Evidence of magmatic CO2-rich Fluids in Peraluminous Graphite-Bearing Leukogranites from deep Freeze Range (Northern Victoria Land, Antarctica)
Fine-grained peraluminous synkinematic leuco-monzogranites (SKG), of Cambro-Ordovician age, occur as veins and sills (up to 20-30 m thick) in the Deep Freeze Range, within the medium to high-grade metamorphics of the Wilson Terrane. Secondary fibrolite + graphite intergrowths occur in feldspars and...
Published in: | Contributions to Mineralogy and Petrology |
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1994
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Online Access: | http://hdl.handle.net/10281/174648 https://doi.org/10.1007/BF00286836 |
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ftunivmilanobic:oai:boa.unimib.it:10281/174648 2024-04-14T08:02:49+00:00 Evidence of magmatic CO2-rich Fluids in Peraluminous Graphite-Bearing Leukogranites from deep Freeze Range (Northern Victoria Land, Antarctica) Frezzotti, M Di Vincenzo, G Ghezzo, C Burke, Eaj Frezzotti, M Di Vincenzo, G Ghezzo, C Burke, E 1994 http://hdl.handle.net/10281/174648 https://doi.org/10.1007/BF00286836 eng eng info:eu-repo/semantics/altIdentifier/wos/WOS:A1994NX68500001 volume:117 issue:2 firstpage:111 lastpage:123 numberofpages:13 journal:CONTRIBUTIONS TO MINERALOGY AND PETROLOGY http://hdl.handle.net/10281/174648 doi:10.1007/BF00286836 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-0028554825 info:eu-repo/semantics/closedAccess Petrology granites Antarctica GEO/07 - PETROLOGIA E PETROGRAFIA info:eu-repo/semantics/article 1994 ftunivmilanobic https://doi.org/10.1007/BF00286836 2024-03-21T02:10:55Z Fine-grained peraluminous synkinematic leuco-monzogranites (SKG), of Cambro-Ordovician age, occur as veins and sills (up to 20-30 m thick) in the Deep Freeze Range, within the medium to high-grade metamorphics of the Wilson Terrane. Secondary fibrolite + graphite intergrowths occur in feldspars and subordinately in quartz. Four main solid and fluid inclusion populations are observed: primary mixed CO2 + H2O inclusions + Al2SiO5 +/- brines in garnet (type 1) early CO2-rich inclusions (+/- brines) in quartz (type 2) early CO2 + CH4 (up to 4 mol%) +/- H2O inclusions + graphite + fibrolite in quartz (type 3); late CH4 + CO2 + N2 inclusions and H2O inclusions in quartz (type 4). Densities of type 1 inclusions are consistent with the crystallization conditions of SKG (almost-equal-to 750-degrees-C and 3 kbar). The other types are post-magmatic: densities of type 2 and 3 inclusions suggest isobaric cooling at high temperature (almost-equal-to 700 -550-degrees-C). Type 4 inclusions were trapped below 500-degrees-C. The SKG crystallized from a magma that was at some stage vapour-saturated; fluids were CO2-rich, possibly with immiscible brines. CO2-rich fluids (+/- brines) characterize the transition from magmatic to post-magmatic stages; progressive isobaric cooling (T< 670-degrees-C) led to a continuous decrease of f(O2), entering in the graphite stability field; at the same time, the feldspars reacted with CO2-rich fluids to give secondary fibrolite + graphite. Decrease of T and f(O2) can explain the progressive variation in the fluid composition from CO2-rich to CH4 and water dominated in a closed system (in situ evolution). The presence of N2 the late stages indicates interaction with external metamorphic fluids. Article in Journal/Newspaper Antarc* Antarctica Victoria Land Università degli Studi di Milano-Bicocca: BOA (Bicocca Open Archive) Deep Freeze Range ENVELOPE(163.750,163.750,-74.250,-74.250) Victoria Land Contributions to Mineralogy and Petrology 117 2 111 123 |
institution |
Open Polar |
collection |
Università degli Studi di Milano-Bicocca: BOA (Bicocca Open Archive) |
op_collection_id |
ftunivmilanobic |
language |
English |
topic |
Petrology granites Antarctica GEO/07 - PETROLOGIA E PETROGRAFIA |
spellingShingle |
Petrology granites Antarctica GEO/07 - PETROLOGIA E PETROGRAFIA Frezzotti, M Di Vincenzo, G Ghezzo, C Burke, Eaj Evidence of magmatic CO2-rich Fluids in Peraluminous Graphite-Bearing Leukogranites from deep Freeze Range (Northern Victoria Land, Antarctica) |
topic_facet |
Petrology granites Antarctica GEO/07 - PETROLOGIA E PETROGRAFIA |
description |
Fine-grained peraluminous synkinematic leuco-monzogranites (SKG), of Cambro-Ordovician age, occur as veins and sills (up to 20-30 m thick) in the Deep Freeze Range, within the medium to high-grade metamorphics of the Wilson Terrane. Secondary fibrolite + graphite intergrowths occur in feldspars and subordinately in quartz. Four main solid and fluid inclusion populations are observed: primary mixed CO2 + H2O inclusions + Al2SiO5 +/- brines in garnet (type 1) early CO2-rich inclusions (+/- brines) in quartz (type 2) early CO2 + CH4 (up to 4 mol%) +/- H2O inclusions + graphite + fibrolite in quartz (type 3); late CH4 + CO2 + N2 inclusions and H2O inclusions in quartz (type 4). Densities of type 1 inclusions are consistent with the crystallization conditions of SKG (almost-equal-to 750-degrees-C and 3 kbar). The other types are post-magmatic: densities of type 2 and 3 inclusions suggest isobaric cooling at high temperature (almost-equal-to 700 -550-degrees-C). Type 4 inclusions were trapped below 500-degrees-C. The SKG crystallized from a magma that was at some stage vapour-saturated; fluids were CO2-rich, possibly with immiscible brines. CO2-rich fluids (+/- brines) characterize the transition from magmatic to post-magmatic stages; progressive isobaric cooling (T< 670-degrees-C) led to a continuous decrease of f(O2), entering in the graphite stability field; at the same time, the feldspars reacted with CO2-rich fluids to give secondary fibrolite + graphite. Decrease of T and f(O2) can explain the progressive variation in the fluid composition from CO2-rich to CH4 and water dominated in a closed system (in situ evolution). The presence of N2 the late stages indicates interaction with external metamorphic fluids. |
author2 |
Frezzotti, M Di Vincenzo, G Ghezzo, C Burke, E |
format |
Article in Journal/Newspaper |
author |
Frezzotti, M Di Vincenzo, G Ghezzo, C Burke, Eaj |
author_facet |
Frezzotti, M Di Vincenzo, G Ghezzo, C Burke, Eaj |
author_sort |
Frezzotti, M |
title |
Evidence of magmatic CO2-rich Fluids in Peraluminous Graphite-Bearing Leukogranites from deep Freeze Range (Northern Victoria Land, Antarctica) |
title_short |
Evidence of magmatic CO2-rich Fluids in Peraluminous Graphite-Bearing Leukogranites from deep Freeze Range (Northern Victoria Land, Antarctica) |
title_full |
Evidence of magmatic CO2-rich Fluids in Peraluminous Graphite-Bearing Leukogranites from deep Freeze Range (Northern Victoria Land, Antarctica) |
title_fullStr |
Evidence of magmatic CO2-rich Fluids in Peraluminous Graphite-Bearing Leukogranites from deep Freeze Range (Northern Victoria Land, Antarctica) |
title_full_unstemmed |
Evidence of magmatic CO2-rich Fluids in Peraluminous Graphite-Bearing Leukogranites from deep Freeze Range (Northern Victoria Land, Antarctica) |
title_sort |
evidence of magmatic co2-rich fluids in peraluminous graphite-bearing leukogranites from deep freeze range (northern victoria land, antarctica) |
publishDate |
1994 |
url |
http://hdl.handle.net/10281/174648 https://doi.org/10.1007/BF00286836 |
long_lat |
ENVELOPE(163.750,163.750,-74.250,-74.250) |
geographic |
Deep Freeze Range Victoria Land |
geographic_facet |
Deep Freeze Range Victoria Land |
genre |
Antarc* Antarctica Victoria Land |
genre_facet |
Antarc* Antarctica Victoria Land |
op_relation |
info:eu-repo/semantics/altIdentifier/wos/WOS:A1994NX68500001 volume:117 issue:2 firstpage:111 lastpage:123 numberofpages:13 journal:CONTRIBUTIONS TO MINERALOGY AND PETROLOGY http://hdl.handle.net/10281/174648 doi:10.1007/BF00286836 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-0028554825 |
op_rights |
info:eu-repo/semantics/closedAccess |
op_doi |
https://doi.org/10.1007/BF00286836 |
container_title |
Contributions to Mineralogy and Petrology |
container_volume |
117 |
container_issue |
2 |
container_start_page |
111 |
op_container_end_page |
123 |
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1796317765584289792 |