^<230>Th-normalized fluxes of biogenic components from the central and southernmost Chilean margin over the past 22,000 years

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Author(s)

    • FUKUDA MIHO
    • Department of Earth and Evolution Sciences, University of Tsukuba
    • HARADA NAOMI
    • Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology
    • SATO MIYAKO
    • Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology
    • LANGE CARINA B.
    • COPAS Center and Department of Oceanography, University of Concepcion
    • AHAGON NAOKAZU
    • Kochi Core Center, Japan Agency for Marine-Earth Science and Technology
    • KAWAKAMI HAJIME
    • Mutsu Institute for Oceanography, Japan Agency for Marine-Earth Science and Technology
    • PANTOJA SILVIO
    • COPAS Center and Department of Oceanography, University of Concepcion
    • MATSUMOTO TAKESHI
    • Physics and Earth Sciences, Graduate School of Engineering and Science, University of the Ryukyu
    • MOTOYAMA ISAO
    • Department of Earth and Environmental Sciences, Faculty of Science, Yamagata University

Abstract

We report on <sup>230</sup>Th-normalized fluxes of biogenic components—total organic carbon (TOC), total nitrogen (TN), calcium carbonate (CaCO<sub>3</sub>), and biogenic opal (Si<sub>OPAL</sub>)—from two sediment cores collected at 36°S off central Chile and covering the past 22 thousand years (kyr) (site PC-1), and at 52°S near the Pacific entrance of the Strait of Magellan and encompassing the past 13 kyr (site PC-3). During 13-8 calendar kyr before present (cal kyr BP), the <sup>230</sup>Th-normalized TOC flux at the PC-1 site was relatively high, pointing to increased productivity, whereas a marked decrease in the flux characterized the periods around 22-14 and 8-5 cal kyr BP. In contrast, at the PC-3 site, the <sup>230</sup>Th-normalized TOC flux was low during the last deglaciation until ~6 cal kyr BP, and then abruptly increased in the late Holocene. The <sup>230</sup>Th-normalized fluxes suggest that, compared to other periods, the biological pump functioned less effectively during 22-14 cal kyr BP and the middle Holocene off central Chile, and during 13-6 cal kyr BP off southernmost Patagonia. The changes from glacial to interglacial in the <sup>230</sup>Th-normalized biogenic components, which were controlled by changes in upwelling intensity at the PC-1 site and by the inflow of nutrients from the Pacific at the PC-3 site, can be explained by changes in wind direction and intensity associated with the latitudinal displacement of the southern westerly belt. In contrast, we found no obvious relationship during the deglacial and Holocene periods between El Niño activity and biogenic component fluxes at the PC-1 site, even though at present El Niño events are negatively correlated with primary productivity in the upwelling area off Chile.

Journal

  • GEOCHEMICAL JOURNAL

    GEOCHEMICAL JOURNAL 47(2), 119-135, 2013-04-01

    GEOCHEMICAL SOCIETY OF JAPAN

References:  85

Cited by:  2

Codes

  • NII Article ID (NAID)
    10031170197
  • NII NACSIS-CAT ID (NCID)
    AA00654975
  • Text Lang
    ENG
  • Article Type
    Journal Article
  • ISSN
    00167002
  • Data Source
    CJP  CJPref  J-STAGE 
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