A fluid inclusion and stable isotope study of 200 Ma of fluid evolution, Galway Granite, Connemara, Ireland

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doi: 10.1007/s004100050327
Authors:O'Reilly, C.; Jenkin, G. R. T.; Feely, M.; Alderton, D. H. M.; Fallick, A. E.
Author Affiliations:Primary:
University College, Galway, Ireland
Other:
Scottish Universities Research and Reactor Center, United Kingdom
Royal Holloway University of London, United Kingdom
Volume Title:Contributions to Mineralogy and Petrology
Source:Contributions to Mineralogy and Petrology, 129(2-3), p.120-142. Publisher: Springer International, Heidelberg-New York, International. ISSN: 0010-7999
Publication Date:1997
Note:In English. 117 refs.; illus., incl. 4 tables, geol. sketch map
Summary:Fluid inclusions in granite quartz and three generations of veins indicate that three fluids have affected the Caledonian Gallway granite. The earliest fluid was a H2O-CO2-NaCl fluid of moderate salinity (4-10 wt.% NaCl eq.) that deposited late-magmatic molybdenite mineralized quartz veins and formed the earliest secondary inclusions in granite quartz. Homogeneous quartz δ 18O across the batholith suggests that these quartz veins precipitated at high T (perhaps 600°C) and P (1-3 kbar) from magmatic fluids. The second fluid was a H2O-NaCl-KCl low-moderate salinity (0-10 wt.% NaCl eq.), moderate T (270-340°C), high δ D (-18 ± 0/00), low δ 18O (0.5-2.00/00) fluid of meteoric origin. This fluid forms the most common inclusion type in granite quartz and penetrated the batholith via quartz veins. The final fluid was a H2O-NaCl-CaCl2-KCl fluid with variable salinity (8-20 wt.% NaCl eq.), T (125-205°C), δ D (-17 to -450/00), δ 18O (-3 to +1.20/00), δ 13C (-19 to 00/00) and δ 34Ssulphate (13 to 230/00) that deposited veins with quartz, fluorite, calcite, baryte, galena, chalcopyrite, sphalerite and pyrite; these conditions are interpreted as the result of mixing of two fluid end-members, one a contemporaneous surface fluid (probably mixed meteoric water and evaporated sea-water) and the other a basinal brine derived from the adjacent Carboniferous sequence. [R.A.H.]
Sections:Geochemistry
Subsections:Igneous rocks
Subjects:Batholiths; Caledonian Orogeny; Chemical composition; Chlorite; Chlorite group; D/H; Fluid inclusions; Geologic thermometry; Granites; Hydrogen; Igneous rocks; Inclusions; Intrusions; Isotope ratios; Isotopes; Metagabbro; Metaigneous rocks; Metamorphic rocks; O-18/O-16; Oxygen; P-T conditions; Paleozoic; Plutonic rocks; Quartz veins; S-34/S-32; Sheet silicates; Silicates; Stable isotopes; Sulfur; Veins; Connemara; Europe; Galway Granite; Galway Ireland; Ireland; Western Europe
Abstract Numbers:99M/513
Record ID:1999008569
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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005 20190221173000.0
008 190110e199710 vp a 0 0 eng d
040 |a ViAlAGI  |c ViAlAGI 
072 7 |a 02D  |2 georeft 
072 7 |a 05A  |2 georeft 
100 1 |a O'Reilly, C.  |e analytic author  |u University College, Galway 
245 1 2 |a A fluid inclusion and stable isotope study of 200 Ma of fluid evolution, Galway Granite, Connemara, Ireland 
300 |a p. 120-142 
500 |a In English. 117 refs. 
500 |a Abstract number: 99M/513 
500 |a Abstractor: R.A.H. 
500 |a Category Section: Geochemistry 
500 |a Category Subsection: Igneous rocks 
500 |a Affiliation: University College; Galway; IRL; Ireland 
500 |a Affiliation: Scottish Universities Research and Reactor Center; ; GBR; United Kingdom 
500 |a Affiliation: Royal Holloway University of London; ; GBR; United Kingdom 
500 |a Key title: Contributions to Mineralogy and Petrology 
500 |a Source note: Contributions to Mineralogy and Petrology, 129(2-3), p.120-142. Publisher: Springer International, Heidelberg-New York, International. ISSN: 0010-7999 
500 |a Publication type: journal article 
504 |b 117 refs. 
510 3 |a GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom 
520 |a Fluid inclusions in granite quartz and three generations of veins indicate that three fluids have affected the Caledonian Gallway granite. The earliest fluid was a H<2`O-CO<2`-NaCl fluid of moderate salinity (4-10 wt.% NaCl eq.) that deposited late-magmatic molybdenite mineralized quartz veins and formed the earliest secondary inclusions in granite quartz. Homogeneous quartz δ >18`O across the batholith suggests that these quartz veins precipitated at high T (perhaps 600°C) and P (1-3 kbar) from magmatic fluids. The second fluid was a H<2`O-NaCl-KCl low-moderate salinity (0-10 wt.% NaCl eq.), moderate T (270-340°C), high δ D (-18 ± 0/00), low δ >18`O (0.5-2.00/00) fluid of meteoric origin. This fluid forms the most common inclusion type in granite quartz and penetrated the batholith via quartz veins. The final fluid was a H<2`O-NaCl-CaCl<2`-KCl fluid with variable salinity (8-20 wt.% NaCl eq.), T (125-205°C), δ D (-17 to -450/00), δ >18`O (-3 to +1.20/00), δ >13`C (-19 to 00/00) and δ >34`S<sulphate` (13 to 230/00) that deposited veins with quartz, fluorite, calcite, baryte, galena, chalcopyrite, sphalerite and pyrite; these conditions are interpreted as the result of mixing of two fluid end-members, one a contemporaneous surface fluid (probably mixed meteoric water and evaporated sea-water) and the other a basinal brine derived from the adjacent Carboniferous sequence. 
650 7 |a Batholiths  |2 georeft 
650 7 |a Caledonian Orogeny  |2 georeft 
650 7 |a Chemical composition  |2 georeft 
650 7 |a Chlorite  |2 georeft 
650 7 |a Chlorite group  |2 georeft 
650 7 |a D/H  |2 georeft 
650 7 |a Fluid inclusions  |2 georeft 
650 7 |a Geologic thermometry  |2 georeft 
650 7 |a Granites  |2 georeft 
650 7 |a Hydrogen  |2 georeft 
650 7 |a Igneous rocks  |2 georeft 
650 7 |a Inclusions  |2 georeft 
650 7 |a Intrusions  |2 georeft 
650 7 |a Isotope ratios  |2 georeft 
650 7 |a Isotopes  |2 georeft 
650 7 |a Metagabbro  |2 georeft 
650 7 |a Metaigneous rocks  |2 georeft 
650 7 |a Metamorphic rocks  |2 georeft 
650 7 |a O-18/O-16  |2 georeft 
650 7 |a Oxygen  |2 georeft 
650 7 |a P-T conditions  |2 georeft 
650 7 |a Paleozoic  |2 georeft 
650 7 |a Plutonic rocks  |2 georeft 
650 7 |a Quartz veins  |2 georeft 
650 7 |a S-34/S-32  |2 georeft 
650 7 |a Sheet silicates  |2 georeft 
650 7 |a Silicates  |2 georeft 
650 7 |a Stable isotopes  |2 georeft 
650 7 |a Sulfur  |2 georeft 
650 7 |a Veins  |2 georeft 
651 7 |a Connemara  |2 georeft 
651 7 |a Europe  |2 georeft 
651 7 |a Galway Granite  |2 georeft 
651 7 |a Galway Ireland  |2 georeft 
651 7 |a Ireland  |2 georeft 
651 7 |a Western Europe  |2 georeft 
700 1 |a Jenkin, G. R. T.,  |e analytic author 
700 1 |a Feely, M.,  |e analytic author 
700 1 |a Alderton, D. H. M.,  |e analytic author 
700 1 |a Fallick, A. E.,  |e analytic author 
773 0 |t Contributions to Mineralogy and Petrology  |d Heidelberg-New York : Springer International, Oct. 1997  |x 0010-7999  |y CMPEAP  |n Contributions to Mineralogy and Petrology, 129(2-3), p.120-142. Publisher: Springer International, Heidelberg-New York, International. ISSN: 0010-7999 Publication type: journal article  |g Vol. 129, no. 2-3  |h illus., incl. 4 tables, geol. sketch map 
856 |u urn:doi: 10.1007/s004100050327