Counterclockwise tectonometamorphic evolution of the Pringles Metamorphic Complex, Sierras Pampeanas of San Luis (Argentina)

Delpino, Sergio; Bjerg, Ernesto; Ferracutti, Gabriela; Mogessie, Aberra

doi:10.1016/j.jsames.2006.09.019

Cited by 41 publications

(50 citation statements)

References 45 publications

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“…Granulite-facies metamorphism, which would result from the emplacement of (ultra-) mafic intrusions, occurred during the beginning of the Famatinian cycle ( Fig. 3; Hauzenberger et al 2001;Steenken et al 2005Steenken et al , 2006Delpino et al 2007). Granulitefacies assemblages grade into amphibolite and greenschist facies assemblages (Hauzenberger et al 2001;Delpino et al 2007).…”

Section: M2mentioning

confidence: 99%

“…1) consists of upper to mid-crustal, mainly siliciclastic metasediments and shows a continuous, northeast to southwest transition from very low-and low-grade metamorphic clastic sediments into amphibolite facies and migmatitic Delpino et al (2007) and b the P-T path for the Sierra de Comechingones after Guereschi and Martino (2008). Note that the trajectories are different for the Sierra de Comechingones and the Pringles Metamorphic Complex.…”

Section: Main Geological Features Of Other Basement Blocks In the Easmentioning

confidence: 99%

“…In the Pringles Metamorphic Complex, 506-480 Ma mafic to ultramafic bodies for which back-arc or marginal basin settings were proposed (Sims et al 1998;Hauzenberger et al 2001;Steenken et al 2008) are represented by norites to gabbro-norites with minor ultramafic rocks. On both sides of the mafic to ultramafic bodies, a metamorphic gradient from granulite to greenschist facies is observed (Delpino et al 2007), and therefore a contact metamorphic origin for the granulite-facies paragenesis was suggested (Hauzenberger et al 2001;Steenken et al 2005Steenken et al , 2006. Amphibole-bearing gabbros associated with the calc-alkaline complexes of the Sierra de Chepes, i.e.…”

Section: Ordovician Mafic Rocks In the Sierra De San Luis And Sierra mentioning

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: M2mentioning

confidence: 99%

Section: Main Geological Features Of Other Basement Blocks In the Easmentioning

confidence: 99%

Section: Ordovician Mafic Rocks In the Sierra De San Luis And Sierra mentioning

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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“…2; 460-435 Ma stage). Differences between intermediate-pressure metamorphism in La Aguadita Formation and low-pressure metamorphism associated to extension described for the other Ordovician units croping out to the east and north (Steenken et al, 2006;Delpino et al, 2007;Fernández et al, 2008;Verdecchia, 2009) could be attributed to their diachronic development. The characteristics of the tectono-metamorphic event that affected La Aguadita Formation indicate a compressive regime that is compatible with the termination of the subduction and with the beginning of the terrane collision and lithosphere cooling and thickening (cf.…”

Section: Regional Implications Of the Low-grade Metamorphism In The Fmentioning

confidence: 86%

“…Medium-to high-grade metamorphism linked to this orogeny is well described in rocks cropping out east-southeast of the study region (cf. Steenken et al, 2004;2006;Delpino et al, 2007;Verdecchia, 2009), suggesting the existence of low-pressure metamorphism coupled with back-arc extension and subsequent closure of the basins.…”

Section: Introductionmentioning

confidence: 99%

Low-grade metamorphism of Cambro-Ordovician successions in the Famatina belt, Southern-Central Andes: Burial-inversion history linked to the evolution of the proto-Andean Gondwana margin

Collo¹,

Campo²,

Nieto³

2011

andgeo

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ABSTRACT. The metamorphic P-T conditions of low-grade units from the Famatina belt, Central Andes of Argentina, were estimated through petrography, X-ray diffraction, and electron microscopy. For the Middle-Upper Cambrian Negro Peinado Formation a tectono-metamorphic event associated with intense intrafoliar folding, with estimated temperatures between 290 and 400°C (KI CIS : 0.16-0.27Δº2θ, biotite blastesis and compositional homogeneity in dioctahedral micas) and intermediate pressure conditions (white mica b parameter: 9.010Å-9.035Å), was recognized. The Achavil Formation (Middle-Upper Cambrian) presents a main metamorphic event associated with temperatures between 200 and 290°C (KI CIS : 0.26-0.41Δº2θ) and intermediate-to low-pressure conditions (white mica b parameter values: 8.972Å-9.017Å). Some illitic substitution in dioctahedral micas also indicates lower metamorphic grade than the Negro Peinado Formation. For Upper Cambrian to Middle Ordovician sequences a burial metamorphic pattern, with a progressive decrease in metamorphic grade from Volcancito Formation to Cerro Morado Group (ca. 490-465 Ma; KI CIS : 0.31-0.69Δº2θ) and absence of tendency changes linked to stratigraphic discontinuities was proposed. Mica and chlorite are the main phyllosilicates in the oldest units, while Ilt/ Sme (R3) mixed-layer is almost the only one in the youngest. White mica b parameter indicates intermediate-to low-pressure conditions for all these sequences. This burial metamorphic pattern presents a marked break as the youngest Ordovician unit (La Aguadita Formation, after ca. 452 Ma) records higher metamorphic conditions (IK CIS : 0.28-0.19Δº2θ) than units from the Ordovician arc, with estimated temperatures between 270 and 330ºC and intermediate-pressure conditions. Our results indicate that basin contraction and inversion processes related to the Ordovician Ocloyic Orogeny involved at least two well-discriminated and not superposed metamorphic episodes in this region. Keywords: Western Gondwana margin, Ocloyic orogeny, Famatina belt, Low-grade metamorphism.285 Collo et al./ Andean Geology 38 (2): 284-318, 2011 RESUMEN. Metamorfismo de bajo grado de sucesiones cambro-ordovícicas en el cinturón del Famatina, Andes Centrales de Argentina: Historia de enterramiento-exhumación ligada a la evolución del margen proto-andino de Gondwana. Las condiciones P-T del metamorfismo de las unidades de bajo grado del cinturón del Famatina, Andes Centrales de Argentina, fueron estimadas mediante petrografía, difracción de rayos-X y microscopía electrónica. La Formación Negro Peinado (Cámbrico Medio-Superior) fue afectada por un evento tectono-metamórfico asociado con un plegamiento intrafoliar intenso, para el cual se estimaron temperaturas entre 290 y 400°C (IK CIS : 0,16-0,27 Δº2θ, blástesis de biotita y homogeneidad composicional en micas dioctaédricas) y presiones intermedias (parámetro b de la mica blanca: 9,010 Å y 9,035 Å). La Formación Achavil (Cámbrico Medio-Superior) presenta un evento metamórfico asociado con temperaturas ent...

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Multiple migmatite events and cooling from granulite facies metamorphism within the Famatina arc margin of northwest Argentina

et al. 2014

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The Famatina margin records an orogenic cycle of convergence, metamorphism, magmatism, and extension related to the accretion of the allochthonous Precordillera terrane. New structural, petrologic, and geochronologic data from the Loma de Las Chacras region demonstrate two distinct episodes of lower crustal migmatization. The first event preserves a counterclockwise pressure-temperature path in kyanite-K-feldspar pelitic migmatites that resulted in lower crustal migmatization via muscovite dehydration melting at ∼12 kbar and 868 • C at 461 ± 1.7 Ma. The shape of the pressure temperature path and timing of metamorphism are similar to those of regional midcrustal granulites and suggest pervasive Ordovician migmatization throughout the Famatina margin. One-dimensional thermal modeling coupled with regional isotopic data suggests Ordovician melts remained at temperatures above their solidus for 20-30 Ma following peak granulite facies metamorphism, throughout a time period marked by regional oblique convergence. The onset of synconvergent extension occurred only after regional migmatites cooled beneath their solidus and was synchronous with the cessation of Precordillera terrane accretion at ∼436 Ma. The second migmatite event was regionally localized and occurred at ∼700 • C and 12 kbar between 411 and 407 Ma via vapor saturated melting of muscovite. Migmatization was synchronous with extension, exhumation, and strike-slip deformation that likely resulted from a change in the plate boundary configuration related to the convergence and collision of the Chilenia terrane.

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Counterclockwise tectonometamorphic evolution of the Pringles Metamorphic Complex, Sierras Pampeanas of San Luis (Argentina)

Cited by 41 publications

References 45 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

Low-grade metamorphism of Cambro-Ordovician successions in the Famatina belt, Southern-Central Andes: Burial-inversion history linked to the evolution of the proto-Andean Gondwana margin

Multiple migmatite events and cooling from granulite facies metamorphism within the Famatina arc margin of northwest Argentina

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