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Datasets with geocode "DISTANCE"

Mostrando recursos 1 - 20 de 286

  1. A deep-sea coral record of the North Atlantic

    Eltgroth, Selene F; Adkins, Jess; Robinson, Laura F; Southon, John; Kashgarian, Michaele
    Our record of Younger Dryas intermediate-depth seawater D14C from North Atlantic deep-sea corals supports a link between abrupt climate change and intermediate ocean variability. Our data show that northern source intermediate water (~1700 m) was partially replaced by 14C-depleted southern source water at the onset of the event, consistent with a reduction in the rate of North Atlantic Deep Water formation. This transition requires the existence of large, mobile gradients of D14C in the ocean during the Younger Dryas. The D14C water column profile from Keigwin (2004) provides direct evidence for the presence of one such gradient at the beginning...

  2. (Table 3) Radiocarbon age determination of Desmophyllum dianthus samples

    Eltgroth, Selene F; Adkins, Jess; Robinson, Laura F; Southon, John; Kashgarian, Michaele

  3. (Table 3) Radiocarbon age determination of Desmophyllum dianthus samples

    Eltgroth, Selene F; Adkins, Jess; Robinson, Laura F; Southon, John; Kashgarian, Michaele

  4. Geochemistry and stable isotope record of black shales and inoceramids from the Demerara Rise

    Jiménez Berrocosco, Álvaro; MacLeod, Kenneth G; Calvert, Stephen E; Elorza, Javier
    The bulk rock geochemistry and inoceramid isotopic composition from Cenomanian to Santonian, finely laminated, organic-rich black shales, recovered during Ocean Drilling Program Leg 207 on Demerara Rise (western tropical North Atlantic), suggest persistent anoxic (free H2S) conditions within the sediments and short-term variations within a narrow range of anoxic to episodically dysoxic bottom waters over a ~15 Ma time interval. In addition to being organic-rich, the 50-90 m thick sections examined exhibit substantial bulk rock enrichments of Si, P, Ba, Cu, Mo, Ni, and Zn relative to World Average Shale. These observations point to high organic burial fluxes, likely driven...

  5. (Table S8) Carbonate isotopic ratios across the growth lines of the inoceramid D3, ODP Hole 207-1261A

    Jiménez Berrocosco, Álvaro; MacLeod, Kenneth G; Calvert, Stephen E; Elorza, Javier

  6. (Table S7) Carbonate isotopic ratios across the growth lines of the inoceramid D5, ODP Hole 207-1261A

    Jiménez Berrocosco, Álvaro; MacLeod, Kenneth G; Calvert, Stephen E; Elorza, Javier

  7. (Table S6) Carbonate isotopic ratios across the growth lines of the inoceramid T5, ODP Hole 207-1261A

    Jiménez Berrocosco, Álvaro; MacLeod, Kenneth G; Calvert, Stephen E; Elorza, Javier

  8. Skeletal density of Porites

    Gagan, Michael K; Dunbar, Gavin B; Suzuki, Atsushi
    Paleotemperature estimates based on coral Sr/Ca have not been widely accepted because the reconstructed glacial-Holocene shift in tropical sea-surface temperature (~4-6°C) is larger than that indicated by foraminiferal Mg/Ca (~2-4°C). We show that corals over-estimate changes in sea-surface temperature (SST) because their records are attenuated during skeletogenesis within the living tissue layer. To quantify this process, we microprofiled skeletal mass accumulation within the tissue layer of Porites from Australasian coral reefs and laboratory culturing experiments. The results show that the sensitivity of the Sr/Ca and d18O thermometers in Porites will be suppressed, variable, and dependent on the relationship between skeletal...

  9. (Table 2) Skeletal bulk density microprofile data for free-growing and laboratory cultured Porites

    Gagan, Michael K; Dunbar, Gavin B; Suzuki, Atsushi

  10. Age determination and geochemistry of corals from the North Pacific

    Hill, Tessa M; LaVigne, M; Spero, Howard J; Guilderson, Thomas P; Gaylord, B; Clague, David A
    A depth transect of deep-sea bamboo corals along the California margin provides evidence that coral strontium to calcium ratios (Sr/Ca[coral]) record seawater Sr/Ca ratios (Sr/Ca[sw]). A calibration was constructed utilizing Sr/Ca[coral] ratios and previously published Pacific Sr/Ca[sw] data (R**2 = 0.53, n = 12, p < 0.01): Sr/Ca[coral] (mmol/mol) = 4.62*Sr/Ca[sw] (mmol/mol) - 36.64. Sr/Ca[sw] is ultimately governed by the remineralization of Sr-containing shells of surface water-derived marine organisms (e.g., Acantharia) at intermediate water depths. California margin Sr/Cacoral records from 792 and 1295 m document fluctuations in Sr/Ca[sw] that appear decadal-scale. These results suggest that Sr/Casw may not be as...

  11. (Table 3) Age determination and calculated growth rates of corals

    Hill, Tessa M; LaVigne, M; Spero, Howard J; Guilderson, Thomas P; Gaylord, B; Clague, David A

  12. Seawater carbonate chemistry and concentration boundary layers around complex assemblages of macroalgae in a laboratory experiment

    Cornwall, Christopher E; Hepburn, Christopher D; Pilditch, Conrad A; Hurd, Catriona L
    Metabolic processes have the potential to modulate the effects of ocean acidification (OA) in nearshore macroalgal beds. We investigated whether natural mixed assemblages of the articulate coralline macroalgae Arthrocardia corymbosa and understory crustose coralline algae (CCA) altered pH and O2 concentrations within and immediately above their canopies. In a unidirectional flume, we tested the effect of water velocity (0-0.1 m/s), bulk seawater pH (ambient pH 8.05, and pH 7.65), and irradiance (photosynthetically saturating light and darkness) on pH and O2 concentration gradients, and the derived concentration boundary layer (CBL) thickness. At bulk seawater pH 7.65 and slow velocities (0 and...

  13. Stable carbon isotope record of Porites corals from the Gulf of Aqaba

    Al-Rousan, Saber; Felis, Thomas
    To study long-term variations in surface ocean d13C, we investigated coral skeletal d13C records of 20 colonies of the shallow-water coral Porites spp. from the northern Gulf of Aqaba and the northern Red Sea. The coral colonies represent different water depths, a wide range of different periods (Last Interglacial, Holocene, the last centuries, the last decades), and various growth rates. Records from modern and fossil corals show irregular seasonal cycles, attributed mainly to the seasonal cycle of light. No attenuation in the amplitude of the seasonal skeletal d13C cycle with depth is evident, and no significant correlation between mean annual...

  14. Coral d13C record from the Northern Gulf of Aqaba, sample El-15a

    Al-Rousan, Saber; Felis, Thomas

  15. Coral d13C record from the Northern Gulf of Aqaba, sample Aq-19A

    Al-Rousan, Saber; Felis, Thomas

  16. (Table 2) Uranium series results of Villars Cave stalagmite Vil-stm14

    Wainer, Karine; Genty, Dominique; Blamart, Dominique; Hoffmann, Dirk; Couchoud, Isabelle
    We present a new high resolution speleothem stable isotope record from the Villars Cave (SW-France) that covers part of marine isotope stage (MIS) 3. The Vil14 stalagmite grew between ~52 and 29 ka. The d13C profile is used as a palaeoclimate proxy and clearly shows the interstadial substages 13, 12 and 11. The new results complement and corroborate previously published stalagmite records Vil9 and Vil27 from the same site. The Vil14 stalagmite chronology is based on 12 Th-U dating by MC-ICP-MS and 3 by TIMS. A correction for detrital contamination was done using the 230Th/232Th activity ratio measured on clay...

  17. (Table 2) Uranium series results of Villars Cave stalagmite Vil-stm14

    Wainer, Karine; Genty, Dominique; Blamart, Dominique; Hoffmann, Dirk; Couchoud, Isabelle
    We present a new high resolution speleothem stable isotope record from the Villars Cave (SW-France) that covers part of marine isotope stage (MIS) 3. The Vil14 stalagmite grew between ~52 and 29 ka. The d13C profile is used as a palaeoclimate proxy and clearly shows the interstadial substages 13, 12 and 11. The new results complement and corroborate previously published stalagmite records Vil9 and Vil27 from the same site. The Vil14 stalagmite chronology is based on 12 Th-U dating by MC-ICP-MS and 3 by TIMS. A correction for detrital contamination was done using the 230Th/232Th activity ratio measured on clay...

  18. Isotope characterisation of Villars Cave stalagmites

    Genty, Dominique; Combourieu-Nebout, Nathalie; Peyron, Odile; Blamart, Dominique; Wainer, Karine; Mansuri, Fatima; Ghaleb, Bassam; Isabello, Lauren; Dormoy, Isabelle; von Grafenstein, Ulrich; Bonelli, Stefano; Landais, Amaelle; Brauer, Achim
    We present a new mid-latitude speleothem record of millennial-scale climatic variability during OIS3 from the Villars Cave that, combined with former published contemporaneous samples from the same cave, gives a coherent image of the climate variability in SW-France between ~55 ka and ~30 ka. The 0.82 m long stalagmite Vil-stm27 was dated with 26 TIMS U-Th analyses and its growth curve displays variations that are linked with the stable isotopes, both controlled by the climatic conditions. It consists in a higher resolved replicate of the previously published Vil-stm9 and Vil-stm14 stalagmites where Dansgaard-Oeschger (DO) events have been observed. The good...

  19. (Table 2c) Uranium series results of Villars Cave stalagmite Vil-stm27

    Genty, Dominique; Combourieu-Nebout, Nathalie; Peyron, Odile; Blamart, Dominique; Wainer, Karine; Mansuri, Fatima; Ghaleb, Bassam; Isabello, Lauren; Dormoy, Isabelle; von Grafenstein, Ulrich; Bonelli, Stefano; Landais, Amaelle; Brauer, Achim

  20. (Appendix) Age determination and stable isotope record of Villars Cave stalagmite Vil-stm27

    Genty, Dominique; Combourieu-Nebout, Nathalie; Peyron, Odile; Blamart, Dominique; Wainer, Karine; Mansuri, Fatima; Ghaleb, Bassam; Isabello, Lauren; Dormoy, Isabelle; von Grafenstein, Ulrich; Bonelli, Stefano; Landais, Amaelle; Brauer, Achim

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