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Magmatic precursors of hydrothermal fluids at the Ro Blanco Cu-Mo deposit, Chile: links to silicate magmas and metal transport


Davidson, P and Kamenetsky, VS and Cooke, DR and Frikken, P and Hollings, P and Ryan, C and van Achterbergh, E and Mernagh, T and Skarmeta, J and Serrano, L and Vargas, R, Magmatic precursors of hydrothermal fluids at the Rio Blanco Cu-Mo deposit, Chile: links to silicate magmas and metal transport, Economic Geology, 100, (5) pp. 963-978. ISSN 0361-0128 (2005) [Refereed Article]

DOI: doi:10.2113/100.5.963


In most porphyry systems the obscuring effects of hydrothermal processes and subsequent alteration, along with limited exposure of source rocks, preclude a detailed understanding of how and where metals and volatiles were derived. However, in this study we examine melt inclusions which have escaped alteration and that sampled all of the phases coexisting in the magma, in late- and postmineral rhyolitic units from the Río Blanco Cu-Mo deposit, Chile. These inclusions demonstrate the existence of a volatile-rich melt, the exsolution from it of an aqueous volatile-rich phase, initially as melt + vapor bubble emulsions, and the disruption of these emulsions into melt and primary magmatic fluids. Trapping of these emulsions may explain the occurrence of melt inclusions containing widely varying proportions of melt and aqueous fluid found at Río Blanco. We demonstrate the sequestering of metals into the exsolved volatile phases and the derivation from these of possible ore-forming hydrothermal fluids, with particular reference to the implications for metal transport. Melt inclusions show differences between adjacent comagmatic intrusions that may be directly related to the extent of mineralization of the respective bodies. In one of the Río Blanco postmineral rhyolite bodies melt inclusions show exsolution of the volatile-rich phase but only minor evidence of trapping of a metal-rich vapor. In contrast, inclusions from an adjacent late mineral rhyolite body show similar volatile phase exsolution but also provide evidence of ponding of metal-rich hydrothermal fluids during the final stages of cooling. © 2005 Society of Economic Geologists, Inc.

Item Details

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)
UTAS Author:Cooke, DR (Professor David Cooke)
UTAS Author:Frikken, P (Mr Peter Frikken)
UTAS Author:Hollings, P (Professor Peter Hollings)
ID Code:39017
Year Published:2005
Web of Science® Times Cited:23
Deposited By:Centre for Ore Deposit Research - CODES CoE
Deposited On:2005-08-01
Last Modified:2007-10-17

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