Volatile exsolution at the Dinkidi Cu-Au porphyry deposit, Philippines; a melt-inclusion record of the initial ore-forming process

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doi: 10.1130/0091-7613(1999)027<0691:VEATDC>2.3.CO;2
Authors:Kamenetsky, Vadim S.; Wolfe, Rohan C.; Eggins, Stephen M.; Mernagh, Terrence P.; Bastrakov, Evgeniy
Author Affiliations:Primary:
University of Tasmania, School of Earth Sciences and Centre for Ore Deposit Research, Hobart, Tasmania, Australia
Australian National University, Australia
Australian Geological Survey Organisation, Australia
Volume Title:Geology (Boulder)
Source:Geology (Boulder), 27(8), p.691-694. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0091-7613
Publication Date:1999
Note:In English. 28 refs.; illus., incl. sect., 1 table, sketch map
Summary:Immiscible phases derived from degassing silicate magmas are considered to be precursors of metal-bearing hydrothermal fluids in porphyry deposits. The development of melt-inclusion techniques provides a window into this critical period of porphyry formation, when the cooling, decompression, and crystallization of silicate melts result in the formation of immiscible phases. The record of magmatic to hydrothermal evolution is presented using inclusions in clinopyroxene phenocrysts from the syenitic Balut dike, one of the host-rock lithologies for mineralization at the Dinkidi Cu-Au porphyry deposit, Philippines. Primary inclusions include silicate glass, multiphase aggregates comprising salts, silicates, sulfates, carbonates, sulfides and oxides, and highly saline aqueous fluids. Various analyses, including in situ laser ablation inductively coupled plasma-mass spectrometry of the multiphase inclusions, determined elevated concentrations of Cl, S, As, Tl, K, Na, and a number of metals, including those that form ore-grade deposits (e.g., Cu) and those that do not (e.g., Mo, Pb, Zn, and W) at the Dinkidi porphyry deposit. Silicate melt and multiphase salt-rich inclusions in clinopyroxene are interpreted as having originally formed as immiscible phases at magmatic temperatures.
Subsections:Minerals and ores
Subjects:Chain silicates; Clinopyroxene; Copper ores; Dikes; Exsolution; Fluid inclusions; Geochemistry; Gold ores; Immiscibility; Inclusions; Intrusions; Magmatism; Melts; Metal ores; Mineral deposits, genesis; Phase equilibria; Phenocrysts; Polymetallic ores; Porphyry copper; Pyroxene group; Silicates; Volatiles; Asia; Far East; Luzon; Philippine Islands; Balut Dike; Caraballo Mountains; Didipio Complex; Dinkidi Deposit
Coordinates:N160000 N160000 E1213000 E1213000
Abstract Numbers:00M/581
Record ID:1999055480
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
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