Volcanic feldspars anomalous fading: Evidence for two different mechanisms

• Published in: Radiation measurements 2015-10, Vol.81, p.218-223
• Main Authors: Guérin, Gilles, Visocekas, Raphaël
• Format: Article
• Language: English
• Subjects: Anomalous fading; Conductivity; Continental interfaces, environment; Crystal disorder; Freezing of fading; Hopping; Luminescence; Ocean, Atmosphere; Plagioclase; Sanidine; Sciences of the Universe; Tunnelling; Volcanic feldspars
• ISSN: 1350-4487; 1879-0925
• DOI: 10.1016/j.radmeas.2015.08.009

This study presents measurements of anomalous fading of feldspars extracted from volcanic units from the Auvergne (France) and Patmos Island (Greece). We measured the fading rate for samples stored at ambient temperature, and also at liquid nitrogen temperature. A strongly different behaviour is then observed, the fading is reduced to values usually obtained and explained by pure tunnelling recombination of charges to near enough luminescence centres, which is athermal. We suggest that the temperature dependent or “frozen” part of the fading is relevant to a different mechanism, which is “hopping”, already proposed in the mid-sixties, which preserves the experimental logarithmic fading decreasing law. •Anomalous fading of TL of volcanic feldspars is drastic in a few weeks.•Anomalous fading after two decades of storage is twice the fading after one decade.•After storage for two decades at 77 K the fading is practically suppressed.•Anomalous fading is due at least to two several different mechanisms.•Volcanic feldspars have disordered lattice and electrons can hop from trap to trap.