Australia

Cashman, Richard

doi:10.7765/9781526123824.00007

Cited by 1 publication

(3 citation statements)

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“…In an active vertically protracted volcanic system (e.g. [8]), one might expect that such partially solidified sills will be subject to further injection of magma of similar composition. It is therefore of interest to explore how a new intrusion might interact with a sill which has already evolved to form a bulk mushy zone from the crystalline convecting layer that overlies a stratified cumulate layer, as a result of crystal sedimentation.…”

Section: Secondary Emplacement Of Meltmentioning

confidence: 99%

“…The model suggests that in long-lived, vertically extensive magmatic systems (e.g. [8]) the sub-volcanic mush is likely to be heterogeneous with respect to its density and composition on short length-scales. This has important implications for the dynamics of such systems, impacting the depths at which melts are intruded and the ability for magmas to ascend through the crust (e.g.…”

Section: Conclusion and Volcanological Implicationsmentioning

confidence: 99%

“…[1][2][3][4]). Recent petrological, geochemical and geophysical constraints point to a picture in which magmatic systems transcend the entire crust and comprise a vertical distribution of sills, containing magmas of different compositions and crystallinities [5][6][7][8][9]. In general, the magma becomes progressively more fractionated with height in the crust, as new melts injected into deeper sills cool and crystallize high melting point minerals; these minerals may form cumulate mush layers, while some of the remaining silicate liquid ascends to shallower crustal levels [10,11].…”

Section: Introductionmentioning

confidence: 99%

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Some fluid mechanical constraints on crystallization and recharge within sills

Woods

Stock

2019

Phil. Trans. R. Soc. A.

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The injection of hot magma into a sill can lead to heating and melting of the walls and roof of the reservoir while the injected magma cools and crystallizes. If the crystals are relatively dense, they will try to sediment from the injected magma to form a cumulate layer. In this cumulate layer, the crystals form a porous framework which traps the melt as it is built up. As the melt within the sill continually cools and precipitates dense crystals, there will be a gradual reduction in the density of the remaining silicate liquid. As a result, the melt which is progressively trapped in the pore space of the cumulate layer will become stably stratified in density. Using an idealized model of the fluid mechanical and thermodynamical principles, we explore some of the controls on the thickness and density stratification of cumulate layers following replenishment of a sill-like magma chamber. We show the balance between jamming of the crystal laden melt to form a homogeneous layer and the formation of a stratified cumulate zone depends on the cooling time scale compared to the sedimentation time scale. A key finding is that the composition and stratification in a packed crystal–melt suspension and the associated cumulate layer formed by cooling an intrusion of hot melt injected into the crust may have considerable variability, depending on the properties of the overlying roof melt and the size and hence fall speed of crystals which form in the melt. This article is part of the Theo Murphy meeting issue ‘Magma reservoir architecture and dynamics’.

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Section: Secondary Emplacement Of Meltmentioning

confidence: 99%

Section: Conclusion and Volcanological Implicationsmentioning

confidence: 99%