Abstract
Abstract. In this study we have applied different indices based on long-chain diols, i.e., the
long-chain diol index (LDI) as a proxy for past SST, the
diol index as an indicator of past upwelling conditions, and the nutrient diol
index (NDI) as a proxy for nitrate and phosphate concentrations in seawater.
The proxies were analyzed in marine sediments recovered at ODP Site 1234,
located within the Peru–Chile upwelling system, with a ∼2 kyr
resolution covering the last 150 kyr. We also generated
TEX86H and U37K′ temperature and planktonic
δ18O records, as well as total organic carbon (TOC) and
accumulation rates (ARs) of TOC and lipid biomarkers (i.e., C37
alkenones, GDGTs, dinosterol, and loliolide) to reconstruct past phytoplankton
production. The LDI-derived SST record covaries with TEX86H-
and U37K′-derived SST records as well as with the planktonic
δ18O record, implying that the LDI reflects past SST
variations at this site. TOC and phytoplankton AR records indicate increased
export production during the last interglacial (MIS 5), simultaneous with a
peak in the abundance of preserved Chaetoceros diatoms, suggesting
intensified upwelling during this period. The diol index is relatively low
during the upwelling period, but peaks before and after this period,
suggesting that Proboscia diatoms were more abundant before and
after the period of upwelling. The NDI reveals the same trends as the diol
index, suggesting that the input of nitrate and phosphate was minimal during
upwelling, which is unrealistic. We suggest that the diol index and NDI
should perhaps be considered as indicators for Proboscia productivity instead of upwelling conditions or nutrient concentrations.
Funder
European Research Council
Subject
Paleontology,Stratigraphy,Global and Planetary Change
Reference146 articles.
1. Abrantes, F.: Diatom assemblages as upwelling indicators in surface
sediments off Portugal, Mar. Geol., 85, 15–39, 1988.
2. Abrantes, F. and Moita, M. T.: Water column and recent sediment data on
diatoms and coccolithophorids, off Portugal, confirm sediment record of
upwelling events, Oceanol. Acta, 22, 318–336,
1999.
3. Abrantes, F., Lopes, C., Mix, A., and Pisias, N.: Diatoms in Southeast
Pacific surface sediments reflect environmental properties, Quaternary
Sci. Rev., 26, 155–169, 2007.
4. Anabalón, V., Morales, C. E., Escribano, R., and Angélica Varas, M.:
The contribution of nano- and micro-planktonic assemblages in the surface
layer (0–30m) under different hydrographic conditions in the upwelling area
off Concepción, central Chile, Prog. Oceanogr., 75, 396–414, 2007.
5. Berger, W.H., Fischer, K., Lai, C., and Wu., G.: Ocean productivity and
organic carbon flux. Part I. Overview and maps of primary production and
export productivity, University of California, San Diego, La Jolla, California, 1987.
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