Osl dating labs

16 Apr

Optical dating techniques employ ubiquitous quartz or feldspar grains to directly date the deposition of sedimentary units.As such, the optical dating methods allow the systematic chronological evaluation of Quaternary-age sedimentary sequences.The OLD Laboratory also provides a commercial luminescence dating service and works closely with clients in industry, archaeological organizations, environmental institutes and other academic groups.The OSL Laboratory was set up in 2003 as the Luminescence Dating Laboratory in the Department of Geography.Mineral separations are performed by standard techniques using heavy liquids and hydrofluoric acid (HF) to digest non-quartz minerals and etch the outer 10 to 20 µm of quartz grains which are affected alpha radiation.The purity of the quartz extract is primal for effective dating because a small amount contamination (1%) by potassium feldspar and other minerals can dominate the luminescence emissions.This technique, as thermoluminescence, was originally developed in the 1950s and 1960s to date fired archaeological materials, like ceramics (Aitken, 1985).

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In the past 15 years there have been significant advances in luminescence dating with the advent of single aliquot and grain analysis, and associated protocols with blue/green diodes that can effectively compensated for laboratory induced sensitivity changes (Murray and Wintle, 2003; Wintle and Murray, 2006; Duller, 2012) and render accurate ages for the past ca. Most recently, the development of protocols for inducing the thermal-transfer of deeply trapped electrons has extended potentially OSL dating to the 106 year timescale for well solar-reset quartz and potassium feldspar grains from eolian and littoral environments (Duller and Wintle, 2012).

Common silicate minerals like quartz and potassium feldspar contain lattice-charge defects formed during crystallization and from subsequent exposure to ionizing radiation.

These charge defects are potential sites of electron storage with a variety of trap-depth energies.

The exposure of quartz and feldspar grains to sunlight for 60 seconds effectively diminishes the time-stored OSL signal to a low definable level.

This residual level is the point from which the geological OSL signal accumulates post burial.