Open AccessLuminescence dating of M iddle P leistocene proglacial deposits from northern S witzerland: methodological aspects and stratigraphical conclusions
Author(s) -
Lowick Sally E.,
Buechi Marius W.,
Gaar Dorian,
Graf Hans R.,
Preusser Frank
Publication year - 2015
Publication title -
boreas
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.95
H-Index - 74
eISSN - 1502-3885
pISSN - 0300-9483
DOI - 10.1111/bor.12114
Subject(s) - feldspar , geology , thermoluminescence dating , quartz , optically stimulated luminescence , sedimentary depositional environment , chronology , mineralogy , sedimentary rock , plagioclase , luminescence , paleontology , geochemistry , structural basin , materials science , optoelectronics
Optically stimulated luminescence ( OSL ) dating was applied to proglacial deposits from the K lettgau V alley in northern S witzerland, which is understood to record several phases of glaciation prior to the L ast I nterglacial. The aim was to provide an independent chronology for the different sedimentary units to understand better the complex depositional history of the region. This time range requires care when assessing the reliability of the luminescence protocols applied. Equivalent doses for fine‐ and coarse‐grain quartz remained below 300 G y, while dose response curves for both fractions continued to display growth above 500 G y. Dose recovery tests confirmed the ability of the single aliquot regenerative ( SAR ) protocol to recover laboratory doses of a similar size to burial doses, and isothermal decay measurements confirmed the stability of the quartz signal. Having passed rigorous testing criteria, quartz OSL ages of up to ∼200 ka were considered reliable but significantly underestimated expected ages and prompt a reconsideration of earlier interpretations of the stratigraphy for this site. Rather than representing three separate glaciations, quartz luminescence ages instead suggest that these deposits record up to four independent ice advances during M arine I sotope S tage 6. For both single grain and single aliquot feldspar dating, it was not possible to separate the conflicting influences of anomalous fading and partial bleaching. However, uncorrected feldspar central age model ages were found to be in reasonable agreement with quartz age estimates, and suggest that feldspar ages may still offer useful additional information in this region.