Petrología del complejo volcánico Barril Niyeu(Mioceno inferior), Patagonia Argentina

The Oligocene Somún Curá plateau is the largest volcanic field in the northern extra-andean Patagonia of Argentina. It is mostly composed of alkaline to transitional aphyric olivine basalts that cover a sub-circular area of ~25,000 km 2. Several early Miocene post-plateau volcanic events resulted in...

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Autores principales: Remesal, M.B., Salani, F.M., Cerredo, M.E.
Formato: JOUR
Materias:
Argentina
Barril niyeu
Bimodal volcanism
Miocene
Patagonia
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_10268774_v29_n2_p463_Remesal
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_10268774_v29_n2_p463_Remesal2023-10-03T15:57:00Z Petrología del complejo volcánico Barril Niyeu(Mioceno inferior), Patagonia Argentina Remesal, M.B. Salani, F.M. Cerredo, M.E. Argentina Barril niyeu Bimodal volcanism Miocene Patagonia The Oligocene Somún Curá plateau is the largest volcanic field in the northern extra-andean Patagonia of Argentina. It is mostly composed of alkaline to transitional aphyric olivine basalts that cover a sub-circular area of ~25,000 km 2. Several early Miocene post-plateau volcanic events resulted in small monogenetic centres and large bimodal complexes. The Barril Niyeu Volcanic Complex(BNVC) is one of the largest post-plateau bimodal centres built through several stages of eruptive activity outpoured from at least five vents(presently cauldrons) of distinct trachyte/rhyolite and basaltic compositions. New whole rock K/Ar dating of early trachyte(20.6±0.4 Ma) and late basaltic(18.7±0.4 Ma) rocks constrain the time span of the BNVC activity within 2-2.5 My. The earliest eruptive stage of the BNVC produced viscous trachyte lava restricted to the volcanic centre, followed by two explosive eruptive episodes of dominant intermediate to acid composition: The first episode produced air-fall, mainly plinian(lesser strombolian) and pyroclastic flow deposits and the second was dominated by ignimbritic pyroclastic flows. Basaltic lava, minor breccia and spatter cone deposits dominate the final stage. The magmatic series of the BNVC involves basaltic/trachybasaltic and trachyte/rhyolite compositions, with a characteristic gap in the 52-67% SiO 2 range. Transitional olivine basalt is the most primitive rock of the series(Mg# = 66; Ni = 160 ppm; Cr = 290 ppm) and shows a chemical composition compatible with a liquid that evolved through the crystal fractionation of a basaltic magma derived from partial melting(8-10%) of a lherzolithic source. Major and trace element contents and element ratios suggest differentiation through crystal fractionation from an olivine basaltic magma. Intraplate-like Th/Yb, and Ta/Yb ratios characterize basalts, whereas high LILE/REE(Ba/La) ratios suggest the contribution of a subordinated subduction zone component. In addition, Rb/Nb ratios along with a relative Th enrichment in some basalt suggest assimilation of upper crustal rocks. Isotopic compositions(Sr-Nd) of BNVC basalts suggest a source from a depleted mantle and minor contribution of EM1 melts. Somún Curá magmatism is attributed to a process of lithospheric delamination associated with gravitational disturbances during plate reorganization, with subordinated contributions from detached segments of a foundered subducted slab(Aluk plate?). Fil:Remesal, M.B. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Salani, F.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Cerredo, M.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_10268774_v29_n2_p463_Remesal
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Argentina
Barril niyeu
Bimodal volcanism
Miocene
Patagonia
spellingShingle Argentina
Barril niyeu
Bimodal volcanism
Miocene
Patagonia
Remesal, M.B.
Salani, F.M.
Cerredo, M.E.
Petrología del complejo volcánico Barril Niyeu(Mioceno inferior), Patagonia Argentina
topic_facet Argentina
Barril niyeu
Bimodal volcanism
Miocene
Patagonia
description The Oligocene Somún Curá plateau is the largest volcanic field in the northern extra-andean Patagonia of Argentina. It is mostly composed of alkaline to transitional aphyric olivine basalts that cover a sub-circular area of ~25,000 km 2. Several early Miocene post-plateau volcanic events resulted in small monogenetic centres and large bimodal complexes. The Barril Niyeu Volcanic Complex(BNVC) is one of the largest post-plateau bimodal centres built through several stages of eruptive activity outpoured from at least five vents(presently cauldrons) of distinct trachyte/rhyolite and basaltic compositions. New whole rock K/Ar dating of early trachyte(20.6±0.4 Ma) and late basaltic(18.7±0.4 Ma) rocks constrain the time span of the BNVC activity within 2-2.5 My. The earliest eruptive stage of the BNVC produced viscous trachyte lava restricted to the volcanic centre, followed by two explosive eruptive episodes of dominant intermediate to acid composition: The first episode produced air-fall, mainly plinian(lesser strombolian) and pyroclastic flow deposits and the second was dominated by ignimbritic pyroclastic flows. Basaltic lava, minor breccia and spatter cone deposits dominate the final stage. The magmatic series of the BNVC involves basaltic/trachybasaltic and trachyte/rhyolite compositions, with a characteristic gap in the 52-67% SiO 2 range. Transitional olivine basalt is the most primitive rock of the series(Mg# = 66; Ni = 160 ppm; Cr = 290 ppm) and shows a chemical composition compatible with a liquid that evolved through the crystal fractionation of a basaltic magma derived from partial melting(8-10%) of a lherzolithic source. Major and trace element contents and element ratios suggest differentiation through crystal fractionation from an olivine basaltic magma. Intraplate-like Th/Yb, and Ta/Yb ratios characterize basalts, whereas high LILE/REE(Ba/La) ratios suggest the contribution of a subordinated subduction zone component. In addition, Rb/Nb ratios along with a relative Th enrichment in some basalt suggest assimilation of upper crustal rocks. Isotopic compositions(Sr-Nd) of BNVC basalts suggest a source from a depleted mantle and minor contribution of EM1 melts. Somún Curá magmatism is attributed to a process of lithospheric delamination associated with gravitational disturbances during plate reorganization, with subordinated contributions from detached segments of a foundered subducted slab(Aluk plate?).
format JOUR
author Remesal, M.B.
Salani, F.M.
Cerredo, M.E.
author_facet Remesal, M.B.
Salani, F.M.
Cerredo, M.E.
author_sort Remesal, M.B.
title Petrología del complejo volcánico Barril Niyeu(Mioceno inferior), Patagonia Argentina
title_short Petrología del complejo volcánico Barril Niyeu(Mioceno inferior), Patagonia Argentina
title_full Petrología del complejo volcánico Barril Niyeu(Mioceno inferior), Patagonia Argentina
title_fullStr Petrología del complejo volcánico Barril Niyeu(Mioceno inferior), Patagonia Argentina
title_full_unstemmed Petrología del complejo volcánico Barril Niyeu(Mioceno inferior), Patagonia Argentina
title_sort petrología del complejo volcánico barril niyeu(mioceno inferior), patagonia argentina
url http://hdl.handle.net/20.500.12110/paper_10268774_v29_n2_p463_Remesal
work_keys_str_mv AT remesalmb petrologiadelcomplejovolcanicobarrilniyeumiocenoinferiorpatagoniaargentina
AT salanifm petrologiadelcomplejovolcanicobarrilniyeumiocenoinferiorpatagoniaargentina
AT cerredome petrologiadelcomplejovolcanicobarrilniyeumiocenoinferiorpatagoniaargentina
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