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  • 1
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The advantage of using oceanic sediments to infer palaeocli-matic conditions of eastern Asia is the reliability and uniformity of the dating techniques for marine sediments. Late Pleistocene variations in 518O values in the CaCO3 of benthic foraminifera shells reflect the changing oxygen-isotope ...
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2018-09-12
    Description: Much uncertainty exists about the state of the oceanic and atmospheric circulation in the tropical Pacific over the last glacial cycle. Studies have been hampered by the fact that sediment cores suitable for study were concentrated in the western and eastern parts of the tropical Pacific, with little information from the central tropical Pacific. Here we present information from a suite of sediment cores collected from the Line Islands Ridge in the central tropical Pacific, which show sedimentation rates and stratigraphies suitable for paleoceanographic investigations. Based on the radiocarbon and oxygen isotope measurements on the planktonic foraminifera Globigerinoides ruber, we construct preliminary age models for selected cores and show that the gradient in the oxygen isotope ratio of G. ruber between the equator and 8°N is enhanced during glacial stages relative to interglacial stages. This stronger gradient could reflect enhanced equatorial cooling (perhaps reflecting a stronger Walker circulation) or an enhanced salinity gradient (perhaps reflecting increased rainfall in the central tropical Pacific).
    Type: Article , PeerReviewed
    Format: text
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  • 3
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    PANGAEA
    In:  Supplement to: Han, Zhiyong; Liu, Dunyi; Hovan, Steven A (2002): Lightness timescale for terrestrial sediments in the past 500,000 years. Paleoceanography, 17(3), 20-1-20-7, https://doi.org/10.1029/2001PA000731
    Publication Date: 2023-05-12
    Description: The Nihewan Beds at Yangyuan reflect apparently continuous, high-resolution deposition of fluvial-lacustrine sediment in the climatically important loess deposit regions of north China. The Hutouliang section forms the upper portion of Nihewan Beds deposited during the Brunhes magnetic polarity chron. Lightness values measured on successive samples display similar variability to the aeolian flux record of oceanic sediment core V21-146 located downwind from this area in the North Pacific. The oxygen isotope timescale of core V21-146 was transferred to the lightness curve to provide a preliminary timescale allowing more detailed age control in the Hutouliang section. This timescale will provide useful assistance in dating boundary ages of the loess-soil sequence in China and interpreting regional climatic data.
    Keywords: China; Hutouliang
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 4
    Publication Date: 2023-05-12
    Keywords: Age model; China; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; Hutouliang; Lithologic unit/sequence; Lithology/composition/facies
    Type: Dataset
    Format: text/tab-separated-values, 54 data points
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  • 5
    Publication Date: 2023-05-12
    Keywords: Age model; China; DEPTH, sediment/rock; Hutouliang
    Type: Dataset
    Format: text/tab-separated-values, 27 data points
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  • 6
    Publication Date: 2023-06-27
    Description: Deep Sea Drilling Project (DSDP) Site 215 provides an expanded section across the Paleocene/Eocene boundary, the most complete mid-latitude sequence from a Southern Hemisphere location in the Indo-Pacific area. The events of this transition occurred during a span of about 1.2 m.y. Oxygen isotope values derived from benthic foraminiferal calcite decrease by about 1.0 per mil, a decrease most likely related to warming of deep ocean waters. Turnovers of benthic foraminifera accompany d18O changes and culminate in the predominant extinction event at the end of the Paleocene Epoch. Carbon isotope ratios also shift dramatically toward lighter values near the end of the Paleocene, beginning about 0.45 m.y. after oxygen isotope values start to change. The intensity of Southern Hemisphere atmospheric circulation as recorded by grain sizes of eolian particles shows a large and rapid reduction beginning another 0.45 m.y. later. A significant reduction of zonal wind strength at the Paleocene/Eocene boundary, until now observed only at Northern Hemisphere locations, appears to have been a global phenomenon related to decreased latitudinal thermal gradients occasioned by more effective poleward heat transport via the deep ocean.
    Keywords: 22-215; Deep Sea Drilling Project; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP; DSDP/ODP/IODP sample designation; Glomar Challenger; Indian Ocean//BASIN; Leg22; Median, grain size; Nuttallides truempyi, δ13C; Nuttallides truempyi, δ18O; Sample code/label; Sample comment; δ13C, carbonate
    Type: Dataset
    Format: text/tab-separated-values, 121 data points
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  • 7
    Publication Date: 2023-06-27
    Keywords: Age model; Age model, SPECMAP chronology, Imbrie et al. (1984); DEPTH, sediment/rock; Foraminifera, benthic δ18O; PC; Piston corer; V21; V21-146; Vema
    Type: Dataset
    Format: text/tab-separated-values, 624 data points
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  • 8
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    PANGAEA
    Publication Date: 2023-06-27
    Keywords: 22-215; Age model; Age model, biostratigraphy; Ageprofile Datum Description; Deep Sea Drilling Project; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP; Glomar Challenger; Indian Ocean//BASIN; Leg22
    Type: Dataset
    Format: text/tab-separated-values, 14 data points
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  • 9
    Publication Date: 2023-06-27
    Keywords: 22-215; Accumulation rate, terrigenous; AGE; Calculated; Deep Sea Drilling Project; Density, dry bulk; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP; DSDP/ODP/IODP sample designation; Glomar Challenger; Indian Ocean//BASIN; Leg22; Sample code/label; Sedimentation rate; Terrigenous; Wet-chemistry (Rea & Janecek, 1981)
    Type: Dataset
    Format: text/tab-separated-values, 155 data points
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  • 10
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    PANGAEA
    In:  Supplement to: Hovan, Steven A; Rea, David K; Pisias, Nicklas G (1991): Late Pleistocene continental climate and oceanic variability recorded in northwest Pacific sediments. Paleoceanography, 6(3), 349-370, https://doi.org/10.1029/91PA00559
    Publication Date: 2023-06-27
    Description: Core V21-146 provides a continuous record of northwest Pacific pelagic sedimentation spanning the past 530,000 years. Downcore variations of delta18O from benthic foraminiferal calcite were correlated to the SPECMAP record to provide an age model for late Pleistocene paleoclimatic and paleoceanographic variation. Fluxes of CaCO3 and eolian material have been determined by combining information about linear sedimentation rates, bulk densities and component percentages. The mass accumulation rate (MAR) of CaCO3 varies from 58 to 1435 mg(cm**2 kyr)**-1 and exhibits the Pacific Ocean pattern of higher accumulation associated with glacial periods for the younger portion of the record. However, the pattern of CaCO3 accumulation appears to shift during the mid-Brunhes so that prior to 350,000 years ago it exhibits an opposite pattern of greater accumulation during interglacial periods. The flux of eolian dust is a proxy measure of the source area aridity and correlates well to the loess-soil stratigraphy in China. Dust fluxes range from 43 to 718 mg(cm**2 kyr)**-1 and are greater by a factor of about 4 during glacial times. Cross-spectral analysis of the eolian flux and oxygen isotope records shows an inphase and coherent relationship at each of the major orbital periodicities of 100, 41, and 19 kyr. Eolian grain sizes, generally used as a proxy record of wind intensity, range from 8.4 phi (2.9 µm) to 6.2 phi (13.6 µm). A change in grain size variability occurs near about 300 ka such that the older portion is characterized by lower-frequency and higher-amplitude fluctuations than the younger portion. Power spectra for the eolian grain size record show dominant peaks at 100 and 50 kyr and a broad 25-35 kyr peak but coherency to the oxygen isotope curve at only the 100 and 33 kyr periodicities. The phase relationship for eccentricity between the eolian grain size and delta18O records suggests that at the 100 kyr frequency the smallest grain sizes are associated with glacial conditions.
    Keywords: PC; Piston corer; V21; V21-146; Vema
    Type: Dataset
    Format: application/zip, 2 datasets
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