Plaster and magnets: Modelling magnetic fabric development in magma intrusions using scaled analogue experiments

0572311 - GFÚ 2024 RIV NL eng J - Journal Article
Martin, S. A. - Závada, Prokop - Kavanagh, J. L.
Plaster and magnets: Modelling magnetic fabric development in magma intrusions using scaled analogue experiments.
Tectonophysics. Roč. 855, May (2023), č. článku 229820. ISSN 0040-1951. E-ISSN 1879-3266
R&D Projects: GA ČR(CZ) GA22-12828S
Institutional support: RVO:67985530
Keywords : analogue modelling * intrusion emplacement * fluid flow * anisotropy of magnetic susceptibility * magma * dyke
OECD category: Geology
Impact factor: 2.9, year: 2022
Method of publishing: Open access
https://www.sciencedirect.com/science/article/pii/S004019512300118X

Understanding magma behaviour during emplacement within the crust is vital for understanding the dynamic processes occurring in volcanic systems. However, linking the static record of magma flow to its dynamic origin is challenging, particularly as macroscopic indicators of magma flow are often not observed, absent and/or have been modified after emplacement. Anisotropy of magnetic susceptibility (AMS) has been used as an important tool in field studies to infer magma flow direction, using the magnetic fabric as a record of the magma intrusion dynamics and to identify magma source regions. Here, we describe a new method to explore magnetic fabric development in magma intrusions and lava flows using scaled analogue laboratory experiments. Coloured mixtures of Plaster of Paris (the magma analogue) seeded with magnetite particles were loaded concentrically into a piston and injected through a central port in the base of a box filled with compacted fine-grained wheat flour (the crust analogue). This created a series of interconnected sheet and tube-like 'magma' intrusions which eventually breached the surface to feed a model 'lava flow'. Once solidified, the intrusions were excavated and sampled for AMS, with the results showing that magnetic fabrics were preserved. A new dynamic scaling analysis shows the plaster mixture represents the intrusion of dacite magma into the shallow crust. These models provide proof-of-concept that this new methodology and scaling analysis can be used to explore AMS development in viscous (dacite) magma intrusions in nature, with the potential for direct comparison with field-based indicators of magma flow dynamics.
Permanent Link: https://hdl.handle.net/11104/0343053