Luminescence Dating facility
Luminescence dating is a trapped charge technique whereby electrons are ‘trapped’ in defects in the minerals such as quartz and feldspar. This trapped signal is light sensitive and builds up over time during a period of no light exposure (during deposition or burial) but when exposed to light (natural sunlight or artificial light in a laboratory) the signal is released from the traps in the form of light – called luminescence. In this facility we aim to sample these minerals (found in all sediments) without exposing them to light so that we can stimulate the trapped signal within controlled laboratory conditions with heat (thermoluminescence – TL) or light (optically stimulated-luminescence – OSL). The amount of light produced is directly proportional to the amount of electrons that have built up over time – this provides a radiometric ‘clock’ that can be used to establish the time since the mineral grains were last exposed to sunlight, which equates to the depositional age.
As most sedimentary processes or events are based on the deposition of sediment these depositional ages are critical to geomorphological research. In addition, the age of sediment deposition is also crucial for the evidence found within the sediment such as pollen, fossils and artefacts and therefore the technique is relevant for paleoclimatology, archaeological and paleontological research. Therefore the facility supports existing research programs investigating climate change, natural hazards, coastal and river management, and human-environment interactions.
The facility houses state-of-the-art luminescence preparation and measuring equipment within two specially designed subdued red-light laboratories. The facility, run by Dr Kira Westaway, contains a fully equip wet room preparation area with a core and tube opening station, HF fume hoods, wet and dry sieving and mineral separation stations, and a ball mill. The dry instrument room contains two ‘Riso’ automated luminescence readers (one with single-grain capabilities and the other with a red TL setup), a low-level beta GM multicounter and two Daybreak 583 thick-source alpha counters all within subdued red light conditions. The entire facility is an AQIS approved place for the processing of quarantined samples and houses a specially designed AQIS storage room. The facility is supported by internal RIBG and MQSIS funding as well as joint ARC LIEF funding in collaboration with UTS, UNSW and UNE. The facility was only opened in 2010 but already many samples have been processed that have contributed to HDR research in the Macquarie Marshes, research into the arrival of modern humans in northern Laos (published in PNAS) and methodological advancement into exploring the use of a dual signal approach (published in Radiation Measurements).
It is not a commercial facility but currently supports 7 Macquarie staff, 7 HDR students, HDR research and undergraduate teaching and 5 external collaborations. Please contact Dr Kira Westaway (kira.westaway@mq.edu.au) for further details.