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
4 results
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Item The Sierra Norte-Ambargasta batholith: Late Ediacarane-Early Cambrian magmatism associated with Pampean transpressional tectonics(Journal of South American earth sciences, 2013) Iannizzotto, Noelia F.; Rapela, Carlos W.; Baldo, Edgardo G.; Galindo Francisco, María Del Carmen; Fanning, C.M.; Pankhurst, R.J.The Sierra Norte-Ambargasta batholith is one of the largest plutonic expressions of the Pampean orogeny in western Argentina. A thorough petrographic, geochemical, isotopic (Sr and Nd) and geochronological (UePb SHRIMP) study is reported. The batholith comprises granitoid rocks that may be subdivided into those affected by Pampean D2 dextral shearing and mylonization and those emplaced after deformation had ceased; representative samples gave UePb zircon ages of 537 ±4 Ma and 530 ±4 Ma respectively. The earlier, dominant, groupwere derived largely frommetaluminous calc-alkaline subduction-related magmas, whereas the late granites are peraluminous. However, all have relatively high initial 87Sr/86Sr ratios (0.706 to at least 0.710, strongly negative εNdt values (-1.7 to -5.9) and, in some cases inherited 600 Ma and 970 Ma zircon, similar to the isotopic and zircon provenance seen in the metamorphic host rocks. A high degree of contamination of the magmas, possibly anatexis in the case of the post-mylonite granite, is related to emplacement during the latestage transpressional docking of the Pampean terrane against the Rio de la Plata craton. The absence of detrital zircon derived from the craton in either the Pampean metasedimentary host rocks or the batholith supports this collisional model for the Pampean orogen.Item Sr, C and O isotope composition of marbles from the Sierra de Ancasti, Eastern Sierras Pampeanas, Argentina: age and constraints for the Neoproterozoic–Lower Paleozoic evolution of the proto-Gondwana margin(Geologica acta, 2011) Murra, Juan Alberto; Baldo, Edgardo G.; Galindo Francisco, María Del Carmen; Casquet Martín, César; Pankhurst, R.J.; Rapela, Carlos W.; Dahlquist, Juan A.The Sierra Brava Complex on the eastern flank of the Sierra de Ancasti consists of marbles, metabasites, calc-silicate rocks, psammo-pelitic schists and gneisses. In the central part of this sierra a thick succession of banded schists (Ancasti Formation) crops out. Regional metamorphism of these rocks is attributed to the Famatinian orogeny (Ordovician), metamorphic grade increasing westwards and southwards and culminating in a migmatite complex on the western side of the Sierra. The meta-carbonate rocks are subdivided into a northeastern group (low-grade calcite marbles), and a southeastern group (high-grade calcite and calcite-dolomite marbles). Twenty-three marble samples were analysed for Sr isotope composition and Rb, Mn, Mg and Ca contents, and six for C and O isotope composition. An Ediacaran depositional age of 570 –590Ma is inferred by reference to the trend of 87Sr/86Sr in Neoproterozoic seawater. Thus the metacarbonates are probably slightly older than the Ancasti Formation (equivalent to the Puncoviscana Formation of northern Argentina), which has a maximum sedimentation age of ca. 570Ma. Ediacaran depositional ages have also been reported for metacarbonates elsewhere in Argentina, Uruguay and Brazil. We propose that the Sierra de Ancasti carbonates on one hand, and those in the Western Sierras Pampeanas (Difunta Correa Sequence) and -tentativelythe Corumbá Group of Brazil on the other, represent platforms on opposite margins of the extinct Clymene Ocean, whereas Neoproterozoic carbonate successions such as the Loma Negra Formation (Tandilia, southern Argentina) and the Arroyo del Soldado Group (Uruguay) were deposited on the eastern side (present coordinates) of the Río de la Plata craton, which at the time occupied a position farther to the north.Item Age, Sr and Nd-Isotope Systematics, and Origin of Two Fluorite Lodes, Sierras Pampeanas, Argentina(International geology review, 1997) Galindo Francisco, María Del Carmen; Pankhurst, R.J.; Casquet Martín, César; Coniglio, Jorge; Baldo, Edgardo G.; Rapela, Carlos W.; Saavedra, JulioFluorite mineralization at the La Nueva and Bubu mines yields Sm-Nd ages of 131 ± 22 and 117 ± 26 Ma, respectively. Thus, the mineralization most probably is related to a late Gondwanian (Lower Cretaceous) extensional and magmatic event that affected the Sierras Pampeanas basement during the opening of the Atlantic Ocean. Hydrothermal fluids involved in the formation of the fluorite probably were of meteoric origin, their isotopic composition (Sr and Nd) resulting largely from the incongruent dissolution of feldspars in the host porphyritic granites.Item Grenvillian massif-type anorthosites in the Sierras Pampeanas(Journal of the Geological Society, 2004) Casquet Martín, César; Pankhurst, R.J.; Rapela, Carlos W.; Galindo Francisco, María Del Carmen; Dahlquist, Juan A.; Baldo, Edgardo G.; Saavedra, Julio; González Casado, José Manuel; Fanning, C.M.We report the discovery of massif-type anorthosites in the Andean basement of the Western Sierras Pampeanas of Argentina. U–Pb zircon dating (by sensitive high-resolution ion microprobe) of a cogenetic gabbronorite dyke yields ages of 1070 ± 41 Ma for igneous emplacement and 431 ± 40 Ma for metamorphism. These anorthosites are petrologically and geochemically comparable with those of the Grenville province of Laurentia. Palaeogeographical reconstructions of Rodinia at 1.0–1.1 Ga suggest that the Sierras Pampeanas anorthosites were part of a large anorthosite province in the late Mesoproterozoic.