Late Quaternary Monsoonal Variations in the Western Arabian Sea Based on Cross-Spectral Analyses of Geochemical and Micropalaeontological Data (ODP Leg 117, Core 728A)

W. G.H.Z. Ten Kate*, A. Sprenger, T. N.F. Steens, C. J. Beets

*Corresponding author for this work

    Research output: Chapter in Book / Report / Conference proceedingChapterAcademicpeer-review

    Abstract

    ODP Hole 728A (Leg 117), located at a semi-enclosed slope basin on the continental margin of Oman, underlies a seasonally monsoon-enhanced upwelling zone. The sediment composition reflects past environmental fluctuations which are linked to variations in the monsoon system. These include seasonal upwelling, palaeoproductivity, variation in the extent of the OMZ and aeolian input. The top-most Pleistocene (21.5 m; 524 ka) was sampled at 25-cm intervals for micropalaeontological, geochemical and stable isotope analyses. Twelve of the micropalaeontological and geochemical variables determined have been used as proxy indicators. These are assumed to be directly related to wind strength (Ti, Cr), biological productivity (CaC03, TOC, U, Ba, Br and I), intensity of the OMZ (planktonic foraminiferal tests whole-fragments ratio) and upwelling-induced productivity (δ 13C Globigerina bulloides-δ 13C Neogloboquadrina dutertrei). Examination for coherence and phase relationship with the SPECMAP stacked δ 180 record, using cross-spectral analyses, has revealed that productivity proxies vary in concert with OMZ proxies, and are coherent with the orbital cycles of the Milankovitch model. However, upwelling and aeolian intensity proxies may not be related directly to the orbital parameters, but show instead a more complicated behaviour.

    Original languageEnglish
    Title of host publicationInternational Association of Sedimentologists Series
    PublisherWiley & Blackwell
    Pages127-143
    Number of pages17
    ISBN (Electronic)9781444304039
    ISBN (Print)9780632037360
    DOIs
    Publication statusPublished - 29 Apr 2009

    Keywords

    • Aeolian intensity proxies
    • Late Quaternary monsoonal variations in western Arabian Sea
    • Power spectra of SPECMAP (solid curve)
    • Proxy for intensity of OMZ
    • Seasonal upwelling

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