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Datasets with PANGAEA technical keyword @paleoclimate

Mostrando recursos 1 - 20 de 598

  1. Stable isotope ratios on corals from the Philippines

    Pätzold, Jürgen
    Mit Hilfe der Verteilung stabiler Sauerstoff- und Kohlenstoff-Isotope im Skelett hermatyper Korallen von den Philippinen lassen sich frühere Umweltbedingungen rekonstruieren. Die massive Koralle Porites lobata zeigt saisonale Wachstumsbänder unterschiedlicher Skelettdichte, die durch Röntgenaufnahmen sichtbar gemacht werden können und eine Datierung sowie eine gezielte Probennehme für Isotopen-Analysen ermöglichen. Skelettbänder hoher Dichte werden im Sommer und Bereiche geringer Dichte im Winter gebildet. In den Sauerstoff-Isotopen-Verhältnissen werden die Temperaturen des Oberflächenwassers gespeichert. Die heutige saisonale Schwankung der Wassertemperatur von 4°C kann genau aufgelöst werden. Die Abweichung von thermodynamischen Gleichgewichtsbedingungen ist weitgehend konstant und scheint artspezifisch zu sein. Eine Beziehung zwischen Sauerstoff-Isotopen-Verteilung und Wachstumsraten ist nachweisbar,...

  2. Nd, Pb, and Be isotopes of ferromanaganese crusts of the South Pacific

    van de Flierdt, Tina; Frank, Martin; Halliday, Alex N; Hein, James R; Hattendorf, Bodo; Günther, Detlef; Kubik, Peter W
    The application of radiogenic isotopes to the study of Cenozoic circulation patterns in the South Pacific Ocean has been hampered by the fact that records from only equatorial Pacific deep water have been available. We present new Pb and Nd isotope time series for two ferromanganese crusts that grew from equatorial Pacific bottom water (D137-01, 'Nova', 7219 m water depth) and southwest Pacific deep water (63KD, 'Tasman', 1700 m water depth). The crusts were dated using 10Be/9Be ratios combined with constant Co-flux dating and yield time series for the past 38 and 23 Myr, respectively. The surface Nd and Pb...

  3. Nd, Pb, and Be isotopes of ferromanaganese crusts of the Atlantic Ocean

    Frank, Martin; van de Flierdt, Tina; Halliday, Alex N; Kubik, Peter W; Hattendorf, Bodo; Günther, Detlef
    The isotopic composition of Nd in present-day deep waters of the central and northeastern Atlantic Ocean is thought to fingerprint mixing of North Atlantic Deep Water with Antarctic Bottom Water. The central Atlantic Romanche and Vema Fracture Zones are considered the most important pathways for deep water exchange between the western and eastern Atlantic basins today. We present new Nd isotope records of the deepwater evolution in the fracture zones obtained from ferromanganese crusts, which are inconsistent with simple water mass mixing alone prior to 3 Ma and require additional inputs from other sources. The new Pb isotope time series...

  4. Age determination and sea-surface reconstruction of sediment cores from the Norwegian Sea

    Dolven, J K; Cortese, Giuseppe; Bjorklund, Kjell R
    Polycystine radiolarians are used to reconstruct summer sea surface temperatures (SSSTs) for the Late Pleistocene-Holocene (600-13,400 14C years BP) in the Norwegian Sea. At 13,200 14C years BP, the SSST was close to the average Holocene SSST (~12°C). It then gradually dropped to 7.1°C in the Younger Dryas. Near the Younger Dryas-Holocene transition (~10,000 14C years BP), the SSST increased 5°C in about 530 years. Four abrupt cooling events, with temperature drops of up to 2.1°C, are recognized during the Holocene: at 9340, 7100 ("8200 calendar years event"), 6400 and 1650 14C years BP. Radiolarian SSSTs and the isotopic signal...

  5. Stable oxygen isotope record of corales from the Red Sea

    Al-Rousan, Saber; Al-Moghrabi, Salim M; Pätzold, Jürgen; Wefer, Gerold
    In order to assess the ability of Porites corals to accurately record environmental variations, high-resolution (weekly/biweekly) coral delta18O records were obtained from four coral colonies from the northern Gulf of Aqaba, which grew at depths of 7, 19, 29, and 42 m along one transect. Adjacent to each colony, hourly temperatures, biweekly salinities, and monthly delta18O of seawater were continuously recorded over a period of 14 months (April 1999 to June 2000). Contrary to water temperature, which shows a regular and strong seasonal variation and change with depth, seawater delta18O exhibits a weak seasonality and little change with depth. Positive...

  6. Growth rates and stable carbon and oxygen isotope record of corals from the Red Sea

    Al-Rousan, Saber; Al-Moghrabi, Salim M; Pätzold, Jürgen; Wefer, Gerold
    Monthly delta18O records of 2 coral colonies (Porites cf. lutea and P. cf. nodifera) from different localities (Aqaba and Eilat) from the northern Gulf of Aqaba, Red Sea, were calibrated with recorded sea surface temperatures (SST) between 1988 and 2000. The results show high correlation coefficients between SST and delta18O. Seasonal variations of coral delta18O in both locations could explain 91% of the recorded SST. Different delta18O/SST relations from both colonies and from the same colonies were obtained, indicating that delta18O from coral skeletons were subject to an extension rate effect. Significant delta18O depletions are associated with high extension rates...

  7. Geochemical characterization of black shales from the Tarfaya Basin

    Kolonic, Sadat; Sinninghe Damsté, Jaap S; Böttcher, Michael E; Kuypers, Marcel MM; Kuhnt, Wolfgang; Beckmann, Britta; Scheeder, Georg; Wagner, Thomas
    Organic geochemical and petrological investigations were carried out on Cenomanian/Turonian black shales from three sample sites in the Tarfaya Basin (SW Morocco) to characterize the sedimentary organic matter. These black shales have a variable bulk and molecular geochemical composition reflecting changes in the quantity and quality of the organic matter. High TOC contents (up to 18wt%) and hydrogen indices between 400 and 800 (mgHC/gTOC) indicate hydrogen-rich organic matter (Type I-II kerogen) which qualifies these laminated black shale sequences as excellent oil-prone source rocks. Low Tmax values obtained from Rock-Eval pyrolysis (404-425 MC) confirm an immature to early mature level of...

  8. Nd and Pb isotopes in ferromanganese crusts

    Frank, Martin; Whiteley, N; Kasten, Sabine; Hein, James R; O'Nions, R K
    The intensity of North Atlantic Deep Water (NADW) production has been one of the most important parameters controlling the global thermohaline ocean circulation system and climate. Here we present a new approach to reconstruct the overall strength of NADW export from the North Atlantic to the Southern Ocean over the past 14 Myr applying the deep water Nd and Pb isotope composition as recorded by ferromanganese crusts and nodules. We present the first long-term Nd and Pb isotope time series for deep Southern Ocean water masses, which are compared with previously published time series for NADW from the NW Atlantic...

  9. Calcareous dinoflagellate cycst in the mid-Cenomanian Boreal realm

    Wendler, Jens E; Gräfe, Kai-Uwe; Willems, Helmut
    A transect from the bathyal to proximal shelf facies of the Boreal Realm was investigated to compare spatial and temporal distribution changes of calcareous dinoflagellate cysts (c-dinocysts) throughout the mid-Cenomanian in order to gain information on the ecology of these organisms. Pithonelloideae dominated the cyst assemblages to more than 95% on the shelf, a prevalence that can be observed throughout most of the Upper Cretaceous. The affinity of this group with the dinoflagellates, which is still controversially discussed, can be confirmed, based on evidence from morphological features and distribution patterns. The consistent prevalence of Pithonella sphaerica and P. ovalis in...

  10. Sedimentology and dinoflagellate cycst of the Cap Blanc Nez section

    Wendler, Jens E; Gräfe, Kai-Uwe; Willems, Helmut
    Mid-Cenomanian, precession-controlled (21 ka) chalk-marl couplets of the Cap Blanc Nez section (Anglo-Paris Basin) have been studied with focus on the effects which Milankovitch cycles have had on the palaeoenvironment. In this paper, we present micropalaeontological and lithological proxies that enable the reconstruction of both the cycle architecture and the transformation of the orbitally forced signal into the sediment. A palaeoecological reconstruction based on changes in calcareous dinoflagellate cysts (c-dinocysts) assemblages was carried out, in which two characteristic ecological assemblages of c-dinocysts were identified. Gradual changes in absolute and relative abundance of the cyst species in these assemblages over several...

  11. Stable isotope record of a Bermuda coral

    Kuhnert, Henning; Pätzold, Jürgen; Schnetger, Bernhard; Wefer, Gerold
    Records of skeletal delta18O in monthly and Sr/Ca ratios in half-yearly resolution were obtained from a Bermuda coral (Diploria labyrinthiformis) for the time period 1520-1603 (+/-15 yr) AD within the Little Ice Age. Annual and decadal averages of both sea-surface temperature proxies indicate temperature variabilities of 0.5°C (standard deviation) and 0.3°C, respectively. Both numbers are close to recent instrumental observations. Approximately 30% of the interannual time series variance of delta18O is concentrated in broad bands centered at periods of ~30, 16, and 7.8 yr, the last two reflecting the influence of the North Atlantic Oscillation. Although this large-scale climate signal...

  12. Stable oxygen isotope record from a high-latitude reef off Western Australia

    Kuhnert, Henning; Pätzold, Jürgen; Hatcher, B G; Wyrwoll, K-H; Eisenhauer, Anton; Collins, L B; Zhu, Z R; Wefer, Gerold
    A core from a coral colony of Porites lutea was analysed for stable oxygen isotopic composition*. A 200-year proxy record of sea surface temperatures from the Houtman Abrolhos Islands off west Australia was obtained from coral delta18O. At 29°S, the Houtman Abrolhos are the southernmost major reef complex of the Indian Ocean. They are located on the path of the Leeuwin Current, a southward flow of warm, tropical water, which is coupled to Indonesian throughflow. Coral delta18O primarily reflects local oceanographic and climatic variability, which is largely determined by spatial variability of the Leeuwin Current. However, coherence between coral delta18O...

  13. Stable-isotope records from Dronning Maud Land, Antarctica

    Graf, Wolfgang; Oerter, Hans; Reinwarth, Oskar; Stichler, Willibald; Wilhelms, Frank; Miller, Heinz; Mulvaney, Robert
    The European Project for Ice Coring in Antarctica (EPICA) includes a comprehensive pre-site survey on the inland ice plateau of Dronning Maud Land. This paper focuses on the investigation of the 18O content of shallow firn and ice cores. These cores were dated by profiles derived from dielectric-profiling and continuous flow analysis measurements. The individual records were stacked in order to obtain composite chronologies of 18O contents and accumulation rates with enhanced signal-to-noise variance ratios.These chronologies document variations in the last 200 and 1000 years.The 18O contents and accumulation rates decreased in the 19th century and increased during the 20th...

  14. Chemical measurements from the EPICA Dome C core

    Wolff, Eric W; Fischer, Hubertus; Ruth, Urs; Twarloh, Birthe; Littot, Geneviève C; Mulvaney, Robert; Röthlisberger, Regine; de Angelis, Martine; Boutron, Claude F; Hansson, Margareta E; Jonsell, Ulf; Hutterli, Manuel A; Lambert, Fabrice; Kaufmann, Patrik R; Stauffer, Bernhard; Stocker, Thomas F; Steffensen, Jørgen Peder; Bigler, Matthias; Siggaard-Andersen, Marie-Louise; Udisti, Roberto; Becagli, Silvia; Castellano, Emiliano; Severi, Mirko; Wagenbach, Dietmar; Barbante, Carlo; Gabrielli, Paolo; Gaspari, Vania
    Sea ice and dust flux increased greatly in the Southern Ocean during the last glacial period. Palaeorecords provide contradictory evidence about marine productivity in this region, but beyond one glacial cycle, data were sparse. Here we present continuous chemical proxy data spanning the last eight glacial cycles (740,000 years) from the Dome C Antarctic ice core. These data constrain winter sea-ice extent in the Indian Ocean, Southern Ocean biogenic productivity and Patagonian climatic conditions. We found that maximum sea-ice extent is closely tied to Antarctic temperature on multi-millennial timescales, but less so on shorter timescales. Biological dimethylsulphide emissions south of...

  15. Chemical measurements from the EPICA Dome C core

    Wolff, Eric W; Fischer, Hubertus; Ruth, Urs; Twarloh, Birthe; Littot, Geneviève C; Mulvaney, Robert; Röthlisberger, Regine; de Angelis, Martine; Boutron, Claude F; Hansson, Margareta E; Jonsell, Ulf; Hutterli, Manuel A; Lambert, Fabrice; Kaufmann, Patrik R; Stauffer, Bernhard; Stocker, Thomas F; Steffensen, Jørgen Peder; Bigler, Matthias; Siggaard-Andersen, Marie-Louise; Udisti, Roberto; Becagli, Silvia; Castellano, Emiliano; Severi, Mirko; Wagenbach, Dietmar; Barbante, Carlo; Gabrielli, Paolo; Gaspari, Vania
    Sea ice and dust flux increased greatly in the Southern Ocean during the last glacial period. Palaeorecords provide contradictory evidence about marine productivity in this region, but beyond one glacial cycle, data were sparse. Here we present continuous chemical proxy data spanning the last eight glacial cycles (740,000 years) from the Dome C Antarctic ice core. These data constrain winter sea-ice extent in the Indian Ocean, Southern Ocean biogenic productivity and Patagonian climatic conditions. We found that maximum sea-ice extent is closely tied to Antarctic temperature on multi-millennial timescales, but less so on shorter timescales. Biological dimethylsulphide emissions south of...

  16. Data from the EPICA Dome C ice core EDC

    Augustin, Laurent; Barbante, Carlo; Barnes, Piers R F; Barnola, Jean-Marc; Bigler, Matthias; Castellano, Emiliano; Cattani, Olivier; Chappellaz, Jérôme A; Dahl-Jensen, Dorthe; Delmonte, Barbara; Dreyfus, Gabrielle; Durand, Gael; Falourd, Sonia; Fischer, Hubertus; Flückiger, Jacqueline; Hansson, Margareta E; Huybrechts, Philippe; Jugie, Gérard; Johnsen, Sigfus J; Jouzel, Jean; Kaufmann, Patrik R; Kipfstuhl, Sepp; Lambert, Fabrice; Lipenkov, Vladimir Y; Littot, Geneviève C; Longinelli, Antonio; Lorrain, Reginald D; Maggi, Valter; Masson-Delmotte, Valerie; Miller, Heinz; Mulvaney, Robert; Oerlemans, Johannes; Oerter, Hans; Orombelli, Giuseppe; Parrenin, Frédéric; Peel, David A; Petit, Jean-Robert; Raynaud, Dominique; Ritz, Catherine; Ruth, Urs; Schwander, Jakob; Siegenthaler, Urs; Souchez, Roland; Stauffer, Bernhard; Steffensen, Jørgen Peder; Stenni, Barbara; Stocker, Thomas F; Tabacco, Ignazio; Udisti, Roberto; van de Wal, Roderik S W; van den Broeke, Michiel R; Wilhelms, Frank; Winther, Jan-Gunnar; Wolff, Eric W; Zucchelli, Mario
    The Antarctic Vostok ice core provided compelling evidence of the nature of climate, and of climate feedbacks, over the past 420,000 years. Marine records suggest that the amplitude of climate variability was smaller before that time, but such records are often poorly resolved. Moreover, it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records. Here we report the recovery of a deep ice core from Dome C, Antarctica, that provides a climate record for the past 740,000 years. For the four most recent glacial cycles, the data agree well with the record from...

  17. Data from the EPICA Dome C ice core EDC

    Augustin, Laurent; Barbante, Carlo; Barnes, Piers R F; Barnola, Jean-Marc; Bigler, Matthias; Castellano, Emiliano; Cattani, Olivier; Chappellaz, Jérôme A; Dahl-Jensen, Dorthe; Delmonte, Barbara; Dreyfus, Gabrielle; Durand, Gael; Falourd, Sonia; Fischer, Hubertus; Flückiger, Jacqueline; Hansson, Margareta E; Huybrechts, Philippe; Jugie, Gérard; Johnsen, Sigfus J; Jouzel, Jean; Kaufmann, Patrik R; Kipfstuhl, Sepp; Lambert, Fabrice; Lipenkov, Vladimir Y; Littot, Geneviève C; Longinelli, Antonio; Lorrain, Reginald D; Maggi, Valter; Masson-Delmotte, Valerie; Miller, Heinz; Mulvaney, Robert; Oerlemans, Johannes; Oerter, Hans; Orombelli, Giuseppe; Parrenin, Frédéric; Peel, David A; Petit, Jean-Robert; Raynaud, Dominique; Ritz, Catherine; Ruth, Urs; Schwander, Jakob; Siegenthaler, Urs; Souchez, Roland; Stauffer, Bernhard; Steffensen, Jørgen Peder; Stenni, Barbara; Stocker, Thomas F; Tabacco, Ignazio; Udisti, Roberto; van de Wal, Roderik S W; van den Broeke, Michiel R; Wilhelms, Frank; Winther, Jan-Gunnar; Wolff, Eric W; Zucchelli, Mario
    The Antarctic Vostok ice core provided compelling evidence of the nature of climate, and of climate feedbacks, over the past 420,000 years. Marine records suggest that the amplitude of climate variability was smaller before that time, but such records are often poorly resolved. Moreover, it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records. Here we report the recovery of a deep ice core from Dome C, Antarctica, that provides a climate record for the past 740,000 years. For the four most recent glacial cycles, the data agree well with the record from...

  18. Data from the EPICA Dome C ice core EDC

    Augustin, Laurent; Barbante, Carlo; Barnes, Piers R F; Barnola, Jean-Marc; Bigler, Matthias; Castellano, Emiliano; Cattani, Olivier; Chappellaz, Jérôme A; Dahl-Jensen, Dorthe; Delmonte, Barbara; Dreyfus, Gabrielle; Durand, Gael; Falourd, Sonia; Fischer, Hubertus; Flückiger, Jacqueline; Hansson, Margareta E; Huybrechts, Philippe; Jugie, Gérard; Johnsen, Sigfus J; Jouzel, Jean; Kaufmann, Patrik R; Kipfstuhl, Sepp; Lambert, Fabrice; Lipenkov, Vladimir Y; Littot, Geneviève C; Longinelli, Antonio; Lorrain, Reginald D; Maggi, Valter; Masson-Delmotte, Valerie; Miller, Heinz; Mulvaney, Robert; Oerlemans, Johannes; Oerter, Hans; Orombelli, Giuseppe; Parrenin, Frédéric; Peel, David A; Petit, Jean-Robert; Raynaud, Dominique; Ritz, Catherine; Ruth, Urs; Schwander, Jakob; Siegenthaler, Urs; Souchez, Roland; Stauffer, Bernhard; Steffensen, Jørgen Peder; Stenni, Barbara; Stocker, Thomas F; Tabacco, Ignazio; Udisti, Roberto; van de Wal, Roderik S W; van den Broeke, Michiel R; Wilhelms, Frank; Winther, Jan-Gunnar; Wolff, Eric W; Zucchelli, Mario
    The Antarctic Vostok ice core provided compelling evidence of the nature of climate, and of climate feedbacks, over the past 420,000 years. Marine records suggest that the amplitude of climate variability was smaller before that time, but such records are often poorly resolved. Moreover, it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records. Here we report the recovery of a deep ice core from Dome C, Antarctica, that provides a climate record for the past 740,000 years. For the four most recent glacial cycles, the data agree well with the record from...

  19. First results from stable-istope measurements on ice cores from Dronning Maud Land

    Oerter, Hans; Graf, Wolfgang; Meyer, Hanno; Wilhelms, Frank
    The European Project for Ice Coring in Antarctica (EPICA) focuses on the drilling of two deep ice cores, the first at Dome C and the second at Kohnen station (75°00' S, 0°04' E) in Dronning Maud Land (DML). This paper deals with stable-isotope records from ice cores drilled in DML. In the first season, the deep EPICA DML core reached a depth of 450 m, recovering ice approximately 7000 years old. Generally, the d18O record indicates a stable Holocene climate and shows low variability. However, during the last 4000 years (based on a preliminary time-scale) the d18O values decrease continuously...

  20. EPICA Dome C carbon dioxide concentrations from 650 to 391 kyr BP

    Siegenthaler, Urs; Stocker, Thomas F; Monnin, Eric; Lüthi, Dieter; Schwander, Jakob; Stauffer, Bernhard; Raynaud, Dominique; Barnola, Jean-Marc; Fischer, Hubertus; Masson-Delmotte, Valerie; Jouzel, Jean
    A record of atmospheric carbon dioxide (CO2) concentrations measured on the EPICA (European Project for Ice Coring in Antarctica) Dome Concordia ice core extends the Vostok CO2 record back to 650,000 years before the present (yr B.P.). Before 430,000 yr B.P., partial pressure of atmospheric CO2 lies within the range of 260 and 180 parts per million by volume. This range is almost 30% smaller than that of the last four glacial cycles; however, the apparent sensitivity between deuterium and CO2 remains stable throughout the six glacial cycles, suggesting that the relationship between CO2 and Antarctic climate remained rather constant...

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