Thermoluminescence dating studies of rapidly deposited silts from south-central British Columbia

Abstract

To determine whether Quaternary sediments from small lake and fan deposits can be dated by thermoluminescence (TL) methods, I have applied recently proposed techniques for TL dating to known-age, rapidly deposited silts and have examined the sensitivity of the TL of fine-grain feldspars and quartz to light. These feldspar-dominated silts exhibited little or no detectable anomalous fading. The TL of quartz was observed to be very resistant to light with wavelengths above ~400 nm, whereas that of feldspars was sensitive to all visible wavelengths. No significant resetting of the TL of the 11 ka old glaciolacustrine silt (deposition rate [Formula: see text]) could be detected with these techniques, implying that silts deposited at such rates into small, glacier-bordered lakes cannot be dated by these methods. However, accurate equivalent doses were measured for the derivative 7.5 ka old mudflow silts (~1 mm/year), but only with the use of the R–Γ technique applied to the feldspars.