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Datasets of project "Lamont-Doherty Earth Observatory, Columbia University"

Mostrando recursos 21 - 40 de 546

  1. Organic carbon concentrations and Cd/Ca ratios of sediment core RC13-229

    Oppo, Delia W; Rosenthal, Yair
    A comparison of cadmium/calcium (Cd/Ca) records of benthic foraminifera from a deep Cape Basin and a deep eastern equatorial Pacific core suggests that over the past 400,000 years, the nutrient concentration of Circumpolar Deep Water (CPDW) has always been lower than that of the deep Pacific. The data further suggest that at the 100,000- and 23,000-year orbital periods, the contribution of North Atlantic Deep Water to CPDW is at a maximum during periods of ice growth and at a minimum during periods of ice decay. These results are not in agreement with results based on carbon isotope records of benthic...

  2. Age determination and radionuclides of sediment cores from the Western Atlantic

    Broecker, Wallace S; Lao, Yong; Klas, Mieczyslawa; Clark, Elizabeth; Bonani, Georges; Ivy, Susan; Chen, Chin
    The CO2 record for air bubbles from the Byrd Station ice core suggest a drawdown in the ocean-atmosphere carbon reservoir during the early Holocene. Such a drawdown would require a corresponding increase in the CO3= ion concentration in the deep sea. We report here the results of a search in Atlantic sediments for evidence that the lysocline showed a corresponding deepening. While both the pteropod and the calcite preservation records we have obtained are consistent with expectation, they are not conclusive.

  3. Age determination and radionuclides of sediment cores from the Western Atlantic

    Broecker, Wallace S; Lao, Yong; Klas, Mieczyslawa; Clark, Elizabeth; Bonani, Georges; Ivy, Susan; Chen, Chin
    The CO2 record for air bubbles from the Byrd Station ice core suggest a drawdown in the ocean-atmosphere carbon reservoir during the early Holocene. Such a drawdown would require a corresponding increase in the CO3= ion concentration in the deep sea. We report here the results of a search in Atlantic sediments for evidence that the lysocline showed a corresponding deepening. While both the pteropod and the calcite preservation records we have obtained are consistent with expectation, they are not conclusive.

  4. Sedimentology and stable isotope ratios of the northwest Pacific

    Lyle, Mitchell W; Zahn, Rainer; Prahl, Frederick G; Dymond, Jack R; Collier, Robert W; Pisias, Nicklas G; Suess, Erwin
    The Multitracers Experiment studied a transect of water column, sediment trap, and sediment data taken across the California Current to develop quantitative methods for hindcasting paleoproductivity. The experiment used three sediment trap moorings located 120 km, 270 km, and 630 km from shore at the Oregon/California border in North America. We report here about the sedimentation and burial of particulate organic carbon (Corg) and CaCO3. In order to observe how the integrated CaCO3 and Corg burial across the transect has changed since the last glacial maximum, we have correlated core from the three sites using time scales constrained by both...

  5. Sedimentology and stable isotope ratios of the northwest Pacific

    Lyle, Mitchell W; Zahn, Rainer; Prahl, Frederick G; Dymond, Jack R; Collier, Robert W; Pisias, Nicklas G; Suess, Erwin
    The Multitracers Experiment studied a transect of water column, sediment trap, and sediment data taken across the California Current to develop quantitative methods for hindcasting paleoproductivity. The experiment used three sediment trap moorings located 120 km, 270 km, and 630 km from shore at the Oregon/California border in North America. We report here about the sedimentation and burial of particulate organic carbon (Corg) and CaCO3. In order to observe how the integrated CaCO3 and Corg burial across the transect has changed since the last glacial maximum, we have correlated core from the three sites using time scales constrained by both...

  6. Biogenic opal, carbonat concentrations and stable oxygen isotope ratios of foraminifera from sediment cores of the Southern Ocean

    Charles, Christopher D; Froelich, Philip N; Zibello, Michael A; Mortlock, Richard A; Morley, Joseph J
    We present records of biogenic opal percentage and burial rate in 12 piston cores from the Atlantic and Indian sectors of the Southern Ocean. These records provide a detailed, quantitative description of changing patterns of opal deposition over the last 450 kyr. The striking regional coherence of these records suggests that dissolution in the deep sea and sediment pore waters does not obscure the surface productivity signal, and therefore these opal time series can be used in combination with other surface water tracers to make inferences about the chemistry and circulation of the Southern Ocean under different global climate conditions....

  7. Biogenic opal, carbonat concentrations and stable oxygen isotope ratios of foraminifera from sediment cores of the Southern Ocean

    Charles, Christopher D; Froelich, Philip N; Zibello, Michael A; Mortlock, Richard A; Morley, Joseph J
    We present records of biogenic opal percentage and burial rate in 12 piston cores from the Atlantic and Indian sectors of the Southern Ocean. These records provide a detailed, quantitative description of changing patterns of opal deposition over the last 450 kyr. The striking regional coherence of these records suggests that dissolution in the deep sea and sediment pore waters does not obscure the surface productivity signal, and therefore these opal time series can be used in combination with other surface water tracers to make inferences about the chemistry and circulation of the Southern Ocean under different global climate conditions....

  8. Biogenic opal, carbonat concentrations and stable oxygen isotope ratios of foraminifera from sediment cores of the Southern Ocean

    Charles, Christopher D; Froelich, Philip N; Zibello, Michael A; Mortlock, Richard A; Morley, Joseph J
    We present records of biogenic opal percentage and burial rate in 12 piston cores from the Atlantic and Indian sectors of the Southern Ocean. These records provide a detailed, quantitative description of changing patterns of opal deposition over the last 450 kyr. The striking regional coherence of these records suggests that dissolution in the deep sea and sediment pore waters does not obscure the surface productivity signal, and therefore these opal time series can be used in combination with other surface water tracers to make inferences about the chemistry and circulation of the Southern Ocean under different global climate conditions....

  9. Pollen records and stable isotope ratios of benthic foraminifera from sediment cores of the Sea of Okhotsk

    Morley, Joseph J; Heusser, Linda E; Shackleton, Nicholas J
    In two cores with oxygen isotope stratigraphy from the southern Okhotsk Sea, marine pollen and siliceous microfauna record concurrent late glacial through Holocene variations in regional terrestrial and marine environments. Glacial vegetation around the southern Okhotsk basin, which resembles the present tundra/steppe of the northwest coast of this marginal sea, yields to spruce-dominated boreal forests during the glacial/interglacial transition. Temperate forest components, such as oak, peak during the mid-Holocene. Decreasing oak accompanied by increasing spruce reflects the effect of global cooling on local vegetation during the last 4 kyr. Although the radiolarian fauna in the Okhotsk Sea samples is similar...

  10. Pollen records and stable isotope ratios of benthic foraminifera from sediment cores of the Sea of Okhotsk

    Morley, Joseph J; Heusser, Linda E; Shackleton, Nicholas J
    In two cores with oxygen isotope stratigraphy from the southern Okhotsk Sea, marine pollen and siliceous microfauna record concurrent late glacial through Holocene variations in regional terrestrial and marine environments. Glacial vegetation around the southern Okhotsk basin, which resembles the present tundra/steppe of the northwest coast of this marginal sea, yields to spruce-dominated boreal forests during the glacial/interglacial transition. Temperate forest components, such as oak, peak during the mid-Holocene. Decreasing oak accompanied by increasing spruce reflects the effect of global cooling on local vegetation during the last 4 kyr. Although the radiolarian fauna in the Okhotsk Sea samples is similar...

  11. Pollen records and stable isotope ratios of benthic foraminifera from sediment cores of the Sea of Okhotsk

    Morley, Joseph J; Heusser, Linda E; Shackleton, Nicholas J
    In two cores with oxygen isotope stratigraphy from the southern Okhotsk Sea, marine pollen and siliceous microfauna record concurrent late glacial through Holocene variations in regional terrestrial and marine environments. Glacial vegetation around the southern Okhotsk basin, which resembles the present tundra/steppe of the northwest coast of this marginal sea, yields to spruce-dominated boreal forests during the glacial/interglacial transition. Temperate forest components, such as oak, peak during the mid-Holocene. Decreasing oak accompanied by increasing spruce reflects the effect of global cooling on local vegetation during the last 4 kyr. Although the radiolarian fauna in the Okhotsk Sea samples is similar...

  12. (Table 3) Pollen record of sediment core V32-161

    Morley, Joseph J; Heusser, Linda E; Shackleton, Nicholas J

  13. (Table 3) Pollen record of sediment core V32-161

    Morley, Joseph J; Heusser, Linda E; Shackleton, Nicholas J

  14. (Table 3) Pollen record of sediment core V32-161

    Morley, Joseph J; Heusser, Linda E; Shackleton, Nicholas J

  15. (Table 3) Pollen record of sediment core V32-159

    Morley, Joseph J; Heusser, Linda E; Shackleton, Nicholas J

  16. (Table 3) Pollen record of sediment core V32-159

    Morley, Joseph J; Heusser, Linda E; Shackleton, Nicholas J

  17. (Table 3) Pollen record of sediment core V32-159

    Morley, Joseph J; Heusser, Linda E; Shackleton, Nicholas J

  18. Age models and stable isotope record of sediment cores from the Atlantic Ocean

    Oppo, Delia W; Fairbanks, Richard G
    The high-resolution delta18O and delta13C records of benthic foraminifera from a 150,000-year long core from the Caribbean Sea indicate that there was generally high delta13C during glaciations and low delta13C during interglaciations. Due to its 1800-m sill depth, the properties of deep water in the Caribbean Sea are similar to those of middepth tropical Atlantic water. During interglaciations, the water filling the deep Caribbean Sea is an admixture of low delta13C Upper Circumpolar Water (UCPW) and high delta13C Upper North Atlantic Deep Water (UNADW). By contrast, only high delta13C UNADW enters during glaciations. Deep ocean circulation changes can influence atmospheric...

  19. Age models and stable isotope record of sediment cores from the Atlantic Ocean

    Oppo, Delia W; Fairbanks, Richard G
    The high-resolution delta18O and delta13C records of benthic foraminifera from a 150,000-year long core from the Caribbean Sea indicate that there was generally high delta13C during glaciations and low delta13C during interglaciations. Due to its 1800-m sill depth, the properties of deep water in the Caribbean Sea are similar to those of middepth tropical Atlantic water. During interglaciations, the water filling the deep Caribbean Sea is an admixture of low delta13C Upper Circumpolar Water (UCPW) and high delta13C Upper North Atlantic Deep Water (UNADW). By contrast, only high delta13C UNADW enters during glaciations. Deep ocean circulation changes can influence atmospheric...

  20. Age models and stable isotope record of sediment cores from the Atlantic Ocean

    Oppo, Delia W; Fairbanks, Richard G
    The high-resolution delta18O and delta13C records of benthic foraminifera from a 150,000-year long core from the Caribbean Sea indicate that there was generally high delta13C during glaciations and low delta13C during interglaciations. Due to its 1800-m sill depth, the properties of deep water in the Caribbean Sea are similar to those of middepth tropical Atlantic water. During interglaciations, the water filling the deep Caribbean Sea is an admixture of low delta13C Upper Circumpolar Water (UCPW) and high delta13C Upper North Atlantic Deep Water (UNADW). By contrast, only high delta13C UNADW enters during glaciations. Deep ocean circulation changes can influence atmospheric...

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