At the Bajo de la Alumbrera porphyry Cu-Au deposit, NW Argentina, several key textural elements preserve evidence for volatile separation. Interconnected miarolitic cavities, while being studied extensively in granites, have now been recognized in intrusions related to porphyry Cu mineralization. Pods of saccharoidal quartz are connected by narrow, anastomosing zones of graphic quartz-alkali feldspar intergrowths and ragged biotite (with lesser apatite and magnetite). Their connectivity can be as much as 15 cm; however, more commonly, the interconnected miarolitic cavities are approximately 1 to 2 mm across and 5 cm or less, long. Features such comb-quartz layered textures and magmatic-hydrothermal veins (P veins), combined with aqueous fluid phase equilibria from fluid inclusions, better constrain physical models of exsolution. We interpret these textures in the context of vapour phase formation, coalescence and accumulation in an evolving silicic magma. Recognition of textures, such as the interconnected miarolitic cavities reported here, may provide a simple exploration tool for porphyry Cu deposits, helping explorers to recognize evidence for a potentially fertile intrusions.

Item Type:	Refereed Article
Research Division:	Earth Sciences
Research Group:	Geology
Research Field:	Resource geoscience
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the earth sciences
UTAS Author:	Harris, AC (Dr Anthony Harris)
UTAS Author:	Kamenetsky, VS (Professor Vadim Kamenetsky)
UTAS Author:	White, N (Professor Noel White)
UTAS Author:	Steele, DA (Dr David Steele)
ID Code:	32647
Year Published:	2004
Web of Science® Times Cited:	74
Deposited By:	Centre for Ore Deposit Research - CODES CoE
Deposited On:	2004-08-01
Last Modified:	2007-10-19
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