Late Quaternary monsoonal variations in the western Arabian Sea based on cross-spectral analyses of geochemical and micropalaeontological data (ODP Leg 117, core 728A)

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doi: 10.1002/9781444304039.ch12
Author(s): ten Kate, W. G. H. Z.; Sprenger, A.; Steens, T. N. F.; Beets, C. J.
Author Affiliation(s): Primary:
Free University, Geomarine Centre, Amsterdam, Netherlands
Other:
Petroconsultants, United Kingdom
Volume Title: Orbital forcing and cyclic sequences
Volume Author(s): de Boer, P. L., editor; Smith, D. G.
Source: Orbital forcing and cyclic sequences, edited by P. L. de Boer and D. G. Smith. Special Publication of the International Association of Sedimentologists, Vol.19, p.127-143. Publisher: Blackwell, Oxford, International. ISSN: 0141-3600. ISBN: 978-1-444-30403-9 CODEN: SPISDS
Note: In English. 30 refs.; illus. incl. 2 tables, sketch map
Summary: 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 (CaCO3, TOC, U, Ba, Br and I), intensity of the OMZ (planktonic foraminiferal tests whole-fragments ratio) and upwelling-induced productivity (δ13C Globigerina bulloides - δ13C Neogloboquadrina dutertrei). Examination for coherence and phase relationship with the SPECMAP stacked δ18O 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. Abstract Copyright (1994), The International Association of Sedimentologists.
Year of Publication: 1994
Research Program: ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Arabian Peninsula; Arabian Sea; Asia; C-13; Carbon; Cenozoic; Climate forcing; Continental margin; Cycles; Foraminifera; Geochemistry; Globigerinacea; Indian Ocean; Invertebrata; Isotopes; Leg 117; Microfossils; Milankovitch theory; Monsoons; Neogloboquadrina; Neogloboquadrina dutertrei; O-18; ODP Site 728; Ocean Drilling Program; Oman; Orbital forcing; Oxygen; Oxygen minimum zone; Productivity; Protista; Quaternary; Rotaliina; Seasonal variations; Spectral analysis; Stable isotopes; Upper Quaternary; Upwelling
Coordinates: N174042 N174042 E0594934 E0594933
Record ID: 1994023013
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