Anomalous fading of thermoluminescence in mineral samples

Journal Article · Fri Sep 21 04:00:00 EDT 1973 · Nature (London), v. 245, no. 5421, pp. 143-144

DOI:https://doi.org/10.1038/245143a0· OSTI ID:4423005

Wintle, A G

It is stated that in attempts to date volcanic lava from geologically recent flows (5,000 to 50,000 yr) by measuring the thermoluminescence (TL) from the feldspars present, the results were always significantly lower than the accepted ages of the lava flows. The reason for this discrepancy is a loss of charge carriers from traps that contribute to the TL in the 350 deg to 450 deg region of the glow curve, causing anomalous fading'' that has been directly demonstrated in the laboratory for a variety of feldspars. Details of the experimental work are given, and glow curves are shown for a basalt lava sample from the Massif Central region, showing a 45% TL loss at the 4O0 deg C ordinate after storage for 3 days at room temperature. The behaviour of other lava samples followed this pattern. Quartz showed no loss above the 250 deg C glow curve ordinate; and the profile of the curve was that expected from thermal emptying of the shallower traps only. Various feldspar separates, limestones, fluorapatite, and zircon were also examined, and results are tabulated. It is pointed out that failure to observe fading in a short term experiment does not exclude longer term fading. Fading rate appears to be independent of the type of irradiation unless this is alpha -irradiation; the latter produces grerter fading. The mechanism for fading is being investigated. (UM

• Research Organization: Oxford Univ.
• NSA Number: NSA-29-000414
• OSTI ID: 4423005
• Journal Information: Nature (London), v. 245, no. 5421, pp. 143-144, Journal Name: Nature (London), v. 245, no. 5421, pp. 143-144; ISSN NATUA
• Country of Publication: United Kingdom
• Language: English

Related Subjects

*LAVA-- AGE ESTIMATION
BETA PARTICLES
HIGH TEMPERATURE
LIMESTONE
MEDIUM TEMPERATURE
MINERALS
N44400* --Environmental & Earth Sciences--Radiometric Techniques
PHYSICAL RADIATION EFFECTS
QUARTZ
TEMPERATURE DEPENDENCE