The role of metamorphic fluids in the formation of ore deposits
Published:January 01, 2015
Bruce W. D. Yardley, James S. Cleverley, 2015. "The role of metamorphic fluids in the formation of ore deposits", Ore Deposits in an Evolving Earth, G. R. T. Jenkin, P. A. J. Lusty, I. Mcdonald, M. P. Smith, A. J. Boyce, J. J. Wilkinson
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Many ore deposits are hosted by metamorphic rocks, and metamorphic fluids have been invoked as a source for various deposits, especially gold deposits. Metamorphic fluid compositions reflect original sedimentary environment: continental shelf sequences yield saline metamorphic fluids with little dissolved gas while metasediments from accretionary and oceanic settings host less saline fluids with significant CO2 contents.
The principal difficulty in reconciling ore deposits with a metamorphic origin is that many form quickly (c. 1 Ma), whereas metamorphic heating is slow (c. 10–20 °/Ma). Gravitational instability means that fluid cannot be retained. Metamorphic ores may nevertheless form...
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Ore Deposits in an Evolving Earth
Ore deposits form by a variety of natural processes that concentrate elements into a volume that can be economically mined. Their type, character and abundance reflect the environment in which they formed and thus they preserve key evidence for the evolution of magmatic and tectonic processes, the state of the atmosphere and hydrosphere, and the evolution of life over geological time. This volume presents 13 papers on topical subjects in ore deposit research viewed in the context of Earth evolution. These diverse, yet interlinked, papers cover topics including: controls on the temporal and spatial distribution of ore deposits; the sources of fluid, gold and other components of orogenic gold deposits; the degree of oxygenation in the Neoproterozoic ocean; bacterial immobilization of gold in the semi-arid near-surface environment; and mineral resources for the future, including issues of resource estimation, sustainability of supply and the criticality of certain elements to society.