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dc.contributor.author
Mazzuoli, R.
dc.contributor.author
Vezzoli, L.
dc.contributor.author
Omarini, Ricardo Hector

dc.contributor.author
Acocella, V.
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Gioncada, A.
dc.contributor.author
Matteini, Massimo

dc.contributor.author
Dini, A.
dc.contributor.author
Guillou, H.
dc.contributor.author
Hauser, Natalia

dc.contributor.author
Uttini, A.
dc.contributor.author
Scaillet, S.
dc.date.available
2019-02-20T20:37:07Z
dc.date.issued
2008-12
dc.identifier.citation
Mazzuoli, R.; Vezzoli, L.; Omarini, Ricardo Hector; Acocella, V.; Gioncada, A.; et al.; Miocene magmatism and tectonics of the easternmost sector of the Calama-Olacapato-El Toro fault system in Central Andes at ∼24°S: Insights into the evolution of the Eastern Cordillera; Geological Society of America; Geological Society of America Bulletin; 120; 11-12; 12-2008; 1493-1517
dc.identifier.issn
0016-7606
dc.identifier.uri
http://hdl.handle.net/11336/70564
dc.description.abstract
The Miocene Las Burras - Almagro - El Toro magmatic complex lies ∼300 km to the east of the Central Andes volcanic arc, in the easternmost sector of the transverse Calama - Olacapato - El Toro fault zone. The magmatic rocks of the Las Burras - Almagro - El Toro complex comprise a monzogabbro to monzogranite laccolith like intrusion and basaltic andesite to dacite volcanic rocks that include sevenlithostratigraphic members. New Rb-Sr dates indicate that the intrusive rocks are ca. 14 Ma, and K-Ar dates suggest emplacement ages of ca. 12.8-6.4 Ma for the volcanic rocks. The emplacement of the intrusion was controlled by N-S - striking strike-slip faults in a context of oblique convergence; the volcanism, which occurred along WNW-ESE - and N-S - striking extensional faults, relates to the Calama - Olacapato - El Toro fault zone. Two magmatic phases were recognized. Intrusive and volcanic rocks of the older magmatic phase (ca. 14-13 Ma) are characterized by Ba/Nb (7-14), La/Ta (11-18), and isotopic ratios (87Sr/86Sr: 0.704339-0.705281, 143Nd/144Nd: 0.512713-0.512598), which are intraplate characteristics. The source of the older magmas was isotopically depleted lithospheric mantle rich in K, Rb, and Th. Energy constrained-assimilation and fractional crystallization (EC-AFC) modeling indicates that fractional crystallization and crustal assimilation moderately modified magma composition during its residence in the crust. The products of the younger magmatic phase (ca. 11-6 Ma) have higher Ba/Nb (24-42) and La/Ta (24-30) and 87Sr/86Sr (0.706738-0.708729) and lower 143Nd/144Nd (0.512433-0.512360). The results of EC-AFC modeling exclude a significant role for the upper crust in the generation of the most primitive magmas of this phase. Their compositions can be explained by (1) contamination of the primary magmas having originated in a depleted mantle with a mafic crust, or (2) the contribution of isotopically enriched mantle zones. Shallow differentiation and moderate contamination by continental crust can explain the composition of the intermediate and evolved products of the younger phase. The variation of the magma source characteristics at 11 Ma is discussed in the frame of the complex geo-dynamical setting in this region.
dc.format
application/pdf
dc.language.iso
eng
dc.publisher
Geological Society of America

dc.rights
info:eu-repo/semantics/openAccess
dc.rights.uri
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.subject
Backarc Magmatism
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Central Andes
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Eastern Cordillera
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Geochronology
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Structural Geology
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Volcanic Stratigraphy
dc.subject.classification
Geología

dc.subject.classification
Ciencias de la Tierra y relacionadas con el Medio Ambiente

dc.subject.classification
CIENCIAS NATURALES Y EXACTAS

dc.title
Miocene magmatism and tectonics of the easternmost sector of the Calama-Olacapato-El Toro fault system in Central Andes at ∼24°S: Insights into the evolution of the Eastern Cordillera
dc.type
info:eu-repo/semantics/article
dc.type
info:ar-repo/semantics/artículo
dc.type
info:eu-repo/semantics/publishedVersion
dc.date.updated
2019-02-12T17:09:41Z
dc.journal.volume
120
dc.journal.number
11-12
dc.journal.pagination
1493-1517
dc.journal.pais
Estados Unidos

dc.journal.ciudad
Boulder
dc.description.fil
Fil: Mazzuoli, R.. Università degli Studi di Pisa; Italia
dc.description.fil
Fil: Vezzoli, L.. Università Degli Studi Dell'insubria; Italia
dc.description.fil
Fil: Omarini, Ricardo Hector. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
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Fil: Acocella, V.. Università Degli Studi Roma Tre; Italia
dc.description.fil
Fil: Gioncada, A.. Università degli Studi di Pisa; Italia
dc.description.fil
Fil: Matteini, Massimo. Universidade do Brasília; Brasil
dc.description.fil
Fil: Dini, A.. Istituto Di Geoscienze E Georisorse, Sezione Di Pisa; Italia
dc.description.fil
Fil: Guillou, H.. Centre National de la Recherche Scientifique. Laboratoire des Sciences du Climat et de l'Environnement ; Francia
dc.description.fil
Fil: Hauser, Natalia. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina
dc.description.fil
Fil: Uttini, A.. Università Degli Studi Dell'insubria; Italia
dc.description.fil
Fil: Scaillet, S.. Centre National de la Recherche Scientifique. Laboratoire des Sciences du Climat et de l'Environnement ; Francia
dc.journal.title
Geological Society of America Bulletin

dc.relation.alternativeid
info:eu-repo/semantics/altIdentifier/doi/http://dx.doi.org/10.1130/B26109.1
dc.relation.alternativeid
info:eu-repo/semantics/altIdentifier/url/https://pubs.geoscienceworld.org/gsa/gsabulletin/article/120/11-12/1493-1517/2247
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