Multi-dimensional Luminescence to Assess the Sources of Eroded River Sediments

Objective

Sediment tracing, understanding the mobility and origin of sediments, is fundamental for unlocking the geological record, reconstructing how landscapes respond to a range of external perturbations and mapping occurrences of important natural resources. Luminescence, the light emissions of minerals, e.g., quartz, due to exposure to ionising radiation followed by either light or heat, is emerging as a promising new sediment tracing tool. This is because quartz luminescence properties scale with geomorphic variables, e.g., transport distance, as well as chemical composition. However, fundamental research gaps prevent luminescence being applied as a standard sediment tracing tool. First, model/experimental data show that the timescales over which quartz can preserve sediment routing information are limited before these signals are 'shredded', but precise thresholds are poorly quantified, and no research has been conducted to determine what causes this variability. Second, luminescence provenance studies have typically focussed on a narrow emission window of quartz, which has been shown to be sensitive to transport processes, so may be unsuited to detecting source-to-sink provenance linkages. Multi-LASERS will address these research gaps using an interdisciplinary, experimental research design. The project aims to answer two overarching research questions: 1) How long can a quartz grain retain sediment routing information? And, 2) Is thermoluminescence (TL) emission spectra a reliable sediment provenance tool? Question 1 will be answered by measuring the response of a wide range of quartz samples to high doses of radiation, coupled with trace element geochemistry. Question 2 will be answered by examining the TL characteristics of a suite of rock samples with known provenance associations. Multi-LASERS will equip the fellow with new technical skills in luminescence spectrometry and geochemistry and professional skills like laboratory management.