Thermal divide andesites–trachytes, petrologic evidence, and implications from Jurassic north Patagonian massif alkaline volcanism

Aragón, Eugenio; González, Pablo Diego; Aguilera, Yolanda E.; Cavarozzi, Claudia E.; Llambías, Eduardo Jorge; Rivalenti, Giorgio

doi:10.1016/s0895-9811(03)00046-4

Cited by 8 publications

(6 citation statements)

References 19 publications

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“…This geochronologic datum can be used to correlate other tectonic and silicic magmatic processes in the region that complement general genetic models and tectonic processes. The reported age is almost coincident with the age of several Cordilleran-type granodioritediorite intrusions (Castro et al, 2010(Castro et al, , 2011 and andesitic volcanic rocks in the Paso the Indios region (Aragón et al, 2003). Errors are 1-sigma.…”

Section: Discussion and Concluding Remarkssupporting

confidence: 63%

“…1) of Lonco Trapial, Taquetren and Alvar Formations (Nullo, 1983;Nullo and Proserpio, 1975;Rapela et al, 2005;Aragón et al, 2003), sedimentary rocks of the Upper Cretaceous Chubut group and plateau basalts of late Creataceous and Tertiarry age. The sampled unit is part of the Late Cretaceous-Paleogene alkali plateau basalts and feeding dikes at the Paso de Indios locality.…”

Section: The Paso De Indios Locality Regional Settingmentioning

confidence: 99%

See 1 more Smart Citation

Age and composition of granulite xenoliths from Paso de Indios, Chubut province, Argentina

Castro

Aragón

Díaz‐Alvarado

et al. 2011

Journal of South American Earth Sciences

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Section: Discussion and Concluding Remarkssupporting

confidence: 63%

Section: The Paso De Indios Locality Regional Settingmentioning

confidence: 99%

Age and composition of granulite xenoliths from Paso de Indios, Chubut province, Argentina

Castro

Aragón

Díaz‐Alvarado

et al. 2011

Journal of South American Earth Sciences

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“…The age of the Las Leoneras Formation is certainly constrained by the Middle Jurassic dating of the volcanic facies of the overlying Lonco Trapial Formation [31], [34], [35]. Furthermore, the base of the Lonco Trapial Formation in this region contains sedimentary facies with a well preserved taphoflora that was originally regarded as Middle Jurassic in age [29]–[30], although new evidence suggests this taphoflora is Early Jurassic in age [42], based on comparisons with the flora from the Early Jurassic of northwestern Patagonia and the Antarctic peninsula.…”

Section: Resultsmentioning

confidence: 99%

A New Sauropodomorph Dinosaur from the Early Jurassic of Patagonia and the Origin and Evolution of the Sauropod-type Sacrum

Garrido²,

2011

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BackgroundThe origin of sauropod dinosaurs is one of the major landmarks of dinosaur evolution but is still poorly understood. This drastic transformation involved major skeletal modifications, including a shift from the small and gracile condition of primitive sauropodomorphs to the gigantic and quadrupedal condition of sauropods. Recent findings in the Late Triassic–Early Jurassic of Gondwana provide critical evidence to understand the origin and early evolution of sauropods.Methodology/Principal FindingsA new sauropodomorph dinosaur, Leonerasaurus taquetrensis gen. et sp. nov., is described from the Las Leoneras Formation of Central Patagonia (Argentina). The new taxon is diagnosed by the presence of anterior unserrated teeth with a low spoon-shaped crown, amphicoelous and acamerate vertebral centra, four sacral vertebrae, and humeral deltopectoral crest low and medially deflected along its distal half. The phylogenetic analysis depicts Leonerasaurus as one of the closest outgroups of Sauropoda, being the sister taxon of a clade of large bodied taxa composed of Melanorosaurus and Sauropoda.Conclusions/SignificanceThe dental and postcranial anatomy of Leonerasaurus supports its close affinities with basal sauropods. Despite the small size and plesiomorphic skeletal anatomy of Leonerasaurus, the four vertebrae that compose its sacrum resemble that of the large-bodied primitive sauropods. This shows that the appearance of the sauropod-type of sacrum predated the marked increase in body size that characterizes the origins of sauropods, rejecting a causal explanation and evolutionary linkage between this sacral configuration and body size. Alternative phylogenetic placements of Leonerasaurus as a basal anchisaurian imply a convergent acquisition of the sauropod-type sacrum in the new small-bodied taxon, also rejecting an evolutionary dependence of sacral configuration and body size in sauropodomorphs. This and other recent discoveries are showing that the characteristic sauropod body plan evolved gradually, with a step-wise pattern of character appearance.

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“…Although most of these are literature data (i.e. Garcia et al 1980;Dyar et al 1993;Righter and Carmichael 1993;Ablay et al 1998;De Lima and Nardi 1998;D'Orazio et al 1998;King et al 1999;Renzulli and Santi 2000;Righter and Rosas-Elguera 2001;Stoykov et al 2002;Aragón et al 2003;Harford et al 2003;Mattioli et al 2003;Trumbull et al 2003;Gourgaud and Vincent 2004;Legendre et al 2005;De Hoog et al 2004;Melluso et al 2007;Viccaro et al 2006;Reubi and Blundy 2008;Varol et al 2008;Humphreys et al 2009;Smith et al 2009;Blundy et al 2010), some are also unpublished, PhD, MS and BS thesis data (Menna 2000;Gorini 2008;Puerini 2008;Piscaglia 2011) for extrusive and intrusive products containing calcic amphiboles (i.e. Sumaco, El Reventador and Cerro Negro volcanoes, Andean Northern Volcanic Zone, Ecuador; Apacheta-Aguilucho Volcanic Complex, Andean Central Volcanic Zone, Chile; Cerro Jeu-Jepén pluton, Fuegian Andes, Argentina; Stromboli volcano, Aeolian Islands, Italy; San Vincenzo rhyolites, Tuscan Magmatic Province, Italy), which will be the focus of forthcoming papers.…”

Section: Selection and Uncertainties Of Calcic Amphibole Literature Datamentioning

confidence: 99%

Calcic amphiboles in calc-alkaline and alkaline magmas: thermobarometric and chemometric empirical equations valid up to 1,130°C and 2.2 GPa

Ridolfi

Renzulli

2011

Contrib Mineral Petrol

510

410

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The following article presents constraints of the stability of Mg-rich (Mg/(Mg ? Fe 2? ) [ 0.5) calcic amphibole in both calc-alkaline and alkaline magmas, testing of previous thermobarometers, and formulation of new empirical equations that take into consideration a large amount of literature data (e.g. more than one thousand amphibole compositions among experimental and natural crystals). Particular care has been taken in choosing a large number of natural amphiboles and selecting quality experimental data from literature. The final database of experimental data, composed of 61 amphiboles synthesized in the ranges of 800-1,130°C and 130-2,200 MPa, indicates that amphibole crystallization occurs in a horn-like P-T stability field limited by two increasing curves (i.e. the thermal stability and an upper limit), which should start to bend back to higher pressures. Among calcic amphiboles, magnesiohornblendes and tschermakitic pargasites are only found in equilibrium with calc-alkaline melts and crystallize at relatively shallow conditions (P up to *1 GPa). Kaersutite and pargasite are species almost exclusively found in alkaline igneous products, while magnesiohastingsite is equally distributed in calc-alkaline and alkaline rocks. The reliability of previous amphibole applications was checked using the selected experimental database. The results of this testing indicate that none of the previous thermobarometers can be successfully used to estimate the P, T and fO 2 in a wide range of amphibole crystallization conditions. Multivariate leastsquare analyses of experimental amphibole compositions and physico-chemical parameters allowed us to achieve a new thermobarometric model that gives reasonably low uncertainties (T ± 23.5°C, P ± 11.5%, H 2 O melt ± 0.78wt%) for calc-alkaline and alkaline magmas in a wide range of P-T conditions (up to 1,130°C and 2,200 MPa) and DNNO values (±0.37 log units) up to 500 MPa. The A K- [4] Al relation in amphibole can be readily used to distinguish crystals of calc-alkaline liquids from those of alkaline magmas. In addition, several chemometric equations allowing to estimate the anhydrous composition of the melts in equilibrium with amphiboles of calc-alkaline magmas were derived.

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Thermal divide andesites–trachytes, petrologic evidence, and implications from Jurassic north Patagonian massif alkaline volcanism

Cited by 8 publications

References 19 publications

Age and composition of granulite xenoliths from Paso de Indios, Chubut province, Argentina

Age and composition of granulite xenoliths from Paso de Indios, Chubut province, Argentina

A New Sauropodomorph Dinosaur from the Early Jurassic of Patagonia and the Origin and Evolution of the Sauropod-type Sacrum

Calcic amphiboles in calc-alkaline and alkaline magmas: thermobarometric and chemometric empirical equations valid up to 1,130°C and 2.2 GPa

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