Modelling of sill inception, propagation and growth

We are pleased to inform about a publication from our research group. The paper is published in Earth And Planetary Science Letters and available online at

 http://www.sciencedirect.com/science/article/pii/S0012821X15001879

A model of magma propagation in the crust is presented using a series of analogue experiments, where dyed water is injected at a constant flux into layers of solidified gelatine. Digital image correlation (DIC) is used to calculate incremental strain and finite strain in the deforming host material as it is intruded. This is mapped in 2D for the developing experimental volcanic plumbing system that comprises a feeder dyke and sill. Since the gelatine deforms elastically, strain measurements correlate with stress. Our results indicate that, for constant magma flux, the moment of sill inception is characterised by a significant magmatic pressure decrease of up to ∼60%. This is evidenced by the rapid contraction of the feeder dyke at the moment the sill forms. Sill propagation is then controlled by the fracture properties of the weak interface, with fluid from the feeder dyke extracted to help grow the sill. Pressure drops during sill inception and growth are likely to be important in volcanic systems, where destabilisation of the magmatic plumbing system could trigger an eruption.

 

Model of dyke and sill formation

Model of dyke and sill formation

 

Screenshot_2015-04-29-08-27-33


Welcome to TER

TER is the Tectonics and Earth Resources research group at the University of Newcastle.

In broadest terms, our research examines the geological processes that form the physical environment in which we live. This research is achieved within the plate tectonic framework enabling the formation and dispersal of continents. We aim to identify specific tectonic settings and understand tectonic processes, in order to better understand the growth of the Australian continent and the formation/location of resources undercover.


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