David Heslop: Unmixing of Natural Magnetic Mineral Assemblages
Channel: Institute for Rock Magnetism
Date: 2021-06-04

12th Institute for Rock Magnetism Conference

Session 2: Environmental Magnetism and Proxies


Conveners: Andrew Roberts (ANU) and Anna Lindquist (Macalaster College)


Title: Unmixing of Natural Magnetic Mineral Assemblages — Challenges to Approximating Reality


Author: David Heslop


Institution: Research School of Earth Sciences, Australian National University, Acton 2601, Australia


Abstract:

Magnetic minerals are sensitive to a wide range of natural processes and carry important information concerning past environments. In environmental magnetism, various techniques are used to identify and quantify magnetic minerals in natural materials to assist drawing of inferences concerning past environmental changes. Thus, it is essential to be able to identify and quantify different magnetic mineral subpopulations within a given material. Numerical unmixing techniques, which decompose magnetic remanence curves using collections of basis functions, have contributed significantly to this endeavor. We have, however, under-appreciated the nonuniqueness of these techniques and it is not possible to quantify model uncertainties fully. I will present an automated Bayesian framework for unmixing remanence curves to aid quantification of magnetic mineral subpopulations. By adopting a Bayesian framework, prior knowledge can be incorporated into the unmixing model and full uncertainties can be estimated to enable more robust inferences. Finally, I will consider the role numerical unmixing techniques can play in environmental magnetism and, most importantly, their limitations.