Grenvillian massif-type anorthosites in the Sierras Pampeanas

Casquet, César; Pankhurst, R. J.; Rapela, Carlos W.; Galindo, Carmen; Dahlquist, Juán A.; Baldo, Edgardo G.; Saavedra, J.; Casado, José Manuel González; Fanning, Christopher

doi:10.1144/0016-764904-100

Cited by 46 publications

(34 citation statements)

References 22 publications

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“…A mantle signature is indicated by the low 87 Sr/ 86 Sr initial ratio (0.7045, Pankhurst and 199B), which is confirmed by a juvenile ENdt of +3.B for the meta-trondhjemite dated by U-Pb SHRIMP in this study (SPP414a,6). Generation of this TIG suite in an arc environment is consistent with the low abun dances of HFSE such as Nb and Ta, low Ga/AI ratio (1000 * Gaj AI == and low SrjY (3.7-4.0) ( Casquet et al (2004).…”

Section: The Mogote-corralito Ttg Suitesupporting

confidence: 63%

“…Identified samples in (a) and (b) are those with U-Pb SHRIMP ages determined in this study. The age and Zr content of the jotunite MAZ7 210 is from Casquet et al (2004). The field for the TTG rocks of Las Matras block is from Sato et al (2000), while the field of the Umango orthogneisses is from Varela et al (2003 ).…”

Section: Arc-related Cale-alkaline Orthogneissesmentioning

confidence: 99%

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The Western Sierras Pampeanas: Protracted Grenville-age history (1330–1030 Ma) of intra-oceanic arcs, subduction–accretion at continental-edge and AMCG intraplate magmatism

Rapela

Pankhurst

Casquet

et al. 2010

Journal of South American Earth Sciences

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Section: The Mogote-corralito Ttg Suitesupporting

confidence: 63%

Section: Arc-related Cale-alkaline Orthogneissesmentioning

confidence: 99%

The Western Sierras Pampeanas: Protracted Grenville-age history (1330–1030 Ma) of intra-oceanic arcs, subduction–accretion at continental-edge and AMCG intraplate magmatism

Rapela

Pankhurst

Casquet

et al. 2010

Journal of South American Earth Sciences

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“…1). In N Chile, new and published age data from Belén, Mejillones, and Sierra de Moreno (*525, 505, 470, and 430 Ma) indicate the same age structure as in the southern Puna and its eastern slope Wörner et al 2000;Lucassen and Becchio 2003;Büttner et al 2005) and in the Sierra de Maz-Sierra Umango area (Lucassen and Becchio 2003;Casquet et al 2004;Porcher et al 2004). Attempts to attribute a *1.2 Ga age from metamorphic overgrowth on inherited older zircon to metamorphic conditions of *780°C and 0.8 GPa in Sierra de Maz (Casquet et al 2006) remain ambiguous, because two high T metamorphic overprints (at near identical P-T conditions as those reported by Casquet et al 2006) occurred in the Cambrian and Late Ordovician-Silurian in Sierra de Maz.…”

Section: Metamorphism and Crystallization Agementioning

confidence: 75%

The Early Palaeozoic high-grade metamorphism at the active continental margin of West Gondwana in the Andes (NW Argentina/N Chile)

Lucassen

Becchio

Franz

2010

Int J Earth Sci (Geol Rundsch)

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The evolution of the Early Palaeozoic orogen of West Gondwana in the Cambrian to Ordovician basement of the Andes between *18°and 32°S is investigated for pressure and temperature conditions and age of metamorphism. It is characterized by mid-crust temperatures commonly above the wet granite solidus (*650°C). Widespread felsic migmatite and rare granulite formed at pressures of ca 0.5-0.7 GPa, locally 1.0 GPa. These rocks represent the deepest exhumed sections of the Early Palaeozoic crust. High pressure-low temperature rocks are absent. The crystallization ages, compiled from the literature in combination with new data, for near peak metamorphic conditions of these high-grade metamorphic rocks in NW Argentina and N Chile are *530-500 Ma and *470-420 Ma. Both age groups are spatially overlapping. Radiogenic isotope signatures (Sr, Nd, Pb) are used to characterize the Early Palaeozoic basement. The Pb and Sr isotope compositions of the Early Palaeozoic basement indicate mixing arrays between pre-Palaeozoic unradiogenic and radiogenic crust. Crustal residence ages (Sm-Nd T DM ) indicate a prominent event of crust formation around *2 Ga, which is known continent-wide. This material was recycled during Midproterozoic and Early Palaeozoic orogenies without prominent additions of new crust present in the isotope record, i.e. accretion of compositional exotic material is absent.

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“…1012 Ma (Keppie et al, 2003), are correlated with Grenvillian AMCG suite. Casquet et al (2005) have reported the discovery of massif-type anorthosites covering ca. 50 km 2 in the Andean basement of the Western Sierras Pampeanas of Argentina, including an occurrence of magnetite-apatite-rich rock (nelsonite).…”

Section: Spatial and Temporal Distributionmentioning

confidence: 99%

Fe–Ti–V–P ore deposits associated with Proterozoic massif-type anorthosites and related rocks

Charlier

Namur

Bolle

et al. 2015

Earth-Science Reviews

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a b s t r a c t a r t i c l e i n f oMagmatic rocks containing economic concentrations of iron, titanium, vanadium and phosphorous are commonly associated with massif-type anorthosites and related rocks. This rock association is part of the anorthositemangerite-charnockite-(rapakivi-)granite suites that are restricted to the Proterozoic. Understanding the geochemistry and emplacement mechanisms of ilmenite, magnetite and apatite ore deposits is crucial for exploration, efficient mining operations and ore processing. This review discusses the controlling factors on the grade of an ore, its mineralogy, and its major and trace element distribution. We present petrogenetic models of currently mined deposits (Lac Tio, Tellnes, Damiao) and discuss the characteristics of minor ore bodies from anorthosite provinces worldwide (Grenville, North China Craton, East European Craton, Rogaland, Laramie). Models of formation of anorthosite and related rocks are presented, as well as the nature of the possible parental magmas of the suite. A mineralogical classification of Fe-Ti ores is proposed: (1) Gabbro-noritic ilmenite ore ± apatite ± magnetite; (2) Ti-magnetite-dominated ore; (3) Nelsonite (Fe-Ti oxides + apatite); and (4) Rutile-ilmenite ore. The stability of ilmenite and magnetite is then critically reviewed and the influence of various factors, particularly oxygen fugacity and crystallization pressure, is examined. We discuss liquidus compositions of Fe-Ti oxides and the behavior of important trace elements such as Cr and V, both of which are sensitive to fO 2 variations. Postcumulus evolution of both oxides can occur due to re-equilibration with trapped liquid, re-equilibration with ferromagnesian silicates, exsolution, oxidation, reaction between ilmenite and magnetite, and metamorphic overprinting. These various processes are described and their effects on the oxide geochemistry are emphasized. Several potential ore-forming processes have been invoked and can explain the formation of huge concentration of ilmenite, ±magnetite, ±apatite. Fractional crystallization can be combined with crystal sorting and plagioclase buoyancy to produce relative enrichment of dense ore minerals. Silicate liquid immiscibility can segregate conjugate Si-rich and Fe-rich melts, the latter being enriched in Fe-Ti-P. Magma mixing can produce hybrid magmas located in a single-phase field of the phase diagram and precipitate a pure ilmenite cumulate. Alternative processes are also described, such as ejection of Fe-Ti-enriched residual melts by filter-pressing and compaction, solidstate remobilization of ilmenite in veins, and hydrothermal transport of Fe and Ti from the host anorthosite followed by concentration in veins and lenticular ore bodies. The magnetic properties of Fe-Ti ore deposits present contrasting signatures, depending on whether the natural remanent magnetization is dominated by hemo-ilmenite or multi-domain magnetite. Micro-and macro-scale deformation features of ore rocks are intimately correlated with magma emplacement, and...

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Grenvillian massif-type anorthosites in the Sierras Pampeanas

Cited by 46 publications

References 22 publications

The Western Sierras Pampeanas: Protracted Grenville-age history (1330–1030 Ma) of intra-oceanic arcs, subduction–accretion at continental-edge and AMCG intraplate magmatism

The Western Sierras Pampeanas: Protracted Grenville-age history (1330–1030 Ma) of intra-oceanic arcs, subduction–accretion at continental-edge and AMCG intraplate magmatism

The Early Palaeozoic high-grade metamorphism at the active continental margin of West Gondwana in the Andes (NW Argentina/N Chile)

Fe–Ti–V–P ore deposits associated with Proterozoic massif-type anorthosites and related rocks

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