Discrete barite particles and barium as tracers of paleoproductivity in south Atlantic sediments
作者:
Franz Gingele,
Andreas Dahmke,
期刊:
Paleoceanography
(WILEY Available online 1994)
卷期:
Volume 9,
issue 1
页码: 151-168
ISSN:0883-8305
年代: 1994
DOI:10.1029/93PA02559
数据来源: WILEY
摘要:
Geochemical analyses as well as X ray diffraction measurements were carried out on five sediment cores from the eastern Angola Basin and the equatorial divergence of the South Atlantic. Barite concentrations were calculated from total barium concentrations by subtracting the estimated barium background supplied by “nonbarite” barium carriers. Barite concentrations assessed by this geochemical method show a good correspondence to barite concentrations determined by quantitative X ray diffraction measurements. Barite proved to be an important carrier of barium in the pelagic cores, contributing up to 90% of the total barium concentrations in the sediment, while clastic material provides an important source of barium at sites closer to the African continent. Barite accumulation rates were calculated in order to eliminate the diluting effects of varying inputs of terrigenous and biogenic material. Barite accumulation rates show cyclic variations with maxima corresponding to glacial and minima to interglacial stages. Absolute paleoproduction rates were computed from barite accumulation rates. At the Congo fan and the equatorial divergence they are consistent with calculations based on total organic carbon (TOC) accumulation. At the Walvis Ridge, glacial‐interglacial cycles contrast to a constant paleoproductivity computed from TOC accumul
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