Yamato, P.; Tartèse, R.; Hallot, E.; Boulvais, P.; Poujol, M. and Gallagher, K.
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We present the results of 2D numerical models of flow in a two-phase medium, composed by crystals carried by a viscous melt, subject to a vertical pressure gradient condition. These simulations of magma migration in a vertical dyke show that presence of crystals and their proportion perturb the flow velocity. As shown in previous analytical studies, the presence of crystals leads to a significant drop in vertical velocity. However in our case, this global displacement is accompanied neither by obvious crystal rotation nor by a significant horizontal displacement of crystals towards the dyke centre. Moreover, our results show that separation between crystal and melt occurs under certain conditions, which can lead to geochemical differentiation of magmas during their ascent. We provide, through a quantitative parametric study, the range of values leading to crystal-melt segregation and compare the obtained differentiation rates to natural observations. Consequently, our results have fundamental implications regarding the causes of geochemical heterogeneities in magmatic suites. They provide constrains on differentiation processes during ascent, which is often neglected in comparison with the two classical end-members (i.e., source-related processes vs. emplacement-related processes differentiation.
|Item Type:||Conference Item|
|Copyright Holders:||2010 The Authors|
|Academic Unit/Department:||Science > Physical Sciences|
|Depositing User:||Romain Tartèse|
|Date Deposited:||06 Feb 2012 16:53|
|Last Modified:||23 Oct 2012 14:33|
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