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Spatial and Temporal Offsets Between Proxy Records in a Sediment Drift
Nao Ohkouchi,1*Timothy I. Eglinton,1Lloyd D. Keigwin,2John M. Hayes2
Chronologies for Late Quaternary marine sediment records are
usually based on radiocarbon ages of planktonic foraminifera.Signals
carried by other sedimentary components measured in parallelcan
provide complementary paleoclimate information. A key premiseis that
microfossils and other indicators within a given sedimenthorizon are
of equal age. We show here that haptophyte-derivedalkenones isolated
from Bermuda Rise drift sediments are up to7000 years older than
coexisting planktonic foraminifera. Thistemporal offset, which is
apparently due to lateral transportof 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 thetemporal and the geographic fidelity of
paleoenvironmental recordsencoded by readily transported components of
sediments.
1 Department of Marine Chemistry and
Geochemistry,
2 Department of Geology and
Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
*
Present address: Institute for Frontier Research on Earth
Evolution, 2-15 Natsushima-cho, Yokosuka 237-0061, Japan.
To whom correspondence should be addressed. E-mail:
teglinton{at}whoi.edu
Abrupt Temperature Changes in the Western Mediterranean over the Past 250,000 Years.
B. Martrat, J. O. Grimalt, C. Lopez-Martinez, I. Cacho, F. J. Sierro, J. A. Flores, R. Zahn, M. Canals, J. H. Curtis, and D. A. Hodell (2004)
Science
306, 1762-1765
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