Contribution to the reconstruction of geological evolution of the metamorphic basement of the Cordillera Darwin, Tierra del Fuego, Chile.
The crystalline pre-Andine basement outcrops only in the Cordillera Darwin (Tierra del Fuego) in the extreme southern part of Andean belt. It is located between the Antarctic, Nazca and Scotia Plate. Cordillera Darwin breaks the long ophiolitic belt constituted by the Sarmiento Complex and Rocas Ver...
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ftunivpalermo:oai:iris.unipa.it:10447/41434 2024-01-14T10:00:44+01:00 Contribution to the reconstruction of geological evolution of the metamorphic basement of the Cordillera Darwin, Tierra del Fuego, Chile. ARICO', Pietro FERLA, Paolo DECIMA, A. ARICO', P FERLA, P DECIMA, A 2008 http://hdl.handle.net/10447/41434 http://www.cprm.gov.br/33IGC/1341826.html eng eng ispartofbook:33 IGC, Oslo, 5-14 august 2009 33° International Geological Congress firstpage:1341826 lastpage:1341826 numberofpages:00 http://hdl.handle.net/10447/41434 http://www.cprm.gov.br/33IGC/1341826.html Cordillera Darwin Tierra del Fuego Metamorphism info:eu-repo/semantics/conferenceObject 2008 ftunivpalermo 2023-12-19T23:27:36Z The crystalline pre-Andine basement outcrops only in the Cordillera Darwin (Tierra del Fuego) in the extreme southern part of Andean belt. It is located between the Antarctic, Nazca and Scotia Plate. Cordillera Darwin breaks the long ophiolitic belt constituted by the Sarmiento Complex and Rocas Verdes; many authors agree that the present setting is the result of the Andean orogenesis, that yielded to the closure of a Jurassic marginal basin (now represented by ophiolites) with its overlying sequence of rhyolitic volcanic and volcanoclastic rocks, now represented by the Tobifera Formation and metamorphism during Cretaceous (Cunningham, 1995 and references). The studied rocks, sampled by A.D. in the Sarmiento Peninsula during the 1955 De Agostini expedition, are made of phyllitic quartzites and micaschists with interlayered amphibole-chlorite schists, granitic gneisses and mafic and acid dykes. Texturally two different groups may be distinguished: rocks with one and two schistosity surfaces respectively. Rocks with S2 are quartzites and phyllitic quartzites (metablack-shales and metacherts) and amphibolites with S1 recumbent folded into axial plane S2. The syn-late S1 metamorphism ranges from the greenschist facies to the garnet-staurolite paragenesis. Occurrence of a thermal event is shown by growing of large garnets with post-kynematic rim, micas with decussate texture, poykilitic staurolite, fibrous sillimanite and hornblende substitution of fibrous amphibole. All these minerals are pre-kynematic respect to S2. Based on trace elements geochemistry the amphibolite layers show features typical of island arc tholeiites. The whole S2 sequence is crossed by veins of metamorphosed (S1) acid intrusions and mafic dykes of MORB type. We confirm the presence of a pre-Andean metamorphic basement (with S1 developed during Late Palaeozoic-Lower Triassic, and thermal event during the Mesozoic rifting) and its unmetamorphosed terrigenous cover, all involved in the Cretaceous Andean orogenesis, producing the formation of ... Conference Object Antarc* Antarctic Tierra del Fuego IRIS Università degli Studi di Palermo Antarctic The Antarctic Rocas ENVELOPE(-56.948,-56.948,-63.398,-63.398) Sarmiento ENVELOPE(-68.000,-68.000,-72.000,-72.000) |
institution |
Open Polar |
collection |
IRIS Università degli Studi di Palermo |
op_collection_id |
ftunivpalermo |
language |
English |
topic |
Cordillera Darwin Tierra del Fuego Metamorphism |
spellingShingle |
Cordillera Darwin Tierra del Fuego Metamorphism ARICO', Pietro FERLA, Paolo DECIMA, A. Contribution to the reconstruction of geological evolution of the metamorphic basement of the Cordillera Darwin, Tierra del Fuego, Chile. |
topic_facet |
Cordillera Darwin Tierra del Fuego Metamorphism |
description |
The crystalline pre-Andine basement outcrops only in the Cordillera Darwin (Tierra del Fuego) in the extreme southern part of Andean belt. It is located between the Antarctic, Nazca and Scotia Plate. Cordillera Darwin breaks the long ophiolitic belt constituted by the Sarmiento Complex and Rocas Verdes; many authors agree that the present setting is the result of the Andean orogenesis, that yielded to the closure of a Jurassic marginal basin (now represented by ophiolites) with its overlying sequence of rhyolitic volcanic and volcanoclastic rocks, now represented by the Tobifera Formation and metamorphism during Cretaceous (Cunningham, 1995 and references). The studied rocks, sampled by A.D. in the Sarmiento Peninsula during the 1955 De Agostini expedition, are made of phyllitic quartzites and micaschists with interlayered amphibole-chlorite schists, granitic gneisses and mafic and acid dykes. Texturally two different groups may be distinguished: rocks with one and two schistosity surfaces respectively. Rocks with S2 are quartzites and phyllitic quartzites (metablack-shales and metacherts) and amphibolites with S1 recumbent folded into axial plane S2. The syn-late S1 metamorphism ranges from the greenschist facies to the garnet-staurolite paragenesis. Occurrence of a thermal event is shown by growing of large garnets with post-kynematic rim, micas with decussate texture, poykilitic staurolite, fibrous sillimanite and hornblende substitution of fibrous amphibole. All these minerals are pre-kynematic respect to S2. Based on trace elements geochemistry the amphibolite layers show features typical of island arc tholeiites. The whole S2 sequence is crossed by veins of metamorphosed (S1) acid intrusions and mafic dykes of MORB type. We confirm the presence of a pre-Andean metamorphic basement (with S1 developed during Late Palaeozoic-Lower Triassic, and thermal event during the Mesozoic rifting) and its unmetamorphosed terrigenous cover, all involved in the Cretaceous Andean orogenesis, producing the formation of ... |
author2 |
ARICO', P FERLA, P DECIMA, A |
format |
Conference Object |
author |
ARICO', Pietro FERLA, Paolo DECIMA, A. |
author_facet |
ARICO', Pietro FERLA, Paolo DECIMA, A. |
author_sort |
ARICO', Pietro |
title |
Contribution to the reconstruction of geological evolution of the metamorphic basement of the Cordillera Darwin, Tierra del Fuego, Chile. |
title_short |
Contribution to the reconstruction of geological evolution of the metamorphic basement of the Cordillera Darwin, Tierra del Fuego, Chile. |
title_full |
Contribution to the reconstruction of geological evolution of the metamorphic basement of the Cordillera Darwin, Tierra del Fuego, Chile. |
title_fullStr |
Contribution to the reconstruction of geological evolution of the metamorphic basement of the Cordillera Darwin, Tierra del Fuego, Chile. |
title_full_unstemmed |
Contribution to the reconstruction of geological evolution of the metamorphic basement of the Cordillera Darwin, Tierra del Fuego, Chile. |
title_sort |
contribution to the reconstruction of geological evolution of the metamorphic basement of the cordillera darwin, tierra del fuego, chile. |
publishDate |
2008 |
url |
http://hdl.handle.net/10447/41434 http://www.cprm.gov.br/33IGC/1341826.html |
long_lat |
ENVELOPE(-56.948,-56.948,-63.398,-63.398) ENVELOPE(-68.000,-68.000,-72.000,-72.000) |
geographic |
Antarctic The Antarctic Rocas Sarmiento |
geographic_facet |
Antarctic The Antarctic Rocas Sarmiento |
genre |
Antarc* Antarctic Tierra del Fuego |
genre_facet |
Antarc* Antarctic Tierra del Fuego |
op_relation |
ispartofbook:33 IGC, Oslo, 5-14 august 2009 33° International Geological Congress firstpage:1341826 lastpage:1341826 numberofpages:00 http://hdl.handle.net/10447/41434 http://www.cprm.gov.br/33IGC/1341826.html |
_version_ |
1788066617429590016 |