Geochemistry constraints of Mesozoic-Cenozoic calc-alkaline magmatism in the South Shetland arc, Antarctica
Geochemical data from basalts, basaltic andesites, and andesites of the Mesozoic-Cenozoic (143-44 Ma) from Livingston, Greenwich, Robert, King George, and Ardley Islands of the South Shetland archipelago, Antarctica, are presented. The rocks have variable SiO2 Of approximately 46-61 wt%, Al2O3 of 15...
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ftunivchilecap:oai:www.captura.uchile.cl:2250/2295 2023-05-15T13:43:13+02:00 Geochemistry constraints of Mesozoic-Cenozoic calc-alkaline magmatism in the South Shetland arc, Antarctica Machado, Adriane Lima, E. F. Morata, Diego Oteíza, Orlando Chemale, Farid Jr. Almeida, D. P. M. Figueiredo, A. M. G. Alexandre, F. M. Urrutia, J. L. 2005-03 http://www.captura.uchile.cl/handle/2250/2295 en eng PERGAMON-ELSEVIER SCIENCE CRETACEOUS BYERS GROUP VOLCANIC-ROCKS LIVINGSTON ISLAND PENINSULA STRATIGRAPHY EVOLUTION BASALTS FLUIDS ZONE Artículo de Revista 2005 ftunivchilecap 2013-12-20T10:19:30Z Geochemical data from basalts, basaltic andesites, and andesites of the Mesozoic-Cenozoic (143-44 Ma) from Livingston, Greenwich, Robert, King George, and Ardley Islands of the South Shetland archipelago, Antarctica, are presented. The rocks have variable SiO2 Of approximately 46-61 wt%, Al2O3 of 15-26 wt%, and total alkali (K2O + Na2O) of 2-6 wt%. Most samples have low Mg#, Cr, and Ni, which indicates that they have undergone significant fractional crystallization from mantle-derived melts. The presence of olivine cumulatic in the samples from Livingston and Robert Islands explains some high MgO, Ni, and Cr values, whereas low Rb, Zr, and Nb values could be related to undifferentiated magmas. N-MORB-normalized trace element patterns show that South Shetland Islands volcanic rocks have a geochemical pattern similar to that found for other island arcs, with enrichment in LILE relative to HFSE and in LREE relative to HREE. The geochemistry pattern and presence of calcic plagioclase, orthopyroxene, Mg-olivine, and titanomagnetite phenocrysts suggest a source related to the subduction process. The geochemical data also suggest magma evolution from the tholeiitic to the calc-alkaline series; some samples show a transitional pattern. Samples from the South Shetland archipelago show moderate LREE/HREE ratios relative to N-MORB and OIB, depletion in Nb relative to Yb, and high Th/Yb ratios. These patterns probably reflect magma derived from a lithospheric mantle source previously modified by fluids and sediments from a subduction zone. Article in Journal/Newspaper Antarc* Antarctica Livingston Island South Shetland Islands Universidad de Chile: Captura Ardley ENVELOPE(-58.953,-58.953,-62.201,-62.201) Byers ENVELOPE(-60.283,-60.283,-63.900,-63.900) Greenwich Livingston Island ENVELOPE(-60.500,-60.500,-62.600,-62.600) South Shetland Islands |
institution |
Open Polar |
collection |
Universidad de Chile: Captura |
op_collection_id |
ftunivchilecap |
language |
English |
topic |
CRETACEOUS BYERS GROUP VOLCANIC-ROCKS LIVINGSTON ISLAND PENINSULA STRATIGRAPHY EVOLUTION BASALTS FLUIDS ZONE |
spellingShingle |
CRETACEOUS BYERS GROUP VOLCANIC-ROCKS LIVINGSTON ISLAND PENINSULA STRATIGRAPHY EVOLUTION BASALTS FLUIDS ZONE Machado, Adriane Lima, E. F. Morata, Diego Oteíza, Orlando Chemale, Farid Jr. Almeida, D. P. M. Figueiredo, A. M. G. Alexandre, F. M. Urrutia, J. L. Geochemistry constraints of Mesozoic-Cenozoic calc-alkaline magmatism in the South Shetland arc, Antarctica |
topic_facet |
CRETACEOUS BYERS GROUP VOLCANIC-ROCKS LIVINGSTON ISLAND PENINSULA STRATIGRAPHY EVOLUTION BASALTS FLUIDS ZONE |
description |
Geochemical data from basalts, basaltic andesites, and andesites of the Mesozoic-Cenozoic (143-44 Ma) from Livingston, Greenwich, Robert, King George, and Ardley Islands of the South Shetland archipelago, Antarctica, are presented. The rocks have variable SiO2 Of approximately 46-61 wt%, Al2O3 of 15-26 wt%, and total alkali (K2O + Na2O) of 2-6 wt%. Most samples have low Mg#, Cr, and Ni, which indicates that they have undergone significant fractional crystallization from mantle-derived melts. The presence of olivine cumulatic in the samples from Livingston and Robert Islands explains some high MgO, Ni, and Cr values, whereas low Rb, Zr, and Nb values could be related to undifferentiated magmas. N-MORB-normalized trace element patterns show that South Shetland Islands volcanic rocks have a geochemical pattern similar to that found for other island arcs, with enrichment in LILE relative to HFSE and in LREE relative to HREE. The geochemistry pattern and presence of calcic plagioclase, orthopyroxene, Mg-olivine, and titanomagnetite phenocrysts suggest a source related to the subduction process. The geochemical data also suggest magma evolution from the tholeiitic to the calc-alkaline series; some samples show a transitional pattern. Samples from the South Shetland archipelago show moderate LREE/HREE ratios relative to N-MORB and OIB, depletion in Nb relative to Yb, and high Th/Yb ratios. These patterns probably reflect magma derived from a lithospheric mantle source previously modified by fluids and sediments from a subduction zone. |
format |
Article in Journal/Newspaper |
author |
Machado, Adriane Lima, E. F. Morata, Diego Oteíza, Orlando Chemale, Farid Jr. Almeida, D. P. M. Figueiredo, A. M. G. Alexandre, F. M. Urrutia, J. L. |
author_facet |
Machado, Adriane Lima, E. F. Morata, Diego Oteíza, Orlando Chemale, Farid Jr. Almeida, D. P. M. Figueiredo, A. M. G. Alexandre, F. M. Urrutia, J. L. |
author_sort |
Machado, Adriane |
title |
Geochemistry constraints of Mesozoic-Cenozoic calc-alkaline magmatism in the South Shetland arc, Antarctica |
title_short |
Geochemistry constraints of Mesozoic-Cenozoic calc-alkaline magmatism in the South Shetland arc, Antarctica |
title_full |
Geochemistry constraints of Mesozoic-Cenozoic calc-alkaline magmatism in the South Shetland arc, Antarctica |
title_fullStr |
Geochemistry constraints of Mesozoic-Cenozoic calc-alkaline magmatism in the South Shetland arc, Antarctica |
title_full_unstemmed |
Geochemistry constraints of Mesozoic-Cenozoic calc-alkaline magmatism in the South Shetland arc, Antarctica |
title_sort |
geochemistry constraints of mesozoic-cenozoic calc-alkaline magmatism in the south shetland arc, antarctica |
publisher |
PERGAMON-ELSEVIER SCIENCE |
publishDate |
2005 |
url |
http://www.captura.uchile.cl/handle/2250/2295 |
long_lat |
ENVELOPE(-58.953,-58.953,-62.201,-62.201) ENVELOPE(-60.283,-60.283,-63.900,-63.900) ENVELOPE(-60.500,-60.500,-62.600,-62.600) |
geographic |
Ardley Byers Greenwich Livingston Island South Shetland Islands |
geographic_facet |
Ardley Byers Greenwich Livingston Island South Shetland Islands |
genre |
Antarc* Antarctica Livingston Island South Shetland Islands |
genre_facet |
Antarc* Antarctica Livingston Island South Shetland Islands |
_version_ |
1766185943033708544 |