Investigating Provenance Using Infrared Stimulated Luminescence (IRSL) Characteristics of Feldspar Grains

Abstract:

Infrared stimulated luminescence (IRSL) is a technique typically used on potassium feldspar grains for dating sediment deposition. However, the apparent age of a deposit is not the only valuable piece of information a grain can provide. Recent developments in IRSL protocols, such as post-IR IRSL measurements (pIRIR) and the Super-K grain separation method, have shed new light on the mineralogic controls on luminescence behavior for both alkali and plagioclase feldspars. Preliminary results indicate that characteristics such as pIRIR brightness and change of decay shape with preheat temperature are correlated to relative abundance of Ca-Na-K, minor and trace elemental composition, degree of Al-Si order, and microstructures such as exsolution lamellae. The effects of weathering on luminescence behavior is also considered. Using this information, we investigate the feasibility of comparing IRSL responses of sediments to potential sources to identify the parent rock. While this study focuses on deposits derived from extant igneous and metamorphic bodies, future investigations will expand upon this research to include reworked sediments. Coupled with concurrent studies in using partial bleaching to identify multiple depositional episodes, this research brings us closer to understanding the provenance of a single grain.