The Western Sierras Pampeanas: Protracted Grenville-age history (1330-1030 Ma) of intra-oceanic arcs, subduction-accretion at continental-edge and AMCG intraplate magmatism

New U–Pb SHRIMP zircon ages combined with geochemical and isotope investigation in the Sierra de; Maz and Sierra de Pie de Palo and a xenolith of the Precordillera basement (Ullun), provides insight into; the identification of major Grenville-age tectonomagmatic events and their timing in the Wester...

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Detalles Bibliográficos
Autores principales: Rapela, Carlos Washington, Pankhurst, Robert J., Casquet, César, Baldo, Edgardo G., Galindo, Carmen, Fanning, Christopher, Dahlquist, Juan A.
Formato: Articulo
Lenguaje:Inglés
Publicado: 2010
Materias:
Geología
Sierras Pampeanas
Grenville-age orogeny
Intra-oceanic arc
Arc–continent collision
AMCG complex
U–Pb SHRIMP dating
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/128518
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-128518
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Geología
Sierras Pampeanas
Grenville-age orogeny
Intra-oceanic arc
Arc–continent collision
AMCG complex
U–Pb SHRIMP dating
spellingShingle Geología
Sierras Pampeanas
Grenville-age orogeny
Intra-oceanic arc
Arc–continent collision
AMCG complex
U–Pb SHRIMP dating
Rapela, Carlos Washington
Pankhurst, Robert J.
Casquet, César
Baldo, Edgardo G.
Galindo, Carmen
Fanning, Christopher
Dahlquist, Juan A.
The Western Sierras Pampeanas: Protracted Grenville-age history (1330-1030 Ma) of intra-oceanic arcs, subduction-accretion at continental-edge and AMCG intraplate magmatism
topic_facet Geología
Sierras Pampeanas
Grenville-age orogeny
Intra-oceanic arc
Arc–continent collision
AMCG complex
U–Pb SHRIMP dating
description New U–Pb SHRIMP zircon ages combined with geochemical and isotope investigation in the Sierra de; Maz and Sierra de Pie de Palo and a xenolith of the Precordillera basement (Ullun), provides insight into; the identification of major Grenville-age tectonomagmatic events and their timing in the Western Sierras; Pampeanas. The study reveals two contrasting scenarios that evolved separately during the 300 Ma long; history: Sierra de Maz, which was always part of a continental crust, and the juvenile oceanic arc and; back-arc sector of Sierra de Pie de Palo and Ullun. The oldest rocks are the Andino-type granitic orthogneisses; of Sierra de Maz (1330–1260 Ma) and associated subalkaline basic rocks, that were part of an; active continental margin developed in a Paleoproterozoic crust. Amphibolite facies metamorphism; affected the orthogneisses at ca. 1175 Ma, while granulite facies was attained in neighbouring meta-sediments; and basic granulites. Interruption of continental-edge magmatism and high-grade metamorphism; is interpreted as related to an arc–continental collision dated by zircon overgrowths at 1170–1230 Ma.; The next event consisted of massif-type anorthosites and related meta-jotunites, meta-mangerites; (1092 ± 6 Ma) and meta-granites (1086 ± 10 Ma) that define an AMCG complex in Sierra de Maz. The; emplacement of these mantle-derived magmas during an extensional episode produced a widespread; thermal overprint at ca. 1095 Ma in neighbouring country rocks. In constrast, juvenile oceanic arc and; back-arc complexes dominated the Sierra de Pie de Palo–Ullun sector, that was fully developed ca.; 1200 Ma (1196 ± 8 Ma metagabbro). A new episode of oceanic arc magmatism at 1165 Ma was roughly; coeval with the amphibolite high-grade metamorphism of Sierra de Maz, indicating that these two sectors; underwent independent geodynamic scenarios at this age. Two more episodes of arc subduction are; registered in the Pie de Palo–Ullun sector: (i) 1110 ± 10 Ma orthogneisses and basic amphibolites with; geochemical fingerprints of emplacement in a more mature crust, and (ii) a 1027 ± 17 Ma TTG juvenile; suite, which is the youngest Grenville-age magmatic event registered in the Western Sierras Pampeanas.; The geodynamic history in both study areas reveals a complex orogenic evolution, dominated by convergent; tectonics and accretion of juvenile oceanic arcs to the continent.
format Articulo
Articulo
author Rapela, Carlos Washington
Pankhurst, Robert J.
Casquet, César
Baldo, Edgardo G.
Galindo, Carmen
Fanning, Christopher
Dahlquist, Juan A.
author_facet Rapela, Carlos Washington
Pankhurst, Robert J.
Casquet, César
Baldo, Edgardo G.
Galindo, Carmen
Fanning, Christopher
Dahlquist, Juan A.
author_sort Rapela, Carlos Washington
title The Western Sierras Pampeanas: Protracted Grenville-age history (1330-1030 Ma) of intra-oceanic arcs, subduction-accretion at continental-edge and AMCG intraplate magmatism
title_short The Western Sierras Pampeanas: Protracted Grenville-age history (1330-1030 Ma) of intra-oceanic arcs, subduction-accretion at continental-edge and AMCG intraplate magmatism
title_full The Western Sierras Pampeanas: Protracted Grenville-age history (1330-1030 Ma) of intra-oceanic arcs, subduction-accretion at continental-edge and AMCG intraplate magmatism
title_fullStr The Western Sierras Pampeanas: Protracted Grenville-age history (1330-1030 Ma) of intra-oceanic arcs, subduction-accretion at continental-edge and AMCG intraplate magmatism
title_full_unstemmed The Western Sierras Pampeanas: Protracted Grenville-age history (1330-1030 Ma) of intra-oceanic arcs, subduction-accretion at continental-edge and AMCG intraplate magmatism
title_sort western sierras pampeanas: protracted grenville-age history (1330-1030 ma) of intra-oceanic arcs, subduction-accretion at continental-edge and amcg intraplate magmatism
publishDate 2010
url http://sedici.unlp.edu.ar/handle/10915/128518
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