Person: Galindo Francisco, María Del Carmen
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First Name
María Del Carmen
Last Name
Galindo Francisco
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Geológicas
Department
Mineralogía y Petrología
Area
Petrología y Geoquímica
Identifiers
8 results
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Item A combined zircon Hf isotope and whole-rock Nd and Sr isotopes study of Carboniferous A-type granites, Sierras Pampeanas of Argentina(Journal of South American Earth Sciences, 2020) Dahlquist, Juan Andrés; Galindo Francisco, María Del Carmen; Morales Cámera, Matías M.; Moreno Moreno, Juan Antonio; Alasino, Pablo H.; Basei, Miguel A.S.; Macchioli Grande, MarcosWe report new whole-rock Nd and Sr isotope data for two strongly peraluminous and one slightly peraluminous Carboniferous A-type granitic plutons in the eastern Sierras Pampeanas of Argentina. Our study also integrates previous petrological and geochemical information with in situ U–Pb and Hf isotope data from magmatic and inherited zircon. Strongly peraluminous samples have pronounced negative εNdt values (−7.6 and −7.0) and very high (87Sr/86Sr)t values (0.728778 and 0.747092). These are similar to isotope compositions reported for the Puncoviscan Series, a metasedimentary sequence metamorphosed during the Lower Cambrian and intruded by these granites. Nd and Sr isotope data for the slightly peraluminous sample (εNdt = −3.5 and 87Sr/86Srt = 0.708074), together with previously reported petrological and geochemical data, indicate that the basement of the Sierras de Córdoba participated in the generation of the parental magma. The new data are not easily reconciled with the positive zircon εHft values previously reported for these samples, which suggest dominantly juvenile material in the source. We propose that Hf was transferred from inherited zircon toward the magmatic rim, without complete isotopic homogenization with the magma, as has been hypothesized in previous works. Our results reveal that the indiscriminate use of Hf databases can lead to false inference of crustal growth by mantle addition through time and misleading comparisons between granitic rocks worldwide.Item Late Cambrian – Early Ordovician magmatism in the Sierra de Pie de Palo, Sierras Pampeanas (Argentina): implications for the early evolution of the proto-Andean margin of Gondwana(Geological Magazine, 2020) Ramacciotti, Carlos; Casquet Martín, César; Baldo, Edgardo G.; Alasino, Pablo H.; Galindo Francisco, María Del Carmen; Dahlquist, Juan A.The Sierra de Pie de Palo, in the Argentinean Sierras Pampeanas (Andean foreland), consists of a Mesoproterozoic basement and an Ediacaran – upper Cambrian sedimentary cover that underwent folding, thrusting and metamorphism during the Ordovician Famatinian orogeny. Mafic rocks and granitoids of the easternmost Sierra de Pie de Palo provide information about the magmatic activity at the proto-Andean margin of Gondwana during late Cambrian – Early Ordovician time. Magmatic activity began in the Sierra de Pie de Palo as dykes, sills and small intrusions of tholeiitic gabbros between 490 and 470 Ma, before shortening and regional metamorphism. Variable mantle sources (Nd depleted mantle age, TDM between 1.7 and 1.3 Ga) were involved in the mafic magmatism. Nd-isotope signatures were probably inherited from a Mesoproterozoic subcontinental mantle. Mafic magmatism was coincident with collapse of a Cambrian carbonate-siliciclastic platform that extended along SW Gondwana, and was probably coeval with the beginning of subduction. After mafic magmatism, peraluminous granitoids were emplaced in the Sierra de Pie de Palo along ductile shear zones during a contractional tectonic phase, coeval with moderate to high P/T metamorphism, and with the Cordilleran-type magmatic arc that resulted from a flare-up at c. 470 Ma. Granitoids resulted mainly from partial melting of metasedimentary rocks, although some hybridization with juvenile magmas and/or rocks cannot be ruled out. The evidence shown here further implies that the Pie de Palo block was part of the continental upper plate during the Famatinian subduction, and not an exotic block that collided with the Gondwana margin.Item The Faja Eruptiva of the Eastern Puna and the Sierra de Calalaste, NW Argentina: U–Pb zircon chronology of the early Famatinan orogeny(Journal of iberian geology, 2021) Casquet Martín, César; Alasino, Pablo H.; Galindo Francisco, María Del Carmen; Dahlquist, Juan A.; Baldo, Edgardo G.; Ramacciotti, Carlos; Verdecchia, Sebastián; Larrovere, Mariano Alexis; Rapela, Carlos W.; Recio, C.The Famatinian is a segment of the Ordovician Terra Australis accretionary orogen that stretched along the SW Margin of Gondwana from Australia to Colombia. The present knowledge of this orogenic segment still is incomplete. We present geochemistry and U–Pb SHRIMP zircon geochronology of igneous and metamorphic rocks from the Central Famatinian Domain, one of the several domains recognized by Rapela et al. (Earth Sci Rev 187: 259–285. https://doi.org/10.1016/j.earscirev.2018.10.006) that includes the northern Sierras Pampeanas and the southern Puna of North West Argentina. Six samples of igneous rocks (peraluminous granitoids, mafic and felsic rocks, volcanic/subvolcanic rocks) and six samples of associated meta-sedimentary rocks, all from the Puna were dated and chemically analysed. The results indicate that the Central Famatinian Domain is in turn a composite domain that includes a Cordilleran-type magmatic arc (ca. 470 Ma) and a yuxtaposed fault-bounded older terrain formed in an extensional setting at the very start of the Famatinian orogeny, between 480 and 485 Ma, i.e., shortly after the SW Gondwana margin switched from passive to active. This short period of extension with related sedimentation, volcanism and mainly granitoid plutonism has not been previously recognised. It occurred before the Cordilleran-type magmatic arc -that resulted from a magmatic flare-up between ca. 473 and 468 Ma-, set up coincident with a contractional phase. The evidence confirms that accretionary orogeny results from tectonic switching (pull–push orogeny) and that the extensional and contractional phases are of relatively short duration.Item O–H–Sr–Nd isotope constraints on the origin of the Famatinian magmatic arc, NW Argentina(Geological Magazine, 2020) Alasino, Pablo H.; Casquet Martín, César; Galindo Francisco, María Del Carmen; Pankhurst, R.J.; Rapela, Carlos W.; Dahlquist, Juan A.; Recio, C.; Baldo, Edgardo G.; Larrovere, Mariano Alexis; Ramacciotti, CarlosWe report a study of whole-rock O–H–Sr–Nd isotopes of Ordovician igneous and metamorphic rocks exposed at different crustal palaeodepths along c. 750 km in the Sierras Pampeanas, NW Argentina. The isotope compositions preserved in the intermediate rocks (mostly tonalite) (average δ18O = +8.7 ± 0.5‰, δD = −73 ± 14‰, 87Sr/86Srt = 0.7088 ± 0.0001 and εNdt = −4.5 ± 0.6) show no major difference from those of most of the mafic rocks (average δ18O = +8 ± 0.8‰, δD = −84 ± 18‰, 87Sr/86Srt = 0.7082 ± 0.0016 and εNdt = −4 ± 1.1), suggesting that most of their magmas acquired their crustal characteristics in the mantle. The estimate of assimilation of crustal material (δ18O = +12.2 ± 1.7‰, δD = −89 ± 21‰, 87Sr/86Srt = 0.7146 ± 0.0034 and εNdt = −6.9 ± 0.7) by the tonalite is in most samples within the range 10–20%. Felsic magmas that reached upper crustal levels had isotope values (δ18O = +9.9 ± 1.5‰, δD= −76 ± 5‰, 87Sr/86Srt = 0.7067 ± 0.0010, εNdt = −3.5 ± 1.4) suggesting that they were not derived by fractionation of the contaminated intermediate magmas, but evolved from different magma batches. Some rocks of the arc, both igneous (mostly gabbro and tonalite) and metamorphic, underwent restricted interaction with meteoric fluids. Reported values of δ18O of magmatic zircons from the Famatinian arc rocks (+6 to +9‰) are comparable to our δ18O whole-rock data, indicating that pervasive oxygen isotope exchange in the lower crust was not a major process after zircon crystallization.Item A genetic link between albitic magmas and IOCG mineralization in the Ossa Morena Zone (SW Iberia)(Journal of Iberian Geology, 2021) Carriedo, Jorge; Tornos, Fernando; Chiaradia, Massimo; Galindo Francisco, María Del CarmenA detailed geological and isotopic study of the Colmenar deposit (Ossa Morena Zone, SW Iberia) shows that the magnetite-rich mineralization formed by complex magmatic-hydrothermal processes related to the crystallization of water-rich albite-magnetite igneous rocks derived from the crystallization of unusual melts formed during anatexis in a high temperature-low pressure metamorphic regime. The most likely protolith includes a sequence of iron-rich chemical sediments, amphibolite and possible meta-evaporites of early Cambrian age. The albite-magnetite rock occurs as up to 20 cm-thick dyke and breccia bodies and show complex immiscibility relationships with an albite-K-feldspar-quartz leucogranite. Iron-rich fluids exsolved during the crystallization of these melts are responsible of the formation of hydrothermal breccias and the widespread replacement of the hosting calc-silicate hornfels by a magnetite-ferroactinolite-albite assemblage along syn-mineralization shear zones. Geochronological data obtained for mineralization and related hydrothermal alteration points to a Variscan age (ca. 340 Ma), interpreted also as the age of the high-grade metamorphism driving anatexis at the Valuengo Metamorphic Complex. Despite the low Cu and Au contents, this mineralization shares features with the IOCG systems, which in other districts show a spatial relationship with albite-rich rocks, evaporites and pre-existing iron mineralization. The observations presented from Colmenar support an alternative genetic model with prospective implications for the Ossa Morena Zone that can be extrapolated to other IOCG belts worldwide.Item Isotope geochemistry, age, and origin of the magnetite-vonsenite mineralization of the Monchi Mine, SW Iberia(Journal of Iberian Geology, 2021) Tornos, Fernando; Galindo Francisco, María Del Carmen; Darbyshire, Fiona; Casquet Martín, César; Noble, Stephen R.The Monchi Mine (Ossa Morena Zone, SW Iberia) is a rather unique ore deposit characterized by unusually high Fe grades and an ore assemblage that includes dominant magnetite but with abundant B (vonsenite), U (uraninite), Co (cobaltite), As (löllingite, safflorite) and rare earth elements (allanite). The mineralization occurs at the western edge of a Variscan concentrically zoned gabbro to granodiorite pluton, the Burguillos del Cerro Plutonic Complex. Moreover the western side of the complex is within a large N–S trending dextral strike-slip shear zone in which Ediacaran to early Cambrian metapelitic and calc-silicate hornfels and marble constitute a vertical screen between an outer syn-tectonic sheet of foliated biotite monzogranite and an inner post-tectonic amphibole-biotite diorite unit. The magnetite-vonsenite mineralization is adjacent to the screen and forms large lens-shaped bodies with sharp contacts with the intrusive rocks and is directly related with a granoblastic U-REE-bearing Fe-pyroxene-rich hornfels which is locally brecciated and cemented by pegmatite dominated by albite, K feldspar, quartz, clinoamphibole/biotite and axinite. Within the enclave there is a large post-tectonic exoskarn, including calcic and magnesian types which predates the diorite that mainly replaced the calc-silicate hornfels and the marble. The calcic exoskarn is dominated by grandite and hedenbergite and was retrogressed to actinolite, epidote, calcite and magnetite with variable amounts of pyrite and chalcopyrite. U–Pb TIMS dating of allanite from the U-REE-rich hornfels yielded 337.13 ± 0.99 Ma, i.e., within the range of ages of the Burguillos Plutonic Complex (335–340 Ma). Sr–Nd isotope geochemistry shows that the mineralization (including skarn and massive ore) has isotope signatures (εNd338 between -0.8 and -4.1; 87Sr/86Sr338 = 0.7071–0.7112) mostly intermediate between those of the igneous (− 6.8 to − 2.3; 0.7047–0.7097, respectively) and the sedimentary (− 11.7 to − 8.3; 0.7090–0.7164, respectively) rocks. The massive high grade mineralization could be the result of a syn-magmatic interaction of an unknown protolith with deep sourced fluids that were focused along early thrusts and shear zones probably rooted at a magma chamber in the middle crust. Alternatively it could also be the product of crystallization of a boron-bearing iron melt. This melt would be somewhat similar to the magnetite-(apatite) deposits elsewhere but in which the fluxing agent is boron. Fluids exsolved from these rocks produced a high-temperature magmatic-hydrothermal system that formed the post-tectonic exoskarn. The ultimate origin of these immiscible Fe-B melts could hypothetically be the assimilation at depth of former shallow marine metasediments.Item Early Ordovician magmatism in the Sierra de Ancaján, Sierras Pampeanas (Argentina): implications for the early evolution of the proto-Andean margin of Gondwana(Journal of iberian geology, 2021) Zandomeni, Priscila S.; Verdecchia, Sebastián; Baldo, Edgardo G.; Galindo Francisco, María Del Carmen; Moreno Moreno, Juan Antonio; Casquet Martín, César; Dahlquist, Juan A.; Morales Cámera, Matías M.; Basei, Miguel A.S.; Ramacciotti, CarlosThe Ancaján pluton is a small-scale (ca. 5.34 km2) elongated igneous body of granodiorite to monzogranite composition that crops out in the Sierra the Ancaján (Eastern Sierras Pampeanas), intruding marbles and metasedimentary rocks of the Ediacaran Ancaján series. New SHRIMP and LA-MC-ICP-MS U–Pb zircon analyses from one granodiorite sample yielded a likely Ordovician crystallization age of ca. 473 Ma. Inherited Cambrian, Neoproterozoic, Mesoproterozoic and Paleoproterozoic ages have also been recorded. The Ancaján granitoids are calc-alkalic, magnesian and slightly peraluminous with medium to high K2O (2.44–3.74 wt%) and high Na2O (4.05–4.51 wt%) contents. These geochemical characteristics are comparable to those of the Ordovician Na-rich (TTG-like) magmatism of the Foreland Famatinian Domain (FFD) in the Sierras de Córdoba. Therefore, the Ancaján pluton could represent the northernmost outcrop of such magmatism. Isotopes data (Sr/Sri = 0.7052–0.7055; εNdi = − 0.7 to − 0.4; TDM = 1.24–1.27 Ga) and inherited zircon ages suggest that the parental magma probably resulted from partial melting of a combined source, mainly formed by older subcontinental mantle with mafic–ultramafic oceanic lithosphere composition, along with recycling/assimilation of continental crust involving Pampean granitoids and/or Ediacaran to Cambrian sedimentary protoliths. This interpretation is coincident with that postulated for the Ordovician Na-rich granitoids from the Sierras de Córdoba. The evidence shown here further implies that metasedimentary rocks of the Sierra de Ancaján were part of the continental upper plate during the Famatinian subduction, and corroborate the previous imbrication of the Ancaján and Puncoviscana series during the early Cambrian Pampean Orogeny.Item Thermal maturation of a complete magmatic plumbing system at the Sierra de Velasco, Northwestern Argentina(Geological magazine, 2021) Macchioli Grande, Marcos; Alasino, Pablo H.; Dahlquist, Juan A.; Morales Cámera, Matías M.; Galindo Francisco, María Del Carmen; Basei, Miguel A.S.The formation of magmatic plumbing systems in the crust involves mass and heat transfer from deep to shallow levels. This process modifies the local geotherm and increases the thermal maturation of the crust, affecting the rheological state of the host rock and the composition of magma. Here, we report a petrological, geochemical, isotopic and geochronological integrated study of the Huaco (354 Ma) and Sanagasta (353 Ma, from a new U–Pb zircon age) units from the Carboniferous (Lower Mississippian) Huaco Intrusive Complex, NW Argentina. Similar values of ϵNdt and δ18O, of −3.2 ± 0.7 and +11.2‰ ± 0.3‰ (V-SMOW), respectively, for both units indicate that they shared the same source, as a result of mixing and later homogenization of a crustal component at the Late Devonian (378 to 366 Ma), with metasomatized mantle-derived melts. Slightly higher contents of TiO2, FeO, MgO, CaO and rare earth elements for the Sanagasta unit in comparison with the Huaco unit suggest an increase in the degree of partial melting, which may have been caused by a higher temperature at the lower crust. In addition, the previous structural model of the Huaco Intrusive Complex points to an increase in thermal maturation in the upper crust, which drives a change in the emplacement style from tabular subhorizontal (Huaco) to vertically elongated (Sanagasta) bodies. Therefore, the evolution of the intrusive complex may reflect a generalized thermal maturation of the complete magmatic column, at both upper and lower crustal levels.