Publication Date:
2014-08-18
Description:
Sedimentary proxies used to reconstructmarine productivity suffer fromvariable preservation and
are sensitive to factors other than productivity. Therefore, proxy calibration is warranted. Here we map the
spatial patterns of two paleoproductivity proxies, biogenic opal and barium fluxes, from a set of core-top
sediments recovered in the Subarctic North Pacific. Comparisons of the proxy data with independent estimates
of primary and export production, surface water macronutrient concentrations, and biological pCO2 drawdown
indicate that neither proxy shows a significant correlation with primary or export productivity for the entire
region. Biogenic opal fluxes, when corrected for preservation using 230Th-normalized accumulation rates, show
a good correlation with primary productivity along the volcanic arcs (τ =0.71, p = 0.0024) and with export
productivity throughout the western Subarctic North Pacific (τ = 0.71, p = 0.0107). Moderate and good
correlations of biogenic barium flux with export production (τ = 0.57, p = 0.0022) and with surface water silicate concentrations (τ =0.70, p = 0.0002) are observed for the central and eastern Subarctic North Pacific. For reasons unknown, however, no correlation is found in the western Subarctic North Pacific between biogenic barium flux and the reference data. Nonetheless, we show that barite saturation, uncertainty in the lithogenic barium corrections, and problems with the reference data sets are not responsible for the lack of a significant correlation between biogenic barium flux and the reference data. Further studies evaluating the factors controlling the variability of the biogenic constituents in the sediments are desirable in this region.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
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