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Submitted on June 20, 2002 Spatial and Temporal Offsets Between Proxy Records in a Sediment Drift
1 Institute for Frontier Research on Earth Evolution (IFREE), 2-15 Natsushima-cho, Yokosuka 237-0061, Japan; Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA. * To whom correspondence should be addressed. E-mail: teglinton{at}whoi.edu . Chronologies for Late Quaternary marine sediment records are usually based on radiocarbon ages of planktonic foraminifera. Signals carried by other sedimentary components measured in parallel can provide complementary paleoclimate information. A key premise is that microfossils and other indicators within a given sediment horizon are of equal age. We show here that haptophyte-derived alkenones isolated from Bermuda Rise drift sediments are up to 7000 years older than coexisting planktonic foraminifera. This temporal offset, which is apparently due to lateral transport of alkenones on fine-grained particles from the Nova Scotian margin, markedly influences molecular estimates of sea-surface temperatures. More broadly, the observation raises questions about both the temporal and geographic fidelity of paleoenvironmental records encoded by readily transported components of sediments.
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Science. ISSN 0036-8075 (print), 1095-9203 (online)