Magma ascent in layered elastic media: insights from field studies and analogue experiments
Ben Rogers, Geology MESci Student at the University of Liverpool, will present his work on "Magma ascent in layered elastic media: insights from field studies and analogue experiments".
Polarised light image of an analogue experiment. Gelatine is photoelastic, such that the internal stresses acting on the medium appear as interference colours when polarised light shines through it.
Magma is transported through the Earth’s brittle crust via magmatic intrusions. A series of analogue experiments are presented, modelling intrusion growth and their interaction with a layered elastic medium. These analogue experiments consisted of heterogeneous layers of gelatine (a crustal analogue) which were injected with dyed water (a magma analogue) to generate models of intrusive crustal magmatic bodies. By varying the strength of the interface and the stiffness contrast between the upper and lower gelatine layers a variety of structures and processes were generated, including dykes, sills, dyke-sill hybrids, dyke arrest and dyke penetration. Both stiffness contrast and interface strength were found to frequently cause the deviation of a propagating dyke by causing it to arrest or deflect and intrude the interface to form a sill. Fracture toughness values were calculated to inform on the relative strength of both the analogue body and the interface, to attempt to quantify the behaviour of these structures. The experiments were informed by observations of the intrusions of the Little Minch Sill Complex taken during a period of field work on the Isle of Skye, Scotland.