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Posted by / 08-Jan-2018 14:49

Quartz osl dating

Reconstructing dust Mass Accumulation Rate (MAR) from loess deposits is critical to understanding past atmospheric mineral dust activity and requires accurate independent age models from loess deposits across Europe and Asia.

Previous correlations of loess in Europe and China have tended to focus on multi-millennial timescales, with no detailed examination of dust MAR at the two ends of the Eurasian loess belt on shorter, sub-orbital scales.

With the assistance of Fugro UK we have developed a method for converting the measured water content to a time-averaged water content for each sample.

The limiting factor in the age range for luminescence dating is the 'saturation' of the signal at large dose rates (i.e. Accurate age determination therefore becomes increasingly difficult for older samples and there is a loss in dating precision (an increase in statistical uncertainty).

A residue of pure quartz is extracted by chemical digestion in hydrochloric acid, hydrogen peroxide and fluorosilicic acid, in a process which may take several weeks.

The luminescence of each sample is measured using industry-standard Luminescence Readers (manufactured by Risoe National Laboratories, Denmark) which incorporate 90Sr beta-sources, and 470nm LED optical stimulation.

For instance, a sample with an actual water content of 44% giving an age of 40Ka dated using a water content value of 30% may give a false age of 31Ka (the precise values depend on the details of the sediment chemistry).

However, it is possible to identify saturated samples through measurement.This is done in collaboration with the University of Oxford Luminescence Dating Laboratory.Although a relatively new technique, particularly in subaqueous sediments, Strata Data have pioneered its industrial application in dating superficial seabed deposits for geohazard risk assessment.However, as reported before, it seems the quartz OSL technique is only capable of accurate age determination up to accrued doses of ca. 30–40 ka) due to approaching field saturation of the quartz OSL signal.Two age-depth models were used to reconstruct dust MARs, where one utilises OSL data solely and the other additionally makes assumptions about sedimentation rates.

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