Exploring IRSL50 fading variability in bedrock feldspars and implications for OSL thermochronometry

Pierre G. Valla*, Sally E. Lowick, Frédéric Herman, Jean Daniel Champagnac, Philippe Steer, Benny Guralnik

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

14 Citations (Scopus)

Abstract

Optically Stimulated Luminescence (OSL) is a well-established Quaternary dating method, which has recently been adapted to application in low-temperature thermochronometry. The Infra-Red Stimulated Luminescence (IRSL) of feldspar, which so far is the most promising target signal in thermochronometry, is unfortunately prone to anomalous fading. The fading of feldspar IRSL is at times not only challenging to measure, but also laborious to incorporate within luminescence growth models. Quantification of IRSL fading is therefore a crucial step in OSL thermochronometry, raising questions regarding (i) reproducibility and reliability of laboratory measurements of fading, as well as (ii) the applicability of existing fading models to quantitatively predict the level of IRSL field saturation in nature. Here we investigate the natural luminescence signal and anomalous fading of IRSL measured at 50 °C (IRSL50) in 32 bedrock samples collected from a variety of lithologies and exhumation settings (Alaska and Norway). We report a large span of IRSL50 fading rates between samples (g2days ranging from ∼0.5 to ∼45%/decade), which further demonstrates (i) a good reproducibility between two common fading measurement protocols, and (ii) the ability of tunnelling models to predict the level of feldspar IRSL50 field saturation in nature. We observe higher IRSL50 fading in feldspar with increasing Ca content, although other factors cannot be dismissed at present. Finally, our dataset confirms that the applicability of feldspar IRSL50 in OSL thermochronometry is limited to rapidly-exhuming settings or warm subsurface environments.

Original languageEnglish
Pages (from-to)55-66
JournalQuaternary Geochronology
Volume36
DOIs
Publication statusPublished - 2016

Keywords

  • Anomalous fading
  • Feldspar IRSL
  • Luminescence
  • OSL thermochronometry

Fingerprint Dive into the research topics of 'Exploring IRSL<sub>50</sub> fading variability in bedrock feldspars and implications for OSL thermochronometry'. Together they form a unique fingerprint.

  • Cite this