On the unchanging shape of thermoluminescence peaks in preheated feldspars: Implications for temperature sensing and thermochronometry

Abstract

Significant advances have been made during the past 10 years in our understanding of the nature of thermoluminescence (TL) signals from feldspars. Modeling insights into the luminescence mechanism have been obtained based on quantum tunneling, and this has led to the development of new analytical equations for quantifying the luminescence signals. In addition, Monte Carlo studies have helped researchers understand the effect of random distributions of charges and of energy distributions on the TL signals. From an experimental point of view, there has been renewed interest in using these signals for particle temperature sensing in the microseconds-to-seconds time scale, and in thermochronometry applications involving a much larger geological time scale (103–105 yr). One of the fundamental issues in these field applications is the difficulty of calibrating the TL signals from feldspars as a function of the preheating temperature and of the preheating time.This paper presents new analytical expressions describing the changes in the TL glow curves in feldspar samples, when they are heated at different temperatures and for different preheat times. The behavior of the TL glow curves is described and some universal characteristics of TL glow curves are pointed out, which can be useful in analyzing regenerative TL signals. Good agreement is found between the analytical equations and experimental data for several geological feldspar samples. The insights obtained from the new equations and the model can help in understanding how feldspar TL signals record recent or geologic thermal signatures in temperature sensing and thermochronometry applications.