Time constraints on the tectonic evolution of the Eastern Sierras Pampeanas (Central Argentina)

Siegesmund, Siegfried; Steenken, André; Martino, Roberto; Wemmer, Klaus; Luchi, Mónica G. López de; Frei, Robert; Presnyakov, S. L.; Guereschi, Alina B.

doi:10.1007/s00531-009-0471-z

Cited by 80 publications

(82 citation statements)

References 74 publications

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“…1). The eastern sector of these basement units is mainly affected by the Pampean orogeny, which is characterized by late Neoproterozoic sedimentation and Ediacaran to Cambrian deformation, magmatism and metamorphism (Rapela et al 2007;Siegesmund et al 2010). The western sector is dominated by the Famatinian orogeny, which is characterized by Cambrian marine sedimentation and late Cambrian to Ordovician magmatism (Sims et al 1998;Steenken et al 2006).…”

Section: Geological Background Of the Main Basement Units Of The Eastmentioning

confidence: 99%

“…The Sierra Norte, Sierras de Ambargasta and Sumampa, constitute a major block mostly made up of Ediacaran to early Cambrian arc-related I-type calc-alkaline granitoid intrusions named the Sierra Norte-Ambargasta Batholith (SNAB) (Lira et al 1997;Siegesmund et al 2010). Magmatic activity ceased in the late Cambrian with the emplacement of the Oncán porphyritic rhyolite dykes (Rapela et al 1991;494 ± 11 Ma).…”

Section: Sierras De Córdoba and Sierra Nortementioning

confidence: 99%

“…The Eastern Sierras Pampeanas constitute polyphase deformed basement units, which were structured by three events: the Ediacaran to early Cambrian (580-510 Ma) Pampean, the late Cambrian-Ordovician (500-440 Ma) Famatinian and the Devonian-Carboniferous (400-350 Ma) Achalian orogenies (Aceñolaza and Toselli 1981;Rapela et al 1998;Stuart-Smith et al 1999;Steenken et al 2006;López de Luchi et al 2007;Drobe et al 2009Drobe et al , 2010Siegesmund et al 2010). These orogenies are related to the accretion of different terranes integrated into the protoAndean margin of Gondwana.…”

Section: Introductionmentioning

confidence: 99%

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The Neoproterozoic-early Paleozoic metamorphic and magmatic evolution of the Eastern Sierras Pampeanas: an overview

Steenken¹,

Luchi

Dopico

et al. 2010

Int J Earth Sci (Geol Rundsch)

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The Eastern Sierras Pampeanas were structured by three main events: the Ediacaran to early Cambrian (580-510 Ma) Pampean, the late Cambrian-Ordovician (500-440 Ma) Famatinian and the Devonian-Carboniferous (400-350 Ma) Achalian orogenies. Geochronological and Sm-Nd isotopic evidence combined with petrological and structural features allow to speculate for a major rift event (Ediacaran) dividing into two Mesoproterozoic major crustal blocks (source of the Grenvillian age peaks in the metaclastic rocks).This event would be coeval with the development of arc magmatism along the eastern margin of the eastern block. Closure of this eastern margin led to a Cambrian active margin (Sierra Norte arc) along the western margin of the eastern block in which magmatism reworked the same crustal block. Consumption of a ridge segment (input of OIB signature mafic magmas) which controlled granulite-facies metamorphism led to a final collision (Pampean orogeny) with the western Mesoprotrozoic block. Sm-Nd results for the metamorphic basement suggest that the T DM age interval of 1.8-1.7 Ga, which is associated with the less radiogenic values of eNd (540) (-6 to -8), can be considered as the mean average crustal composition for the Eastern Sierras Pampeanas. Increasing metamorphic grade in rocks with similar detrital sources and metamorphic ages like in the Sierras de Córdoba is associated with a younger T DM age and a more positive eNd (540) value. Pampean pre-540 Ma granitoids form two clusters, one with T DM ages between 2.0 and 1.75 Ga and another between 1.6 and 1.5 Ga. Pampean post-540 Ma granitoids exhibit more homogenous T DM ages ranging from 2.0 to 1.75 Ga. Ordovician re-activation of active margin along the western part of the block that collided in the Cambrian led to arc magmatism (Famatinian orogeny) and related ensialic back-arc basin in which high-grade metamorphism is related to mid-crustal felsic plutonism and mafic magmatism with significant contamination of continental crust. T DM values for the Ordovician Famatinian granitoids define a main interval of 1.8-1.6, except for the Ordovician TTG suites of the Sierras de Córdoba, which show younger T DM ages ranging from 1.3 to 1.0 Ga. In Devonian times (Achalian orogeny), a new subduction regime installed west of the Eastern Sierras Pampeanas. Devonian magmatism in the Sierras exhibit process of mixing/assimilation of depleted mantle signature melts and continental crust. Achalian magmatism exhibits more radiogenic eNd (540) values that range between 0.5 and -4 and T DM ages younger than 1.3 Ga. In pre-Devonian times, crustal reworking is dominant, whereas processes during Devonian times involved different geochemical and isotopic signatures that reflect a major input of juvenile magmatism.

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Section: Geological Background Of the Main Basement Units Of The Eastmentioning

confidence: 99%

Section: Sierras De Córdoba and Sierra Nortementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Neoproterozoic-early Paleozoic metamorphic and magmatic evolution of the Eastern Sierras Pampeanas: an overview

Steenken¹,

Luchi

Dopico

et al. 2010

Int J Earth Sci (Geol Rundsch)

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“…Esto sugiere que las cuencas sedimentarias del Cámbrico medio al Ordovícico Inferior habrían compartido áreas de aporte similares de tipo margen pasivo (basamento continental extenso) y arco magmático félsico, con diferente participación de componentes máficos en consistencia con Drobe et al (2011), y apoyándose, además, con la evidencia que arrojan los circones detríticos. La presencia de circones ʻpampeanosʼ indica que las rocas ígneas volcánicas a plutónicas, mayoritariamente intermedias a ácidas, vinculadas a esta orogénesis (Sierras de Córdoba, Sierra NorteAmbargasta; Rapela et al, 1998;Siegesmund et al, 2010;Iannizzotto et al, 2013; Fig. 1) fueron una importante fuente de circones detríticos y demás material clástico que conformaron los protolitos de los complejos metamórficos analizados (Fig.…”

Section: Correlación Con Otros Complejos Metamór-ficos De Las Sierrasunclassified

“…550-515 Ma) y la Famatiniana (Cám-brico tardío a Ordovícico; ca. 500-440 Ma), a las que siguen eventos más discretos de magmatismo y deformación devónico-carboníferos asociados a la orogenia Achaliana (e.g., Rapela et al, 1998;Sims et al, 1998;Pankhurst et al, , 2000Dahlquist et al, 2010;Otamendi et al, 2008Otamendi et al, , 2012Rapela et al, 2007;Siegesmund et al, 2010;Steenken, et al, 2011;Casquet et al, 2012). En la última década se ha incrementado significativamente la información geoquímica, isotópica y geocronológica (especialmente U-Pb en circones detríticos) de las rocas metasedimentarias de la región de las Sierras Pampeanas Orientales (e.g., Sims et al, 1998;López de Luchi et al, 2003;Escayola et al, 2007;Rapela et al, 2007;Collo et al, 2009;Drobe et al, 2009Drobe et al, , 2011Verdecchia y Baldo, 2010;Adams et al, 2011;Verdecchia et al, 2011;Murra et al, 2011;Larrovere et al, 2012;Iannizzotto et al, 2013), permitiendo discriminar las diferentes paleocuencas, principalmente aquellas que funcionaron durante el Neoproterozoico tardío al Ordovícico temprano.…”

Section: Introductionunclassified

Geoquímica de las rocas metasedimentarias del Cámbrico medio al Ordovícico temprano de la Sierra de Los Llanos (Sierras Pampeanas, Argentina): Fuente de sedimentos, correlación y ambiente geotectónico

Verdecchia

Murra

Baldo

et al. 2014

Andgeo

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RESUMEN.El complejo metamórfico de la Sierra de Los Llanos está constituido por rocas paraderivadas metamorfizadas en condiciones de bajo a alto grado y representadas por filitas, esquistos, gneises y migmatitas que afloran como grandes septos dentro de las unidades magmáticas del Ordovícico inferior. Localmente se reconocen rocas corneanas asociadas a la intrusión de cuerpos de composición básica. Las rocas metasedimentarias de este complejo muestran composiciones químicas equivalentes a pelitas y areniscas del tipo sublitoarenita y subarcosa. Las relaciones de Ti/Zr (5,(4)(5)(6)(7)(8)4), La/Sc (5,2-8,5), Th/Sc >1 (2,2-3,4), La/Th (2,0-2,5) y Zr/Sc (60-103), junto a las concentraciones de Hf (7,9 a 12,4 ppm) y Sc (4,4-5,2 ppm) en las metapsamitas son indicativas de una fuente enriquecida en componentes félsicos o de materiales reciclados y con reducida participación de componentes máficos. La correlación geoquímica de estas unidades con las metapsamitas de los complejos metamórficos Chepes, La Cébila y Pringles sugiere una misma composición del área fuente para todos ellos. Las concentraciones de Ti, Zr, Hf, La, Th y Sc son variables y no permiten definir claramente un determinado contexto geotectónico, sugiriendo además que la composición de los protolitos fue mayormente controlada por procesos sedimentarios y no por la heterogeneidad composicional de las fuentes. La integración de la información geoquímica con los datos geocronológicos conocidos y la correlación regional de los complejos metamórficos ordovícicos permite reforzar la propuesta de definir como principales áreas fuente de estos complejos las rocas ígneas y metamórficas de la faja orogénica Pampeana y del Cratón del Río de La Plata. La información aportada es consistente, además, con la existencia de una extensa plataforma continental en el margen suroccidental de Gondwana durante el Cámbrico medio al Ordovícico temprano. Palabras clave: Complejo Metamórfico Los Llanos, Geoquímica de rocas metasedimentarias, Cámbrico tardío, Orogénesis Pampeana, Orogénesis Famatiniana, Sierras Pampeanas Orientales.381 Verdecchia et al. / Andean Geology 41 (2): 380-400, 2014 ABSTRACT. Geochemistry of middle Cambrian to early Ordovician metasedimentary rocks of the Sierra de Los Llanos (Sierras Pampeanas, Argentina): Source of sediments, correlations and geotectonic setting. The metamorphic complex of Sierra de Los Llanos is composed of low-to high-grade metasedimentary rocks, namely phyllites, schists, gneisses and migmatites that out crop like large septa within lower Ordovician magmatic units. Cornubianite associated with the intrusion of basic composition bodies are locally recognized. Chemical compositions of these metasedimentary rocks are equivalent to pelite and arenite (sublitharenite-subarkose). Chemical ratios of Ti/Zr (5.4-8.4), La/Sc (5.2-8.5), Th/Sc >1 (2.2-3.4), La/Th (2.0-2.5) and Zr/Sc (60-103), along with contents of Hf (7.9 a 12.4 ppm) and Sc (4.4-5.2 ppm) in meta-psammites, suggest that the source of the sediments was enriched in felsic compon...

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Timing of deformation in the Sarandí del Yí Shear Zone, Uruguay: Implications for the amalgamation of western Gondwana during the Neoproterozoic Brasiliano‐Pan‐African Orogeny

et al. 2016

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U‐Pb and Hf zircon (sensitive high‐resolution ion microprobe ‐SHRIMP‐ and laser ablation‐inductively coupled plasma‐mass spectrometry ‐LA‐ICP‐MS‐), Ar/Ar hornblende and muscovite, and Rb‐Sr whole rock‐muscovite isochron data from the mylonites of the Sarandí del Yí Shear Zone, Uruguay, were obtained in order to assess the tectonothermal evolution of this crustal‐scale structure. Integration of these results with available kinematic, structural, and microstructural data of the shear zone as well as with geochronological data from the adjacent blocks allowed to constrain the onset of deformation along the shear zone at 630–625 Ma during the collision of the Nico Pérez Terrane and the Río de la Plata Craton. The shear zone underwent dextral shearing up to 596 Ma under upper to middle amphibolite facies conditions, which was succeeded by sinistral shearing under lower amphibolite to upper greenschist facies conditions until at least 584 Ma. After emplacement of the Cerro Caperuza granite at 570 Ma, the shear zone underwent only cataclastic deformation between the late Ediacaran and the Cambrian. The Sarandí del Yí Shear Zone is thus related to the syncollisional to postcollisional evolution of the amalgamation of the Río de la Plata Craton and the Nico Pérez Terrane. Furthermore, the obtained data reveal that strain partitioning and localization with time, magmatism emplacement, and fluid circulation are key processes affecting the isotopic systems in mylonitic belts, revealing the complexity in assessing the age of deformation of long‐lived shear zones.

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Time constraints on the tectonic evolution of the Eastern Sierras Pampeanas (Central Argentina)

Cited by 80 publications

References 74 publications

The Neoproterozoic-early Paleozoic metamorphic and magmatic evolution of the Eastern Sierras Pampeanas: an overview

The Neoproterozoic-early Paleozoic metamorphic and magmatic evolution of the Eastern Sierras Pampeanas: an overview

Geoquímica de las rocas metasedimentarias del Cámbrico medio al Ordovícico temprano de la Sierra de Los Llanos (Sierras Pampeanas, Argentina): Fuente de sedimentos, correlación y ambiente geotectónico

Timing of deformation in the Sarandí del Yí Shear Zone, Uruguay: Implications for the amalgamation of western Gondwana during the Neoproterozoic Brasiliano‐Pan‐African Orogeny

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