Investigation of optically stimulated luminescence behavior of quartz from crystalline rock surfaces: A look forward

Optically stimulated luminescence (OSL) dating has recently been applied to crystalline (i.e. igneous and metamorphic) rock surfaces. With the advent of this technique, early studies can guide improvements to the methodology that will lead to more robust age constraints. Low OSL sensitivity, poor me...

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Bibliographic Details
Published inQuaternary geochronology Vol. 36; pp. 161 - 173
Main Authors Simkins, Lauren M., DeWitt, Regina, Simms, Alexander R., Briggs, Sophie, Shapiro, Russell S.
Format Journal Article
LanguageEnglish
Published Elsevier B.V 01.09.2016
Subjects
Antarctic beaches
Cathodoluminescence
Crystalline rocks
Microdosimetry
Optically stimulated luminescence
Rock surfaces
IRSL
Optically stimulated luminescence
Microdosimetry
Rock surfaces
EDS
SAR
OSL
CL
IR
Antarctic beaches
Cathodoluminescence
Crystalline rocks
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Summary:Optically stimulated luminescence (OSL) dating has recently been applied to crystalline (i.e. igneous and metamorphic) rock surfaces. With the advent of this technique, early studies can guide improvements to the methodology that will lead to more robust age constraints. Low OSL sensitivity, poor measurement reliability, and equivalent dose scatter are common problems with dating quartz from crystalline rock surfaces. We investigate OSL characteristics of quartz extracted from crystalline Antarctic beach cobbles. Comparison of OSL behavior with cathodoluminescene characteristics and mineral composition and texture does not show a distinct relationship, suggesting luminescence behavior results from the natural radiation environment and post-crystallization transport history, rather than provenance source and the nature of crystal defects. Elemental composition of processed samples used for OSL measurements indicates standard methods of chemical preparation are not always suitable to extract pure quartz samples. Additionally, heterogeneous radiation production and attenuation poses a problem for estimating dose rates, in particular regarding beta contributions that dominate effective dose rates. We determine the sensitivity of effective dose rates to water content parameters and crystal size needed to calculate dose rates for crystalline rock surfaces. An increase in the value of all modelled parameters serves to reduce effective dose rates and, thus increase OSL ages. Dose rates are most sensitive to crystal size, which can introduce large uncertainty in burial ages from crystalline rocks due to heterogeneous crystal morphology (i.e. size and shape). This study provides a step forward in understanding the challenges and improving the methodology of luminescence dating of quartz from crystalline rock surfaces.
ISSN:1871-1014
1878-0350
DOI:10.1016/j.quageo.2016.09.002