Raúl Lira

Universidad Nacional de Córdoba

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Michael J. Dorais

Brigham Young University

Fernando Colombo

Consejo Nacional de Investigaciones Científicas y Técnicas

María José Espeche

Universidad Nacional de Córdoba

MÁ

Miguel Ángel Galliski

Centro Científico Tecnológico - Mendoza

Edward M. Ripley

Indiana University Bloomington

Alina B. Guereschi

Universidad Nacional de Córdoba

Marco Esteban Biglia

Universidad Nacional de Córdoba

R. J. Sureda

National University of Salta

Marco E. Biglia

Universidad Nacional de Córdoba

María F. Poklepovic

Dirección de Investigación y Desarrollo

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Consejo Nacional de Investigaciones Científicas y Técnicas

AgResearch

Universidad Nacional de Córdoba

Commonwealth Scientific and Industrial Research Organisation

Agriculture and Agri-Food Canada

University College Dublin

Agriculture and Food

Colombian Corporation for Agricultural Research - AGROSAVIA

Instituto de Investigaciones Agropecuarias

Massey University

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Ecandrewsite (ZnTiO3) in Amphibolites, Sierras de Córdoba, Argentina: Mineral Chemistry and Comparison with Different Worldwide Paragenetic Occurrences

The Canadian Mineralogist (2022)

María José Espeche Raúl Lira

ABSTRACT Ecandrewsite (ZnTiO3) and other ilmenite-group minerals have been found in amphibolites of the Sierras de Córdoba basement, Argentina, in an area where zinc is a relatively widespread element in the associated metasedimentary and metaigneous sequences. Ilmenite group minerals occur as anhedral to subhedral, tens to a hundred micrometer-sized relic inclusions in titanite. Electron microprobe analyses reveal compositions along a discontinuous solid-solution trend ranging from manganoan ferroan ecandrewsite toward ilmenite s.s., passing through intermediate members such as ferroan manganoan ecandrewsite, zincian manganoan ilmenite, and manganoan ilmenite. Considering that thermodynamic constraints do exist for the solubility of ZnTiO3 in ilmenite under mid- to high-grade regional metamorphic conditions, we believe that ecandrewsite and Zn-rich ilmenite compositions were attained by metasomatic fluid–mineral reactions during retrograde regional metamorphism, i.e., after the centripetal replacement of protolithic Zn-bearing ilmenite group species by titanite. The original composition of the ilmenite group species might have been Zn-poor ilmenite; however, the attainment of ecandrewsite compositions possibly needed an external supply of zinc provided by the fluid. The variations of the zinc contents were controlled by the substitution of Fe by Zn + Mn in the absence of any type of regular zonation. This is the first worldwide report of ecandrewsite in amphibolites, which has so far been described in quartz-rich metasediments, quartz-gahnite exhalites, kyanitic schists, nepheline syenites, metamorphosed volcanic hosted massive sulfide (VHMS) mineralizations, and albitites. The presence of ecandrewsite in amphibolite, as has been proved for zincian ilmenite and gahnite in other metasedimentary sequences elsewhere in the world, could become another pathfinder or indicator mineral for Zn-enriched portions of the crust.

Ilmenite

Titanite

Metasomatism

Paragenesis

10.3749/canmin.2100055

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Citations (4)

Erratum: Rumen microbial community composition varies with diet and host, but a core microbiome is found across a wide geographical range

Scientific Reports (2016)

Gemma Henderson Faith Cox Siva Ganesh Arjan Jonker Wayne Young

Ruminant livestock are important sources of human food and global greenhouse gas emissions. Feed degradation and methane formation by ruminants rely on metabolic interactions between rumen microbes and affect ruminant productivity. Rumen and camelid foregut microbial community composition was determined in 742 samples from 32 animal species and 35 countries, to estimate if this was influenced by diet, host species, or geography. Similar bacteria and archaea dominated in nearly all samples, while protozoal communities were more variable. The dominant bacteria are poorly characterised, but the methanogenic archaea are better known and highly conserved across the world. This universality and limited diversity could make it possible to mitigate methane emissions by developing strategies that target the few dominant methanogens. Differences in microbial community compositions were predominantly attributable to diet, with the host being less influential. There were few strong co-occurrence patterns between microbes, suggesting that major metabolic interactions are non-selective rather than specific.

10.1038/srep19175

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Citations (58)

Los diques comendíticos de Papachacra (Catamarca): magmatismo peralcalino en sierras Pampeanas orientales

Fernando Colombo Raúl Lira María Sol Oleary Colombo Celso Gaeta Tassinari

Fil: Colombo, Fernando. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Cordoba. Facultad de Ciencias Exactas Fisicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; Argentina

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Geochemical evolution of granites from the Achala batholith of the Sierras Pampeanas, Argentina

Geological Society of America Special Papers (1990)

Raúl Lira Alicia Kirschbaum

The Achala batholith is a post-orogenic intrusion of probable Silurian age exposed in the Sierra de Cordoba in the eastern Sierras Pampeanas of central Argentina (31°6′S to 32°2′S; 64°29′W to 65°7′W). The batholith was emplaced into late Precambrian amphibolite- and granulite-facies metamorphic rocks. Five comagmatic granitoid facies, all monzogranite in composition, have been recognized. Geochemical data suggest these granitoids formed by a magmatic differentiation process that began with porphyritic and fine-grained facies B, C, and D, and ended with leucogranite facies A. Biotite-apatite enclaves that are interpreted as cumulates and tonalitic nodules occur in facies B. Less abundant rock types...

Batholith

Porphyritic

Leucogranite

10.1130/spe241-p67

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Citations (48)

Chemical and textural relations of britholite- and apatite-group minerals from hydrothermal REE mineralization at the Rodeo de los Molles deposit, Central Argentina

American Mineralogist (2019)

Melanie Lorenz Uwe Altenberger Robert B. Trumbull Raúl Lira Mónica Lopez de Luchi

Abstract Britholite group minerals (REE,Ca)5[(Si,P)O4]3(OH,F) are widespread rare-earth minerals in alkaline rocks and their associated metasomatic zones, where they usually are minor accessory phases. An exception is the REE deposit Rodeo de los Molles, Central Argentina, where fluorbritholite-(Ce) (FBri) is the main carrier of REE and is closely intergrown with fluorapatite (FAp). These minerals reach an abundance of locally up to 75 modal% (FBri) and 20 modal% (FAp) in the vein mineralizations. The Rodeo de los Molles deposit is hosted by a fenitized monzogranite of the Middle Devonian Las Chacras-Potrerillos batholith. The REE mineralization consists of fluorbritholite-(Ce), britholite-(Ce), fluorapatite, allanite-(Ce), and REE fluorcarbonates, and is associated with hydrothermal fluorite, quartz, albite, zircon, and titanite. The REE assemblage takes two forms: irregular patchy shaped REE-rich composites and discrete cross-cutting veins. The irregular composites are more common, but here fluorbritholite-(Ce) is mostly replaced by REE carbonates. The vein mineralization has more abundant and better-preserved britholite phases. The majority of britholite grains at Rodeo de los Molles are hydrothermally altered, and alteration is strongly enhanced by metamictization, which is indicated by darkening of the mineral, loss of birefringence, porosity, and volume changes leading to polygonal cracks in and around altered grains. A detailed electron microprobe study of apatite-britholite minerals from Rodeo de los Molles revealed compositional variations in fluorapatite and fluorbritholite-(Ce) consistent with the coupled substitution of REE3+ + Si4+ = Ca2+ + P5+ and a compositional gap of ~4 apfu between the two phases, which we interpret as a miscibility gap. Micrometer-scale intergrowths of fluorapatite in fluorbritholite-(Ce) minerals and vice versa are chemically characterized here for the first time and interpreted as exsolution textures that formed during cooling below the proposed solvus.

Fluorapatite

Allanite

Titanite

Metasomatism

Nepheline syenite

10.2138/am-2019-6969

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Citations (13)

Calc-alkaline arc granitoid activity in the Sierra Norte-Ambargasta Ranges, central Argentina

Journal of South American Earth Sciences (1997)

Raúl Lira Hugo A. Millone Alicia Kirschbaum Rodolfo S. Moreno

Batholith

Diorite

Continental arc

10.1016/s0895-9811(97)00013-8

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Citations (81)

Genesis and New Mineral Chemistry Data of Carlosbarbosaite, a Potential U and Nb Ore Source from Miarolitic-, A-Type Granites and NYF Pegmatites of the La Chinchilla Pluton, Velasco Ranges, La Rioja, Argentina

The Canadian Journal of Mineralogy and Petrology (2023)

Raúl Lira Javier Garjón Marco E. Biglia Orquídea Morello Alina B. Guereschi

Abstract The La Chinchilla granite is a ∼3.75 km2 epizonal pluton of Lower Carboniferous age located in Sierra de Velasco, Sierras Pampeanas, Argentina. Equigranular micropegmatitic and porphyritic main granite types host abundant millimeter- to <2 m-sized miarolitic pegmatites and pockets of simple major mineralogy (±beryl). Both granite types host micrometer-sized accessory species [i.e., monazite-(Ce), several high field strength element oxide species, ilmenite, cassiterite, fluorapatite] and fluorite. A F-Na-rich fluid phase promoted strong albitization at late-miarolitic stages, along with crystallization of extremely F-rich polylithionite and fluorite, and the formation of replacing pyrochlore group species associated with a second generation of cassiterite. The increase of the Ta# from hydroxycalciopyrochlore to hydroxycalciomicrolite and from micromiarolitic cassiterite (cassiterite 1) to hydrothermal cassiterite (cassiterite 2) supports Nb-Ta fractionation at hydrothermal temperatures. Carlosbarbosaite [(UO2)2Nb2O6(OH)2·2H2O] occurs as a pseudomorphic or short-range transported phase. Low-T, hydrothermal carlosbarbosaite formed after the replacement of columbite-(Fe), U-free Nb-bearing ilmenite, and likely after U-bearing pyrochlore supergroup species and a columbite group mineral, plausibly due to interaction with a hydrothermal, U6+(±Nb±Ta)-enriched fluid, in some cases a SiO2-bearing fluid. This fluid likely represents a lower T, less alkaline, and more oxidizing fluid that evolved from the higher T F-Na-rich fluids active during the late-miarolitic hydrothermal stage. Low-T, hydrothermal carlosbarbosaite has the ideal U-,Nb-rich endmember composition, though it is significantly richer in Ca and poorer in total Nb+Ta but with higher Nb# than that from the type locality. Supergene fluids deposited the transported type, which attained economic concentrations in a fault zone where restricted, likely alkaline oxidizing conditions could have favored Nb mobility.

Cassiterite

Pegmatite

Fluorite

Columbite

Wolframite

Ilmenite

Greisen

Peralkaline rock

10.3749/2300008

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Citations (1)

Mineral Chemistry Evolution of Magmatic Li-Bearing Micas and Li-Loss During Postmagmatic Phengitization in an A-Type Granite: A Mass Balance Approach at La Chinchilla Pluton, Sierra De Velasco, La Rioja, Argentina

Raúl Lira Marco Esteban Biglia Francisco José Parra Alina B. Guereschi

La Chinchilla granite (~ 3.75 km2) is an epizonal pluton intruded during the Lower Carboniferous in Sierra de Velasco, Sierras Pampeanas, northwestern Argentina. Three facies have been distinguished in the pluton, being equigranular micropegmatitic and porphyritic the main two granite types, which host abundant millimeter to < 2 m sized miarolitic pegmatites and pockets of simple granitic mineralogy (± beryl). Micrometer-sized accessory magmatic species are monazite-(Ce), several high field strength element oxide species, ilmenite, cassiterite (1), fluorapatite and fluorite. Primary Li-bearing micas with variable degrees of late to postmagmatic replacement occur in abundances that range from ~ 2 to 7 %. Textural evidence and mineral chemistry allow to distinguish between early granitic and late bladed miarolitic micas. The mineral chemistry composition of the primary micas shows members of the siderophyllite-polylithionite series. Replacing phases are Li-muscovite (phengite). Electron probe microanalyses of primary micas of both main granite types suggest that these are compositionally distinct intrusives, which probably differentiated independently, though further research is needed for confirmation. According to mica chemistry, the porphyritic unit is more enriched in Li than the equigranular granite; in addition, the equigranular micropegmatitic unit was more intensely affected by fluid-rock interaction processes and is significantly richer in U and Be. An F-Na rich fluid phase developed strong albitization during late miarolitic stages, along with crystallization of extremely F-rich polylithionite, fluorite, pyrochlore group species and cassiterite (2). In terms of mass balance, the phengite replacement process is characterized by the conservation of Si, Al and K, a slight gain of Na and Ba, and a systematic loss of orderly decreasing Fe > F > Li > Mn > Ti > Mg > Zn. Likely, the muscovite-forming fluid was the same simultaneously involved in the hydrothermal alteration of high field strength element accessory species, largely included in primary micas, which generated secondary U- and Nb-rich species such as carlosbarbosaite. The hydrothermal late miarolitic to postmagmatic fluid-mineral replacement of primary magmatic micas released significant amounts of Li, of which about 59 wt. % of the Li2O content of protholithic micas (i.e., 1 to 2.4 wt. % Li2O) was inherited by replacing Li-bearing muscovite and the remaining 41 wt. % was given off the system. It is calculated that ~ 1.5 km3 of La Chinchilla body would have expelled ~ 0.33 million tons of Li2O, just considering than only 30 % of primary siderophyllite-polylithionite was muscovitized. Such a Li2O tonnage was likely transferred to the paleohydrological cycle during Carboniferous times, when the La Chinchilla stock was still undergoing its cooling down path. Currently, evidence of the final fate of mobilized Li is lacking.

10.2139/ssrn.4705796

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Hydrothermal alteration and REE-Th mineralization at the Rodeo de Los Molles deposit, Las Chacras batholith, central Argentina

Contributions to Mineralogy and Petrology (1992)

Raúl Lira Edward M. Ripley

Microcline

Batholith

Porphyritic

Allanite

10.1007/bf00310751

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