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Datasets with PANGAEA technical keyword @paleoclimate

Mostrando recursos 1 - 20 de 1.181

  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. 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,...

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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...

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