Miocene-Pliocene alkenone and coccolithophorid stable isotopic data for sea surface condition reconstructions in the Eastern Equatorial Pacific (IODP Site U1338). (Invited)
Abstract
Coccolithophores play an important role in earth’s biogeochemical cycles due to their great abundance, fast turnover rates, and their ability to carry out photosynthesis and calcification. Although calcareous nannofossils are major producers of carbonates and alkenones in the ocean, the use of coccoliths as a recorder of seawater δ18O and δ13C has been limited by the difficulty of isolating them from the bulk carbonates. Here, we present temperature and δ18O reconstructions over the mid-Miocene through the Plio-Pleistocene from IODP Site U1338 of Expedition 320/321 in the Eastern Equatorial Pacific. Isotopic data were obtained from mono-specific Noealherabdaceae dominated coccolith fine fractions isolated using the granulometric separation technique developed by Minoletti et al., (2009). The nannofossil assemblage compositions and the alkenone-derived SSTs were determined in the same samples and combined to the δ18O and δ13C values measured on the alkenone producing coccoliths to evaluate past sea-surface environmental conditions prevailing in the Equatorial Pacific. These new data based on organic and inorganic compounds produced by coccolithophores offer the potential to extract environmental informations including: sea surface temperature (alkenone unsaturation ratio) and salinity and fertility conditions (coccolith isotopic ratio). Using multiple geochemical proxies derived from a single group of plankton have huge potential for paleoenvironmental reconstructions.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFMPP22B..03B
- Keywords:
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- 1041 GEOCHEMISTRY / Stable isotope geochemistry;
- 1055 GEOCHEMISTRY / Organic and biogenic geochemistry;
- 4231 OCEANOGRAPHY: GENERAL / Equatorial oceanography