Volatile exsolution at the Dinkidi Cu-Au porphyry deposit, Philippines: a melt inclusion record of the initial ore-forming process
journal contribution
posted on 2023-05-16, 11:59authored byVadim Kamenetsky, Wolfe, R, Eggins, SM, Mernagh, TP, Bastrakov, E
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.
History
Publication title
Geology
Volume
27
Issue
8
Pagination
691-694
ISSN
0091-7613
Department/School
School of Natural Sciences
Publisher
Geological Society of America
Place of publication
Boulder, Colorado, USA
Repository Status
Restricted
Socio-economic Objectives
Other mineral resources (excl. energy resources) not elsewhere classified