Skip to content

2D analogue models of magma emplacement in the visco-elastic crust

^^Uddalak Biswas^1^, Olivier Galland1, Andreas Carlson2

  • Affiliations:  1Physics of Geological Processes, The Njord Centre, Department of Geosciences, University of Oslo, Blindern, 0316 Oslo, Norway 2Department of Mathematics, Mechanics Division, University of Oslo, Oslo 0316, Norway 

  • Presentation type: Poster

  • Presentation time: Thursday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 196

  • Programme No: 1.8.27

  • Theme 1 > Session 8

Abstract

The Earth's crust exhibits very complex rheology depending upon several physio-chemical conditions like temperature, pressure and lithology. This complex rheology of the crustal rocks is challenging to model. Thus, most researchers model magma propagation through crustal rocks of end-member rheologies such as viscous, coulomb and elastic materials. However, they are not sufficient to capture the whole spectrum of rheological behaviours of the host rock. In this work, we performed a series of 2D magma injection experiments considering laponite gels as crustal rock analogues. According to our rheological measurements, laponite in deionised water solution exhibits a range of rheological behaviours from purely viscous to visco-elastic to purely elastic depending upon varying concentration (weight-percentage, wt%) in the water. We used laponite gels of 2 wt% to 3.5 wt% to test the effects of the gel's yield stress = [0.597 - 10.6] Pa as a lab-scale crustal rock analogue, and used dyed oil and water (viscosity= 65 and 1 mPa.s) as magma equivalents. Our experiments revealed a range of intrusion shapes, from thin liquid-filled cracks of simple to more massive fluid intrusions of complex shapes, indicating their varied mechanism of formation from brittle fracturing to ductile flow. To reveal gel deformation accommodating the emplacement of the intrusion, we implemented image analysis combining photoelastic properties of laponite gel and Digital Image Correlation. The resulting quantitative results allow us correlating the intrusion morphologies with the deformation mechanisms within the gel. Finally, we propose a model that connects the host rheology with the magma emplacement mechanism.