This study examines melt inclusions containing bubbles of aqueous fluid (L, V, and L + V), occurring in rhyolites from the Okataina Volcanic Centre, New Zealand, and the Río Blanco Cu-Mo deposit, Chile. We demonstrate that these aqueous fluids coexisted with silicate melts (magmas) and represent either post-trapping exsolution (in the case of Okataina), or co-trapping of phases already coexisting in the magma (in the case of Río Blanco). Microthermometry proves that some of the bubbles are a single-phase aqueous liquid, and all are shown by PIXE analysis to be metal rich saline solutions. As such, these aqueous fluids provide the closest approximation to direct testing of the proposition that cooling magmas exsolve metal-rich aqueous fluid. In the case of pre-trapping exsolution at Río Blanco we show that some inclusions record and preserve magmatic emulsions (melt + aqueous fluid) that are the first stage in the evolution of hydrothermal fluids. We demonstrate that heating experiments on volatile-rich melt inclusions can produce in-situ exsolution of hypersaline metal-rich aqueous fluid bubbles, potentially permitting magma-chamber processes to be experimentally modelled. © 2006 Elsevier B.V. All rights reserved.

Item Type:	Refereed Article
Research Division:	Earth Sciences
Research Group:	Geology
Research Field:	Igneous and metamorphic petrology
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the earth sciences
UTAS Author:	Davidson, P (Dr Paul Davidson)
UTAS Author:	Kamenetsky, VS (Professor Vadim Kamenetsky)
ID Code:	51594
Year Published:	2007
Web of Science® Times Cited:	28
Deposited By:	Centre for Ore Deposit Research - CODES CoE
Deposited On:	2007-08-01
Last Modified:	2011-09-29
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