Jurassic cooling ages in Paleozoic to early Mesozoic granitoids of northeastern Patagonia: 40Ar/39Ar, 40K–40Ar mica and U–Pb zircon evidence

Dopico, Carmen I. Martínez; Tohver, Eric; Luchi, Mónica G. López de; Wemmer, Klaus; Rapalini, Augusto E.; Cawood, Peter A.

doi:10.1007/s00531-016-1430-0

Cited by 19 publications

(13 citation statements)

References 30 publications

(88 reference statements)

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“…The here obtained monazite ages are similar to the U‐Pb SHRIMP zircon age of 175.9 ± 4.9 Ma reported for a granulite xenolith enclosed in Paleogene basalts to the south of the North Patagonian Massif (Castro, Aragón, et al, ), whereas slightly older Early Jurassic intraplate deformation was documented by K‐Ar and Ar/Ar mica data of Paleozoic granitoids in the northeastern North Patagonian Massif (Martínez Dopico et al, ). Recently, extension‐related very low‐grade metamorphism was recognized in the Southern and Northern Neuquén Precordillera (Suárez & González, ).…”

Section: Discussion and Interpretationsupporting

confidence: 87%

The Late Paleozoic Tectonometamorphic Evolution of Patagonia Revisited: Insights From the Pressure‐Temperature‐Deformation‐Time (P‐T‐D‐t) Path of the Gondwanide Basement of the North Patagonian Cordillera (Argentina)

et al. 2019

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Combined field structural analysis with in situ electron probe microanalysis Th‐U‐Pb monazite dating, petrologic, and microstructural data provides a reconstruction of the pressure‐temperature‐deformation‐time (P‐T‐D‐t) path of the Gondwanide basement of the North Patagonian Cordillera. For samples from the Challhuaco hill, the timing of development of the metamorphic S2 foliation and associated L2 lineation and tight to isoclinal F2 folds is constrained by monazite ages of 299 ± 8 and 302 ± 16 Ma during peak metamorphic conditions of ~ 650 °C and 11 kbar, achieved during prograde metamorphism and progressive deformation. Metamorphism and deformation of metamorphic complexes of the North Patagonian Andes seem to record Late Paleozoic crustal thickening and are coeval with metamorphism of accretionary complexes exposed further west in Chile, suggesting a coupled Late Devonian‐Carboniferous evolution. Instead of the result of continental collision, the Gondwanide orogeny might thus be essentially linked to transpression due to advancing subduction along the proto‐Pacific margin of Gondwana. On the other hand, second generation of monazite ages of 171 ± 9 and 170 ± 7 Ma constrains the timing of low‐grade metamorphism related to kink band and F3 open fold development during Jurassic transtension and emplacement of granitoids. Finally, a Cretaceous overprint, likely resulting from hydrothermal processes, is recorded by monazite ages of 110 ± 10 and 80 ± 20 Ma, which might be coeval with deformation along low‐grade shear zones during the onset of Andean transpression.

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Section: Discussion and Interpretationsupporting

confidence: 87%

The Late Paleozoic Tectonometamorphic Evolution of Patagonia Revisited: Insights From the Pressure‐Temperature‐Deformation‐Time (P‐T‐D‐t) Path of the Gondwanide Basement of the North Patagonian Cordillera (Argentina)

et al. 2019

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“…Granitoid plutons belonging to the Navarrete and Pailem an plutonic complexes and representing a widespread Permian magmatic event intrude all the previously mentioned units (Giacosa, 1997;Caminos, 2001;Pankhurst et al, 2006;Varela et al, 2008;L opez de Luchi et al, 2008;Gozalvez, 2009a;García et al, 2014b;Martínez Dopico et al, 2016).…”

Section: Regional Geology Of the Eastern North Patagonian Massifmentioning

confidence: 94%

“…It contains foliated granitoids and leucogranites, heterogeneously foliated porphyroid granodiorites (Tardugno Granodiorite), with minor paragneisses, schists, amphibolites and marbles (Caminos, 1983(Caminos, , 2001Caminos and Llambías, 1984;Chernicoff and Caminos, 1996b). Conventional and SHRIMP UePb zircon ages include Terreneuvian (Tardugno Granodiorite), Ordovician and Permian-Triassic magmatism (Basei et al, 2002;Rapalini et al, 2013;Chernicoff et al, 2013;Pankhurst et al, 2014;Martínez Dopico et al, 2016). A SHRIMP UePb detrital zircon study provides a Carboniferous maximum depositional age from a biotitic paragneiss-schist (Chernicoff et al, 2013).…”

Section: Regional Geology Of the Eastern North Patagonian Massifmentioning

confidence: 99%

The Nahuel Niyeu basin: A Cambrian forearc basin in the eastern North Patagonian Massif

Greco

González

Sato

et al. 2017

Journal of South American Earth Sciences

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Early Paleozoic basement of the eastern North Patagonian Massif includes low-and high grade metamorphic units, which consist mainly of alternating paraderived metamorphic rocks (mostly derived from siliciclastic protoliths) with minor intercalations of orthoderived metamorphic rocks. In this contribution we provide a better understanding of the tectonic setting in which the protoliths of these units were formed, which adds to an earlier suggested idea. With this purpose, we studied the metasedimentary rocks of the low-grade Nahuel Niyeu Formation from the Aguada Cecilio area combining mapping and petrographic analysis with UePb geochronology and characterization of detrital zircon grains. The results and interpretations of this unit, together with published geological, geochronological and geochemical information, allow us to interpret the sedimentary and igneous protoliths of all metamorphic units from the massif as formed in a forearc basin at~520e510 Ma (Nahuel Niyeu basin). It probably was elongated in the~NWeSE direction, and would have received detritus from a proximal source area situated toward its northeastern side (present coordinates). The basin might be related to an extensional tectonic regime. Most likely source rocks were: (1) 520e510 Ma, acidic volcanic rocks (an active magmatic arc), (2)~555 e>520 Ma, acidic plutonic and volcanic rocks (earlier stages of the same arc), and (3) latest Ediacaran-Terreneuvian, paraderived metamorphic rocks (country rocks of the arc). We evaluate the Nahuel Niyeu basin considering the eastern North Patagonian Massif as an autochthonous part of South America, adding to the discussion of the origin of Patagonia.

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“…The first reliable time constraints for these rocks were established with WR Rb-Sr isochrons yielding late Permian to Middle Triassic ages (Pankhurst et al, 1992), superseding previous mistaken Carboniferous ages. U-Pb zircon crystallization ages were provided by Pankhurst et al (2006), and after by Martínez Dopico et al (2017b) and Luppo et al (2019). Together with thermochronological data (Martínez Dopico et al, 2013a,b;2017b), mica cooling ages bracketed the evolution of the rocks between mid-Permian (Kungurian-Roardian) and Middle Triassic (Anisian).…”

Section: Geological Backgroundmentioning

confidence: 99%

“…U-Pb zircon crystallization ages were provided by Pankhurst et al (2006), and after by Martínez Dopico et al (2017b) and Luppo et al (2019). Together with thermochronological data (Martínez Dopico et al, 2013a,b;2017b), mica cooling ages bracketed the evolution of the rocks between mid-Permian (Kungurian-Roardian) and Middle Triassic (Anisian). Sm-Nd, Lu-Hf and O isotopic data are available from Pankhurst et al (2006), Fanning et al (2011) and Castillo et al (2017).…”

Section: Geological Backgroundmentioning

confidence: 99%

Geochemistry and geochronology of the shallow-level La Esperanza magmatic system (Permian-Triassic), Northern Patagonia

Dopico

Luchi

Rapalini

et al. 2019

Journal of South American Earth Sciences

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The La Esperanza plutonic-volcanic complex is the largest Late Paleozoic-Early Triassic composite magmatic system of northern Patagonia. This paper reports new SHRIMP U-Pb zircon ages and K-Ar muscovite dating as well as whole-rock geochemical data for selected units. In addition, we present some new and reprocessed whole-rock Sr isotopic compositions. On the basis of the new and published data, three compositionally and isotopically distinct high-K magnesian calc-alkaline series were distinguished. Two of these are characterized by high Ba-Sr: (i) biotite and muscovite bearing rhyolites and granites (265 ± 2 Ma; 260 ± 2 Ma) and (ii) metaluminous amphibole-biotite bearing granodiorites (273 ± 2 Ma), monzogranites (255 ± 2 Ma), dacites (253 ± 2 Ma), and slightly peraluminous granites (dated herein as 251 ± 2 Ma). There is also a low Ba-Sr series of high-silica metaluminous rocks (granites and acid dike swarms; 250 ± 2 Ma and ≈244 ± 2 Ma). Geochemistry coupled with geochronology revealed a pulsatory multi-sourced open magmatic system with mafic magma replenishment and reactivation of crystal mushes that occurred before upward migration to upper crustal levels. Mafic magmas alternated with crust-derived magmas incrementally assembled in subvolcanic levels over 30 Ma. Zircon crystallization and mica cooling ages in the granite units allowed detection of two magmatic lulls, between 270 and 265 Ma and between 260 and 255 Ma. Both episodes coincide with a period of exhumation in upper crustal levels. The new temporal and geochemical constraints allow correlation of the La Esperanza plutonic-volcanic complex with the Los Menucos Group (258-248 Ma), encompassing a volume of magmatism comparable to a moderately sized large igneous silicic province. These mid-to-late Permian to Middle Triassic rocks record the transition between subduction-related magmatism (> 273 Ma) and post-orogenic extensional magmatism (< 250 Ma) in the Gondwana margin. Even though this magmatism would be coeval with the proposed collision of the Patagonia terrane, no expected syn-collisional magmatism or associated deformation were found in upper crustal levels. However, the different nature and melting conditions of the inferred sources of the magmas that crystallized before 270 Ma, between 265 and 260 Ma, and from 255 to 245 Ma, suggest that the La Esperanza plutonic-volcanic complex was assembled during a 30 Ma period of major plate reorganization.

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Jurassic cooling ages in Paleozoic to early Mesozoic granitoids of northeastern Patagonia: 40Ar/39Ar, 40K–40Ar mica and U–Pb zircon evidence

Cited by 19 publications

References 30 publications

The Late Paleozoic Tectonometamorphic Evolution of Patagonia Revisited: Insights From the Pressure‐Temperature‐Deformation‐Time (P‐T‐D‐t) Path of the Gondwanide Basement of the North Patagonian Cordillera (Argentina)

The Late Paleozoic Tectonometamorphic Evolution of Patagonia Revisited: Insights From the Pressure‐Temperature‐Deformation‐Time (P‐T‐D‐t) Path of the Gondwanide Basement of the North Patagonian Cordillera (Argentina)

The Nahuel Niyeu basin: A Cambrian forearc basin in the eastern North Patagonian Massif

Geochemistry and geochronology of the shallow-level La Esperanza magmatic system (Permian-Triassic), Northern Patagonia

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