BAYESIAN ANALYSIS OF PAIRED IN SITU 14C AND 10BE MEASUREMENTS: INSIGHTS INTO COMPLEX EXPOSURE HISTORIES

Studies employing measurements of two or more in situ cosmogenic nuclides are powerful approaches to addressing geomorphic questions, such as complex exposure histories or burial dating. A key emerging application in this regard uses paired in situ ¹⁴C-¹⁰Be measurements from proglacial bedrock to constrain both (1) the waxing and waning of glaciers and ice sheets during the Holocene Epoch, and (2) the present subglacial dynamics (e.g., abrasion rates). By combining a well-posed geomorphic model with Bayesian analysis, we can uniquely solve for the exposure duration, burial duration, and distribution of glacial abrasion rates across a glacial trough. While Bayesian analysis is a recent advance in the interpretation of these and other datasets, precise measurement of ¹⁴C and ¹⁰Be, sometimes at very low concentrations is perhaps the most critical requirement for success. We will discuss the use of Bayesian analysis in cosmogenic nuclides studies, both in our particular project and more generally, as well as advances in ¹⁴C and ¹⁰Be measurements.