First Occurrence Research Articles

Campanian to Eocene dinoflagellate cyst biostratigraphy from the Tahar and Sekada sections at Arba Ayacha, western External Rif, Morocco

Our detailed palynological study of the Upper Cretaceous–Lower Eocene marly succession from the Sekada and Tahar sections in southern Arba Ayacha, westernmost External Rif Chain (northwestern Morocco), has provided precise age determinations based on dinoflagellate cyst biostratigraphy. Dinoflagellate cysts (dinocysts), which are the dominant palynomorphs, allowed us to recognize the following ages: Late Campanian, Early and Late Maastrichtian, Danian, Selandian, Thanetian and Early Ypresien. Published studies on the western External Rif based on lithostratigraphy, show conflicting ages of Late Cretaceous (Senonian) and Early Eocene. Our age determinations are based on dinocyst events, which are more reliable. We recognize the Late Campanian on the First Occurrence (FO) and Last Occurrence (LO) of Exochosphaeridium? masureae, and the FO of Cerodinium spp., and the LOs of Cribroperidinium wilsonii subsp. wilsonii, Odontochitina porifera and Trithyrodinium suspectum. The Early Maastrichtian is denoted by the FOs of Alterbidinium varium and Palaeocystodinium golzowense and the LO of Alterbidinium acutulum. We define the Late Maastrichtian on the FOs of Disphaerogena carposphaeropsis and Glaphyrocysta perforata, and the LOs of Alisogymnium euclaense, Dinogymnium spp., Isabelidinium cooksoniae, and Pterodinium cretaceum, plus the worldwide latest Maastrichtian acme of Manumiella seelandica. Marking the Danian is the overall range of Senoniasphaera inornata, the FOs of Carpatella cornuta, Damassadinium californicum and Membranilarnacia? tenella. Species having LOs in the Selandian incude Cerodinium diebelii, Manumiella seelandica, Senoniasphaera inornata, Palaeocystodinium australinum and Cerodinium speciosum. We recognize the Thanetian mainly on the FO of Homotryblium tenuispinosum and based the worldwide terminal Thanetian acme of Apectodinium spp. The Early Ypresian is characterized by the FO of Deflandrea phosphoritica and a high abundance of Apectodinium spp. and Kenleyia spp. Thus, we now know that the rocks outcropping in the Sekada and Tahar sections are Late Campanian to Early Ypresian in age.

The Pliocene Mediterranean infilling of the Messinian Erosional Surface: New biostratigraphic data based on calcareous nannofossils (Bajo Segura Basin, SE Spain)

The Bajo Segura Basin (eastern Betic Cordillera) is a Mediterranean marginal basin where the Messinian Erosional Surface (MES), formed during the Messinian Salinity Crisis sea-level fall, is well developed. Overlying this major discontinuity the lower Pliocene transgressive sediments record the reflooding of the Mediterranean and the return to an open marine environment, the continental shelf being rebuilt after the Messinian erosion. The stratigraphic and biostratigraphic study of seven sections allow two transgressive-regressive sequences filling the MES to be distinguished, correlated with the previously distinguished Mediterranean offshore seismic units. Ten calcareous nannofossil bioevents have been identified. The lower sequence can be dated according to nannofossil biozones NN12 to NN14 and the upper sequence by NN15 to NN16. The boundary between both lower Pliocene sedimentary sequences is dated by the First Common Occurrence (FCO) of Discoaster asymmetricus in the uppermost sediment of the lower sequence and the First Occurrence (FO) of Discoaster tamalis in the lowermost part of the upper sequence. This discontinuity can be calibrated at between 4.1 and 4.0 Ma ago.

Planktonic foraminiferal biostratigraphy and assemblages in the Bering Sea during the Pliocene and Pleistocene: IODP sites U1340 and U1343

IODP Site U1340 and Site U1343 in the Bering Sea have been investigated with regard to planktonic foraminifers and fragmentation. The base of Site U1340 dates back to the Early Pliocene and the base of Site U1343 to the Early Pleistocene. Site U1340 is situated at Bowers Ridge, the southern Bering Sea. Site U1343 is situated near the gateway to the Arctic Ocean in the northern Bering Sea. At both sites there are none or very few planktonic foraminifers during the Pliocene and early Pleistocene. After 1.3–1.4Ma the planktonic foraminifers are continuously present for most of the samples examined. Three stratigraphic events have been identified in this study. The first occurrence (FO) of Neogloboquadrina inglei is observed at 1.4–1.5Ma, although this event may be affected by poor preservation of foraminifers in older sediments. The observed age of the change in the coiling ratio of Neogloboquadrina pachyderma from right to left at 1.2Ma agrees with the dating of the same event at the Californian margin. The age of the last occurrence (LO) of N. inglei also seems to match the same event from the Californian margin at 0.7Ma. This implies that these events are robust regional events for the entire northern Pacific. Multivariate analyses of the quantitative planktonic foraminifer data show three main faunal assemblages. The oldest assemblage from 1.3–1.4Ma to 1.2Ma is dominated by N pachyderma s.l. (dex) together with Globigerina bulloides. Other species in this fauna are N. inglei, N. pachyderma s.l. (sin), Globigerina umbilicata and Turborotalita quinqueloba. After 1.2Ma the faunal assemblage is dominated by N. pachyderma s.l. (sin), but the remaining species are the same as before. At 0.7Ma N. inglei disappears, whilst the remaining fauna assemblage stays the same, with N. pachyderma s.l. (sin) still dominating, reflecting subpolar–polar conditions. Prior to 1.4–1.3Ma there are very few or no planktonic foraminifers. Low shell fragmentation and lower TOC suggest that the lack of planktonic foraminifers in these sediments cannot be explained either by a shoaling of the carbonate compensation depth or by enhanced supralysoclinal dissolution. Instead, we argue that the appearance of abundant foraminifers in the sediment reflects the same evolutionary adaption of N. pachyderma (sin) to cold conditions to have occurred after 1.1–1.0Ma as in the North Atlantic.

The stratigraphically earliest record of Diplomoceras cylindraceum (heteromorph ammonite) – implications for Campanian/Maastrichtian boundary definition

A fragmentary specimen of the diplomoceratid heteromorph Diplomoceras cylindraceum , one of three ammonite markers used for the definition of the base of the Maastrichtian Stage, is recorded from the middle Campanian of the Roztocze Hills, southeast Poland. The new find, well constrained by associated ammonites and inoceramid bivalves, represents the earliest well-dated occurrence of this species worldwide to date. Therefore, the first occurrence (FO) of D. cylindraceum is conspicuously below the traditional base of the Maastrichtian as defined by the FO of the belemnite Belemnella lanceolata . Indeed, this is also far below the boundary designated in the Global Stratotype Section at Tercis les Bains (Landes, France). A comparison of the FOs of D. cylindraceum in sections acrossEurope clearly shows a significant diachroneity, which diminishes its value for definition of the Campanian/Maastrichtian boundary.

Geochemical and palaeontological characterization of a new K-Pg Boundary locality from the Northern branch of the Neo-Tethys: Mudurnu – Göynük Basin, NW Turkey

A Cretaceous-Paleogene (K-Pg) succession is studied in detail in the Mudurnu-Göynük basin in northwestern Turkey. To characterize the K-Pg transition in this basin, two stratigraphic sections were measured and sampled at high resolution: the Okçular and the Göynük North sections. These sections were analysed for siderophile trace elements, including Ir and other platinum group elements (PGE: Ru, Rh, Pd, Ir, Pt), bulk stable carbon isotopes, calcareous nannofossils, planktic foraminifera and organic-walled dinoflagellate cysts (dinocysts). In this basin, the upper Maastrichtian consists of monotonous grey mudstones, mostly intercalated with turbidites and the basal Danian is characterised by grey mudstones, that are overlain by a rhythmic alternation of limetones and mudstones. The K-Pg boundary is marked by a thin, reddish ejecta layer, characterized by an enrichment of PGE and an abrupt negative shift in bulk δ13C. This ejecta layer is followed by 15–17 cm of thick darker, clayey mudstone, the so-called boundary clay. The upper Maastrichtian to lower Danian interval displays a succession of biostratigraphic events, such as the globally recognized spike of the dinocyst taxon Manumiella druggii in the Maastrichtian, followed by the extinction of Cretaceous planktic foraminifera at the K-Pg boundary, and a subsequent rapid succession of First Occurrences (FOs) of dinocysts, such as Senoniasphaera inornata, Membranilarnacia? tenella and Damassadinium californicum and planktic foraminifera, including Parvularugoglobigerina eugubina and Subbotina triloculinoides in the lower Danian. Overall the sedimentological and palaeontological data suggest that the studied sites in the Mudurnu-Göynük basin were deposited under normal marine conditions, likely in an outer neritic to upper bathyal environment. Our geochemical and biostratigraphic characterization of the K-Pg boundary transition in the Mudurnu-Göynük basin provides a new K-Pg boundary record in the Northern branch of the Neo-Tethys and allows a detailed comparison with K-Pg boundary sections worldwide.

Biostratigraphical correlations of the calcareous nannofossil Marthasterites furcatus in the Bohemian Cretaceous Basin and Outer Flysch Carpathians, Czech Republic

The first occurrence (FO) of Marthasterites furcatus was correlated with the FOs of other nannofossils, inoceramid bivalves and foraminifers in the Bohemian Cretaceous Basin and Outer Flysch Carpathians. The correlation showed that the FO of M. furcatus was diachronous, becoming younger from east to west. In the Silesian Unit it appears in the lower Turonian in association with Eprolithus moratus (UC6b nannofossil Zone). In the Pavlovské vrchy klippes it appears in the upper middle Turonian together with Lithastrinus septenarius (UC9 Zone). In the Bohemian Cretaceous Basin, the FO of M. furcatus was observed in the lower upper Turonian just above the FO of Liliasterites angularis. The presence of M. furcatus in Turonian strata is scarce and discontinuous up to its sudden quantitative increase (represented by 5–27% in assemblages) below the FO of the inoceramid bivalve species Cremnoceramus waltersdorfensis and C. deformis erectus in the Turonian–Coniacian boundary interval. The top of the M. furcatus acme was recorded below the FO of Micula staurophora. The second quantitative rise of M. furcatus (12% in assemblage) was found in the lower lower Campanian of the Pavlovské vrchy klippes above the FO of Broinsonia parca parca in the UC14a Zone and the last occurrence of the planktonic foraminifer Whiteinella baltica. Above this second acme M. furcatus disappears. The significantly earlier appearance of M. furcatus in the Silesian Basin may be connected with a southeast-heading surface current from the North European epicontinental sea where the species appeared in the early Turonian too.

Late Cretaceous–early Paleocene ostracod biostratigraphy of Scientific Drilling Sk1(N) in the Songliao Basin, northeast China

Cretaceous non-marine deposits are widespread in China and have been studied comprehensively. The Songliao Basin in northeast China is thought to be well suited for investigation of Cretaceous biostratigraphy. However, despite much research having been conducted in the basin, little is known about its Late Cretaceous biostratigraphy and paleoenvironment. Here, we establish a high-resolution biostratigraphy of the Late Cretaceous based on ostracods from borehole SK1(n) in the Songliao Basin, northeast China. As part of the present study, 45 species assigned to 20 genera have been recovered, with one new species (Ilyocypris bisulcatan. sp.) and five ostracod assemblages: theCypridea gunsulinensis–Mongolocypris magnaassemblage, which is marked by the first occurrence (F.O.) ofIlyocyprimorphawith nodes and spines; theIlyocyprimorpha–Limnocypridea sunliaonensis–Periacanthellaassemblage, which ranges from the F.O. ofIlyocyprimorphawith nodes and spines to the F.O. ofStrumosiasp.; theStrumosia inanditaassemblage from the F.O. ofStrumosiasp. to the lower occurrence (L.O.) ofStrumosia inandita; theTalicypridea amoena–Metacypris kaitunensis–Ziziphocypris simakoviassemblage from the F.O. ofMongolocypris apiculata(Cea) andTalicypridea amoenato the F.O. ofIlyocyprissp.; and theIlyocyprisassemblage from the F.O. ofIlyocyprissp. to the L.O. ofIlyocypris bisulcatan. sp.Moreover, the zonal fossilIlyocypris bisulcatan. sp. of Zone 5 is here described for the first time from the upper Mingshui Formation, and Paleocene charophyte genera includingNeocharaandGrovesicahrahave been found to coexist with the Zone 5 fauna. The age of theIlyocyprisAssemblage is assigned to the latest Maastrichtian to the earliest Danian.

Integrated stratigraphy of the St. Thomas section (Malta Island): A reference section for the lower Burdigalian of the Mediterranean Region

Abstract The 91.15 m thick St. Thomas section belongs to the Middle Globigerina Limestone, which is the intermediate member of the Globigerina Limestone Formation, and crops out along the eastern cliff of the Delimara Peninsula (the south-eastern part of Malta Island). The sedimentary record is composed of alternating calcareous marls and marly limestones with subordinated prominent bioturbated indurated limestones that are deposited in a pelagic environment. For the first time paleomagnetic analyses of a Burdigalian succession have provided reliable data that allow the identification of five magnetozones that have been correlated to the Astronomically Tuned Neogene Time Scale, spanning the Early Miocene C6n–C5Dn interval. Calcareous plankton quantitative analyses integrated with paleomagnetic analyses, allowed us to identify and date several bioevents that have great potential for Mediterranean and extra-Mediterranean correlations in the interval between ~ 19.7 and ~ 17.2 Ma. In particular, the complete distributional range of the calcareous nannofossil Sphenolithus belemnos has been recorded as follows: the First Occurrence (FO) at 19.12 Ma, the First Common Occurrence (FCO) at 19.05 Ma, the Last Common Occurrence (LCO) at 18.44 Ma, and the Last Occurrence (LO) at 18.02 Ma. In addition, the FO and the FCO of Sphenolithus heteromorphus have been documented at 18.29 Ma and at 17.99 Ma, respectively. A new paracme interval in the lower part of the range of this species is described between 17.56 and 17.31 Ma. Concerning the planktonic Foraminifera, the main bioevents are the Common Interval top of Paragloborotalia siakensis at 19.55 Ma, a Common Interval of Globoquadrina dehiscens between 19.34 and 18.48 Ma, the Globigerinoides subquadratus FO at 18.43 Ma, and the onset of an acme interval of Paragloborotalia acrostoma that changes its coiling from random to prevalently sinistral at the same time, at 18.40 Ma. These new biostratigraphic data allowed us to place the succession in the standard Mediterranean calcareous plankton zonal schemes and to make some amendments to these schemes. The FCO of S. belemnos was revealed a more reliable marker than its FO for the base of the MNN3a Zone. With regard to the planktonic Foraminifera, the P. acrostoma AB-r/s has been used as a subzonal marker of the G. dehiscens / Catapsydrax dissimilis Zone, which now comprises three subzones instead of two. The deep marine paleoenvironmental setting, the excellent outcrops and the recognition of a continuous succession of bio-magnetostratigraphic events suggest that the St. Thomas section should be considered as a reference section for the lower Burdigalian of the Mediterranean area and for future studies in the definition of the Burdigalian GSSP.

The Global Boundary Stratotype and Section Point (GSSP) for the base of the Santonian Stage, “Cantera de Margas”, Olazagutia, northern Spain

The GSSP for the base of the Santonian Stage is defined at 94.4 m in the eastern border of the Cantera de Margas quarry, Olazagutia (Navarra, N. Spain: 42o 52' 05.3 N, 2o 11' 40 W) and marked by the first occurrence (FO) of the inoceramid bivalve Platyceramus undulatoplicatus. This first occurrence is located about 9 m below the contact between a lower marly unit and an upper more calcareous unit. The FO of the planktonic foraminifer Sigalia carpatica is the secondary marker of the GSSP and first occurs 7 m below the primary marker, but it becomes consistently present about 4.2 m above the boundary. In addition, six peaks in the carbon stable isotope curve can be recognized between the Kingsdown Event 17.2 m below and the Bedwell Event 12.35 m above the GSSP. The basal Santonian GSSP was approved by the International Subcommission on Cretaceous Stratigraphy in September 2010, by the International Commision of Stratigraphy in April 2012, and ratified by the International Union of Geological Sciences in January 2013.

Upper Furongian (Cambrian) conodonts from the Degerhamn quarry road section, southern Öland, Sweden

The Alum Shale Formation exposed at the Degerhamn quarry road section, southern Öland, Sweden, contains a diversified assemblage of euconodonts, paraconodonts and protoconodonts, the majority of which have ranges confined to the Furongian Series (Cambrian). The first occurrence (FO) of the cosmopolitan euconodont species Proconodontus muelleri is recorded in the uppermost part of the Ctenopyge spectabilis trilobite Zone and the first appearance datum of Cordylodus? andresi is in the upper part of the Parabolina lobata trilobite Zone. Three new successive paraconodont associations are introduced: (1) the Furnishina Association, (2) the Prooneotodus Association and (3) the Westergaardodina Association, which, respectively, correspond to deeper marine, deep marine and shallow marine conditions. The genus Stenodontus Chen & Gong is revised in multielement taxonomy. New species formally named are Furnishina holmi and Westergaardodina asinina; Furnishina sp. A and Furnishina sp. B are described in open nomenclature.

The Global Stratotype Sections and Point (GSSP) for the base of the Jurassic System at Kuhjoch (Karwendel Mountains, Northern Calcareous Alps, Tyrol, Austria)

The Global Stratotype Section and Point (GSSP) defining the base of the Jurassic System Lower Jurassic Epoch and Hettangian Stage is situated at the Kuhjoch pass, Karwendel Mountains, Northern Calcareous Alps, Austria (47°29'02N/11°31'50E). The Triassic-Jurassic (T-J) boundary is exposed at Kuhjoch West and at Kuhjoch East, and corresponds to the first occurrence (FO) of the ammonite Psiloceras spelae tirolicum. The Golden Spike was fixed at Kuhjoch East. The section displays a high and continuous sedimentation rate with a constant facies trend across the boundary level. Other bio-events include the FO of the aragonitic foraminifer Praegubkinella turgescens, and of diverse ostracod species 1.0-3.40 cm below the FO of P. spelae and 3.2 m below P. spelae occurs the continental palynomorph Cerebropollenites thiergartii. Because of the lack of other terrestrial microfloral events this is yet the FO event closest to the FO of P. spelae and allows a correlation with nonmarine sediments. The δ 13 C org record shows a strong initial negative excursion at the boundary between the Kossen and Kendlbach formations, 5.8 m (Kuhjoch W) below the T-J boundary, a shift to more positive δ 13 C org in the Schattwald Beds and a gradual decline to more negative values at the transition of the Schattwald Beds to the proximate Tiefengraben Mb. The stratotype point lies within a zone of smaller negative and positive δ 13 C org peaks, which is superimposed on a longer lasting main negative shift. According to recent investigations, the radiometric age of the T-J boundary is about 201,3 Ma.

Cretaceous Oceanic Anoxic Event 2 in the Arobes section, northern Spain: nannofossil fluctuations and isotope events

Abstract The Cenomanian–Turonian boundary interval of the Arobes section, northern Spain, represents the maximum depth of a relatively shallow succession. The investigated section extends within the Rotalipora cushmani and Whiteinella archaeocretacea planktonic foraminiferal zones, and from UC3 up to UC8 nannofloral zones, respectively. The Oceanic Anoxic Event 2 (OAE2) is about 16 m thick and includes a positive δ 13 C excursion, from 3 up to 5.5‰. The first peak of δ 13 C is situated towards the upper part of the Rotalipora cushmani planktonic foraminiferal zone, while the second peak of δ 13 C is situated in the lower part of the Whiteinella archaeocretacea planktonic foraminiferal zone. The plateau, the youngest phase of OAE2, ends slightly above the first occurrence (FO) of the nannofossil Quadrum gartneri . Based on nannofloral fluctuation, an unstable environment is recognized from the last occurrence (LO) of the nannofossil Axopodorhabdus albianus up to the FO of the nannofossil Quadrum gartneri . Mesotrophic, eutrophic and oligotrophic nannofossils have successive peaks throughout the OAE2. In the lower part of OAE2, especially in the trough phase and second build-up, productivity increased. The calcareous dinoflagellate Thoracosphaera spp. peaks up to almost 30% in the lower part of the second build-up phase. The critical nannofloral turnover episode is characterized by impoverished calcareous nannofossil assemblages and temporary disappearances of high-fertility taxa, such as Biscutum constans and Zeugrhabdotus erectus . This shift in nannofloral assemblages starts in the last stages of OAE2; that is, towards the top of the second build-up phase and also covers the main part of the plateau phase of δ 13 C.

Upper Cretaceous to Lower Eocene calcareous nannofossil biostratigraphy from Malaqet and Mundassah sections western flank of the Northern Oman Mountains

This work is the first attempt to undertake a biostratigraphic study on calcareous nannofossil assemblages of the exposed Upper Cretaceous to Lower Eocene rocks at the Malaqet and Mundassah sections, NW Oman. The Upper Cretaceous to Lower Eocene rocks belong to the Simsima Formation and the Muthaymimah Formation. Specimens of calcareous nannofossils identified during this study have been ascribed to 67 different species. The Cretaceous/Palaeocene boundary can be placed in correspondence with the unconformity between the mentioned formations. The presence of a big hiatus in this area is suggested by the absence of the latest Maastrichtian Micula prinsii nannofossil Zone, and the Palaeocene NP1 and NP2 nannofossil Zones. In the two study sections, the Danian/Selandian boundary is placed at the level of the first occurrence (FO) of Fasciculithus tympaniformis (base of NP5 Zone).At Jabal Mundassah, the Selandian/Thanetian boundary is positioned at the FO of Discoaster mohleri, which is used to define the base of NP7/8 Zone. Unfortunately, a major hiatus is detected at the Selandian/Thanetian boundary at the Jabal Malaqet section as indicated by the absence of NP6 and NP7/8 Zones. The Paleocene/Eocene boundary is placed at the base of Subzone NP9b at Jabal Mundassah, whereas at Jabal Malaqet the Paleocene/Eocene boundary interval is missing and a major hiatus is testified by the absence of the NP9b Subzone and NP10 Zone. This work is the first attempt to undertake a biostratigraphic study on calcareous nannofossil assemblages of the exposed Upper Cretaceous to Lower Eocene rocks at the Malaqet and Mundassah sections, NW Oman. The Upper Cretaceous to Lower Eocene rocks belong to the Simsima Formation and the Muthaymimah Formation. Specimens of calcareous nannofossils identified during this study have been ascribed to 67 different species. The Cretaceous/Palaeocene boundary can be placed in correspondence with the unconformity between the mentioned formations. The presence of a big hiatus in this area is suggested by the absence of the latest Maastrichtian Micula prinsii nannofossil Zone, and the Palaeocene NP1 and NP2 nannofossil Zones. In the two study sections, the Danian/Selandian boundary is placed at the level of the first occurrence (FO) of Fasciculithus tympaniformis (base of NP5 Zone).At Jabal Mundassah, the Selandian/Thanetian boundary is positioned at the FO of Discoaster mohleri, which is used to define the base of NP7/8 Zone. Unfortunately, a major hiatus is detected at the Selandian/Thanetian boundary at the Jabal Malaqet section as indicated by the absence of NP6 and NP7/8 Zones. The Paleocene/Eocene boundary is placed at the base of Subzone NP9b at Jabal Mundassah, whereas at Jabal Malaqet the Paleocene/Eocene boundary interval is missing and a major hiatus is testified by the absence of the NP9b Subzone and NP10 Zone.

Identification and characterisation of the Oligocene–Miocene boundary (base Neogene) in the eastern North Sea Basin — based on dinocyst stratigraphy, micropalaeontology and δ13C-isotope data

For the first time a combined palynological and δ13C-isotope study has identified the Oligocene–Miocene boundary — and thus the base of the Neogene — within the North Sea Basin. The type section, the Lemme–Carrosio section in northern Italy, is correlated with the Frida-1 well in the eastern (Danish) part of the North Sea Basin using a combination of data from a previous dinocyst stratigraphic study and new δ13C-isotope data. The results show that the Oligocene–Miocene boundary is located at a depth of 1440m in the Frida-1 well. The Frida-1 δ13C-isotope curve further reflects the Mi-1 glaciation event also recorded in the Lemme–Carrosio section.The dinocyst events bracketing the boundary in Frida-1 are; the last occurrence (LO) of Distatodinium biffii at 1630m, below the boundary, the LO of Chiropteridium spp. at 1370m and first occurrence (FO) of Ectosphaeropsis burdigalensis at 1330m, both above the boundary. An influx of Deflandrea phosphoritica is found in an interval immediately below the boundary (1532–1490m), while the genus Homotryblium occurs abundantly in a broader interval (1650–1330m) encompassing the boundary.Hitherto unpublished data combined with new data provide a series of stratigraphically important nanno- and micropalaeontological events that frame/characterise the Oligocene–Miocene boundary within the North Sea Basin; an almost monospecific assemblage of Reticulofenestra bisecta at 1630m, the LO of Elphidium subnodosum at 1625m, the LO of Aulacodiscus insignis quadrata (Diatom sp. 3 of King, 1983) at 1610m, the LO of Karreriella seigliei at 1580m and the LO of Pararotalia canui at 1570m, all below the boundary, and the FO of Aulacodiscus aemulans (Diatom sp. 5 of King, 1983) at 1410m and the LO of Aulacodiscus aemulans at 1250m, both above the boundary.The dinocyst, nanno- and micropalaeontological studies thus provide a series of bioevents and abundance variations which can be used to locate and to correlate the Oligocene–Miocene boundary within the eastern North Sea Basin more precisely than was previously possible.

Nannofossil record across the Cenomanian-Coniacian interval in the Bohemian Cretaceous Basin and Tethyan foreland basins (Outer Western Carpathians), Czech Republic

Nannofossil record across the Cenomanian-Coniacian interval in the Bohemian Cretaceous Basin and Tethyan foreland basins (Outer Western Carpathians), Czech Republic Nannofossil biostratigraphy and mutual correlation was worked out for the Cenomanian-Coniacian deposits of the Bohemian Cretaceous Basin (BCB) and Outer Western Carpathians (OWC) in the territory of the Czech Republic. Similar assemblages of the BCB and from sediments deposited on the SE slopes of West European Platform, Waschbergždánice-Subsilesian Unit, OWC support the hypothesis that the two areas were connected by a sea way (nowadays the Blansko trough). The nannoflora of the Silesian Unit, OWC show more afinity to high latitudes as is documented by the presence of Marthasterites furcatus in the Lower Turonian, UC6b and UC7 Zones. Turonian and Coniacian deep-water flysch sediments of the Silesian Unit and Magura Group of Nappes provide nannofossils on rare occassions. Strongly atched nannofossils dominated by W. barnesiae from Cenomanian black shales of the BCB are comparable to those of the Silesian Unit and reflect a similar shallow nearshore sea. In the BCB, uppermost Cenomanian is marked by the last occurrence (LO) of Axopodorhabdus albianus and first occurrence (FO) of Quadrum intermedium (6 and 7 elements) and lowermost Turonian by a sudden quantitative rise in nannoflora and by the FO Eprolithus octopetalus. First Eiffellithus eximius and thus the base of the UC8 Zone was recorded in the upper part of ammonite Zone Collignoniceras woollgari in the lower Middle Turonian. Lithastrinus grillii is the stratigraphically youngest nannofossil species in this region and indicates the uppermost Coniacian. In the OWC, the Albian-Cenomanian boundary was recorded in the Silesian Unit and is marked by the LO Crucicribrum anglicum and FO Prediscosphaera cretacea and Corollithion kennedyi in the uppermost Albian. The Turonian-Coniacian boundary found both in the BCB and Waschberg-Ždánice-Subsilesian Unit, OWC is indicated by the FO Broinsonia parca expansa and by the base of the interval with common Marthasterites furcatus. In both areas, events were found closely below the FO inoceramid species Cremnoceramus waltersdorfensis. The Coniacian-Santonian boundary interval (Waschberg-Ždánice-Subsilesian and Foremagura Units, OWC) is indicated by Lithastrinus grillii occasionally accompanied by Lucianorhabdus ex gr. cayeuxii, Hexalithus sp. and Arkhangelskiella specillata.

Paleomagnetic and chronostratigraphic constraints on the Middle to Late Miocene evolution of the Transylvanian Basin (Romania): Implications for Central Paratethys stratigraphy and emplacement of the Tisza–Dacia plate

From the Oligocene onwards, the complex tectonic evolution of the Africa–Eurasia collision zone led to paleogeographic and biogeographic differentiation of the Mediterranean and Paratethys, two almost land-locked seas, in the area formerly occupied by the western Tethys Ocean. Episodic isolation of the basins triggered strong faunal endemism leading to the introduction of regional stratigraphic stages for the Paratethys. Chronostratigraphic control on the Paratethys stages remains rudimentary compared to the cyclostratigraphically constrained Mediterranean stages. This lack of chronostratigraphic control restricts the insight in the timing of geodynamic, climatic, and paleobiogeographic events and thereby hinders the identification of their causes and effects. In this paper, we here derive better age constraints on the Badenian, Sarmatian and Pannonian Central Paratethys regional stages through integrated 40Ar/39Ar, magnetostratigraphic, and biostratigraphic research in the Transylvanian Basin. The obtained results help to clarify the regions Middle Miocene geodynamic and paleobiogeographic evolution. Six new 40Ar/39Ar ages were determined for tuffs intercalating with the generally deep marine basin infill. Together with data from previous studies, there is now a total of 9 radio-isotopically dated horizons in the basin. These were traced along seismic lines into a synthetic seismic stratigraphic column in the basin center and serve as first order tie-points to the astronomically tuned Neogene timescale (ATNTS). Paleomagnetically investigated sections were treated similarly and their polarity in general corroborates the 40Ar/39Ar results. The integrated radio-isotopic and magnetostratigraphic results provide an improved high-resolution time-frame for the sedimentary infill of the Transylvanian Basin. Early Badenian deep water sedimentation is characterized by accumulation of the Dej Tuff Complex in response to a period of intensive volcanism, the onset of which is constrained between the first occurrence (FO) of Orbulina suturalis at 14.56Ma and 14.38±0.06Ma. During the subsequent Badenian Salinity Crisis (BSC) up to 300m of salt accumulate in the basin center. The faunal turnover that marks the Badenian–Sarmatian Boundary is dated at 12.80±0.05Ma. A second phase of intense volcanism occurs at 12.4Ma and leads to deposition of the middle Sarmatian tuff complex (Ghiriş, Hădăreni, Turda and Câmpia Turzii tuffs). Rates of sediment accumulation strongly diminish in the basin center at the onset of the Pannonian stage coincident with an approximately 20° CW tectonic rotation of the Tisza–Dacia plate. Concurrent enhanced uplift in the Eastern a'nd Southern Carpathians leads to the isolation of the Central Paratethys and triggers the transition from marine to freshwater conditions. An additional Pannonian to post-Pannonian 6° of CW rotation is related to the creation of antiform geometries in the Eastern Carpathians which are notably larger in the north than in the south. An 8.4Ma age is determined for the uppermost Pannonian sediments preserved in the central part of the Transylvanian Basin. Two sections belonging to middle Pannonian Zone D, and the lower part of Zone E (Subzone E1) are found to cover the 10.6–9.9Ma time-interval.

Biostratigraphy and paleoenvironments in a northwestern Tethyan Cenomanian-Turonian boundary section (Austria) based on palynology and calcareous nannofossils

The Ultrahelvetic Rehkogelgraben section of the Eastern Alps of Austria comprises a c. 5 m thick sequence of upper Cenomanian to lower Turonian pelagic sediments including black shales in a northwestern Tethyan paleogeographic setting.The following calcareous nannofossil events were recognized in stratigraphic order: The first occurrence (FO) of Quadrum intermedium, the LOs of Lithraphidites acutus and Corollithion kennedyi, the FO of Eprolithus octopetalus, and the FO of Quadrum gartneri. Thus, nannofossil zones UC 4, UC 5c, UC 6 and UC 7 could be recognized.Palynological investigations and palynofacies analysis give additional information especially from the black shale layers and the carbonate-free interval in the section. Five out of seven samples from this interval have yielded some low diversity but distinctive palynological associations. Sporomorphs dominate in the associations, being represented mainly by age diagnostic Normapolles species as Atlantopollis microreticulatus, Atlantopollis reticulatus together with Complexiopollis praeatumescens, Complexiopollis christae and Complexiopollis funiculus. The concurrent presence of these pollen species is regarded as characteristic for latest Cenomanian and early Turonian assemblages.A low diversity dinocyst association is identified, dominated by the Cyclonephelium compactum –Cyclonephelium membraniphorum complex, together with Isabelidinium and Circulodinium species. The dinocyst association is encountered in palynofacies rich in marine organic matter of granular amorphous composition. The palynofacies points to deposition in a distal, low-energy, stressed anoxic environment with high continental input. The palaeoenvironmental significance of the low diversity Cyclonephelium/Eurydinium association is typical for Cenomanian-Turonian black shale sequences.Nannofossil indices and dinoflagellate associations indicate rather low-productivity, low-nutrient settings during at least the later part of OAE 2, and thus confirm interpretations based on foraminiferal assemblages.

Calcareous nannofossil changes during the Mid-Pleistocene Revolution: Paleoecologic and paleoceanographic evidence from North Atlantic Site 980/981

New quantitative data on calcareous nannofossil assemblages through 583–1138 thousand years ago (kyr) have been acquired in high sample resolution (2–3ky) at northern Atlantic ODP (Ocean Drilling Program) Site 980/981. Assemblage composition reflects a temperate paleobioprovince suggesting significant influx of warm North Atlantic Current at the site location during the mid-Pleistocene transition, between Marine Isotope Stage (MIS) 35 and 15.Three intervals have been described based on changes in nannofossil composition and abundance fluctuations of taxa. Reticulofenestrids are abundant just in the first interval (MIS 35–22), which is also characterised by the absence of Gephyrocapsa (>4μm) and C. pelagicus s.l., the latter occurring in upper MIS 24 only. The second interval corresponds to the expanded warm MIS 21 that is accompanied by high carbonate content, absence of both nannofossil reworking and ice rafted debris (IRD), higher abundance of C. leptoporus (5–8μm) and H. carteri, and absence of C. pelagicus s.l. and medium gephyrocapsids. The third interval (MIS 20–15) records the occurrence of C. pelagicus s.l. and medium Gephyrocapsa, generally higher abundance and higher amplitude fluctuations of helicoliths, and absence of reticulofenestrids. The major changes in nannofossil assemblages seem to be the result of combined paleoenvironmental factors related to sea surface water features (temperature and nutrient availability, sea-ice cover) and possibly to deep and intermediate water production of both Northern and Southern Hemisphere origin during glacial and interglacial phases. Complex inter-relationships between environmental parameters and evolutionary/ecological factors are inferred to explain the patterns of Coccolithus pelagicus subspecies, whose distribution and abundance fluctuations are compared with the available patterns of Turborotalia quinqueloba and Neogloboquadrina pachyderma (left coiled) at Site 980 and with the C. pelagicus subspecies patterns from North Atlantic DSDP (Deep Sea Drilling Project) Site 607 and South Atlantic ODP Site 1090.Data collected provide additional information on stratigraphic distribution of selected taxa; the First Occurrence (FO) of Gephyrocapsa omega is confirmed as a diachronous event, even in the Atlantic Ocean, while the First and Last Common Occurrence (FCO, LCO) of R. asanoi appear as diachronous and synchronous events, respectively, on a global scale.

High-resolution integrated stratigraphy of the upper Burdigalian-lower Langhian in the Mediterranean: the Langhian historical stratotype and new candidate sections for defining its GSSP

Results of high-resolution integrated stratigraphic studies (calcareous plankton and magnetostratigraphy) of three Mediterranean sections (La Vedova in Central Italy, Contrada Pesciarello in Sicily and St. Peter’s Pool in Malta) and one deep-sea core from the mid-latitude North Atlantic (DSDP Hole 608) are here synthesized. They are compared with those of previously studied deep marine sections in the Mediterranean including the historical stratotype, with the aim to select the most suitable section and criterion to define the Langhian GSSP (Global Stratotype Section and Point). This study significantly improves the existing magnetobiostratigraphic framework for the upper Burdigalian-lower Langhian and opens new perspectives for defining the Langhian GSSP. An extensive review of the first stages of the Globigerinoides-Praeorbulina evolutionary lineage pointed out that the Praeorbulina datum, historically used (and/or suggested) to approximate the base of the Langhian, coincides with the First Occurrence (FO) of P. glomerosa curva instead of P. sicana which is here included in the genus Globigerinoides. The FO of P. glomerosa curva occurs close to the C5Br/C5Bn.2n reversal boundary. As a consequence, the two recommended guiding criteria to recognize the base of the Langhian, i.e. the Praeorbulina datum and the top of Chron C5Cn.1n, can not be applied together, as these two events differ in age by ~740 kyr. The selection of either of these two criteria will imply a different duration for the Langhian: relatively short, in case the FO of P. glomerosa curva is selected, or longer and probably more acceptable, in case the top of Chron C5Cn.1n is selected. The primary calcareous plankton biohorizons which, according to our data, appoximate the top of Chron C5Cn.1n, are the Last Common Occurrence (LCO) of the calcareous nannofossil Helicosphaera ampliaperta and the LCO of the planktonic foraminifer Paragloborotalia bella. Other calcareous plankton events have been recorded close to the same magnetic reversal, such as a short influx of H. ampliaperta (Ia1) and the Paragloborotalia siakensis Acme0. The P. siakensis Acmea End (AaE) and the Sphenolithus heteromorphus Paracme End (PE) represent the primary plankton biohorizons associated with the P. glomerosa curva FO. Two of the three studied Mediterranean sections (La Vedova and St. Peter’s Pool), each from different point of view, are potentially suitable to be proposed as candidates for the definition of the Langhian GSSP. Yet, further studies on stable isotope stratigraphy and cyclostratigraphy, including astronomical tuning are necessary before the most suitable section and guiding criterion can be selected.

Ntegrated stratigraphy of St. Peter's Pool section (Malta): New age for the Upper Globigerina Limestone member and progress towards the Langhian GSSP

The St. Peter’s Pool section, that outcrops at Delimara Peninsula (south-eastern part of Malta Island), belongs to the Upper Globigerina Limestone, the youngest member of the Globigerina Limestone formation. The high resolution integrated study performed on it revealed the great potentiality of this section for a further development of the Mediterranean Langhian biostratigraphy and for a better understanding of the geology of the Maltese Archipelago. Calcareous plankton quantitative analyses allowed the definition of several bioevents with a great potential for biostratigraphic studies. Some of them are already well-known, such as the Helicosphera ampliaperta LCO (Last Common Occurrence), the paracme interval of Sphenolithus heteromorphus and the Acmea interval of Paragloborotalia siakensis, while the potential of Paragloborotalia bella LCO and the P. siakensis Acme0 are documented for the first time in the Mediterranean area. Other bioevents were recognized through qualitative analyses, such as the Paragloborotalia acrostoma LO (Last Occurrence), the Globigerinoides sicanus FO (First Occurrence), the Paragloborotalia birnageae LO, the Globorotalia mariae mariae FO and the P. bella LO. The St. Peter’s Pool section is characterized by a continuous sedimentation from the upper part of MMi3 Zone to the lower part of MMi4c Subzone of planktonic foraminiferal zonation of Di Stefano et al. (2008) and from the uppermost part of MNN4a Zone to the lower part of MNN5a Zone of calcareous nannofossil zonation (Di Stefano et al. 2008). The magnetostratigraphic interpretation, though rather uncertain, enabled us to identify the C5Cn–C5Br interval. On the basis of the bio-magnetostratigraphic events recognized in the St. Peter’s Pools section, we were able: i) to date the base of the Upper Globigerina Limestone member outcropping in the Delimara Peninsula; ii) to obtain the Burdigalian age for the Upper Globigerina Limestone member, that is the oldest ever recognized in the Maltese Archipelago and iii) to propose this section as potential candidate for the definition of the Langhian GSSP (Global Stratotype Section and Point), thanks to the high quality of calcareous plankton content, the deep paleoenvironmental setting, the suitability for future cyclostratigraphic studies and, finally, the easy accessibility to the outcrops.