The Ushuaia Hornblendite (Tierra del Fuego): Petrography, geochemistry and geochronology
The Ushuaia Hornblendite (Tierra del Fuego): petrography, geochemistry and geochronology. Petrographic descriptions and geochemical and geochronological data are given for the so-called Ushuaia Hornblendite, a complex of mesocratic and melanocratic hydrated rocks that crops out in the vicinity of th...
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2002
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00044822_v57_n2_p133_Acevedo http://hdl.handle.net/20.500.12110/paper_00044822_v57_n2_p133_Acevedo |
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paper:paper_00044822_v57_n2_p133_Acevedo2023-06-08T14:25:34Z The Ushuaia Hornblendite (Tierra del Fuego): Petrography, geochemistry and geochronology Geochemistry Geochronology Hornblendite Petrography Cretaceous geochemistry geochronology hornblende mineralogy petrography Argentina The Ushuaia Hornblendite (Tierra del Fuego): petrography, geochemistry and geochronology. Petrographic descriptions and geochemical and geochronological data are given for the so-called Ushuaia Hornblendite, a complex of mesocratic and melanocratic hydrated rocks that crops out in the vicinity of the city of Ushuaia, Tierra del Fuego. The complex consists mainly of hornblendites and hornblendite-piroxenites, diorites, gabbros, syenites and monzodiorites. The mineralogy of the most representative specimen shows that it is composed of hornblende and diopside as essential minerals, with biotite and potassic feldspar as minor constituents, and sphene, apatite, and opaque minerals (mainly magnetite, ilmenite, pyrite and chalcopyrite) as accessories. Alteration processes include albitization, epidotization, chloritization and carbonatization, that represent substantial chemical changes that would affect any chemical classification of the rocks. Nevertheless, it is considered that the parental magma was of calc-alkaline Andean Type, related to the Andean Batholith, produced during regional subduction, and not in any way to an ophiolitic sequence. The calc-alkaline geochemistry is attributed to partial melting. In fact, the magma did not derive from primary mantle melts but came from evolved and contaminated mantle fluids that ascended toward crustal levels, thus favouring an assimilation process, in a magmatic arc setting. Potassium-argon whole-rock dating of one hornblendite sample gave an age of 113 ± 5 Ma. 2002 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00044822_v57_n2_p133_Acevedo http://hdl.handle.net/20.500.12110/paper_00044822_v57_n2_p133_Acevedo |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Geochemistry Geochronology Hornblendite Petrography Cretaceous geochemistry geochronology hornblende mineralogy petrography Argentina |
| spellingShingle |
Geochemistry Geochronology Hornblendite Petrography Cretaceous geochemistry geochronology hornblende mineralogy petrography Argentina The Ushuaia Hornblendite (Tierra del Fuego): Petrography, geochemistry and geochronology |
| topic_facet |
Geochemistry Geochronology Hornblendite Petrography Cretaceous geochemistry geochronology hornblende mineralogy petrography Argentina |
| description |
The Ushuaia Hornblendite (Tierra del Fuego): petrography, geochemistry and geochronology. Petrographic descriptions and geochemical and geochronological data are given for the so-called Ushuaia Hornblendite, a complex of mesocratic and melanocratic hydrated rocks that crops out in the vicinity of the city of Ushuaia, Tierra del Fuego. The complex consists mainly of hornblendites and hornblendite-piroxenites, diorites, gabbros, syenites and monzodiorites. The mineralogy of the most representative specimen shows that it is composed of hornblende and diopside as essential minerals, with biotite and potassic feldspar as minor constituents, and sphene, apatite, and opaque minerals (mainly magnetite, ilmenite, pyrite and chalcopyrite) as accessories. Alteration processes include albitization, epidotization, chloritization and carbonatization, that represent substantial chemical changes that would affect any chemical classification of the rocks. Nevertheless, it is considered that the parental magma was of calc-alkaline Andean Type, related to the Andean Batholith, produced during regional subduction, and not in any way to an ophiolitic sequence. The calc-alkaline geochemistry is attributed to partial melting. In fact, the magma did not derive from primary mantle melts but came from evolved and contaminated mantle fluids that ascended toward crustal levels, thus favouring an assimilation process, in a magmatic arc setting. Potassium-argon whole-rock dating of one hornblendite sample gave an age of 113 ± 5 Ma. |
| title |
The Ushuaia Hornblendite (Tierra del Fuego): Petrography, geochemistry and geochronology |
| title_short |
The Ushuaia Hornblendite (Tierra del Fuego): Petrography, geochemistry and geochronology |
| title_full |
The Ushuaia Hornblendite (Tierra del Fuego): Petrography, geochemistry and geochronology |
| title_fullStr |
The Ushuaia Hornblendite (Tierra del Fuego): Petrography, geochemistry and geochronology |
| title_full_unstemmed |
The Ushuaia Hornblendite (Tierra del Fuego): Petrography, geochemistry and geochronology |
| title_sort |
ushuaia hornblendite (tierra del fuego): petrography, geochemistry and geochronology |
| publishDate |
2002 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00044822_v57_n2_p133_Acevedo http://hdl.handle.net/20.500.12110/paper_00044822_v57_n2_p133_Acevedo |
| _version_ |
1768541635887497216 |