Specific facies differentiation of Early Cretaceous (Berriasian–Hauterivian) foraminifer communities in the Ust’-Yenisei basin

This paper is concerned with study and comparison of Berriasian, Valanginian, and lower Hauterivian foraminifer associations in northeastern West Siberia. Micropaleontological analysis of the Lower Cretaceous deposits of the Ust’-Yenisei region has given an insight into the taxonomic composition of microfossils in the studied sections. Analysis of the stratigraphic occurrence of foraminifers has revealed four successive biostratons in zones and beds. Communities of Berriasian, Valanginian, and earliest Hauterivian microbenthos are reconstructed, the regularities of their evolution are established, and the succession of bionomic zones is determined.     

Palynostratigraphy of the Upper Cretaceous and Paleogene Deposits in the South of Western Siberia by Example of Russkaya Polyana Boreholes,Omsk Trough

The detailed study of Boreholes 8, 10, and 2 in the Russkaya Polyana district (Omsk Trough) made it possible to reveal the complex structure of the Upper Cretaceous sediments formed in unstable conditions of the marginal part of the Western Siberian basin. The Pokur, Kuznetsovo, Ipatovo, Slavgorod, and Gan’kino formations were subjected to palynological analysis and substantiation of their Late Cretaceous age. Eight biostratigraphic units with dinocysts and five units with spores and pollen from the Albian to the Maastrichtian were identified. The joint application of biostratigraphic and magnetostratigraphic methods made it possible to reveal the stratigraphic breaks in the studied sedimentary stratum and to estimate their scope. The age of the Lower Lyulinvor Subformation was specified in the marginal part of the Omsk Trough. The ingression traces of the Western Siberian basin in the Albian were found for the first time in the considered region.     

Paleontological and magnetostratigraphic data on Upper Cretaceous deposits from borehole no. 8 (Russkaya Polyana District, Southwestern Siberia)

This work presents results of complex research (palynological, macro- and microfaunistic, and paleomagnetic) of Upper Cretaceous deposits, opened by borehole no. 8 in the Russkaya Polyana District (the southern margin of the Omsk Depression, Southwestern Siberia). The paleontological data obtained allowed us to establish the age of deposits. Based on dinocysts, nannoplankton and spore-pollen complexes, the section of borehole no. 8 has been divided into Pokur, Kuznetsovo, Ipatovo, Slavgorod, and Gan’kino Formations. This work gives data on the composition of zonal palynomorphs, nannoplankton, and microfaunistic complexes. Based on the complex data obtained, the magnetostratigraphic section of Upper Cretaceous deposits has been developed. The section consists of three magnetozones: normal and two reversed polarity magnetozones. The Pokur, Kuznetsovo and Ipatovo Formation (Cenomanian-Santonian) belong to the long normal polarity magnetozone; the Slavgorod and Gan’kino Formations (Campanian-Maastrichtian), separated by a stratigraphic break, belong to reversed polarity magnetozones. The magnetostratigraphic section has been correlated with the general magnetostratigraphic and magnetochronological time scales.     

Upper cretaceous radiolarians of the East European platform and their biostratigraphic significance

Radiolarian assemblages from the Upper Cretaceous carbonate-cherty deposits of the East European platform are analyzed. Biostratigraphic subdivisions ranked as radiolarian beds are distinguished in sediments of the Moscow syneclise, Voronezh anteclise, and the Ul’yanovsk-Saratov depression. The correlation between biostratigraphic beds established in three tectonic structures and variants of their coordination with radiolarian subdivisions in southern and northern areas of Russia are considered. The key importance of radiolarians for the subdivision and correlation of the Upper Cretaceous cherty deposits is demonstrated.     

Magnetostratigraphy of the Campanian–Maastrichtian Bakchar Basin (southeastern West Siberia)

In this paper the results of magnetostratigraphic studies of the Upper Cretaceous penetrated by two wells (S-124 and S-114) drilled in the Tomsk structural-facies zone (Bakchar iron ore deposit) are presented. The obtained biostratigraphic data show that the sediments formed in the Campanian–Maastrichtian time interval. The high-temperature component of the remanent magnetization identified in the rocks allowed us to compile paleomagnetic columns for each well and correlate the columns, using paleontological data, with each other and with the general magnetostratigraphic and magnetochronological scales. In magnetostratigraphic sections of two wells, the Campanian reverse-polarity Slavgorod Formation (R(km)) with a normal-polarity horizon is correlated with Chron C33(r) (top) and C33(n) (bottom) of the Gradstein scale, and the Maastrichtian normal-polarity Gan’kino Formation with a thin reverse-polarity horizon (N(mt)) is correlated with Chron C30 of this scale.     

The Campanian-Maastrichtian stage boundary in the Aktulagai section (North Caspian depression)

Distribution of belemnites and benthic foraminifers in the Campanian-Maastrichtian boundary layers of the Aktulagai section, one of Upper Cretaceous reference sections in the east of the European paleobiogeographic region (EPR) is discussed. The base of Lanceolata Beds defined by A.D. Arkhangelsky in 1912 is well-substantiated biostratigraphic level corresponding to boundary between the Campanian and Maastrichtian stages. In spacious outcrops of Upper Cretaceous deposits in the Aktulagai Plateau (Aktyubinsk region, Kazakhstan Republic), “primitive Belemnella forms” (two rostra plates) appearing above that base distinctly replace the genus Belemnitella dominant in the Campanian. Seven successive zonal assemblages of benthic foraminifers (one plate) are established in the boundary interval. The Aktulagai reference section of Upper Cretaceous sediments can be used to trace the Campanian-Maastrichtian boundary from the eastern EPR to Boreal regions of Russia based on abundant micro-and nannofossils.     

Réflexions sur la « révolution danienne » dans les Pyrénées

This work disproves the magmatic (ophitic rises) and sedimentological (submarine trans-Pyrenean trough filled with breccias and hemipelagites) arguments presented in favour of a Danian distension step following a major Upper to Late Cretaceous Pyrenean compression phase. In the western Pyrenees (Bearn area) the tholeiitic magmatism is really Triassic or Lowermost Liassic in age. The ophites cross mechanically the Jurassic and Cretaceous enclosing sedimentary beds without any contact metamorphism, which could give proof of a Palaeocene age for the magmatic emplacement. As for the supposed submarine breccias rich in planktonic foraminifera, they really correspond to diapiric Early Cretaceous breccias, to Cretaceous or Tertiary tectono-karstic breccias or to Quaternary colluvial deposits. The Danian/Selandian trough does not exist. The proposed interpretation assigns that the Palaeocene interval must be included within the long compression (transpression) period, which begins in the Upper Cretaceous times and increases during the Early Cenozoic, leading to the main structural step of the Pyrenean cycle, towards the Middle–Upper Eocene. To cite this article: J. Canérot, C. R. Geoscience 338 (2006).     

Sedimentological and stratigraphic evolution of northern Lebanon since the Late Cretaceous: implications for the Levant margin and basin

This paper presents an updated review of the Upper Mesozoic and Cenozoic sedimentological and stratigraphic evolution of the Levant margin with a focus on the northern Lebanon. Facies and microfacies analysis of outcrop sections and onshore well cores (i.e., Kousba and Chekka) supported by nannofossil and planktonic foraminifers biostratigraphy, allowed to constrain the depositional environments prevailing in the Turonian to Late Miocene. The “Senonian” (a historical term used to define the Coniacian to Maastrichtian) source rock interval was subdivided into four sub-units with related outer-shelfal facies: (1) Upper Santonian, (2) Lower, (3) Upper Campanian, and (4) Lower Maastrichtian. This Upper Cretaceous rock unit marks the major drowning of the former Turonian rudist platform. This paper confirms the Late Lutetian to Late Burdigalian hiatus, which appears to be a direct consequence of major geodynamic events affecting the Levant region (i.e., the continued collision of Afro-Arabia with Eurasia), potentially enhanced by regressional cycles (e.g., Rupelian lowstand). The distribution of Late Burdigalian–Serravallian rhodalgal banks identified in northern Lebanon was controlled by pre-existing structures inherited from the pulsating onshore deformation. Reef barriers facies occur around the Qalhat anticline, separating an eastern, restricted back-reef setting from a western, coastal to open marine one. The acme of Mount Lebanon’s uplift and exposure is dated back to the Middle–Late Miocene; it led to important erosion of carbonates that were subsequently deposited in paleo-topographic lows. The Late Cretaceous to Cenozoic facies variations and hiatuses show that the northern Lebanon was in a higher structural position compared to the south since at least the Late Cretaceous.     

Late Cretaceous (Santonian) Atractosteus (Actinopterygii,Lepisosteidae) remains from Hungary (Iharkút,Bakony Mountains)

Lepisosteid fishes are well known from the Upper Cretaceous of Europe, but only by fragmentary remains from some Cenomanian and Campanian–Maastrichtian deposits. Here we report various cranial and postcranial remains of gars, discovered in the Upper Cretaceous (Santonian) Csehbánya Formation of Iharkút (Bakony Mountains, Hungary). These remains represent one of the most diverse assemblages of lepisosteid fish material from Upper Cretaceous continental deposits of Europe. Based on tooth morphology, scale-microstructure and the features of the supracleithrum we refer these remains to the genus Atractosteus. Besides some uncertain remains from the Cenomanian of France and Spain, the Santonian aged fossils from Iharkút represent the oldest undisputable occurrence of the family Lepisosteidae in the European continental Cretaceous. Using tooth crown morphology, the surface microstructure of the ganoid scales and the anatomy of the supracleithrum a review of the Late Cretaceous lepisosteid record suggests the occurrence of both Atractosteus and Lepisosteus in the European archipelago.     

Taxonomic composition,paleoecology and biostratigraphy of Late Cretaceous diatoms from Devon Island,Nunavut, Canadian High Arctic

Upper Cretaceous sediments of the Kanguk Formation exposed in Eidsbotn and Viks Fiord grabens on Devon Island, Nunavut, Canadian High Arctic, yielded 91 fossil marine diatom species and varieties (including indeterminate taxa), representing 41 genera. Excellent preservation of the assemblages was aided by shallow burial, protection in downfaulted linear grabens, and the presence of abundant volcanic material. Planktonic species and resting spores comprise nearly 70% of the diatom assemblage, and provided abundant food resources for the Late Cretaceous Arctic ecosystem. Deposition of the approximately 225 m-thick stratigraphic sequence was predominantly in a shallow marine neritic setting, with an upward progression to interbedded terrestrial deposits of the Expedition Fiord Formation, reflecting a regression and eventual persistence of terrestrial facies into the Early Cenozoic. The Kanguk Formation is widespread across the Canadian Arctic, and diatom biostratigraphy indicates a Santonian–Campanian age for the sequences reported herein, based on the presence of Gladius antiquus in the lowermost strata and occurrence of Costopyxis antiqua throughout the succession. However, Amblypyrgus sp. A and Archepyrgus sp. aff. A. melosiroides, encountered in the lower part of the succession, are known exclusively from the Lower Cretaceous. This may suggest a slightly older age. New information on shallow shelf diatom assemblages from this study is compared to reports on two other Late Cretacous Arctic diatom assemblages. These three sites represent an environmental transect from shallow to distal shelf settings and into the oceanic realm.     

Dinosaur eggshells from the Santonian Milk River Formation of Alberta,Canada

The North American fossil record of dinosaur eggshells for the Cretaceous is primarily restricted to formations of the middle (Albian–Cenomanian) and uppermost (Campanian–Maastrichtian) stages, with a large gap in the record for intermediate stages. Here we describe a dinosaur eggshell assemblage from a formation that represents an intermediate and poorly fossiliferous stage of the Upper Cretaceous, the Santonian Milk River Formation of southern Alberta, Canada. The Milk River eggshell assemblage contains five eggshell taxa: Continuoolithus, Porituberoolithus, Prismatoolithus, Spheroolithus, and Triprismatoolithus. These ootaxa are most similar to those reported from younger Campanian–Maastrichtian formations of the northern Western Interior than they are to ootaxa reported from older middle Cretaceous formations (i.e., predominantly Macroelongatoolithus). Characteristics of the Milk River ootaxa indicate that they are ascribable to at least one ornithopod and four small theropod species. The taxonomic affinity of the eggshell assemblage is consistent with the dinosaur fauna known based on isolated teeth and fragmentary skeletal remains from the formation, although most ornithischians and large theropods are not represented by eggshell. Relative to the Milk River Formation eggshell, similar oospecies occurring in younger Cretaceous deposits tend to be somewhat thicker, which may reflect an increase in body size of various dinosaur lineages during the Late Cretaceous.     

Stable isotope characterization of pedogenic and lacustrine carbonates from the Chinese Tian Shan: Constraints on the Mesozoic–Lower Cenozoic palaeoenvironmental evolution

In the Mesozoic–Cenozoic continental deposits of the Tian Shan area, two main levels containing pedogenic carbonates have been identified on both the southern and northern foothills of the range: one in the Upper Jurassic series and one in the Upper Cretaceous–Lower Palaeocene series. In order to reconstruct the palaeoenvironmental and palaeotopographic characteristics of the Tian Shan area during these two periods, we measured the oxygen and carbon isotope composition of these pedogenic carbonates (calcrete and nodules). The stable isotope compositions are homogeneous: most δ¹⁸O values are between 21 and 25‰ and most δ¹³C values are between −4 and −6‰. No distinction can be made between the calcrete and nodule isotopic compositions. The constancy of isotopic values across the Tian Shan is evidence of a development of these calcification features in similar palaeoenvironmental conditions. The main inference is that no significant relief existed in that area at the Cretaceous−Palaeogene boundary, implying that most of the present relief developed later, during the Cenozoic. In addition to the pedogenic carbonates, few beds of limestones interstratified in the Jurassic series of the southern foothills display oxygen and carbon isotope compositions typical of lacustrine carbonates, ruling out brackish water incursion at that period in the region.     

Stratigraphy and micropalaeontology of the upper cretaceous of Western Australia

The distribution, relationships, and stratigraphical significance of the microfaunas (mainly foraminifera) in the Upper Cretaceous deposits of Western Australia are discussed, and palaeogeography and palaeoecology considered.Formations deposited during the Cenomanian-Turonian are the Gearle Siltstone and Alinga Greensand and perhaps the Molecap Greensand. Among the foraminifera recorded are the stratigraphically restricted planktonic formsGlobotruncana (Praeglobotruncana)stephani subspp. andG. helvetica.The Gingin Chalk and the lower part of the Toolonga Calcilutite were deposited during the Santonian. These formations contain the crinoid generaMarsupites andUintacrinus, several species ofGlobotruncana andNeoflabellina, andBolivinoides strigillata. Santonian beds are known in sub-surface sections as far north as the area of the Warroora Anticline.The Toolonga Calcilutite extends up into the lower Campanian, andGlobotruncana arca appears in the fauna. The occurrence of Campanian beds in the Perth Basin cannot be proved; most of the Poison Hill Greensand may be of this age. On foraminiferal evidence, deposition of the Korojon Calcarenite began during the Campanian. Important species identified areGlobotruncana arca,Cibicides voltziana andBolivina incrassata.The upper beds of the Korojon Calcarenite and the Miria Marl are of Maestrichtian age. The Miria Marl contains the speciesGlobotruncana stuarti,G. citae andG. contusa. The upper beds of the Poison Hill Greensand may range into the Maestrichtian.Published by permission of the Director, Bureau of Mineral Resources, Geology and Geophysics, Canberra, Australia.     

Stratigraphy and sedimentation rates of Upper Cretaceous deep-water systems of the Rhenodanubian Group (Eastern Alps, Germany)

In the Bavarian Alps (Germany), west of the Isar River, the abyssal deposits of the Lower Barremian to Upper Campanian Rhenodanubian Group consist of siliciclastic and calcareous turbidites alternating with hemipelagic non-calcareous mudstones. The up to 1500-m-thick succession, deposited in the Penninic Basin to the south of the European Plate, is characterized by a low mean sedimentation rate (c. 25 mm kyr⁻¹) over 60 million years. Palaeocurrents and turbidite facies distribution patterns suggest that sedimentation occurred on a weakly inclined abyssal plain. The highest sedimentation rates (up to 240 mm kyr⁻¹) were associated with the calcareous mud turbidites of the newly defined Röthenbach Subgroup, which includes the Piesenkopf, Kalkgraben and Hällritz formations (Middle Coniacian to Middle Campanian). These calcareous turbidites prograded from the west, and interfinger towards the east with red hemipelagic claystone. A high sea level presumably favoured pelagic carbonate production and accumulation on the shelves and on internal platforms in the western part of the basin, whereas siliciclastic shelves with steep slope angles have bordered the eastern part of the basin, where a dearth of turbidite sedimentation and increased Cretaceous oceanic red beds deposition occurred. In contrast to the eustatically-induced Middle Coniacian to Lower Campanian Cretaceous oceanic red beds (calcareous nannoplankton zones CC14 to CC18), red hemipelagites of Early Cenomanian age (upper part of calcareous nannoplankton zone CC9) and early Late Campanian age (upper part of zone CC21 and zone CC22) are interpreted as the result of regional tectonic activity.     

Seismic stratigraphy,tectonics and depositional history in the Halk el Menzel region,NE Tunisia

In the Halk el Menzel area, the proximal- to pelagic platform transition and related tectonic events during the Upper Cretaceous–Lower Miocene have not been taken into adequate consideration. The integrated interpretation of outcrop and subsurface data help define a seismic stratigraphic model and clarify the geodynamic evolution of the Halk el Menzel block. The sedimentary column comprises marls and limestones of the Campanian to Upper Eocene, overlain by Oligocene to Lower Miocene aged siliciclastics and carbonates.Well to well correlations show sedimentary sequences vary considerably in lithofacies and thicknesses over short distances with remarkable gaps. The comparison of sedimentary sequences cut by borehole and seismic stratigraphic modelling as well help define ten third order depositional sequences (S1–S10). Sequences S1 through S6 (Campanian–Paleocene) are mainly characterized by oblique to sigmoid configurations with prograding sedimentary structures, whereas, sequences S7–S10 (Ypresian to Middle Miocene) are organized in shallow water deposits with marked clinoform ramp geometry. Sedimentary discontinuities developed at sequence boundaries are thought to indicate widespread fall in relative sea level. Angular unconformities record a transpressive tectonic regime that operated from the Campanian to Upper Eocene.The geometry of sequences with reduced thicknesses, differential dipping of internal seismic reflections and associated normal faulting located westerly in the area, draw attention to a depositional sedimentary system developed on a gentle slope evolving from a tectonically driven steepening towards the Northwest.The seismic profiles help delimit normal faulting control environments of deposition. In contrast, reef build-ups in the Eastern parts occupy paleohighs NE–SW in strike with bordering Upper Maastrichtian-Ypresian seismic facies onlapping Upper Cretaceous counterparts.During the Middle–Upper Eocene, transpressive stress caused reactivation of faults from normal to reverse play. This has culminated in propagation folds located to the west; whereas, the eastern part of the block has suffered progressive subsidence. Transgressive carbonate depositional sequences have predominated during the Middle Miocene and have sealed pre-existing tectonic structures.     

The geodynamic evolution of the South-Tethyan,margin in Zanskar,NW-Himalaya,as revealed by the Spongtang ophiolitic melanges

Abstract

— The composite nappe of the Spongtang ophiolite is thrust over Mesozoic and Cenozoic sediments of the North-Indian margin and shelf. The ophiolitic peridotiles tectonic-ally overlie a sedimentary melange, the detailed stratigraphy of which reveals the evolution of the South-Tethyan margin from its opening to its closure. The matrix of the melange is dated as Upper Campanian to Lower Eocene. Volcano-sedimentary olistoliths indicate carbonate platform sedimentation associated with alkaline lavas in the Permian, followed by more pelagic sedimentation of Upper Triassic and mid- Cretaceous age. They derived from external platforms near to the Indian shelf, but separated from it. Composite olistoliths of mid to late Cretaceous age, containing Permian elements, are found in the upper Cretaceous to lower Eocene wildflysch. Primary contacts of melange upon serpentinites indicates that the deeply eroded oceanic crust served partly as a substratum for the melange.     

Upper Cretaceous deposits in the northwest of Saratov oblast,Part 1: Litho- and biostratigraphic analysis of the Vishnevoe section

The work is dedicated to multidisciplinary study of Upper Cretaceous deposits exposed at the day surface in a ravine near the village of Vishnevoe, the Petrovsk district of Saratov oblast. The exposed section includes deposits of the Bannovka, Mozzhevelovyi Ovrag, Mesino-Lapshinovka, Rybushka, Ardym, Lokh formations and of the Borisoglebsk sequence first distinguished in the Volga River basin. Age ranges of the formations studied are confirmed or defined more precisely (the Ardym and Lokh formations) based on fossil faunas of cephalopods, bivalves, radiolarians, planktonic and benthic foraminifers. The middle-upper Coniacian range of the Borisoglebsk sequence is substantiated. Distribution of brachiopods, sponges, radiolarians, ostracodes and calcareous nannoplankton in the section is established. Radiolarian assemblages are used to distinguish biostratigraphic subdivisions corresponding in rank to faunal beds. Based on nannofossil assemblages, zones and subzones of standard zonations after Perch-Nielsen (1985) and Burnett (1998) are established. Stratigraphic ranges of certain radiolarian, ostracode and calcareous nannoplankton taxa are verified.     

The first evidence of paleo-wildfire from the Campanian (Late Cretaceous) of North Africa

Although the fossil record of plant macro- and mesofossils, including fossil charcoal, is patchy geographically and temporally, such remains play an important role for the interpretation of paleoenvironmental and paleoclimatic developments in the continental realm. In Egypt, previous palynological studies on the Upper Cretaceous (Campanian) deposits suggested presence of lush subtropical forests, dominated by angiosperms and pteridophytes, which developed under warm and wet climatic conditions. In the present study, the occurrence of paleo-wildfires during the Late Cretaceous (Campanian) is presented for the first time, based on samples from a surface exposure in the vicinity of the Baris Oasis, south Western Desert, Egypt. Macroscopic charcoal was collected and subsequently analyzed under a stereomicroscope and scanning electron microscope (SEM). The charred wood remains were identified as belonging to gymnosperms, which were important components of the North African paleoflora during the Cretaceous. These charcoal remains represent the first verified occurrence of paleo-wildfires in Africa during the Campanian.     

江苏白垩纪孢粉组合序列

根据近年来获得的孢粉化石材料和前人资料 ,建立了江苏白垩纪的孢粉组合序列 ,它们是 :　 1)贝里阿斯期至凡兰吟期 (Berriasian— Valanginian)的 Schizaeoisporites- Classopollis annulatus- Ginkgocycadophytus nitidus组合 (云合山组 ) ;　 2 )阿普特期至阿尔必期 (Aptian— Albian )的 Cicatricosisporites- Classopollis annulatus-Psilatricolpites组合 (葛村组 ) ;　 3)土伦期 (Turonian )的 Schizaeoisporites- Polycingulatisporites- Cycadopites-Cranwellia组合 (浦口组 ) ;　 4)科尼亚克期至桑顿期 (Coniacian— Santonian)的 Schizaeoisporites- Classopolisannulatus- Lytharites组合 (赤山组 ) ;　 5 )坎潘期 (Campanian )的 Schizaeoisporites- Tricolporopollenitesmicrocirculatus- Betpakdalina组合 (泰州组下部 ) ;　 6 )马斯特里赫特期 (Maastrichtian)的 Pterisisporites-Exesipollenites- K urtzipites组合 (泰州组上部 ) ;　欧特里沃期至巴列姆期 (Hauterivian— Barremian)和塞诺曼期(Cenom ainan)的暂缺。