There is some evidence that optically stimulated luminescence (OSL) dating using the fast component from quartz may underestimate the age by
10% at about 130 ka, or for values of
De of
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. Any significant underestimate in age, if true, would be inconsistent with the expected values for the stability of the OSL trap. However, the alternative explanation, that the age control provided by the beginning of marine isotope stage 5e is
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10% too old, would be very contentious. As part of our continuing investigation of the reliability of quartz ages for older material, we describe results from a deposit on the Seyda River in northern Russia. Quartz was extracted from an organic-rich layer identified as being laid down in either MIS 7.1
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or MIS 7.3 (
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215 ka), and U-series dated to
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, and from the immediately overlying fluvial sand. The resulting mean OSL age of 10 samples from these sedimentary units is
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. The results are also discussed in relation to the earlier quartz studies.