Papers by Jorge A . Sfragulla
La actividad minero-metalúrgica en los distritos mineros El Guaico y La Argentina, en el noroeste... more La actividad minero-metalúrgica en los distritos mineros El Guaico y La Argentina, en el noroeste de la provincia de Córdoba, comenzó a principios del siglo XIX; sin embargo, los antecedentes de la minería en la provincia se remontan a finales del siglo XVI. En la actualidad sobreviven vestigios de lo que otrora fue un foco de beneficio socio-económico para la región, como establecimientos abandonados, hornos de fundición en ruinas y voluminosas escombreras enmascaradas por la vegetación. En 2018 se halló material digno de estudio en escombreras contiguas a las ruinas del horno de fundición de mina La Argentina. Estudios por difracción de rayos X y espectroscopía de energía dispersiva de rayos X permitieron su identificación como litargirio (PbO) con inclusiones de plomo argentífero (Pb ± Ag). Si bien la muestra presentaba indicios texturales de material artificial, el estudio fue motivado debido a que ambos compuestos químicos pueden también formarse en la naturaleza conformado esp...
La Sierra Norte de Cordoba (Sierras Pampeanas de Cordoba-Santiago del Estero), esta constituida p... more La Sierra Norte de Cordoba (Sierras Pampeanas de Cordoba-Santiago del Estero), esta constituida por un complejo metamorfico soportado por intrusiones granitoides, denominadas en conjunto Batolito de la Sierra Norte. Este conjunto esta cubierto parcialmente por sedimentos Mesozoicos y Cenozoicos. La Sierra Norte de Cordoba presenta el clasico esquema de bloques basculados limitados por fallas con rumbo NNE y un sistema subordinado transversal, expresadas por fajas de deformacion donde se identifican cataclasitas y milonitas. En el interior de los bloques se reconocen tambien deformaciones ductiles a modo de fajas en las que afloran extensamente rocas miloniticas. Aspectos criticos de la genesis, cinematica y significado de las fajas de deformacion permanecen desconocidos. A ellas se asocian mineralizaciones de Mn, Fe y Ba y sulfuros de Cl y Mo desconociendose a que regimen deformacional general estan ligados estos fenomenos mineralizantes. Los objetivos de este proyecto son: delimitacion y analisis cinematico de las fajas de deformacion ductil y fragil, determinacion de su distribucion, tipos y zonacion de las rocas de falla, correlacion hacia las Sierras de Sumampa y Ambargasta y hacia las Sierras Chica y Grande y relacion espacial que guardan las mineralizaciones con dichas fajas. La meta final es dilucidar y diferenciar los efectos que han tenido las distintas orogenias sobre este sector ubicado hoy en el antepais andino.
Revista de la Asociación Geológica Argentina, Jun 1, 2003
RESUMEN. La Faja de Deformación Los Túneles (FDLT) se dispone norte-sur, con 75 kilómetros de lar... more RESUMEN. La Faja de Deformación Los Túneles (FDLT) se dispone norte-sur, con 75 kilómetros de largo y 1-5 kilómetros de ancho. Limita al oeste con la falla de Pocho y la zona de falla La Mermela, al este con las rocas del Macizo San Carlos y el gneis Las Palmas, al sur con la faja de deformación Pachango y hacia el norte se extiende paralelamente a las Sierras de Pocho y Guasapampa. Las rocas van desde milonitas al norte, pasando por protomilonitas y luego estromatitas poco deformadas al sur. Concomitantemente con la deformación, habrían ingresado fluidos ricos en H + , en un sistema abierto, los que habrían producido sillimanita y luego abundante muscovita a partir de plagioclasa y biotita. Las condiciones físicas de deformación varían desde la facies de anfibolitas superiores hasta la facies de esquistos verdes. La foliación reconocida es compuesta y está integrada por una foliación predominante C, orientada N 334°/42°E, la que es cortada por bandas de cizalla extensional de bajo ángulo C'. Sobre el plano C hay una lineación de estiramiento de Ms ± Sil ± Qtz, orientada N 50°/43° y con 80°N de cabeceo. La FDLT se interpreta como una faja de deformación dúctil, con movimiento inverso del techo hacia N 230°, que superpone rocas en zona de Sil + Kfs sobre rocas en zona de Sil + Ms. Se reconocen dos inversiones metamórficas de distintas edades y producidas en distintos regímenes de deformación. La FDLT es posmetamórfica con respecto a las metamorfitas regionales y preplutónica con respecto al plutón de Charquina. El período de actividad tectónica oscila entre el Cámbrico superior y el Ordovícico inferior (509-474 Ma), y coincidiría con el acercamiento del terrane Cuyania al margen gondwánico y con las etapas contraccionales póstumas de la colisión del terrane Pampia con el margen occidental de Gondwana.
IAEG/AEG Annual Meeting Proceedings, San Francisco, California, 2018—Volume 6, Aug 26, 2018
In this work a multimethodological approach is taken, complementing field studies with petrograph... more In this work a multimethodological approach is taken, complementing field studies with petrographicmineralogical, compositional and morphological analyses of anthophyllite in the "Coco Solo" mine from the province of Cordoba (Argentina). Fibrous minerals were studied by stereomicroscopy, polarizing light microscopy and SEM. The fibres have positive elongation, straight extinction and slight pleochroism. Thermogravimetric and differential scanning calorimetry (TG/DSC) data allowed the determination of the structural water content and temperature stability. X-ray diffraction was used for the characterization of the mineral fibres before and after heating at 1000 °C to identify the products of thermal decomposition. The crystal structure determined corre sponds to anthophyllite. Finally, morphological analyses on acicular and fibrous phases were conducted. Particles up to ~ 1 pm were analysed by optical microscopy, while particles up to ~0.1 pm were examined by SEM. When complemented, these two techniques are useful to char acterize the morphologies of the particles.
Environmental Earth Sciences, 2013
Vermiculites with impurities of amphibole, a dry fine residue and calcined materials from three d... more Vermiculites with impurities of amphibole, a dry fine residue and calcined materials from three deposits in the province of Córdoba, Argentina, were studied. From a commercial perspective, amphiboles are considered as ''asbestos'', a group of silicate minerals with strong and flexible fibres that are heat resistant and chemically inert, and thus well suited for heat insulation. These fibrous particles have provoked controversies about the toxicity impact on human health and the development of diseases such as mesothelioma, asbestosis or lung cancer. Their commercialization and exploitation are currently prohibited. The sampled minerals were identified with a petrographic microscope, chemical analyses, SEM and XRD. It was concluded that amphibole minerals are present in all the deposits studied and in every phase of plant production, but not all of them have asbestiform characteristics.
Applied Vegetation Science, Oct 1, 2022
Applied Vegetation Science
Geochemistry, 2016
Abstract The quartz veins and pegmatites of the Sierra de Comechingones (Sierras de Cordoba, NE A... more Abstract The quartz veins and pegmatites of the Sierra de Comechingones (Sierras de Cordoba, NE Argentina) belong to the Comechingones Pegmatite field (CPF). For the quartz veins and the zoned pegmatites related parental granites are missing. The country rock of the quartz veins are mylonitic augengneisses in granulite to upper amphibolite facies. Field relations, microscopy, cathodoluminescence, radiometric age data, fluid inclusion, chemical and isotopic composition and literature define the quartz veins as synorogenic formed during the high-temperature phase of the Famatinian (480–460 Ma) event. During the Famatinian up to the Achalian (382–366 Ma) event the synorogenic quartz veins were subjected to high temperature ductile deformation documented by folding, boudinage and finally brittle shearing. K-Ar ages of illite from the shear zones of about 166 Ma document the final cooling of the Sierras Pampeanas below 100 °C. The long lasting thermal and deformational history of the study area is reflected by very different populations of fluid inclusions in vein quartz with remarkably high contents of thermogenic hydrocarbons in the early-formed fluid inclusions. LA–ICP–MS analysis reveals very low lattice-bound trace element contents, i.e. high purity quartz.
Servicio Geológico Minero Argentino. Instituto de Geología y Recursos Minerales eBooks, 2005
Boletín, 2000
UNIRED: PROYECTO PADRINAZGO PUBLICACIONES PERIODICAS ARGENTINAS. Título (A): Hoja geológica 3166 ... more UNIRED: PROYECTO PADRINAZGO PUBLICACIONES PERIODICAS ARGENTINAS. Título (A): Hoja geológica 3166 - IV: Villa Dolores. Autor Personal (A): Bonulami, Aldo; Martino, Roberto; Baldo, Edgardo; Zarco, Juan; Sfragulla ...
ASAGAI, Jul 1, 2009
Re su men En este trabajo se reconoce la reacción álcali-agregado en rocas metamórficas de Córdob... more Re su men En este trabajo se reconoce la reacción álcali-agregado en rocas metamórficas de Córdoba, que se utilizan como agregados para hormigón en obras civiles. A pesar de no poseer minerales considerados normalmente deletéreos, algunas de estas rocas se mostraron reactivas o potencialmente reactivas en los ensayos realizados. Se atribuye la reactividad a la presencia de cuarzo que ha sufrido procesos de deformación con reducción de tamaño del grano y recristalización, ya sea por esfuerzos o blastesis.
Flora, 2021
This paper describes the direct measurements of the structure of iron-bearing liquids using a com... more This paper describes the direct measurements of the structure of iron-bearing liquids using a combination of containerless techniques and insitu high energy x-ray diffraction. These capabilities provide data that is important to help model and optimize processes such as smelting, steel making, and controlling slag chemistry. A successful programme of liquid studies has been undertaken and the Advanced Photon Source using these combined techniques which include the provision of gas mixing and the control of pO 2 and the changing influence of mixed valance elements. It is possible to combine rapid image acquisition with quenching of liquids to obtain the full diffraction patterns of deeply supercooled liquids and the metastable supercooled liquid regime, where the liquid structures and viscosity change most dramatically, can also be explored.
Flora de los afloramientos de mármoles y serpentinitas de las sierras de Córdoba (Argentina). Kur... more Flora de los afloramientos de mármoles y serpentinitas de las sierras de Córdoba (Argentina). Kurtziana 36 (2): 11-45. Los afloramientos rocosos constituyen hábitats importantes desde el punto de vista de conservación de la biodiversidad. En este trabajo se provee de un catálogo de las especies de plantas vasculares que crecen en los afloramientos cálcicos y dolomíticos (mármoles) y serpentinitas de la Sierra de Córdoba, se describe la variación composicional de su flora y se explora su relación litológico-geoquímica sobre la distribución de los grupos florísticos detectados. Treinta y uno (31) afloramientos fueron relevados en un área que se extendió en unos 280 km de latitud y 120 km de longitud (30° 42' a 33° 5' Lat. Sur y 64° 20' a 65° 20' Long. Oeste) y desde los 500 m.s.m hasta los 2000 m.s.m. El área promedio relevada en cada afloramiento fue de aproximadamente 2725 m 2 en donde se realizó el inventario de todas las especies de plantas vasculares presentes, su colección y el muestreo litológico para la evaluación posterior de la geoquímica de las rocas. Se registraron 404 especies distribuidas en 67 familias y 255 géneros. Se mencionan 6 citas nuevas para la provincia. La endemoflora de los 31 afloramientos comprende 88 especies. La riqueza promedio de especies de los afloramientos fue de 68 y la diversidad promedio de H = 4,14. El total de especies medicinales relevadas en los afloramientos fue de 212. Las hemicriptófitas (52%), caméfitas (17 %), fanerófitas (16%) y geófitas (9 %) fueron las formas de vida predominantes. La composición florística a nivel regional, variable a lo largo del gradiente geográfico-y climático-, se sobre impuso a la variación local ambiental (geoquímica, altitud) entre los afloramientos. Se identificó un número mínimo de sitios a conservar que incluyen la máxima biodiversidad a través de los datos disponibles de riqueza, diversidad, número de especies endémicas, y rareza.
Vermiculites with impurities of amphibole, a dry fine residue and calcined materials from three d... more Vermiculites with impurities of amphibole, a dry fine residue and calcined materials from three deposits in the province of Córdoba, Argentina, were studied. From a commercial perspective, amphiboles are considered as ''asbestos'', a group of silicate minerals with strong and flexible fibres that are heat resistant and chemically inert, and thus well suited for heat insulation. These fibrous particles have provoked controversies about the toxicity impact on human health and the development of diseases such as mesothelioma, asbestosis or lung cancer. Their commercialization and exploitation are currently prohibited. The sampled minerals were identified with a petrographic microscope, chemical analyses, SEM and XRD. It was concluded that amphibole minerals are present in all the deposits studied and in every phase of plant production, but not all of them have asbestiform characteristics.
Numerosas canteras de la provincia de Córdoba han sido abiertas y explotadas por rocas serpenti- ... more Numerosas canteras de la provincia de Córdoba han sido abiertas y explotadas por rocas serpenti- níticas, relacionadas con minera- lizaciones de talco y vermiculita, a las que se asocian silicatos asbesti- formes. Con el objeto de identificar estos minerales, considerados potencialmente nocivos para la salud, se realizaron estudios petrográficos macro y microscópicos, mineralógicos, por difractometría de rayos X, y morfológicos con microscopía electrónica de barrido (MEB). Se identificaron crisotilo y anfíboles (tremolita-actinolita y antofilita). El crisotilo se observó en vetillas cross y slip fiber , presenta un desarrollo cristalino variable, es incoloro, tiene extinción recta y baja birre- fringencia. Con MEB se observaron fibras muy extensas, poco densas y flexibles. El proceso de separación manual, permitió obtener fibras individuales de pocos micrones de largo, cón una relación largo/ancho superior a 100. La tremolita-actinolita presenta hábito prismático, es muy frágil, con fractura según divaje, extinción oblicua, birrefringencia alta y marcado pleocroismo. La antofilita tiene hábito fibroso y asbesti- forme, fractura astillosa, gran desarrollo cristalino, extinción recta, birrefringencia moderada y está débilmente coloreada. Se presenta asociada con talco, dorita, vermiculita, flogopita, cromita y dolomita. La presencia de estos minerales asbestíformes es un alerta para intensificar los controles ambientales relacionados a la actividad minera actual. Su degradación es inexorable y alcanzado el tamaño óptimo, se podrían incorporar al material particulado de la atmósfera
Lightweight concrete has a lower unit weight than conventional concrete and a high thermal insula... more Lightweight concrete has a lower unit weight than conventional concrete and a high thermal insulation capacity. It is manufactured with either natural or artificial lightweight aggregates. Vermiculite, one of the natural lightweight aggregates used, is a micaceous material that when heated increases its original volume due to an exfoliation process, so its incorporation in concrete or mortar imparts very low density. These natural materials usually contain impurities such as asbestiform minerals that can be released during the expansion process, causing a harmful environmental effect. Commercial asbestos-containing materials are currently banned due to the asbestos-related lung diseases they cause. In the province of Córdoba, Argentina, there are vermiculite mines where impurities such as asbestos group minerals have been identified. Studies using stereomicroscope, petrographic microscope, XRD, SEM, DTA and chemical analyses were conducted to characterize the different types of asbestos present and determine their particle size to assess whether they could be harmful to human health. Mica group minerals, abundant quartz and amphiboles were identified. The latter occur as isolated green crystals and their average length is 900 µm. Tremolite was determined by XRD. The aim of the present work is to reveal the presence of these minerals and warn about their use and disposal at the end of the useful service life of the work.
La Judita mine is located at 70 Km NE of Uspallata, in the province of Mendoza, cióse to San Juan... more La Judita mine is located at 70 Km NE of Uspallata, in the province of Mendoza, cióse to San Juan limit. The outerops are irregular bodies elongated N-S, of small dimensions (with a length not exceeding 500 meters), emplaced on the western flank of the Precordillera. The main work is a quarry from which 500 tons m3 of material was extracted, constituted by tale with minor amount of chlorite, tremolite, calcite and iron oxides and hidroxides. Steatized sector, serpentini- zed altered zone and the chloritic schist (country rock of intrusive) were analyzed. Two polymorphs of serpentine were identified: antigorite (the main mineral developed during the serpentinization of the ultramafic rock) and chry- sotile in veins with irregular distribution. In the intensely altered zone, it was observed that tale is cióse related with chlorite, calcite and iron oxides. In the tale ore asbestiform morphologies were not distinguished, although in the serpentinitic bodies, cióse to the mine, chrysotile veins were recognize
La mina La Isla se localiza a 2,5 Km al sur de la localidad de José de la Quintana, en el departa... more La mina La Isla se localiza a 2,5 Km al sur de la localidad de José de la Quintana, en el departamento Santa María de la provincia de Córdoba (Argentina). Sus coordenadas son 31o49’30.6”S y 64o24’53”O (Figura 1a). La región presenta afloramientos del Complejo Metamórfico La Falda, compuesto por gneises biotíticosmuscovíticos bandeados (79 %) con intercalaciones de ortogneises leucotonalíticos (9 %), mármoles dolomíticos (8 %), anfibolitas y rocas calcosilicáticas (3 %) (Lucero Michaut et al. 2000). Este basamento aparece intruído por diques basálticos de edad cretácica (> 1%) similares a los descriptos por Gordillo y Lencinas (1969). Los antecedentes sobre este yacimiento son escasos, sólo pueden citarse los trabajos de Viltes (2011) que describe la geología del depósito y el de Lescano et al. (2012) sobre la mina Soledad, perteneciente al mismo distrito minero. Los trabajos mineros realizados, consistentes en destapes y canteras a cielo abierto, han permitido observar cuerpos ul...
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Papers by Jorge A . Sfragulla
chapter aims to summarize historical and up-to-date knowledge on the geology, mineralogy, geochemistry and
geochronology of Devonian-Carboniferous magmatic bodies exposed north of Cerro Champaquí in Córdoba Province,
including the vast Achala batholith and other five small satellite plutons located West and North of the main intrusion.
The Achala batholith (ca. 2500 km2) is discordantly intruded into medium to high grade metasedimentary country
rocks of dominantly Cambrian to Neoproterozoic age of the Pampean orogenic cycle. It is composed of several magmatic
suites and numerous facies; two-mica monzogranites are by far the most largely exposed lithologies whereas tonalite
and granodiorite outcropos are areally more restricted. Muscovite (± almandine-rich garnet) leucomonzogranite is the
most evolved rock that occurs as marginal plutons or facies, or as late aplitic dikes. The most mafic representatives are
small bodies of quartz-diorite and sienodiorite that occur in a reduced number of outcrops. The magmatic evolutive
cycle ends with intragranitic differentiated Be-P-F-Nb-Ta-U-Li mineralized pegmatites of the mixed family and apliticpegmatitic
dikes of simple mineralogy. Far from having worked out all disputes about the complex history of the Achala
batholith, at present there is general conformity to accept its A-type nature. In order to highlight its higher aluminosity
degree compared to true alkaline granites, it has been recently defined as an “aluminous A-type granite”. Moderate to
high ASI values are a primary attribute of the melt, but perluminosity has been acquired through deuteric-hydrothermal
leaching of alkalies. The fluorine enrichment of the Achala granites is an outstanding geochemical feature distinguished
from melt generation to fluorine transfer to the pegmatite, metasomatic and low temperature hydrothermal stages; this
geochemical peculiarity makes it quite distinctive from orogenic Pampean and Famatinian granites. The Achala granites
are alkali-calcic to calc-alkaline and of high–K chemistry; their SiO2 content ranges between ~60 and 76 wt. % (most
within the range 67–74 wt. %), they are poor in Ca, Mg and Ti, and relatively enriched in incompatible trace elements
and Nb, with low K/Rb and very highy Rb/Sr ratios; all geochemical data is indicative of strong differentiation and fractional
crystallization within each granite suite, which shows a monotonous trend of decreasing Ti, Zr, Fe, Mg, Ca, Ba, Sr,
REE, Th and U, and increasing Si, Rb and Na + K with fractionation. Large Rb versus little K2O variation suggests pegmatite-
hydrothermal overprinting on granitic compositions. U/Pb zircón geochronological data for the most important
granite type (i.e., the coarse grained to porphyritic two-mica monzogranite), yielded an Upper Devonian age within a
narrow range between 362 and 383 Ma (379 ± 4, 370 ± 8 and 368 ± 2 Ma). Older reported ages of 403 and 390 Ma have
been interpreted as the initial activity of the Achala magmatism, to which some lode type Au and polimetallic mineralization
hosted in metasedimentary Cambrian country rocks, are likely related. Rb/Sr and K/Ar data obtained from whole
rock and micas, respectively, have yielded Carboniferous ages in granitic and pegmatitic muscovites. Regarding the nature
of the source of the batholith it is generally acknowledged the predominance of a metasedimentary protolith but from
different perspectives, one that holds solely crustal recycling without intervention of juvenile inputs, and others that
involve the participation of asthenospheric magma or, in its absence, fenitization-like metasomatism over crustal rocks,
to better explain the A-type granite signal. The geotectonic setting of the Achala batholith is as well subject of discussion,
howsoever it is commonly accepted that emplacement occured in a within-plate-, extensional regime after cease of Ordovician
regional deformation. Five smaller-sized plutons (4 to 80 km2), named from South to North: Loma de la
Población, La Yeya Sur, San José, Serrezuela Oriental and Occidental, and Capilla del Monte, are emplaced West and
North of the Achala batholith. All these granite bodies are considered to be contemporaneous to the main Achala intrusion,
because they share common features like the following: 1- They were not affected by Ordovician mylonitization,
2- Their peraluminous, fluorine-rich mineralogical and geochemical signature which is distinctive over Pampean and
Ordovician granitoids, 3- Their pegmatitic fractionates and hydrothermal-related processes distinguished for being
volatile-rich (F and B), with Be-Nb-Ta-P-U, and Au, Pb-Ag-Zn and W-Bi associated mineralization, and, 4- Some of
them, like La Yeya Sur and Capilla del Monte, are directly related by their Devonian age. The belonging of the Serrezuela
bodies to the Achala cycle should better be reconsidered because, besides their Carboniferous age, other strong similarities
relate them to some tourmaline-rich intrusives of the Sierras de Velasco and Ancasti in La Rioja and Catamarca provinces,
in which particular case they could be counted among a group probably unrelated to the Achala event.
in four different economic pegmatitic fields. In three of them the pegmatites are roughly aligned in north-south trending
belts known from east to west as Alta Gracia, Comechingones and Altautina pegmatite fields. The fourth, named Punilla,
has pegmatites included in, or near the postorogenic Achala batholith which is emplaced telescoping the previous PT
conditions in which the Pampean basement evolved. The Alta Gracia pegmatitic field contains Muscovite class pegmatites
developed in a thick, mostly psamopelitic, accrecionary prism possibly during a second stage of migmatization during
the Pampean orogeny and approximately emplaced at 600° C and 6-7 kbar. The Comechingones pegmatitic field has
pegmatites of the Muscovite-Rare Element Class and LCT (Li-Cs-Ta) petrogenetic family, with industrial minerals and
scarce U- Ta- Be-mineralization. The pegmatites are sincinematic with the Guacha Corral shear zone and they were fractionated
from parental leucogranites generated possibly by partial melting of Pampean protoliths by shear heating during
the Famatinian orogeny. The Altautina pegmatitic field encompasses pegmatites of Muscovite-Rare Element class in the
north to Li-bearing Rare Element pegmatites in the south. This LCT pegmatite field possibly develops by partial melting
of pelitic rocks from an accrecionary wedge at a high-T low-P Abukuma-type metamorphic episode during the latest
stages of the Pampean orogeny. The Punilla pegmatitc field has preferently intragranitic NYF pegmatites of Beryl-
Columbite-Phosphate subtype fractionated from the A-type Upper Devonian-Lower Carboniferous Achala granitic
batholith. These pegmatites have a very diversified accesory mineralogy of secondary origin that yield three new mineral
phosphates. The magmatic stage of crystallization of these pegmatites is approximately in the range 580–530° C and 3-
1,7 kbar.