species (i.e., Dinopterygium cladoides, Litosphaeridium arundum, Odontochitina rhakodes and Systematophora cretacea) suggest a middle Albian age for the carbonate platform of the Guarujá Formation. The lower part of the Guarujá Formation was not dated by other microfossils. An uppermost Albian or lower Cenomanian age is suggested for the base of the Itanhaém Formation on the basis of species Palaeohystrichophora infusorioides and Ovoidinium verrucosum. The Cenomanian-Turonian boundary cannot be characterized by dinocysts. Species Atopodinium iuvene, which is known from Turonian sediments in Europe, was found at the top of the Itajaí-Açu Formation. The observed dinocyst bioevents (i.e., last occurrence) are correlated with known foraminiferal, nannofossil and other palynological bioevents. The diversity of the assemblages remains constant throughout the various palaeoenvironments as these are reflected by the Guarujá and Itajaí-Açu Formations, but relative abundances of taxa are variable. Genera Coronifera, Florentinia, Ovoidinium, Spiniferites and Trichodinium are abundant in the carbonate platform assemblages (Guarujá Formation). Genera Cribroperidinium and Cyclonephelium are abundant in detrital sediments (Itajaí-Açu Formation). Only one species (Subtilisphaera guarujaensis n. sp.) is restricted to the carbonate platform environment.     

Cenomanian-Turonian rudists from Western Sinai, Egypt: Systematic paleontology and paleoecology

The Cenomanian-Turonian sequence is well exposed in western central Sinai and contains a considerable number of rudist species. The identified rudists belong to Radiolitidae, Hippuritidae and Requieniidae. Fifteen species are described, belonging to ten genera: Requienia, Toucasia, Apricardia, Radiolites, Eoradiolites, Praeradiolites, Sphaerulites, Sauvagesia, Hippurites, and Vaccinites. Eleven species are reported in the Cenomanian and four species in the Turonian. Within the Cenomanian, two new species are described: Requienia tortuosi and Eoradiolites lenisexternus. The genus Requienia and the species Apricardia carentonenis d’Orbigny, Eoradiolites syriacus (Conrad), Sphaerulites agariciformis Delamétherie, Sphaerulites depressus Blanckenhorn and Vaccinites cf. grossouvrei (Douvillé) are reported for the first time from Egypt. The Cenomanian and Turonian rudists in the western Sinai show either elevator or clinger morphotypes, with the predominance of the former type; recumbent mode of life is rarely represented by some Requieniidae. The elevators are of isolated and clustered occurrences and more represented in the Cenomanian sequence. Rudists of the study area are mainly of parautochthonous fabrics with low to dense packing. Autochthonous fabrics are also achieved by some species, mainly in the Turonian. The disappearance of rudists from the middle part of the sequence and above the Cenomanian/Turonian boundary is due to a deeper setting that resulted from sea-level rise or seafloor subsidence (shelf drowning). The occurrence of rudists with oysters and other benthic fossils in the siliciclastic and carbonate sediments of the Cenomanian and Turonian sedimentary rocks in the Sinai indicate that the sequence was deposited on a broad, shallow shelf. Although the first marine transgression invaded the central Sinai in the late Cenomanian, transgressive deepening conditions continued until the Turonian. The rudists of central Sinai are of Tethyan affinity with significant relation with North Africa, the Middle East, and Southern Europe.     

Découverte d’une nouvelle faune d’âge cénomanien dans la région de Forthassa (Atlas saharien occidental,Algérie) : Implications biostratigraphiques et paléoenvironnementales

The upper Cretaceous of the eastern part of the Ksour Mountains (Western Saharan Atlas, Algeria) is classically subdivided into three fossiliferous lithostratigraphic formations: El Rhelida (lower Cenomanian), Mdaouer (lower-middle Cenomanian) and Rhoundjaïa (upper Cenomanian-lower Turonian). The western part of the Ksour Mountains, which is less documented and poorly known, is here the subject of a detailed sedimentological and palaeontological study. Near Hassi Djeifa locality (Forthassa) the upper Cretaceous is represented by the upper part of Mdaouer Formation and by the lowermost part of Rhoundjaïa Formation. The deposits attributed to the Mdaouer Formation are composed of reddish or green marlstone intercalated by biolaminated limestone, bioclastic limestone with gastropods and bivalves, and sandstone. The selachians (Mafdetia tibniensis, Baharipristis bastetiae), pycnodontiform fishes, and ostracod fauna (Damonella spp., Ilyocypris? sp., Cypridea sp., Paracypria? sp.) coming from marly beds are studied in detail. The two selachian species (Order of Rajiformes) were so far restricted to the Early Cenomanian of Egypt. Our sedimentological and palaeontological data support a probable Early Cenomanian age of the studied deposits and indicate a coastal plain palaeoenvironment continually influenced by the action of tide.     

Biometry of Cenomanian–Turonian placoliths: a proxy for changes of fertility and surface‐water temperature?

Most publications discussing Cenomanian–Turonian calcareous nannofossils focus on abundance fluctuations across the boundary interval. So far, there have been no studies that deal with the influence of palaeoenvironmental changes on the size of common Cenomanian–Turonian nannofossil taxa. The genera Biscutum, Broinsonia, Prediscosphaera, Retecapsa and Watznaueria have therefore been analysed from 19 samples of Cenomanian–Turonian age from the Goban Spur, northeast Atlantic. The genus Biscutum shows a slight decrease of mean length from 4.14 μm in the Cenomanian to 3.94 μm in the Turonian. Broinsonia is marked by a decrease from 6.07 μm in the Cenomanian to 5.64 μm in the Turonian. On the other hand, Prediscospheara increases in size from 4.98 μm in the Cenomanian to 5.61 μm in the Turonian. Two genera (Retecapsa, Watznaueria) show no significant changes in their mean length. The mean size of Biscutum is perhaps controlled by nutrients, where larger specimens may have preferred the more fertile palaeoenvironment of the Late Cenomanian. The size decrease of Biscutum in the Turonian is probably related to reduced nutrient availability. The genus Prediscosphaera spp., may have favoured low‐fertility conditions, as its mean size increases in the Turonian. A worldwide decline of the frequency of Broinsonia spp. during the Cenomanian–Turonian transition implies that this genus is not solely controlled by the nutrient content. The size of Broinsonia spp. may have been therefore influenced by the latest Cenomanian warming event. The increase in sea‐surface temperature may have been unfavourable for Broinsonia spp. as reflected by decreasing mean size and frequency. □Calcareous nannofossils, biometry, morphometry, Oceanic Anoxic Event 2.     

Mammalian Faunal Succession in the Cretaceous of the Kyzylkum Desert

Both metatherians and eutherians are known from the Early Cretaceous (Barremian, 125 mya; million years ago) of China, while eutherian-dominated mammalian faunas appeared in Asia at least by the earliest Late Cretaceous (Cenomanian, 95 mya). The approximately 99–93 my old (Cenomanian) Sheikhdzheili l.f. from western Uzbekistan is a small sample of only eutherians, including three zhelestids and a possible zalambdalestoid. The much better-known 90 my old (Turonian) Bissekty l.f. at Dzharakuduk in the central Uzbekistan includes 15 named and unnamed species, based on ongoing analyses. Of these, 12 are eutherians represented by at least the three groups—asioryctitheres, zalambdalestids, and zhelestids—plus an eutherian of uncertain position—Paranyctoides. Zalambdalestids and zhelestids have been argued to be related to the origin of the placental gliriforms (Euarchontoglires) and ferungulates (Laurasiatheria), respectively. Although there are four previously recognized metatherians, we believe three are referable to the deltatheroid Sulestes karakshi and the fourth, Sailestes quadrans, may belong to Paranyctoides. There is one multituberculate and one symmetrodont in the Bissekty l.f. While comparably aged (Turonian) localities in North America have somewhat similar non-therians, they have more metatherians and no eutherians. The next younger localities (early Campanian, ∼80 mya) in North America have both a zhelestid and Paranyctoides, suggesting dispersal of eutherians from Asia. At Dzharakuduk, the approximately 85 my old (late Turonian/Coniacian) Aitym l.f. is much less well known than the Bissekty l.f., but yields nearly identical taxa, with two non-therians, one metatherian, and six eutherians.     

A new mosasauroid (Squamata) from the Late Cretaceous (Turonian) of Morocco

Tethysaurus nopcsai gen. et sp. nov. is described on the basis of both cranial and postcranial material from the Late Cretaceous (Early Turonian) of the Goulmima region, southern Morocco. This new mosasauroid is mainly characterized by a parietal table ending posteriorly in two pointed pegs; jugal with a large ascending ramus; splenial with a large and notched dorsomedial process; surangular exposed medially ventral to the coronoid; large paracotylar and parazygosphenal foramina on vertebrae. A phylogenetic analysis shows that Tethysaurus is the sister-group of Mosasauridae. It fills the gap between the aigialosaurids (mainly Cenomanian) and the mosasaurids (known from the Middle-Late Turonian to the Latest Maastrichtian). To cite this article: N. Bardet et al., C. R. Palevol 2 (2003).     

The Cenomanian–Turonian boundary in Jordan: Ammonite biostratigraphy and faunal turnover

Well-exposed fossiliferous Upper Cenomanian–Lower Turonian marine sedimentary rocks are present in west-central Jordan. Ammonites serve as an important faunal marker for this interval and can be used to subdivide the Cenomanian–Turonian transition into two upper Cenomanian biozones (Neolobites vibrayeanus and Vascoceras cauvini) and two lower Turonian biozones (Vascoceras proprium and Choffaticeras segne). A revised stratigraphic range of the Vascoceras cauvini Zone in the study area is proposed, consisting of the Metoicoceras geslinianum and Neocardioceras juddii zones of the standard zonation. Based on intercontinental biostratigraphic correlation, a minor unconformity appears to be present around the Cenomanian–Turonian boundary, and a part of the lower Turonian is probably missing. In addition, a faunal turnover is recorded in the uppermost Cenomanian, marked by the disappearance of most of the Cenomanian taxa, including Costagyra olisiponensis (Sharpe), Ceratostreon flabellatum (Goldfuss), Ilymatogyra africana (Lamarck), Rhynchostreon suborbiculatum (Lamarck), Harpagodes nodosus (Sowerby), and Heterodiadema libycum (Desor). This bioevent is thought to be an effect of the Oceanic Anoxic Event OAE 2; the dramatic shifts in species richness and diversity spanning the Cenomanian–Turonian boundary in the study area occurred in response to the major paleoclimatic and paleoenvironmental perturbations prevailing at that time. The stratigraphic and paleontological patterns studied in Jordan are very similar to those recorded in Egypt in terms of litho- and biostratigraphy, event stratigraphy, and macroinvertebrate content, suggesting the presence of uniform triggering mechanisms and bio-sedimentary responses in the Upper Cretaceous basins of the Middle East and providing clues for a high-resolution correlation between the two areas.     

The Cenomanian–Turonian boundary in the northwestern part of the Adriatic Carbonate Platform (Ćićarija Mtn., Istria,Croatia): characteristics and implications

The Cenomanian–Turonian boundary (CTB) in the ?i?arija Mountain region (northern Istria, Croatia) is characterized by calcisphere limestone successions with a firmground and glauconite horizon, bioturbated intervals, tempestites, and slumped structures as well as microbially laminated and organic-rich interbeds deposited in the northwestern part of the intra-Tethyan Adriatic Carbonate Platform (AdCP). Compilation of the results from three studied sections (Vodice–Jelovica, Martinjak and Planik) of litho-, bio-, and microfacies analyses, X-ray diffraction, SEM, EDS, and stable isotope analyses allowed reconstruction of marine paleoenvironmental conditions during this time period. Shallow-marine carbonate deposits of the Milna Formation underlie a drowned-platform succession of the Sveti (Sv.) Duh Formation. The contact between these two formations is sharp and commonly marked by slumped deposits. The Sv. Duh Formation consists of about 100 m of calcisphere wackestone enriched in organic matter. The results of preliminary δ¹³C and δ¹⁸O stable isotope analyses indicate the influence of the global Oceanic Anoxic Event (OAE2) on the deposition of this carbonate succession. Anoxic and hypoxic conditions in the water column lead to major changes in the shallow-marine carbonate system of the AdCP. Numerous benthic foraminifera declined during that time, but planktonic foraminifera and calcareous dinoflagellates diversified and expanded greatly. The results of this research provide new insights into the character of the CTB interval in this part of the Tethyan realm. Local and regional synsedimentary tectonics combined with global upper Cretaceous sea-level dynamics allows the correlation of the investigated deeper-marine lithostratigraphic units with OAE2.     

Late Cretaceous (Cenomanian–Maastrichtian) calcareous nannofossils from Goban Spur (DSDP Sites 549, 551): Implications for the palaeoceanography of the proto North Atlantic

The early late Cretaceous (Cenomanian–early Turonian) is thought to have been one of the warmest periods of the Phanerozoic. This period was characterised by tropical sea surface temperatures of up to 36 °C and a pole-to-equator-gradient of less than 10 °C. The subsequent Turonian–Maastrichtian was characterised by a continuous climatic cooling, peaking in the Maastrichtian. This climatic cooling and the resulting palaeoceanographic changes had an impact on planktic primary producer communities including calcareous nannofossils. In order to gain a better understanding of these Cenomanian–Maastrichtian palaeoceanographic changes, calcareous nannofossils have been studied from the proto North Atlantic (Goban Spur, DSDP Sites 549, 551). In order to see potential differences between open oceanic and shelf dwelling nannofossils, the data from Goban Spur have been compared to findings from the European shelf (northern Germany).A total of 77 samples from Goban Spur were studied for calcareous nannofossils revealing abundant (mean 6.2 billion specimens/g sediment) and highly diverse (mean 63 species/sample) nannofossil assemblages. The dominant taxa are Watznaueria spp. (mean 30.7%), Prediscosphaera spp. (mean 18.3%), Zeugrhabdotus spp. (mean 8.3%), Retecapsa spp. (mean 7.2%) and Biscutum spp. (mean 6.6%). The Cenomanian assemblages of both Goban Spur (open ocean) and Wunstorf (shelf) are characterised by elevated abundances of high fertility taxa like Biscutum spp., Zeugrhabdotus spp. and Tranolithus orionatus. Early Turonian to Maastrichtian calcareous nannofossil assemblages of Goban Spur are, however, quite different to those described from European sections. Oceanic taxa like Watznaueria spp., Retecapsa spp. and Cribrosphearella ehrenbergii dominate in Goban Spur whereas the fertility indicators Biscutum spp. and T. orionatus are more abundant in the European shelf assemblages. This shift from a homogeneous distribution of calcareous nannofossils in the Cenomanian towards a heterogeneous one in the Turonian–Maastrichtian implies a change of the ocean circulation. The “eddy ocean” system of the Cenomanian was replaced by an oceanic circulation similar to the modern one in the Turonian–Maastrichtian, caused by the cooling. The increased pole-to-equator-gradients resulted in an oceanic circulation similar to the modern one.