Reference Type | Journal (article/letter/editorial) |
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Title | The role of metamorphic fluids in the development of the Cornubian orefield: fluid inclusion evidence from south Cornwall |
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Journal | Mineralogical Magazine | ISSN | 0026-461X |
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Authors | Wilkinson, J. J. | Author |
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Year | 1990 (June) | Volume | 54 |
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Issue | 375 |
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Publisher | Mineralogical Society |
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Download URL | https://rruff.info/doclib/MinMag/Volume_54/54-375-219.pdf+ |
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DOI | doi:10.1180/minmag.1990.054.375.08Search in ResearchGate |
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| Generate Citation Formats |
Mindat Ref. ID | 1610 | Long-form Identifier | mindat:1:5:1610:4 |
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GUID | 0 |
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Full Reference | Wilkinson, J. J. (1990) The role of metamorphic fluids in the development of the Cornubian orefield: fluid inclusion evidence from south Cornwall. Mineralogical Magazine, 54 (375) 219-230 doi:10.1180/minmag.1990.054.375.08 |
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Plain Text | Wilkinson, J. J. (1990) The role of metamorphic fluids in the development of the Cornubian orefield: fluid inclusion evidence from south Cornwall. Mineralogical Magazine, 54 (375) 219-230 doi:10.1180/minmag.1990.054.375.08 |
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In | (1990, June) Mineralogical Magazine Vol. 54 (375) Mineralogical Society |
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Abstract/Notes | AbstractVeins developed during contact metamorphism associated with the emplacement of the Cornubian granite batholith contain both H2O-rich and CO2-rich fluid inclusions. Microthermometric data indicate that unmixing of a low-CO2, low-salinity fluid occurred at 400–200°C and 1000–500 bars to produce low-density CO2-rich vapour and saline aqueous fluids (8–42 wt. % NaCl equivalent). Decrepitation-linked ICP analyses show that the cation composition of the brines is dominated by Na, K and Ca, but that significant amounts of Li, Sr, Ba, Fe, Mn, Zn and B are also present. Bulk volatile analyses confirm the dominance of CO2 over N2 and CH4 in the vapour phase, with CO2/N2 molar ratios of 15.3–28.7 and CO2/CH4 molar ratios of 66.9–292. The relative abundance of nitrogen suggests an aureole-derived ‘organic’ component is present.The source of the fluids is ambiguous as they are intermediate in composition between ideal ‘magmatic’ and ‘metamorphic’ end-members. It is proposed that this is due to mixing of the two types of fluid in the contact aureole during granite intrusion. A model is suggested in which magmatic-metamorphic circulation occurred synchronously with granite emplacement and subsequently evolved to a meteoric-dominated system with the bulk of the ore deposits forming in response to the influx of meteoric fluids. |
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