The Famatinian magmatic arc in the central Sierras Pampeanas: an Early to Mid-Ordovician continental arc on the Gondwana margin

Pankhurst, R. J.; Rapela, Carlos W.; Saavedra, J.; Baldo, Edgardo G.; Dahlquist, Juán A.; Pascua, I.; Fanning, Christopher

doi:10.1144/gsl.sp.1998.142.01.17

Cited by 182 publications

(209 citation statements)

References 29 publications

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“…The two rhyolite samples from Cazadero Grande presented by Martina et al (2011), as the Carboniferous Eastern Sierras Pampeanas granites show geochemical affinities with Las Lozas rhyolites in the Y versus Nb and Y+Nb versus Rb tectonic discrimination diagrams (Pearce et al, 1984) plotting in the within plate granites field (Fig. 9) Pankhurst et al (1998), Dahlquist and Galindo (2004), Dahlquist et al (2010), Martina et al (2011 (Dahlquist et al,2010). The last two magma types were probably extracted from a strongly enriched reservoir with negligible mantle contributions.…”

Section: Disscusionmentioning

confidence: 94%

Extensional Carboniferous magmatism at the western margin of Gondwana: Las Lozas valley, Catamarca, Argentina

Coira

Cisterna

Ulbrich

et al. 2016

andgeo

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ABSTRACT. The Las Lozas volcanic sequence, which crops out at northwestern border of the Famatina belt-southeastern Puna, NW Argentina, is constituted mainly by rhyolites and a lesser volume of basalts and trachytes, and volcanoclastic deposits. These rocks, previously considered of Early Paleozoic age, are now assigned to the Lower Pennsylvanian (320 Ma U-Pb age). They represent a bimodal volcanic succession that plot in the subalkaline/tholeiitic (rhyolites), alkaline basalts (basalts) and alkaline (trachytes) fields on the total alkali-silica diagram. The basalts display features comparable to transitional MORB and within-plate tholeiites, with contributions from a mantle source affected by crustal contamination. The acid members also show geochemical affinities to within-plate magmas, and their composition suggest a derivation from continental crustal material with mantle source interaction or a juvenile essentially mantle derived crust. The 320 Ma age from the Las Lozas volcanic succession as well as the 342 and 348 Ma U-Pb ages, from rocks in the nearby Cazadero Grande section, to the south, and the U-Pb ages from Sierra Pampeanas granites (332-357 Ma) highlight the importance achieved by Carboniferous magmatic activity in that region, framed between 320 and 350 Ma. Low strontium initial ratios from the Las Lozas (0.70479-0.70164) indicate a predominant contribution by a juvenile component, while the ratios in the nearby Cazadero Grande (0.71433-0.71233) and Sierras Pampeanas granites (0.717 to 0.7124) point to an input by enriched sources with restricted contribution of a mantle component. Nd isotopes from a basalt from the Las Lozas section (ε Nd(320) with +3.11, T DM with 774.6 Ma) indicates a possible asthenospheric source, with evidence for some mixture between juvenile and reworked crustal material. In contrast Sr-Nd isotopes in a rhyolite from Cazadero Grande (εNd (t) of -2.91 and -0.3, T DM of 1.09 and 1

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Section: Disscusionmentioning

confidence: 94%

Extensional Carboniferous magmatism at the western margin of Gondwana: Las Lozas valley, Catamarca, Argentina

Coira

Cisterna

Ulbrich

et al. 2016

andgeo

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“…In the Sierra de Chepes, an early to middle Cambrian metamorphism was proposed by Pankhurst et al (1998) based on an Rb-Sr errorchron of 513 ± 31 Ma. Banded schist from the Sierras de Chepes yielded detrital ages between 540 and 511 Ma with an average of 525 Ma (Drobe et al 2010 this volume).…”

Section: Time Constraints For the Famatinian Metamorphismmentioning

confidence: 99%

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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“…The composition of VEL-60 17 is very similar to those of granitoids in the Sierra de Zapata of Carboniferous age, which have been interpreted as the last phase of within-plate magmatism (Rapela et al, 1996). Based on these characteristics, VEL-6017 can be distinguished chemically from the ca1c-alkaline granitoids of Ordovician age generated during the Famatinian Orogeny (see Pankhurst et al , 1998;Dahlquist, 2000;Dahlquist et al, 2005, and references therein).…”

Section: General Geochemistry Characteristicsmentioning

confidence: 99%

The San Blas Pluton: An example of Carboniferous plutonism in the Sierras Pampeanas, Argentina

Dahlquist

Pankhurst

Rapela

et al. 2006

Journal of South American Earth Sciences

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AbstraetNew geoehronologieal and geoehemieal data are reported for the San BIas Pluton (SBP), in the northwestern Sierra de Velaseo, Sierras Pampeanas, whieh intrudes Ordovieian granitoids developed during the Famatinian orogeny. A precise Carboniferous age of 340 ± 3 Ma is established by U-Pb dating of zireon using a sensitive high-resolution ion mieroprobe (SHRIMP). The SBP illustrates several petrologieal and geoehemieal eharaeteristies of previously reported Carboniferous granitoids in the Sierras Pampeanas. Their generation is eonsistent with a regional reheating of the erust at approximately 342 Ma, whieh resulted in the forn1ation of relatively large amounts of granitie melts that were emplaeed in higher erustallevels along master fractures (older master shear zones ofLower Paleozoie age). The SBP can be ehemieally defined as a typieal A-type granitoid related to posteollisonal or postorogenie magmatism. Its high REE eontent and extraordinarily high U and Th eoneentrations may have eeonomie signifieanee. Many previously published Devonian and Carboniferous K-Ar dates are reset Ordovieian ages, but the existenee of other Carboniferous bodies in the Sierra de Velaseo eannot be diseounted until detailed mapping of the whole Sierra is eompleted.

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The Famatinian magmatic arc in the central Sierras Pampeanas: an Early to Mid-Ordovician continental arc on the Gondwana margin

Cited by 182 publications

References 29 publications

Extensional Carboniferous magmatism at the western margin of Gondwana: Las Lozas valley, Catamarca, Argentina

Extensional Carboniferous magmatism at the western margin of Gondwana: Las Lozas valley, Catamarca, Argentina

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

The San Blas Pluton: An example of Carboniferous plutonism in the Sierras Pampeanas, Argentina

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