Gravitational Fractionation of Isotopes and Dissolved Components as a first-order process in crustal fluids

Paul D. Bons*, Enrique Gomez-Rivas

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


The origin of ore-forming hydrothermal fluids and mechanisms of ore formation are commonly inferred from chemical and isotopic signatures. Fluid mixing and fluid-rock interaction are well-known processes that modify and produce these signatures, respectively. We propose that gravitational fractionation is an additional, hitherto not considered process that can significantly affect fluid signatures. Gravitational fractionation is the tendency for heavier components in a fluid to concentrate at the base of a reservoir. In stagnant fluids, gravitational fractionation can lead to significant changes in isotopic signatures, but also halogen ratios, within tens of millions of years. Rising fractionated fluids can give the same signatures that are classically and potentially erroneously interpreted as indicating mixing of surface-derived and deeper fluids. Recognition of gravitational fractionation as an additional first-order process affecting fluid composition necessitates a thorough reevaluation of models for crustal fluid flow, especially for the formation of unconformity-related hydrothermal ore deposits.

Original languageEnglish
Pages (from-to)1195-1201
Number of pages7
JournalEconomic Geology
Issue number5
Publication statusPublished - Aug 2013

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