scispace - formally typeset
Search or ask a question

Showing papers on "Foraminifera published in 2007"


Journal ArticleDOI
17 May 2007-Nature
TL;DR: New data from recent sampling expeditions in the deep Weddell Sea and adjacent areas reveal high levels of new biodiversity, challenging suggestions that deep-sea diversity is depressed in the Southern Ocean and providing a basis for exploring the evolutionary significance of the varied biogeographic patterns observed in this remote environment.
Abstract: Shallow marine benthic communities around Antarctica show high levels of endemism, gigantism, slow growth, longevity and late maturity, as well as adaptive radiations that have generated considerable biodiversity in some taxa. The deeper parts of the Southern Ocean exhibit some unique environmental features, including a very deep continental shelf and a weakly stratified water column, and are the source for much of the deep water in the world ocean. These features suggest that deep-sea faunas around the Antarctic may be related both to adjacent shelf communities and to those in other oceans. Unlike shallow-water Antarctic benthic communities, however, little is known about life in this vast deep-sea region. Here, we report new data from recent sampling expeditions in the deep Weddell Sea and adjacent areas (748-6,348 m water depth) that reveal high levels of new biodiversity; for example, 674 isopods species, of which 585 were new to science. Bathymetric and biogeographic trends varied between taxa. In groups such as the isopods and polychaetes, slope assemblages included species that have invaded from the shelf. In other taxa, the shelf and slope assemblages were more distinct. Abyssal faunas tended to have stronger links to other oceans, particularly the Atlantic, but mainly in taxa with good dispersal capabilities, such as the Foraminifera. The isopods, ostracods and nematodes, which are poor dispersers, include many species currently known only from the Southern Ocean. Our findings challenge suggestions that deep-sea diversity is depressed in the Southern Ocean and provide a basis for exploring the evolutionary significance of the varied biogeographic patterns observed in this remote environment.

454 citations


Book ChapterDOI
Ellen Thomas1
01 Jan 2007
TL;DR: In this article, the extinction of deep-sea benthic foraminifera was linked to a global feature of the end-Paleocene environmental change, i.e., rapid global warming.
Abstract: Deep-sea benthic foraminifera live in the largest habitat on Earth, constitute an important part of its benthic biomass, and form diverse assemblages with common cosmopolitan species. Modern deep-sea benthic foraminiferal assemblages are strongly infl uenced by events affecting their main food source, phytoplankton (a relationship known as bentho-pelagic coupling). Surprisingly, benthic foraminifera did not suffer signifi cant extinction at the end of the Cretaceous, when phytoplankton communities underwent severe extinction. Possibly, bentho-pelagic coupling was less strong than today in the warm oceans of the Cretaceous‐Paleogene, because of differences in the process of food transfer from surface to bottom, or because more food was produced chemosynthetically on the seafl oor. Alternatively, after the end-Cretaceous extinction the food supply from the photic zone recovered in less time than previously thought. In contrast, deep-sea benthic foraminifera did undergo severe extinction (30%‐50% of species) at the end of the Paleocene, when planktic organisms show rapid evolutionary turnover, but no major extinction. Causes of this benthic extinction are not clear: net extinction rates were similar globally, but there is no independent evidence for global anoxia or dysoxia, nor of globally consistent increase or decrease in productivity or carbonate dissolution. The extinction might be linked to a global feature of the end-Paleocene environmental change, i.e., rapid global warming. Cenozoic deep-sea benthic faunas show gradual faunal turnover during periods of pronounced cooling and increase in polar ice volume: the late Eocene‐early Oligocene, the middle Miocene, and the middle Pleistocene. During the latter turnover, taxa that decreased in abundance during the earlier two turnovers became extinct, possibly because of increased oxygenation of the oceans, or because of increased seasonality in food delivery. The Eocene-Oligocene was the most extensive of these turnovers, and benthopelagic coupling may have become established at that time.

252 citations



Journal ArticleDOI
TL;DR: This article used brachiopods of Ordovician to Cretaceous age, complemented by published data from belemnites and planktonic foraminifera, to reconstruct the evolution of calcium isotope composition of seawater over the Phanerozoic.

221 citations


Journal ArticleDOI
TL;DR: In this article, foraminiferal assemblages of pre-tsunami and tsunami sediment from the Indian Ocean Tsunami at five sites along the Malaysia-Thailand Peninsula were analyzed to gain information on tsunami sediment source and deposition style.

192 citations


Book ChapterDOI
01 Jan 2007
TL;DR: In this paper, the authors focus on the planktonic foraminifera as tracers of past oceanic environments and highlight the most common and most promising foraminiferal proxies and puts them in the context of modern biological knowledge.
Abstract: Publisher Summary This chapter focuses on the planktonic foraminifera as tracers of past oceanic environments. Paleoceanography has always been closely connected with the study of planktonic foraminifera. The prolific production and excellent preservation of foraminiferal fossils in oceanic sediments has produced probably the best fossil record on Earth, providing unparalleled archives of morphological change, faunal variations, and habitat characteristics. Planktonic foraminifera are the most common source of paleoceanographic proxies, be it through the properties of their fossil assemblages or as a substrate for extraction of geochemical signals. The steady rain of foraminiferal shells is responsible for the deposition of a large portion of deep-sea biogenic carbonate. Stable isotopic signals extracted from planktonic foraminifera soon became a standard tool for the recognition of glacial cycles and eventually facilitated the recognition of orbital pacing of the ice-ages. The chemical composition of foraminiferal calcite proved to be a fertile ground for the development of proxies. The chapter highlights the most common and most promising foraminiferal proxies and puts them in the context of modern biological knowledge.

190 citations


Journal ArticleDOI
TL;DR: The general biodiversity patterns of meio-, macro- and megafaunal taxa are described, based on historical and recent expeditions, and against the background of the geological events and phylogenetic relationships that have influenced the biodiversity and evolution of the investigated taxa.
Abstract: Our knowledge of the biodiversity of the Southern Ocean (SO) deep benthos is scarce. In this review, we describe the general biodiversity patterns of meio-, macro- and megafaunal taxa, based on historical and recent expeditions, and against the background of the geological events and phylogenetic relationships that have influenced the biodiversity and evolution of the investigated taxa. The relationship of the fauna to environmental parameters, such as water depth, sediment type, food availability and carbonate solubility, as well as species interrelationships, probably have shaped present-day biodiversity patterns as much as evolution. However, different taxa exhibit different large-scale biodiversity and biogeographic patterns. Moreover, there is rarely any clear relationship of biodiversity pattern with depth, latitude or environmental parameters, such as sediment composition or grain size. Similarities and differences between the SO biodiversity and biodiversity of global oceans are outlined. The high percentage (often more than 90%) of new species in almost all taxa, as well as the high degree of endemism of many groups, may reflect undersampling of the area, and it is likely to decrease as more information is gathered about SO deep-sea biodiversity by future expeditions. Indeed, among certain taxa such as the Foraminifera, close links at the species level are already apparent between deep Weddell Sea faunas and those from similar depths in the North Atlantic and Arctic. With regard to the vertical zonation from the shelf edge into deep water, biodiversity patterns among some taxa in the SO might differ from those in other deep-sea areas, due to the deep Antarctic shelf and the evolution of eurybathy in many species, as well as to deep-water production that can fuel the SO deep sea with freshly produced organic matter derived not only from phytoplankton, but also from ice algae.

179 citations


Journal ArticleDOI
TL;DR: In this article, the changes in flow and character of the warm Atlantic Water through the last 17,500-cal-yr are reconstructed from the distribution of benthic foraminifera species, planktonic and benthically foraminifiera abundances, stable oxygen isotopes and lithology in two cores from the western and northern shelf of Svalbard.

176 citations


Journal Article
TL;DR: The Adriatic Carbonate Platform (AdCP) was a separate shallow marine depositional system characterized by a lack of terrigenous input and was connected to Gondwana towards the South via Gavrovo- Tripolitza or Apulia as discussed by the authors.
Abstract: The Adriatic Carbonate Platform (AdCP), was a separate shallowmarine depositional system characterized by a lack of terrigenous input and was connected to Gondwana towards the South via Gavrovo– Tripolitza or Apulia. It existed for approximately 120 MY, from the Early Jurassic (Pliensbachian/Toarcian) to the end of the Cretaceous, resulting in a 4000– 6500 m thick succession of almost pure carbonates. However, this is part of a thicker (>8000 m) sequence of predominantly carbonate rocks which forms the Karst Dinarides, and was deposited during more than 270 MY – at least from the Carboniferous (Moscovian) to the Late Eocene. Among many different groups of fossil organisms, benthic foraminifera are especially abundant and well preserved, so they, along with calcareous algae (Dasycladales), are the most important fossils used for age determination and stratigraphic subdivision of shallowmarine carbonate deposits. Within the 257 determined taxa belonging to different foraminiferal families which lived through the Mesozoic, numerous different index fossils occur in assemblages indicating various ages: Early Triassic, Anisian, Carnian, Norian– Rhaetian, Late Sinemurian, Early and Late Pliensbachian (Carixian and Domerian), Early and Late Aalenian, Early and Late Bajocian, Early and Late Bathonian, Callovian, Early and Late Oxfordian, Kimmeridgian, Tithonian, Berriasian, Valanginian, Late Hauterivian, Late Barremian, Early and Late Aptian (Bedulian and Gargasian), Early and Late Albian, Early, Middle and Late Cenomanian, Turonian, Coniacian, Santonian, Early and Late Campanian and Early and Late Maastrichtian. A total of 64 biostratigraphic units – biozones of different categories, from subzone to superzone, were defined within the stratigraphic interval from the Carnian to the Late Maastrichtian. This enabled very detailed biostratigraphic subdivision of the carbonate deposits within the Karst Dinarides. This is one of the most precise sequences, not only in this area, but also among former shallow marine deposits of the entire Neotethyan realm in the present Mediterranean region. The palaeobiogeographic characteristics of biotopes and the composition of foraminiferal assemblages during the Mesozoic were controlled by the position of the study area within the Neotethyan bioprovinces. Until the Albian, this area represented part of the Southern Neotethyan bioprovince, while from the Cenomanian to its final disintegration at the end of the Cretaceous it belonged to a separate, Central Mediterranean Neotethyan bioprovince.

171 citations


01 Jan 2007
TL;DR: In this paper, the use of organic-walled Dinoflagellate Cysts as tracers of sea surface conditions has been studied for reconstructing Cenozoic seawater paleotemperatures from calcareous fossils.
Abstract: Introduction: Paleoceanography, tracers, proxies and methods (C. Hillaire-Marcel, A. de Vernal). Part 1 : Deep Sea Sediment Properties. 1. Deep-sea sediment deposits and properties controlled by currents (I.N. McCave). 2. Continuous physical properties of cored marine sediments (G. St.Onge et al). 3. Magnetic stratigraphy in paleoceanography: reversals, excursions, paleointensity and secular variation (J. Stoner, G. St. Onge). 4. Clay minerals, deep circulation and climate (N. Fagel). 5. Radiocarbon dating of deep-sea sediments (K.A. Hughen). Part 2: Biological tracers and biomarkers. 6. Planktonic foraminifera as tracers of past oceanic environments (M. Kucera). 7. Paleoceanographical proxies based on deep-sea benthic foraminiferal assemblage characteristics (F. Jorissen, C. Fontanier, R. Thomas). 8. Diatoms: From Micropaleontology to Isotope Geochemistry (X. Crosta, N. Koc). 9. Organic-walled Dinoflagellate Cysts: Tracers of sea-surface conditions (A. de Vernal, F. Marret). 10. Coccolithophores: From extant populations to fossil assemblages (J. Giraudeau, L. Beaufort). 11. Biomarkers as paleoceanographic proxies (A. Rosell-Mele, E. McClymont). 12. Deep-sea corals: New Insights to paleoceanography (O.A. Sherwood, M.J. Risk). 13. Transfer functions - Methods for quantitative paleoceanography based on microfossils (J. Guiot, A. de Vernal). Part 3: Geochemical tracers. 14. Elemental Proxies for Palaeoclimatic and Palaeoceanographic Variability in Marine Sediments: Interpretation and Application (S. Calvert, T. Pedersen). 15. Isotopic tracers of water masses and deep currents (C. Claude, B. Hamelin). 16. Paleoflux and Paleocirculation from Sediment 230Th and 231Pa/230Th (R. Francois). 17. Boron Isotopes in Marine Carbonate Sediments and the pH of the Ocean (N.G. Hemming, B. Honisch). 18. The Use of Oxygen and Carbon Isotopes of Foraminifera in Paleoceanography (A.C. Revelo, C. Hillaire-Marcel). 19. Elemental proxies for reconstructing Cenozoic seawater paleotemperatures from calcareous fossils (Y. Rosenthal). Conclusion: Reconstructing and modelling past oceans (K. Meissner).

163 citations


Journal ArticleDOI
TL;DR: In this paper, the authors review the current understanding of foraminiferal production and taphonomic loss in intertidal environments, and examine the extent to which these processes can affect the development of the foraminifera assemblages.

Journal ArticleDOI
TL;DR: In this paper, the authors evaluate sediment-trap flux data from an array of 13 moorings (15 traps) situated in diverse conditions and with global coverage, all for organic carbon flux, calculated coccolith-carbonate flux, and fine fraction flux (when available).
Abstract: There exists a great need to better understand the controls on organic carbon sequestration to the deep sea, by virtue of its role in modulating atmospheric CO 2 concentrations. Recent studies suggest that organic fluxes to the oceanic interior are higher in regions dominated by carbonate sedimentation, thus also concluding that relatively heavy carbonate particles are an effective mineral ballast for organic carbon. CaCO 3 production in the pelagic ocean is mainly mediated by foraminifera and coccolithophores, but the precise role of these carbonate producers as mineral ballast for organic carbon in the ocean has not yet been tested. Here we evaluate sediment-trap flux data from an array of 13 moorings (15 traps) situated in diverse conditions and with global coverage, all for organic carbon flux, calculated coccolith-carbonate flux, and fine fraction flux (when available). Discrepancies are recorded between the amount of carbonate fine fraction and calculated coccolith carbonate, and there is the need to determine the origin of the unknown CaCO 3 in the fine fraction. The coccolith-carbonate flux magnitude is determined not only by the coccolith flux number but also by the carbonate mass of the key species. For example, very abundant coccolithophore species such as Emiliania huxleyi have a very low species-specific carbonate mass, and are therefore of lower carbonate flux significance than expected intuitively. Among the main coccolith carbonate species contributors in our sediment-trap sites are Calcidiscus leptoporus and Helicosphaera carteri, in that these are all relatively massive compared to their numerical abundances. We observed generally positive correlations between calculated coccolith carbonate and organic carbon daily fluxes, suggesting that on a global basis there is a ballasting mechanism at work, seemingly most efficiently with C. leptoporus in the carbonate-dominated North Atlantic. A fairly constant global relationship between annual fluxes of calculated coccolith carbonate and organic carbon implies some uniformity in the PIC/POC “rain ratio”. However, improvements in coccolith carbonate estimation are needed to not only understand this ratio currently, but also to help understand future sequestration of organic carbon to the oceanic interior.

Journal ArticleDOI
TL;DR: Molecular evidence for exceptionally wide distribution of benthic foraminifera, which constitute the major part of deep‐sea meiofauna, support the hypothesis of global distribution of small eukaryotes and suggest thatDeep‐sea biodiversity may be more modest at global scales than present estimates suggest.
Abstract: Despite its often featureless appearance, the deep-ocean floor includes some of the most diverse habitats on Earth. However, the accurate assessment of global deep-sea diversity is impeded by a paucity of data on the geographical ranges of bottom-dwelling species, particularly at the genetic level. Here, we present molecular evidence for exceptionally wide distribution of benthic foraminifera, which constitute the major part of deep-sea meiofauna. Our analyses of nuclear ribosomal RNA genes revealed high genetic similarity between Arctic and Antarctic populations of three common deep-sea foraminiferal species (Epistominella exigua, Cibicides wuellerstorfi and Oridorsalis umbonatus), separated by distances of up to 17 000 km. Our results contrast with the substantial level of cryptic diversity usually revealed by molecular studies, of shallow-water benthic and planktonic marine organisms. The very broad ranges of the deep-sea foraminifera that we examined support the hypothesis of global distribution of small eukaryotes and suggest that deep-sea biodiversity may be more modest at global scales than present estimates suggest.

Journal ArticleDOI
TL;DR: The new genetic data reveal a pattern of Arctic circumpolar isolation and bipolar asymmetry between the Atlantic and Pacific Oceans, and show that the ancestry of North Pacific N. pachyderma is relatively recent.
Abstract: The high-latitude planktonic foraminifera have proved to be particularly useful model organisms for the study of global patterns of vicariance and gene flow in the oceans. Such studies demonstrate that gene flow can occur over enormous distances in the pelagic marine environment leading to cosmopolitanism but also that there are ecological and geographical barriers to gene flow producing biogeographic structure. Here, we have undertaken a comprehensive global study of genetic diversity within a marine protist species, the high-latitude planktonic foraminiferan Neogloboquadrina pachyderma. We present extensive new data sets from the North Pacific and Arctic Oceans that, in combination with our earlier data from the North Atlantic and Southern Oceans, allow us to determine the global phylogeography of this species. The new genetic data reveal a pattern of Arctic circumpolar isolation and bipolar asymmetry between the Atlantic and Pacific Oceans. We show that the ancestry of North Pacific N. pachyderma is relatively recent. It lies within the upwelling systems and subpolar waters of the Southern Hemisphere and remarkably not within the neighboring Arctic Ocean. Instead, the Arctic Ocean population forms a genetic continuum with the North Atlantic population, which became isolated from the southern populations much earlier, after the onset of Northern hemisphere glaciation. Data from the planktonic foraminiferal morphospecies Globigerina bulloides is also introduced to highlight the isolation and endemism found within the subpolar North Pacific gyre. These data provide perspective for interpretation and discussion of global gene flow and speciation patterns in the plankton.

Journal ArticleDOI
TL;DR: A multiproxy record including benthic foraminifera, diatoms and XRF data of a marine sediment core from a SW Greenland fjord provides a detailed reconstruction of the oceanographic and climatic var... as discussed by the authors.
Abstract: A multiproxy record including benthic foraminifera, diatoms and XRF data of a marine sediment core from a SW Greenland fjord provides a detailed reconstruction of the oceanographic and climatic var...

Journal ArticleDOI
TL;DR: In this article, the OMEX core KSGX 40 of the Galicia Mud Deposit, of the NW Iberian outer continental shelf, off the Ria de Vigo (North of Spain) was used to study textural, mineralogical, geochemical, and microfaunal data (benthic foraminifera) along with the BFOI data.

Journal ArticleDOI
TL;DR: In this paper, the authors measured the oxygen isotopic composition of eight species of planktonic foraminifera (pink and white varieties of Globigerinoides ruber and sacculifer without the final chamber) in surface sediment samples from 31 tropical Atlantic deep-sea sediment cores.
Abstract: [1] Past variability in upper ocean thermocline depth is commonly estimated from the abundance of different species of planktonic organisms or the difference in oxygen isotopic composition between two species of planktonic foraminifera, one that lives in the mixed layer and one that lives in or near the thermocline. To test the latter relationships, we measured the oxygen isotopic composition of eight species of planktonic foraminifera (pink and white varieties of Globigerinoides ruber, Globigerinoides sacculifer without the final chamber, Orbulina universa, Pulleniatina obliquiloculata, Globorotalia menardii, Neogloborotalia dutertrei, and Globorotalia tumida) in surface sediment samples from 31 tropical Atlantic deep-sea sediment cores. Bayesian analysis was used to compare measured oxygen isotopic compositions with their predictions based on modern data sets of annual temperatures and oxygen isotopic composition of ocean water in the upper 500 m at the core sites. Posterior probability densities for predictive model parameters were computed. Probability distributions of calcification depth for analyzed species corroborated their ecological preferences inferred from net tow and sediment trap data. Robustness of the habitat signals in core top specimens suggests that reconstructions of the entire upper ocean temperature profiles, not just their thermocline depth or temperature, might be possible.

Journal ArticleDOI
TL;DR: The most expanded records consistently show a bimodal isotope distribution pattern regardless of location, water depth or depositional facies, which suggests one of several possibilities: the isotopic composition of the surface ocean/atmosphere declined in a geologic instant.
Abstract: The Palaeocene-Eocene thermal maximum (PETM) is characterized by a global negative carbon isotope excursion (CIE) and widespread dissolution of seafloor carbonate sediments. The latter feature supports the hypothesis that the PETM and CIE were caused by the rapid release of a large mass (greater than 2000Gt C) of 12C-enriched carbon. The source of this carbon, however, remains a mystery. Possible sources include volcanically driven thermal combustion of organic-rich sediment, dissociation of seafloor methane hydrates and desiccation and oxidation of soil/sediment organics. A key constraint on the source(s) is the rate at which the carbon was released. Fast rates would be consistent with a catastrophic event, e.g. massive methane hydrate dissociation, whereas slower rates might implicate other processes. The PETM carbon flux is currently constrained by high-resolution marine and terrestrial records of the CIE. In pelagic bulk carbonate records, the onset of the CIE is often expressed as a single- or multiple-step excursion extending over 10(4) years. Individual planktonic shell records, in contrast, always show a single-step CIE, with either pre-excursion or excursion isotope values, but no transition values. Benthic foraminifera records, which are less complete owing to extinction and diminutive assemblages, show a delayed excursion. Here, we compile and evaluate the individual planktonic shell isotope data from several localities. We find that the most expanded records consistently show a bimodal isotope distribution pattern regardless of location, water depth or depositional facies. This suggests one of several possibilities: (i) the isotopic composition of the surface ocean/atmosphere declined in a geologic instant (<500yr), (ii) that during the onset of the CIE, most shells of mixed-layer planktonic foraminifera were dissolved, or (iii) the abundances or shell production of these species temporarily declined, possibly due to initial pH changes.

Journal ArticleDOI
TL;DR: A moderately diverse larger foraminiferal fauna from the north-east Italian ‘Arenarie e calcari di S. Urbano’ formation with important stratigraphic, palaeoecological and palaeobiogeographical implications is described with respect to its position in the Western Tethys area as mentioned in this paper.
Abstract: A moderately diverse larger foraminiferal fauna from the north-east Italian ‘Arenarie e calcari di S. Urbano’ formation with important stratigraphic, palaeoecological and palaeobiogeographical implications is described with respect to its position in the Western Tethys area. The fauna is dominated by hyaline perforated and porcellaneous forms including Amphistegina, Archaias, Austrotrillina, Miogypsinoides, Neoplanorbulinella, Neorotalia, Nummulites, Operculina and Spiroclypeus. The presence of Miogypsinoides complanatus allows the age of the formation to be determined as late Chattian (Shallow Benthic Zone SBZ 23). The palaeoenvironmental setting is interpreted as a shallow ramp environment ranging from (1) well lit, highly translucent, shallowest part of the photic zone characterized by Archaias and Austrotrillina, the deeper part of the inner ramp with Nummulites, to (2) the shallow part of the middle ramp with Spiroclypeus and miogypsinids and Operculina, to (3) a deeper middle-ramp setting dominated by coralline rhodoliths along with lepidocylinids. The presence of Archaias hensoni Smout and Eames shows that members of much more diverse Middle Eastern associations of shallow-water larger porcellaneous foraminifera are also present in the north-western parts of the Western Tethys, and reveals a corresponding diversity gradient among larger foraminiferal faunas in the Western Tethys, which is related to a decrease in temperature.

Journal ArticleDOI
TL;DR: In this paper, continuous marine strata spanning the boundary are exposed at Csővar, Hungary, where new integrated stratigraphic data were obtained from multidisciplinary investigations to help reconstruct the end-Triassic and early Jurassic events.

Journal ArticleDOI
TL;DR: The Oligocene-Miocene Asmari Formation of the Zagros Basin is a thick sequence of shallow water carbonate as mentioned in this paper, which is subdivided into 14 microfacies based on their depositional textures, petrographic analysis and fauna.

Journal ArticleDOI
TL;DR: In this paper, specific responses of the regional deep-sea ecosystems to climatic and oceanographic processes during the last 22kyr are revealed by benthic foraminiferal faunas from two cores in the northern and southern Aegean Sea.

Journal ArticleDOI
01 Feb 2007-Geology
TL;DR: In this article, the evolution of the low-to-middle-latitude thermal gradient between the middle Cretaceous climatic optimum and the cooler latest Creta period was investigated using oxygen isotope composition of fossil fish teeth.
Abstract: The oxygen isotope composition of fossil fish teeth, a paleo–upper ocean temperature proxy exceptionally resistant to diagenetic alteration, provides new insight on the evolution of the low- to middle-latitude thermal gradient between the middle Cretaceous climatic optimum and the cooler latest Cretaceous period. The new middle Cretaceous low to middle latitude thermal gradient agrees with that previously inferred from planktonic foraminifera δ 18 O recovered from Deep Sea Drilling Project and Ocean Drilling Program drilling sites, although the isotopic temperatures derived from δ 18 O of fish teeth are uniformly higher by ∼3–4 °C. In contrast, our new latest Cretaceous thermal gradient is markedly steeper than those previously published for this period. Fish tooth δ 18 O data demonstrate that low- to middle-latitude thermal gradients of the middle Cretaceous climatic optimum and of the cooler latest Cretaceous are similar to the modern one, despite a cooling of 7 °C between the two periods. Our new results imply that no drastic changes in meridional heat transport are required to explain the Late Cretaceous climate. Based on climate models, such a cooling without any change in the low to mid- decrease dle latitude thermal gradient supports an atmospheric CO 2 as the primary driver of the climatic evolution recorded during the Late Cretaceous.

Journal ArticleDOI
TL;DR: In this article, the authors constructed an orbital-scale stratigraphy of the sediments covering the last 640kyr by comparing the SPECMAP ∂18O curve and the ∂ 18O curve of planktonic foraminifera (∂18Opf) in the Japan Sea together with the combination zones of dominant planktonics foraminifa species.

Journal ArticleDOI
TL;DR: In this article, high-resolution records of planktonic foraminifera and oxygen isotopes from two sediment cores, A7 and E017, in the middle Okinawa Trough reveal strong and rapid millennial-scale climate changes since similar to 18 to 17 thousand years before present (kyr B.P.).

Journal ArticleDOI
TL;DR: In this paper, living (rose Bengal stained) benthic foraminifera were investigated from thirteen stations ranging from 146-4976m water depth in the Nazare Canyon, located on the Western Iberian continental margin.

Journal ArticleDOI
28 Apr 2007-Facies
TL;DR: In this paper, a detailed palaeoenvironmental model is presented for the Gavrovo-Tripolitza area (southern continental Greece), where marine carbonate platforms existed from the Late Triassic to the Late Eocene.
Abstract: Within the Gavrovo–Tripolitza area (southern continental Greece), marine carbonate platforms existed from the Late Triassic to the Late Eocene. The Middle–Upper Eocene marine shallow-water carbonates of the Klokova Mountain represent remnants of the large volumes of sediment that were produced on a middle ramp sedimentary system which culminated in the Lower Oligocene terrigenous deposits. Facies analysis of Bartonian–Priabonian shallow-water carbonate successions and the integration with palaeoecological analysis are used to produce a detailed palaeoenvironmental model. In the proximal middle ramp, porcelaneous foraminiferal packstone facies is characterised by larger foraminifera such as Praturlonella and Spirolina. These forms thrived in a shallow-water setting with low turbidity, high-light intensity and low-substrate stability. The foraminiferal packstone facies, the thin coralline wacke–packstone facies and the rhodolith packstone facies deposited approximately in the same depth range adjacent to one another in the middle-ramp. Nummulitids (Nummulites, Assilina, Pellatispira, Heterostegina and Spiroclypeus) increase in abundance in the middle to distal mid-ramp together with the orthophragminids. Coralline algae, represented by six genera, are present in all facies. Rhodoliths occur in all facies but they show different shapes and growth forms. They develop laminar sub-ellipsoidal shapes in higher turbulence conditions on mobile sand substrates (foraminiferal packstones and rhodolith rudstones), whilst sub-discoidal shapes often bound by thin encrusting coralline plants in lower hydrodynamic settings. The distinctive characteristics of the palaeoecological middle-ramp gradient are an increase in dominance of melobesioids, a thinning of the encrusting coralline plants and a flattening of the larger benthic foraminiferal shells.

Journal ArticleDOI
TL;DR: The authors investigated census-based techniques for determining the distribution and carbonate production of reef organisms on an emergent platform in central Torres Strait, Australia, and compared the contemporary budget with geological findings to infer shifts in reef productivity over the late Holocene.
Abstract: Complex relationships exist between tropical reef ecology, carbonate (CaCO3) production and carbonate sinks. This paper investigated census-based techniques for determining the distribution and carbonate production of reef organisms on an emergent platform in central Torres Strait, Australia, and compared the contemporary budget with geological findings to infer shifts in reef productivity over the late Holocene. Results indicate that contemporary carbonate production varies by several orders of magnitude between and within the different reef-flat sub-environments depending on cover type and extent. Average estimated reef-flat production was 1.66 ± 1.78 kg m−2 year−1 (mean ± SD) although only 23% of the area was covered by carbonate producers. Collectively, these organisms produce 17,399 ± 18,618 t CaCO3 year−1, with production dominated by coral (73%) and subordinate contributions by encrusting coralline algae (18%) articulated coralline algae, molluscs, foraminifera and Halimeda (<4%). Comparisons between the production of these organisms across the different reef-flat zones, surface sediment composition and accumulation rates calculated from cores indicate that it is necessary to understand the spatial distribution, density and production of each major organism when considering the types and amounts of carbonate available for storage in the various reef carbonate sinks. These findings raise questions as to the reliability of using modal production rates in global models independent of ecosystem investigation, in particular, indicating that current models may overestimate reef productivity in emergent settings.

Journal ArticleDOI
TL;DR: In ecological studies involving the analysis of living (stained) individual tests, to date ∼ 2140 species of benthic foraminifera have been recorded, of these 602 species are agglutinated, 341 porcelaneous and 1197 hyaline.

Journal ArticleDOI
TL;DR: Benthic foraminifera showed that short-term biochemical changes in the sediment are toxic and may be involved in the summer mortality of Pacific oysters.