Middle Pleistocene-Holocene calcareous plankton and benthos biostratigraphy of the Markova Depression,equatorial atlantic

The analysis of nannoplankton, planktonic and benthic foraminifer assemblages provided detailed biostratigraphic characteristics of the upper part of sedimentary cover in the Markova Depression, rift valley of the Mid-Atlantic Ridge. The Gephyrocapsa oceanica and Emiliania huxleyi nannofossil zones, (LO) Helicosphaera inversa biohorizon, Emiliania huxleyi Acme Zone, and planktonic foraminiferal Globigerina calida calida, Globigerina bermudezi and Globorotalia fimbriata subzones were recognized. The compiled paleotemperature curve is correlated with the upper 10 oxygen isotope stages. The recovered deposits were accumulated during 400 ka. Changes in abundance and species composition of benthic foraminifer assemblages are suggested to be correlative with hydrothermal activity outbreaks in the rift zone.     

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.     

An integrated study of upper Campanian-lower Maastrichtian carbon isotopes and calcareous plankton biostratigraphy of the Kurdistan Region,northeastern Iraq

New carbon (δ¹³C) isotope records calibrated by planktonic bioevents provide general support for a late Campanian age assignment of the Shiranish Formation (Fm.) and its boundaries in the Dokan section (NE Iraq). The Shiranish Fm. is characterised at the base by a mid-Campanian unconformity as can be interpreted by absences of nannofossil zones CC20-21. The Shiranish Fm. then spans nannofossil biozones CC22-CC23a (UC15d-e^TP to UC16a^TP). Results obtained on carbon isotopes suggest that diagenesis affected and compromised a few carbonate samples in the uppermost 50 m of the section. However, once these samples are discarded, pristine trends suggest that the top of the section records a negative carbon isotope excursion that is interpreted as CMBa-c events that straddle the Campanian–Maastrichtian boundary. This interpretation is supported by the lowermost occurrence of planktic foraminifers Rugoglobigerina scotti and Contusotruncana contusa some 30 m above the base of the negative excursion and 10 m below a positive excursion identified as the Maastrichtian M1+ event. Discrepancies in the stratigraphic range of several planktic foraminifer bioevents are highlighted and advocate for the need of many more integrated records of planktic foraminifer and nannofossil biostratigraphy alongside carbon isotope stratigraphy in the eastern Tethys in order to improve regional and global schemes.     

An integrated stratigraphic study across the Santonian/Campanian boundary at Bocieniec,southern Poland: A new boundary stratotype candidate

An integrated biostratigraphic (foraminifera, calcareous nannofossils, crinoids), chemostratigraphic (stable carbon isotopes) and magnetostratigraphic study of the Bocieniec section (southern Poland) is presented here. The section presents a continuous and lithologically monotonous sedimentary record across the Santonian–Campanian boundary transition. A large number of macrofossil, foraminiferal and calcareous nannofossil bioevents along with several well-identified carbon-isotope excursions of the upper Santonian and lowermost Campanian are documented. The base of the Campanian is well-constrained by the last occurrence (LO) of the crinoid Marsupites testudinarius, and correlates to the onset of the first δ¹³C positive peak of the Santonian–Campanian Boundary Event (SCBE peak a). A presumable primary Cretaceous paleomagnetic signal highlights the potential presence of the C34N/C33R magnetic reversal although its exact position remains uncertain between peaks a and b of the SCBE. The planktic foraminifer Dicarinella asymetrica is very rare at Bocieniec but a potential LO of this important marker may be recorded in coincidence with peak b of the SCBE. The first occurrence (FO) of calcareous nannofossil Broinsonia parca parca coincides with the lower part of chron C33R and with the early Campanian pilula zone event. A large set of additional nannofossil events and benthic foraminifer events further constrain the stratigraphy of the section and along with the carbon isotopes, allows for correlation with other important sections of the Boreal realm. Although the Bocieniec section is relatively thin and condensed (5.5 m), the successive order of events and presence of all past proposed stratigraphic criteria for the Santonian-Campanian boundary makes it the most complete reference section for this interval at the European and at the global scale. Moreover, this section allows for a precise correlation of the Tethyan and Boreal domains. The Bocieniec section fulfils the geological criteria to be a potential boundary stratotype candidate for the base of the Campanian Stage.     

Correlation of late Cretaceous calcareous nannofossil zones with ammonite zones and planktonic Foraminifera: the Austrian Gosau sections

The late Turonian to early Campanian calcareous nannofossil biostratigraphy of the Austrian Gosau Group is correlated with ammonite and planktonic foraminiferal zones. The standard Tethyan zonations for nannofossils and planktonic foraminifers are applied with only minor modifications. The basal marine sediments of the Gosau Group, bearing late Turonian-early Coniacian macrofossils, belong to the Marthasterites furcatus nannofossil Zone (CC13). The Micula decussata Zone (middle Coniacian to early Santonian) is combined with the Reinhardtites anthophorus Zone because of the rare occurrence of Renhardtites cf. R. anthophorus already in the Coniacian and taxonomic problems concerning the correct identification of this species. The Santonian-Campanian boundary lies within the Calculites obscures Zone (CCl7).     

Tertiary Calcareous Nannofossil Biostratigraphy in the North Part of the South China Sea

The marine Tertiary sequence in the north part of the South China Sea may be divided into 18 LateOligocene to Pliocene calcareous nannofossil zones and one unnamed Eocene assemblage based on an analysisof calcareous nannofossils from 40 offshore boreholes. The unnamed Eocene assemblage has been found onlyon the northeast margin of the Zhujiangkou basin. The 18 cakareous nannofossil zones of the Late Oligoceneto Pliocene were deposited in succession, but their development degrees are different. Among the 18 calcareousnannofossil zones, those corresponding to Martini's (1971) NN4- NN5 zones, NN11 zone and NN13-NN15zones are well developed, relatively persistent laterally and also widely distributed. They are the importantmarkers for the stratigraphical subdivision and correlation of the Upper Tertiary between the various basins inthe north part of the South China Sea. Based on the calcareous nannofossils and the sedimentsry features coup-led with the foraminifer zonation in certain basins, the present paper discusses the sedimentary characteristicsof the marine Tertiary and as well as the distribution and development of the sedimentary hiatus in the region.The calcareous nannofossil markers for the Upper / Lower Tertiary and the Quaternary / Tertiary boundaries,and the characteristics and geological significance of the reworked calcareous nannofossils are also discussed inthe paper.     

新近系全球界线层型剖面及点位(GSSP)简介

新近系全球界线层型剖面及点位(GSSP)位于意大利北部阿莱桑德利亚省卡洛西奥村的勒梅-卡洛西奥剖面,点位在距剖面之顶35m处。根据国际地层委员会的决议,作为界线定义的标志事件是:C6Cn.2n地磁极性时间带的底、浮游有孔虫Paragloborotalia kugleri的最低发生面及钙质超微化石Reticulofenstra bisecta的灭绝面(NN1带的底)附近。     

Sr isotope evolution of Maastrichtian seawater, determined from the chalk of Hemmoor, NW Germany

In 140 metres of Maastrichtian White Chalk (nannofossil chalk) exposed near Hemmoor, NW Germany, values of ⁸⁷Sr/⁸⁶Sr increase from 0.707760 in the Belemnella sumensis Zone (Lower Maastrichtian) at the base of the section (-54.5 m; referred to 0 m at a prominent marl, M900) to 0.707821 in the Belemnella baltica/danica Zone (Upper Maastrichtian) at the top of the section (+84.5 m). A plateau in ⁸⁷Sr/⁸⁶Sr occurs between -5m and +50m in the section, probably as a result of a very high rate of sedimentation in this interval. A belemnite and associated nannofossil chalk have similar ⁸⁷Sr/⁸⁶Sr values, suggesting that there has been little diagenetic alteration of the ⁸⁷Sr/⁸⁶Sr ratios in the chalk, which therefore preserves its original ⁸⁷Sr/⁸⁶Sr. Comparison of ⁸⁷Sr/⁸⁶Sr and nannofossil zonations for sequences at Bidart, France, and DSDP Sites reveals discordance and so possible diachronism of the basal boundaries of nannofossil Zones CC25B and CC25C.     

Calcareous nannofossil and inoceramid biostratigraphies of a Middle Turonian to Middle Coniacian section from the Opole Trough of SW Poland

Well-preserved and rich nannofossil assemblages from Turonian-Coniacian (Upper Cretaceous) marlstone deposits of the Opole Trough in SW Poland have been analysed. Nannoplankton zones (and subzones) UC6 through UC10 were determined. Apparent discrepancies between the Turonian substage ages indicated by the nannofossil zones, which are based on correlations with the standard ammonite zones, and those based on inoceramids are revealed. This illustrates poor correlation between the inoceramid and ammonite events used to indicate the substage boundaries, rather than diachroneity in the nannofossil events.     

The Kantemirovka Paleogene reference section of the Voronezh region

The section on the outskirts of the town of Kantemirovka is proposed to serve as a reference one for Paleogene deposits of the Voronezh region. Observing the requirements of the current Stratigraphic Code of Russia, it is suggested to introduce the Middle Eocene Sergeevka and Tishki formations, which were defined previously by V.P. Semenov as mappable lithostratigraphic units instead of the Kiev Formation (regional stage) in the Paleogene stratigraphic scale of Ukraine, into the regional Paleogene stratigraphic scale of the Voronezh anteclise. The structure of the Sergeevka Formation and hypostratotype of the Tishki Formation defined in this section are considered with the analysis of the distribution of nannofossils, foraminifers, and diatoms in corresponding deposits. Benthic and planktonic foraminifers are used for defining regional biostratigraphic units, which are correlated between each other, with zones of the standard stratigraphic nannofossil scale, and units of the Middle Eocene Kiev regional stage of northern Ukraine. The boundary between the formations under consideration is universally marked by the replacement of carbonate sediments by terrigenous?siliceous facies, disappearance of calcareous fossils, and development of a new biota. These features allow the boundary between these formations to be conditionally correlated with that between the Keresta and Kuma regional stages of the North Caucasus region.     

A review of calcareous nannofossil astrobiochronology encompassing the past 25 million years

This paper presents a review of (astrobiochronological) calibration of Recent to late Oligocene calcareous nannofossil datum events. Biohorizons included in the paper are those of the widely used “standard” nannofossil zonations of Martini, E. [1971. Standard Tertiary and Quaternary calcareous nannoplankton zonation. In: Farinacci, A. (Ed.), Proceedings of the Second International Conference on Planktonic Microfossils Roma. Rome, Ed. Tecnosci. vol. 2, pp. 739–785], and Okada, H., and Bukry, D. [1980. Supplementary Modification and Introduction of Code Numbers to the Low-Latitude Coccolith Biostratigraphy Zonation (Bukry, 1973, 1975). Marine Micropaleontology 51, 321–325], as well as supplementary biohorizons proposed in the literature. The biohorizons have been selected on the basis of the unambiguous taxonomy of the index taxa and their biostratigraphic usefulness. We emphasise the application of rigorous methodology in nannofossil studies which permits an evaluation of biohorizons in terms of reliability, and calibrates their potential correlatability. Astrochronological age estimates rely on the Geologic timescale developed by the ICS in 2004, with some new calibrations included. We provide an overview of the relative position of biohorizons versus the astronomically calibrated ages of magnetic reversals and reference isotope stratigraphies. Surprisingly, there are still few high-resolution quantitative biostratigraphic studies of astrochronologically tuned sections in spite of the central role of such studies in addressing fundamental problems such as the tempo and mode of plankton evolution.     

The Mid-Cenomanian Event in southeastern France: Evidence from palaeontological and clay mineralogical data

Reconstruction of main palaeoenvironmental conditions across the Mid-Cenomanian Event (MCE I) in the hemipelagic Tethyan section of Blieux (Southeast France, Vocontian Basin) is proposed. Quantitative analyses of calcareous nannofossil, ammonoid and clay mineral assemblages have been made and compared with respect to sea level changes and the carbon cycle perturbations. The nannofossil primary productivity, as recorded by nannofossil fluxes and relative abundances of meso-eutrophic taxa, is low just below and during the MCE Ia, then slightly increases in the interval including the MCE Ib. The clay assemblages mainly consist of illite/smectite mixed-layers with a smaller proportion of kaolinite. The percentage of kaolinite strongly decreases in the interval including the MCE Ia and slightly increases in the interval including the MCE Ib. The clay assemblages are mainly detrital in origin and reflect environmental changes including differential settling processes, climate, intensity of runoff and detrital sources. The ammonoid assemblages are characterised by a significant change during the MCE I: planispirals (mainly Schloenbachia) are dominant until the MCE Ia, whereas heteromorphs (mainly Sciponoceras) become dominant from the MCE Ib onwards. Strongly oligotrophic levels in sea surfaces are recorded during the MCE Ia and are related both to arid climatic conditions and major sea level fall (both 3rd order and medium scale lowstand deposits). A decrease in bathymetry could partly explain the decrease in the relative abundance of Schloenbachia. The first occurrence of Sciponoceras took place during the MCE Ib; this second positive increase in δ¹³C is not associated with enhanced nannofossil primary productivity. No clear relations can be established between the occurrence of Sciponoceras and trophic resources.     

Stratigraphy of the Lower Cretaceous Sediments from the Carpathian Bend Area, Romania

The Lower Cretaceous sediments of the Ceahl?u Nappe (from the bend region of the Romanian Carpathians) were investigated from lithological and micropaleontological (calcareous nannoplankton) points of view. Our investigations revealed that the studied deposits were sedimented within the latest Tithonian-Albian interval. The calcareous nannofossil assemblages of the turbidite calcareous successions (the Sinaia Formation) were assigned to the NJK-?NC5 calcareous nannofossil zones, which cover the Late Tithonian-Early Barremian interval. The sandy-shaly turbidites, which followed the calcareous turbidites of the Sinaia Formation, are Early Barremian-Early Albian in age (interval covered by the ?NC5-NC8 calcareous nannofossil zones). Because the studied deposited are mainly turbidites, many reworked nannofossils from older deposits are present in the calcareous nannofloras. Thus, some biozones (i.e., NC5), defined based on the last occurrences of nannofossils, could not be identified. The calcareous nannofossil assemblages are composed of Tethyan taxa (which dominate the nannofloras) and cosmopolitan taxa. During two intervals (the Late Valanginian and across the Barremian/Aptian boundary), Tethyan and cosmopolitan nannofossils, together with Boreal ones, were observed. This type of mixed calcareous nannoplankton assemblage is indicative for sea-level high-stand, which allows the nannofloral exchange between the Tethyan and Boreal realms, within the two-above mentioned intervals.     

The Lundergård Clay and its Foraminifera, a new formation in the marine Quaternary of Denmark

Knudsen, Karen Luise: The Lundergard Clay and its Foraminifera, a new formation in the marine Quaternary of Denmark. Boreas, Vol. 1, pp. 289–297. Oslo, 1st December, 1972.
Samples from marine Quaternary clay deposits at Lundergård in Vendsyssel have been analysed for their content of Foraminifera. The clay, which is called the Lundergård Clay, contains a typical arctic foraminifer fauna with Quinqueloculina stalkeri and Elphidium ustulatum as characteristic species. To attempt an age determination of the Lundergård Clay, the fauna is compared with foraminifer assemblages from other marine Quaternary deposits of Vendsyssel and adjacent areas. The deposit may represent a hitherto unknown facies of the Older Yoldia Clay of Vendsyssel, which is supposed to be of Weichselian interstadial age, or it may be older and can perhaps be correlated with the Holderness Basement Till of Saale interstadial age.     

The biostratigraphy of the uppermost calcareous nannofossils of Cretaceous deposit in both Shahdar and Namazgah sections (NE Iran)

A moderately various calcareous nannofossil assemblage of 44 species assigned to 24 genera is identified in samples collected from the Shahdar section and 18 genera and 43 species in Namazgah section. Testing of calcareous nannofossil has permitted recognition of few important coccolith events in stratigraphic interval occupied by the uppermost layers of Cretaceous in the Shahdar and Namazgah sections. These events are correlated to the CC24–CC26 of Sissingh (Geol Minjbouw 56: 37–65, 1977) in two sections. According to these biozones, the age of the studied sections in Shahdar and Namazgah is Early Maastrichtian–Late Maastrichtian. On the basis of paleoecological interpretation, the last layers related to the Cretaceous deposits in two sections were deposited in shallow marine environment in relatively low latitude, and the depth of the basin from the Cretaceous deposits toward Fajan Formation is minimized.     

The Global boundary Stratotype Section and Point （GSSP） of the Tortonian Stage （Upper Miocene） at Monte Dei Corvi

The GSSP of the Tortonian Stage, which per definition marks the base of the Tortonian and, hence, the boundary between the Serravallian and Tortonian Stages of the Middle and Upper Miocene Subseries, has recently been defined and ratified by the IUGS. The boundary stratotype-section is Monte dei Corvi (Italy) where the Tortonian GSSP is now formally at the mid-point of the sapropel of small-scale sedimentary cycle no. 76, close to the last common occurrences (LCOs) of the calcareous nannofossil Discoaster kugleri and the planktonic foraminifer Globigerinoides subquadratus and associated with the short normal subchron C5r.2n. The GSSP level coincides closely with oxygen isotope event Mi-5 and the associated glacio-eustatic sea-level low-stand of supercycle T3.1 and concurrent deep-sea hiatus NH4,and is dated astronomically at 11.608 Ma. The Monte Gibliscemi section is accepted as an auxiliary boundary stratotype because the better preservation of the calcareous microfossils in this section enables quantitative analyses and the construction of a stable isotope record.     

Tectonics,sea-level changes and palaeoenvironments in the early Pleistocene of Rome (Italy)

The historical site of the Monte Mario lower Pleistocene succession (Rome, Italy) is an important marker of the Pliocene/Pleistocene boundary. Recently, the Monte Mario site was excavated and restudied. A spectacular angular unconformity characterizes the contact between the Monte Vaticano and the Monte Mario formations, which marks the Pliocene/Pleistocene boundary. Biostratigraphical analyses carried out on ostracod, foraminifer, and calcareous nannofossil assemblages indicate an Early Pliocene age (topmost Zanclean, 3.81–3.70 Ma) for the underlying Monte Vaticano Formation, whereas the Monte Mario Formation has been dated as early Pleistocene (Santernian, 1.66–1.59 Ma). Palaeomagnetic analyses point to C2Ar and C1r2r polarity chrons for the Monte Vaticano and the Monte Mario formations, respectively. The Monte Mario Formation consists of two obliquity-forced depositional sequences (MM1 and MM2) characterized by transgressive systems tracts of littoral marine environments at depths, respectively, of 40–80 m and 15–20 m. The data obtained from foraminifer and ostracod assemblages allow us to reconstruct early Pleistocene relative sea-level changes near Rome. At the Plio/Pleistocene transition, a relative sea-level drop of at least 260 m occurred, as a result of both tectonic uplift of the central Tyrrhenian margin and glacio-eustatic changes linked to early Pleistocene glaciation (Marine Isotope Stage 58).     

Calibration of Early Cretaceous dinoflagellate zones from the NWS of Australia to the global time scale through calcareous nannofossils

Palynomorphs and nannofossils were examined from the Lower Cretaceous interval of the well North Scarborough-1, drilled on the Exmouth Plateau, North West Shelf of Australia. Integration of the chronostratigraphic information from both fossil groups revealed discrepancies in the age information with the nannofossils suggesting a younger age than dinoflagellate cysts. The nannofossil events have a stronger tie to the global time scale than the dinoflagellate zones which are mainly local. The direct comparison of nannofossil and dinoflagellate events in the same section allows for improved stratigraphic precision and a revised correlation of Australian dinoflagellate zonal ages to the global time scale, GTS12. Global nannofossil ages confirm a Barremian–late Hauterivian age for the Muderongia australis Zone, but the Systematophora areolata to Dissimulidinium lobispinosum Zones appear to be 1–2 my younger than previously estimated.     

Evolution of an early Eocene pull‐apart basin in the Central Pontides (Northern Turkey): New insights into the origin of the North Anatolian Shear Zone

Although the North Anatolian Shear Zone is one of the main lithospheric‐scale strike‐slip deformation zone in the world, playing a prominent role in the complex geodynamic interaction among the Eurasian, Anatolian and Arabian plates, the onset time of its activity remains highly controversial. Here, we tackle this issue by utilizing nannofossil biostratigraphy on deposits from the Ta?cilar basin, a pull‐apart basin that we have identified inside the North Anatolian Shear Zone overprinting the Intra‐Pontide suture zone. The syn‐tectonic sedimentary succession of the Ta?cilar basin developed completely during the early Eocene (Ypresian; CNE4–CNE5 Zones). The strike‐slip faulting related to the initial onset of the North Anatolian Shear Zone can likely be constrained within the Ypresian, suggesting that the westward escape of the Anatolian plate along the North Anatolian Shear Zone started in the early Eocene.     

基于斑岩成矿体系结构的深部找矿预测——以鄂东丰山铜金矿田为例

深部找矿预测已成为当前成矿学和成矿预测学的科学前沿和研究重点.近年来,在丰山矿田找矿研究中,不但发现了卡林型金矿和一些新的找矿线索,而且还取得一些对矿田成矿的新认识.这些新发现和新认识,为建立完善的斑岩成矿体系三维准实体模型和深部找矿预测提供了新的机遇和条件.矿田包括夕卡岩型铜金矿、斑岩型铜钼矿、热液脉型多金属(金)矿和卡林型金矿等矿床类型,它们常与燕山期花岗闪长斑岩相伴,是在同一成矿系统中形成的斑岩成矿系列,松弛化的推覆构造控制矿田成岩成矿作用.矿田斑岩成矿体系结构在矿床类型等方面具有明显的分带性,利用这种分带性,优选找矿靶区和找矿方法,确定找矿靶位,经工程验证于深部发现铜金工业矿体.