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We determined the composition of ,30-m.y.-old solutions extracted from fluid inclusions in one of the world’s largest and richest silver ore deposits at Fresnillo, Mexico. Silver concentrations average 14 ppm and have a maximum of 27 ppm. The highest silver, lead and zinc concentrations correlate with salinity, consistent with transport by chloro-complexes and confirming the importance of brines in ore formation. The temporal distribution of these fluids within the veins suggests mineralization occurred episodically when they were injected into a fracture system dominated by low salinity, metal-poor fluids. Mass balance shows that a modest volume of brine, most likely of magmatic origin, is sufficient to supply the metal found in large Mexican silver deposits. The results suggest that ancient epithermal ore-forming events may involve fluid packets not captured in modern geothermal sampling and that giant ore deposits can form rapidly from small volumes of metal-rich fluid.

Item Type:	Refereed Article
Keywords:	GEOCHEMISTRY GEOLOGY MINERALOGY PETROLOGY
Research Division:	Earth Sciences
Research Group:	Geochemistry
Research Field:	Exploration geochemistry
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the earth sciences
UTAS Author:	Wilkinson, JJ (Professor Jamie Wilkinson)
ID Code:	88295
Year Published:	2013
Web of Science® Times Cited:	14
Deposited By:	Centre for Ore Deposit Research - CODES CoE
Deposited On:	2014-01-24
Last Modified:	2017-11-06
Downloads:	344 View Download Statistics