|
|
|
|
|
NUEVA LOCALIDAD CON COLEMANITA
EN LA PUNA ARGENTINA (MINA NARCISO, DEPARTAMENTO DE SUSQUES, JUJUY) ALONSO, Ricardo N.*, RUIZ,
Teresita del V.** y QUIROGA, Alicia G.** * CONICET – UNSa, Buenos Aires
177, 4400-Salta. E-mail: rnalonso@sinectis.com.ar ** UNSa, FCN, Buenos Aires
177, 4400-Salta. E-mail: ruiz@unsa.edu.ar y gquiroga@unsa.edu.ar ABSTRACT:
A
NEW COLEMANITE DEPOSIT IN THE PUNA REGION (NARCISO MINE, SUSQUES DEPARTMENT,
JUJUY PROVINCE). A new discovery
of colemanite (Ca2B6O11·5H2O)
in the Puna region, Key words:
Colemanite, Borate deposits, Neogene, Puna, Central Andes
|
|
ESTUDIO FISICOQUÍMICO DE LA
ESPECIE MINERAL CILINDRITA (FePb3Sn4Sb2S14) BARONE Vicente L*. , BOTTO Irma L.*
, SCHALAMUK , Isidoro B. ** * Centro de Química Inorgánica (CEQUINOR-CONICET)
Facultad de Ciencias Exactas, Universidad Nacional de La Plata, (botto@quimica.unlp.edu.ar) ** División Geología Aplicada del Museo de La Plata,
Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata ABSTRACT: PHYSICO-CHEMICAL STUDY OF THE CYLINDRITE
MINERAL SPECIE (FePb3Sn4Sb2S14). This work, about the characterization of the
sulfosalt cylindrite (FePb3Sn4Sb2S14)
from Pirquitas ( Keywords:
cylindrite, sulfosalt, physico-chemical propierties. |
|
NEOFORMACIÓN DE
PALYGORSKITA, SEPIOLITA Y FLUORITA EN UN PETROCALCID XÉRICO DEL NE DE LA
PROVINCIA DEL CHUBUT The studies on
soil genesis recently carried out in the Northeast of Chubut province
(Patagonia) resulted in the identification of palygorskite and sepiolite in a
Petrocalcid soil developed on old fluvioglacial deposits (“Rodados
Patagónicos”, RP). The aim of this study was to analyze the factors and
processes of palygorskite and sepiolite formation. The profile shows a
petrocalcic horizon where sepiolite >> palygorskite >>
Mg-smectites were identified. Small quantities of fluorite were also
identified by XRD, which was corroborated by the ionic activities of Ca2+
and F- in the soil solution. The presence of sepiolite in the
petrocalcic horizon soil was confirmed by observations in the SEM. According
to the analytical determinations, the fibrous clay mineral would have been
formed from dissolution-precipitation processes of Mg-phyllosilicate and from
the Mg2+ supplied by the soil solution during the precipitation of
low-Mg calcite. The waterlogging and alkaline conditions favourable to the
formation of palygorskite are determined by the abrupt textural transition
between the fine materials of the superficial horizons and the coarse
deposits of RP. The presence of fluorite in the most developed and alkaline
calcretes explains the geochemical control of the Ca2+ which starts with the calcite precipitation.
Keywords: sepiolite; palygorskite; fluorite;
Petrocalcid; northeastern |
|
NODULOS Y CONCRECIONES DE BARITINA Y DE MANGANESO EN EL
PALEÓGENO DE LA PROVINCIA DEL CHUBUT BRODTKORB, Milka K.de * y ARIZMENDI, Alicia.> * CONICET - Facultad de Ciencias Físicas y Naturales, UBA. ABSTRACT: BARITE
AND MANGANESE NODULES AND CONCRETIONS IN THE PALEOGENE OF |
|
DANALITA EN UNA
PEGMATITA RELACIONADA AL CUERPO EL PORTEZUELO (GRANITO PAPACHACRA),
CATAMARCA, ARGENTINA COLOMBO, Fernando CONICET - Museo
de Mineralogía ¨Dr. Stelzner¨- Universidad Nacional de Córdoba. e-mail:
fcolombo@com.uncor.edu ABSTRACT: DANALITE IN A PEGMATITE RELATED TO THE EL
PORTEZUELO BODY (PAPACHACRA GRANITE), CATAMARCA, ARGENTINA Danalite, ideally Fe2+4Be3(SiO4)3S,
has been found in an aplite-pegmatite dyke genetically related to the
Papachacra Granite (central The danalite was found in the dumps, within a
segregation of coarse
K-feldspar>>quartz in a mass of aplite It forms anhedral to
subhedral grains up to 15 mm long, dark brownish red with a black film on the
surface and intense greasy luster. Its refractive index is 1.761(3). EDS analyses show Fe>>Si>S,Mn>>Zn,Al,
with a Fe:Mn ratio of about 4:1. |
|
ÓPALO-CT DE UNA PEGMATITA EN CERRO BLANCO
(CÓRDOBA, ARGENTINA) COLOMBO, Fernando CONICET - Museo
de Mineralogía ¨Dr. Stelzner¨- Universidad Nacional de Córdoba. e-mail:
fcolombo@com.uncor.edu ABSTRACT: OPAL-CT FROM A PEGMATITE IN CERRO BLANCO (CÓRDOBA,
ARGENTINA). Opal-CT occurs in a pegmatite in Cerro Blanco (near
Tanti, Córdoba Province, Argentina), as masses up to several dm3
in a very quartz-rich zone. The
opal-CT forms groups of fine lamellae up to 3 cm long, included in quartz
(mostly chalcedony, but sometimes macrocrystalline) and associated with some
muscovite. It is light gray to light brownish and almost lusterless. Under UV
it shows no response, but the host chalcedony fluoresces bright yellowish
green. Its X-ray pattern shows the
following peaks (d spacing in Å, normalized intensity): 4.290 (72),
4.089 (100) and 2.489 (22). The most intense peak shows a long tail towards
high 2q. The opal-CT precipitated during a late hydrothermal
stage. |
|
ATACAMITA DEL PÓRFIDO
CUPRÍFERO TACA TACA BAJO, SALTA (ARGENTINA) COLOMBO, Fernando y LIRA,
Raúl CONICET - Museo
de Mineralogía ¨Dr. Stelzner¨- Universidad Nacional de Córdoba. e-mail:
fcolombo@com.uncor.edu,
rlira@com.uncor.edu ABSTRACT: ATACAMITE FROM THE TACA TACA
BAJO PORPHYRY COPPER, SALTA (ARGENTINA). Atacamite, Cu2(OH)3Cl, was
found as isolated crystals and crystal groups lining a fissure in a drilling
core of Taca Taca Bajo porphyry copper. Orientation is a
= Z, b = X, c = Y; pleochroism is very weak, b =
yellowish green, g = a = emerald green. Cell dimensions (in Å),
refined in space group Pnam, are a = 6.0252(5), b = 9.1113(7), c =
6.8615(7), V = 376.67(5) Å3. The powder X-ray diagram has a good
match with PDF file 25-0269. No lines other than those of atacamite were
found. EDS analyses show only Cl and Cu. Published data on atacamite genesis indicate that
conditions prevailing during its precipitation were low temperature
(<200ºC), a pH of 4 or higher, a content of CuCl+ around 20% of total
dissolved Cu2+ and absence of important quantities of higher
chloro-complexes. Keywords: atacamite – Taca Taca Bajo
porphyry copper – oxidation zone – Salta
|
|
BEAVERITA,
PLUMBOJAROSITA Y OTROS MINERALES SECUNDARIOS
DE Pb-Cu-Zn DE LA ZONA DE OXIDACIÓN
DE LA MINA MARÍA DEL VALLE, DISTRITO LAS AGUADAS, SAN LUIS COLOMBO, Fernando*, LIRA, Raúl* y
PANNUNZIO MINER, E. V.** * CONICET - Museo de
Mineralogía ¨Dr. Stelzner¨. Universidad Nacional de Córdoba. fcolombo@com.uncor.edu, rlira@com.uncor.edu ** CONICET – INFIQ -
Universidad Nacional de Córdoba. eminer@mail.fcq.unc.edu.ar ABSTRACT: BEAVERITE, PLUMBOJAROSITE AND
OTHER SECONDARY Pb-Cu-Zn MINERALS FROM THE OXIDATION ZONE OF THE MARÍA DEL
VALLE MINE, LAS AGUADAS DISTRICT, SAN LUIS. María del Valle mine is a hydrothermal vein deposit
located some 15 km East of Quines (San Luis Province, Argentina). A suite of
secondary Pb-Cu-Zn species was found in the oxidation zone. Beaverite occurs
intermixed with plumbojarosite as microcrystalline masses up to 1 cm thick
encrusting quartz and galena altered to cerussite. They are greenish yellow
to brownish yellow and have silky to earthy luster. EDS analyses show Pb and Fe
(S is masked by the PbMa line), with very minor Cu, K, Na, Al and Si.
No As or P were detected. Cell dimensions are: (beaverite) a = 7.2446(9) Å, c
= 17.109(2) Å, V = 777.6(2);
(plumbojarosite) a = 7.3068(5) Å, c
= 33.566(3)Å, V = 1552.0(2) Å3. These alunite-group minerals formed
due to the attack of galena by low temperature acid solutions. Other species found at María del Valle mine include
mottramite crusts (no Zn detectable by EDS),
hemimorphite crystals to 0.8 mm showing forms {010}, {110}, {301} and
{031}, goethite intimately intermixed with plumbojarosite, malachite,
azurite, abundant massive and crystallized cerussite, gypsum and celestite. Keywords: beaverite -
plumbojarosite – secondary Pb-Cu-Zn minerals – María del Valle – San Luis |
|
LA MORGANITA DE LA PEGMATITA LAS TAPIAS, CÓRDOBA
(ARGENTINA): UN CASO
DE BERILO NO HEXAGONAL COLOMBO, Fernando*, PANNUNZIO MINER, Elisa V.**,
CARBONIO, Raúl E.**, SFRAGULLA, Jorge*** y LIRA, Raúl* *CONICET -
Museo de Mineralogía ¨Dr. Stelzner¨- Universidad Nacional de Córdoba. e-mail:
fcolombo@com.uncor.edu,
rlira@com.uncor.edu ** INFIQ-Depto. de
Físico-Química (F.C.Q.)- Univ. Nac. de Córdoba. e-mail: eminer@mail.fcq.unc.edu.ar, carbonio@mail.fcq.unc.edu.ar ***: Cátedra
de Petrología Ignea y Metamórfica (F.C.E.F.y N.) - Universidad Nacional de Córdoba. e-mail:
sfragulla@hotmail.com ABSTRACT: MORGANITE FROM LAS TAPIAS
PEGMATITE, CÓRDOBA ( The
Las Tapias pegmatite (31º56'32'' S, 65º05'08'' W) is an LCT-type body
which hosted one of the largest beryl concentrations in the world (over 3,200
tones). Pink beryl (morganite) occurs very infrequently as palest to light
pink, translucent fillings or replacements related to cracks in greenish to
off-white beryl masses. EDS analyses show that the morganite contains Na and
Cs, while the greenish beryl contains traces of Fe in addition to Na and Cs.
Refractive indices and c/a = 1.001
(hexagonal setting) point to an alkali-bearing beryl, as morganite commonly is. Departure
from the hexagonal symmetry is indicated by biaxial optic figures and the
presence of small peaks (at 8.314, 8.209, 8.106, 4.652, 3.600, 3.338 and
3.171 Å) in the powder X-ray diffraction pattern, which could not be indexed
in space group P6/mcc with a unit cell
similar to that reported for truly hexagonal beryl. The observed reflections
(except for a very minor peak at 8.83 Å) can be reproduced with a monoclinic
cell a 18.5569(8), b 16.1021(8), c 9.1991(2), b 90.500(3), V 2748.6(2). Heating to 900ºC for 16 hours resulted in
merging of some reflections. No definite conclusion can be drawn about the
origin of biaxiality, but it seems to be rather widespread in beryl from
pegmatites and warrants further investigation. . ..... Keywords: alkali beryl -
morganite - biaxial - Las Tapias -
Córdoba ......... |
|
CARACTERES TEXTURALES
Y COMPOSICIONALES DE OXIDOS DE Fe Y Ti EN DEPOSITOS ARENOSOS MODERNOS DEL
PARTIDO DE TRENQUE LAUQUEN, NOROESTE DE LA PROVINCIA DE BUENOS AIRES de
BARRIO, Raúl E.* **; RIBOT, Alejandro M. ** *** y PITTORI, Carlos A. *** *Instituto
de Recursos Minerales (INREMI), UNLP. debarrio@inremi.unlp.edu.ar **
Facultad de Ciencias Naturales y Museo (UNLP) ***
LEMIT-Comisión de Investigaciones Científicas de la Provincia de Buenos Aires
(CICBA), aribot@museo.fcnym.unlp.edu.ar; cpalejandro@infovia.com.ar ABSTRACT: TEXTURAL AND COMPOSITIONAL CHARACTERISTICS OF
Fe-Ti OXIDES FROM MODERN SAND DEPOSITS, TRENQUE LAUQUEN, NORTHWESTERN Chemical and textural features of detrital Fe-Ti
oxides from modern sand deposits at Trenque Lauquen area, northwestern of These deposits are composed by brown yellowish fine
to very fine sands bearing about 3% heavy transparent and opaque minerals. Predominance of titanomagnetite clasts free of
exsolutions or with fine intergrowths along (111) planes, supports a volcanic source. Keywords: textural and chemical features – Fe-Ti oxides – modern
sands – Buenos Aires
|
LA WOLLASTONITA
DEL SKARN JULIANA II, SAN MARCOS SIERRA, PROV. DE CORDOBA.
DOMÍNGUEZ, Eduardo***; GARRIDO, Mirta**, GOMEZ,
Cristina* y ALIOTTA, Guida* *** Cátedra de Geología de Yacimientos. CONICET. e-mail: edomin@criba.edu.ar ** Cátedra
de Geología de Yacimientos. UNS.
e-mail: mgarrido@criba.edu.ar * Cátedra de Geología General. UNS. e-mail: mcgomez@criba.edu.ar;
galiotta@criba.edu.ar ABSTRACT: THE WOLLASTONITE OF SKARN
“JULIANA II”. SAN
MARCOS SIERRA, PROVINCIA DE CÓRDOBA A sample of 30 kg of mineral coming from the "Juliana II" skarn mine was studied in order to determine the possibility of achieving in laboratory a wollastonite (Wo) of commercial purity. “Juliana II” is one of the bodies outcropping at the Quilpo - La Fronda sector, near San Marcos Sierra, Córdoba. The skarn outcrop has an elongated west–east crest surrounded by less prominent granites and metamorphic rocks. The body is ellipsoidal, length 320 m, and 30 wide; it has a minimal vertical extension of 40 m. It has a ribbon texture with strong visible variations due to the foliations and the garnet crystals content and size. Its bands strike 267° and a dip 76° S. The contact with the country rock, pegmatite granite and aplite veins, is not visible in the field. Good geological and mineralogical studies of this body ant its relationship with the regional environment can be found in previous reports. The mineralogy consists of wollastonite, garnet (grossularite), vesubianite and scarce plagioclase. Their average contents on microscopic slides were: wollastonite: 40%, diopside: 40%, vesubianite: 15% and garnet, plagioclase and quartz: 5%. Wollastonite has fibrous to columnar crystals. Diopside appears as euhedral to subhedral crystals aligned or in clusters. Vesubianite is intergrowth with the wollastonite. Plagioclase is oligoclase showing a mirmequitic texture. The wollastonite is released thoroughly in mesh 70 (212 microns) and it can be magnetically concentrated to good purity in the 120 (125 microns) and 230 (63 microns) mesh. The fibers have a length to wide ratio from 7:1 to 4:1 and they can be classified as short type fibers. The magnetic wollastonite recovery varies between 30 and 40 % and it is similar to its abundance in the petrographic slides. The concentrated has a similar purity to that currently found in the imported mineral used in ceramics. The mineralized body dimensions encourage the study prosecution tending to define the mineral answer to the industrial magnetic concentration. Keywords: Skarn, wollastonite, magnetic concentration
|
|
hallazgo
de zincsilita acompañADA DE willemita Y HEMIMORFITA en la veta lastenia del
distrito Pb-zn campana mahuida, neuquén Gallegos, Ernesto*, Berbeglia,
Yanina*, Martínez Dopico,
Carmen I.*, Lagorio, Silvia
L.**, Vattuone, María E.** ***
y Latorre, Carlos O.** *** *
Departamento de Ciencias Geológicas, Facultad de Ciencias Exactas y
Naturales, Universidad de Buenos Aires, Argentina. e-mail:
ernestog@gl.fcen.uba.ar, yanina@berbeglia.com.ar, carmen@gl.fcen.uba.ar ** Cátedra de Mineralogía, Departamento de Ciencias Geológicas, Facultad de Ciencias Exactas y
Naturales, Universidad de Buenos Aires, Argentina. e-mail: lagorio@gl.fcen.uba.ar *** INGEIS (CONICET), Ciudad Universitaria, 1428,
Buenos Aires, Argentina. e-mail: elena@gl.fcen.uba.ar,
latorre@gl.fcen.uba.ar ABSTRACT: finding of zincsilite ASSOCIATED WITH
willemite AND HEMIMORPHITE in the lastenia vein of the campana mahuida pb-zn
district, neuquén The mineralogy of the
second worldwide discovery of zincsilite (Zn3 Si4.O10
(OH)2.4H2O) was studied by petrographic microscope,
XRD, HREM and EDS. Other zinc silicates as hemimorphite and willemite
crystallize together. All of them are found in the oxidation zone, from
epithermal Lastenia veins of the Pb-Zn district, Campana Mahuida, Patagonian
Andes, Neuquén. Zincsilite is a rare montmorillonite group mineral without
Al. Crystals show some milimeters in lenght, they are monoclinic, with
laminar pseudohexagonal {001} habit
forming parallel groups. It is traslucent, with white colour and
pearly luster and has perfect cleavage
{001}. The optical character shows: 2Va = 50° and strong dispersion r>v. Chemical
analyses by EDS show a similar composition of the zincsilite type locality.
Zinc silicates originate from sphalerite in the silica rich oxidation zone in
relatively acidic environment, that preclude carbonate crystallization. Keywords: Zincsilite,
Willemite, Hemimorphite, hydrothermal veins, Campana Mahuida, Neuquén. |
|
Primer hallazgo de
buddingtonita en Argentina en el yacimiento Pan de Azucar, Jujuy Godeas, Marta y
Litvak, Vanesa D ABSTRACT: En el yacimiento Pan de Azúcar, Jujuy, en el área de alteración
adularia-sericita-cuarzo se detectó un feldespato de baja temperatura de tipo
adularia, con amonio en su estructura -buddingtonita-, por medio del método
de espectrometría de reflectancia SWIR. El ion amonio bajo la forma de
materia orgánica fue aportado por fluidos procedentes de metasedimentitas
finas del basamento próximo al área. |
BUDDINGTONITA EN EL DEPÓSITO EPITERMAL EL
PANTANITO, MENDOZA
GODEAS, Marta* y RUBINSTEIN, Nora** *SEGEMAR. Av. J. A. Roca
651-8º piso. sector 9. Buenos Aires. **CONICET- Universidad de Buenos Aires. Facultad de
Ciencias Exactas y Naturales. Departamento de Geología. Pabellón II. 1º piso.
1428. Buenos Aires. mgodea@secind.mecon.gov.ar, nora@gl.fcen.uba.ar key words: buddingtonite,
ammonium ion, adularia, epithermal, low-sulfidation |
HEXAHIDRITA
EN LA SIERRA DE RINCONADA, JUJUY, PUNA ARGENTINA
HERRMANN Carlos J*, GODEAS Marta* y MORELLO
Orquídea** *Servicio Geológico Minero
Argentino. Av. Julio A. Roca 651 piso
8 sector 9 (1322) Ciudad de Buenos Aires e-mail:
cherrm@secind.mecon.gov.ar; mgodea@secind.mecon.gov.ar ** Comisión Nacional de
Energía Atómica. e-mail: morello@cnea.gov.ar ABSTRACT: HEXAHYDRITE AT SIERRA DE RINCONADA, JUJUY, ARGENTINE PUNA. In this paper hexahydrite found at sierra de
Rinconada, Santo Domingo mine, is described. This mineral was analysed by X-ray diffraction and
SWIR reflectance spectroscopy methods. Hexahydrite composition was also
checked by chemical analysis. Keywords:
hexahydrite, Mg sulfates, sierra de Rinconada, Acoite Formation. |
|
INCLUSIONES FLUIDAS
EN PIROXENOS ALOJADOS EN LAVAS ALCALINAS, SIERRA DE QUEUPUNIYEU LABUDÍA, Carlos 1,
NTAFLOS, Theodoros 2 y BJERG, Ernesto 1 1 CONICET - Departamento de Geología, Universidad Nacional
del Sur, San Juan 670, B8000ICN Bahía Blanca, Argentina. ghlabudi@criba.edu.ar 2 Department of Geological Sciences, ABSTRACT: FLUID INCLUSIONS IN PYROXENES FROM THE SIERRA DE QUEUPUNIYEU ALKALINE
LAVAS. Melt and
fluid inclusions reflect interaction between basaltic magma volatiles and
early-formed minerals. Queupuniyeu Hills, located NW of Somoncura basaltic
plateau, is one of the main areas where alkaline basalts crops out in Keywords: pyroxene, alkaline lavas, fluid
inclusions. |
|
UTILIZACIÓN DE LA
ESPECTROSCOPÍA DE FTIR EN LA DETERMINACIÓN DE LA MINERALOGÍA DE ARCILITAS DEL
SISTEMA DE TANDILIA, PROVINCIA DE BUENOS AIRES. LÓPEZ,
Katthy1,
BOTTO Lia2
y ETCHEVERRY Ricardo3 1DAAD. German Academic Exchange Service.
katthylopez@inremi.fcnym.unlp.edu.ar 2CEQUINOR.
Centro de Química Inorgánica. Facultad de Ciencias Exactas de la Universidad
Nacional de La Plata. botto@quimica.unlp.edu.ar. 1 y 3INREMI. Instituto de Recursos
Minerales. Facultad de Ciencias Naturales y Museo de la Universidad Nacional
de La Plata. retcheve@museo.fcnym.unlp.edu.ar ABSTRACT: INFRARED
ESPECTROSCOPY IN CLAYSTONE FROM GEOLOGIC SYSTEM OF TANDILIA, Infrared absorption espectroscopy is a physico-chemical method universally
applied to the study of clay minerals structure. It is sensitive to the
chemical composition, the isomorphous substitution and the structural order.
The aim of this paper is provide general information about this technique in
the clay study comparing the results with those of x-ray diffraction (DRX).
In the analyzed samples are used claystones from Villa Mónica Formation
(Precambric)and Balcarce Formation (Ordovicic), of Tandilia Geologic
System. The mineralogy of Villa Mónica
Formation claystone is related to the illite, illite/esmectite, quartz,
feldespar presence and Balcarce Formation
is associated to the kaolinite and feldespar mineral species. The result from FTIR spectroscopy, which
are in agreement en the that were obtained from XRD, allow determine the
structural order in kaolinite and differentiate the semectite types. Keywords: Infrared espectroscopy, clay,
minerals, Tandilia, Geology. |
|
FREIESLEBENITA, DIAFORITA, PIRARGIRITA Y ACANTITA DE
MINA LA CAROLINA, DEPARTAMENTO PRINGLES, PROVINCIA DE SAN LUIS MÁRQUEZ-ZAVALÍA, María Florencia * y
GALLISKI, Miguel Angel * * IANIGLA, CRICYT, CONICET, e-mail:
mzavalia@lab.cricyt.edu.ar; galliski@lab.cricyt.edu.ar ABSTRACT: FREIESLEBENITE, DIAPHORITE, PYRARGYRITE AND ACANTHITE
FROM LA CAROLINA MINE, DEPARTAMENTO PRINGLES, SAN LUIS. La Keywords: acanthite,
diaphorite, freieslebenite, pyrargyrite,
|
|
CEOLITAS
DE LA FORMACIÓN LONCO TRAPIAL EN EL RÍO CHUBUT MEDIO MASSAFERRO, Gabriela I.* y HALLER, Miguel J.* * Universidad Nacional de
la Patagonia San Juan Bosco y CENPAT-CONICET. e-mail:
gim@cenpat.edu.ar; haller@cenpat.edu.ar Abstract: CEOLITES OF THE LONCO TRAPIAL FORMATION IN
THE An association of calcic
ceolites and secondary minerals fills veins and vesicles in Jurassic
andesites of Lonco Trapial Formation. This paragenesis correspond to the
lower part of ceolite facies, formed by near neutral hidrothermal fluids with
temperatures between 100-120°C. Keywords: Ceolites, Lonco
Trapial, Jurassic, Chubut. |
|
Inclusiones fluidas en esfalerita de Mina
Chocaya, provincia de Jujuy MONTENEGRO,
T., COIRA, B. y BRODTKORB, M.K. de Resumen: La
mineralización de Pb-Zn-Ag de Mina Chocaya, en Jujuy, es de tipo epitermal de
sulfuración intermedia, de acuerdo con la textura y alteración . El estudio
de inclusiones fluidas en esfalerita revela salinidades entre 3,3 y 4,9% eq.
en NaCl y temperaturas entre 201 y 253°C, confirmando la anterior
caracterización. En ámbitos geológicos similares y cercanos, se han
encontrado, anteriormente, similares parámetros. |
|
CARACTERIZACIÓN DE LA ESFALERITA DE LAS MANIFESTACIONES
EPITERMALES DEL AREA LA JOSEFINA, MACIZO DEL DESEADO, PROVINCIA DE SANTA CRUZ MOREIRA
Pilar*, FÉRNANDEZ Raúl**, RÍOS Francisco J.*** y SCHALAMUK Isidoro B.**** *Instituto
de Recursos Minerales-UNLP-CONICET.e-mail: pilimoreira@inremi.unlp.edu.ar ** Instituto de Recursos Minerales-UNLP-CICBA.
e-mail:rfernand@inremi.unlp.edu.ar ***CDTN- Comissão Nacional de Energia Nuclear,
Brasil: e-mail: javier@cdtn.br **** Instituto de Recursos Minerales-UNLP-CONICET.
e-mail:ischala@inremi.unlp.edu.ar ABSTRACT: SPHALERITE
CHARACTERIZATION FROM EPITHERMAL OCURRENCES OF LA JOSEFINA AREA, MACIZO DEL
DESEADO, SANTA CRUZ PROVINCE.
Fluid inclusions and % molar SFe content in
sphalerite from La Josefina, Keywords: epithermal
deposit, sulfidation state, sphalerite, SFe % molar content, fluid
inclusions, Macizo del Deseado. |
PRESENCIA DE SODIOURANOSPINITA, YUKONITA Y REEVESITA, MINA SAN
SANTIAGO, LA RIOJA. TRES NUEVAS CITAS DE MINERALES EN LA REPÚBLICA ARGENTINA
MORELLO,
O * y BRODTKORB, M.K.de ** * Comisión Nacional de Energía Atómica. e-mail:
morello@cnea.gov.ar ** CONICET – UBA. e-mail: milkabro@gl.fcen.uba.ar ABSTRACT: SODIUM URANOSPINITE, YUKONITE AND REEVESITE FROM SAN
SANTIAGO MINE, LA RIOJA. THREE NEW DATES OF MINERALS
IN ARGENTINA.
The
first occurrence in Argentina of three secondary minerals, sodium
uranospinite (Na2,Ca)
(UO2)2 (AsO4)2.5H2O, yukonite Ca2 Fe33+(AsO4)4 (OH).12H2O and reevesite Ni6 Fe23+(CO3)(OH)16 . 4H2O, are described. These minerals were found in alterated
zone of San Santiago Mine, La Rioja. They were studied optically and by means
of XRD and EDAX.
Keywords: sodium
uranospinite, yukonite, reevesite, alteration zone.
|
CORKITA EN LA CANTERA PIEDRAS BLANCAS BLOQUE DE SAN RAFAEL, MENDOZA.
MORELLO,
O. * y RUBINSTEIN, N. ** * Comisión Nacional de Energía Atómica. e-mail:
morello@cnea.gov.ar ** CONICET – UBA. e-mail:
nora@gl.fcen.uba.ar ABSTRACT:
CORKITE FROM PIEDRAS BLANCAS QUARRY, MENDOZA.
The
first occurrence in
|
|
Inclusiones
fluidas en analcima de la Formación CaÑadòn Asfalto, Paso de Indios, Chubut. NILLNI,
Adriana* *Cátedra de
Mineralogía. UNPSJB, Ruta 1, Km 4. (9005) Comodoro Rivadavia.
anillni@unpata.edu.ar, adriananillni@yahoo.com.ar abstract: fluid inclusion studies in analcime of caÑadón
asfalto formation, paso de indios, Fluid inclusions in analcime crystals coming from
cavities of olivine basalts of the Cañadon Asfalto Formation are
analyzed. The samples belong to a
profile carried out to the south of Cerro Condor, on the western riverbank of
the For this purpose, fluid
inclusions in barite crystals that are associated to the zeolite have been
analyzed too. This was carried out, in
principle, considering that all these minerals have been formed under similar
conditions, or that the same ones have not varied considerably through the time. The homogenization temperatures in analcime vary
between 130 and 150°C and in barite between 130 and 167°C, that which demonstrates that the data
obtained from the zeolite can be considered for the interpretations. Keywords: analcime, barite, fluid inclusions. |
|
Inclusiones fluidas en cuarzo,
fluorita y calcita de Estancia Tres Hermanas y Estancia La Beatriz, sector NE
del Macizo del Deseado, provincia de Santa Cruz. NILLNI,
Adriana*, FRACCHIA, Diego** y
GUZMAN, Sebastián*. * Cátedra de Mineralogía. UNPSJB,
Km 4 (9005), Comodoro Rivadavia. anillni@unpata.edu.ar **fracchiadiego@yahoo.com.ar Abstract: Fluid
inclusion studies in quartz, fluorite and calcite from Tres Hermanas and La
Beatriz prospects, In
northeastern sector of Deseado Massif, Estancia Tres Hermanas (TH) and
Estancia La Beatriz (LB) precious metals prospects contain veins of quartz,
fluorite and calcite. According to the literature, fluorite is only present
on eastern side of Deseado Massif; moreover, for LB is here formally
mentioned for the first time. Our project focuses on the nature of these
occurrences. The veins in TH are hosted by
pre-Permian metamorphics; those in LB, by jurassic volcanics of Bajo Pobre
Formation and Bahía Laura Group. They occupy small extensional jogs and faults. The vein
systems are represented by silicification, breccias and stockworks with
different mineralization stages, that in order of precipitation are: in TH,
bladed calcite, pseudomorphic and massive quartz, and colourless to violet
fluorite; in LB, several pulses of calcite and fluorite, quartz and
chalcedony, and finally barren calcite. In
polished sections we have found gold particles, of up to 5 μm, in pseudomorphic quartz,
fluorite of different colours and massive calcite from TH, and in fluorite
and quartz from LB. Fluid
inclusions occur in quartz, fluorite and calcite. In TH, inclusions data in
quartz represent moderate temperature (190 to 220 ºC), low salinity (3 to 4
% NaCl eq.),
probable boiling fluids (which we consider to have been responsible for the
Au-Ag transport and deposition); in fluorite low temperature (150 to 190 ºC)
and low salinity (2,5 to 3 % NaCl eq.) fluids. In LB, inclusions data in
different fluorites represent similar conditions of salinity (2 to 3 and 2,5
to 3,5 % NaCl eq.), but dissimilar temperatures (150 to 175 and 100 to
130ºC), and in calcite 125 to 140 ºC and 0,5 to 1,5 % NaCl eq. These calcite
fluids represent the cooling stage of a system previously diluted. As other mineralizations of the Deseado Massif, TH and LB veins pertain to the low sulphidation epithermal type, but are distinguished by the presence of fluorite. Keywords: Macizo
del Deseado, Estancia Tres Hermanas, Estancia La Beatriz, fluorite, fluid
inclusions. |
|
CHRISSTANLEyita,
Ag2Pd3Se4, y su aNÁLOGo cuprífero jagüeÍta, Cu2Pd3Se4, de la mina el chire, DEPARTAMENTO GRAL.
LAMADRID, provincia de La Rioja, Argentina PAAR,
Werner H.1, SUREDA, Ricardo J.2 y Dan TOPA1 1 – Department of Geography, Geology and
Mineralogy, Division of Mineralogy and Material Sciences, 2 - CONICET - Cátedra de Mineralogía, Facultad
de Ciencias Naturales, Universidad Nacional de Salta, 4400 Salta, Argentina. E-mail:
sureda@sinectis.com.ar ABSTRACT: Chrisstanleyite, Ag2Pd3Se4, and its copper aNALOGUE jagüeite, Cu2Pd3Se4, from El
Chire mine, General Lamadrid department, La Rioja province, Argentina. The Sierra de Umango and Los Llantenes mining
districts in the Northwestern Sierras Pampeanas and the Precordillera of La
Rioja province, Key words: chrisstanleyite
– jagüeite – PGE selenide ores – El Chire mine – La Rioja Precordillera. |
|
Merenskyita,
PdTe2, en las menas de selenio, COBRE Y plata de
la mina Las Asperezas, DISTRITO MINERO SIERRA DE UMANGO, provincia de La
Rioja, Argentina PAAR,
Werner H.1, TOPA, Dan1, SUREDA, Ricardo J.2,
STUMPFL Eugen F.3 y Helmut MÜHLHANS3 1 – Department of Geography, Geology and
Mineralogy, Division of Mineralogy and Material Sciences, 2 - CONICET - Cátedra de Mineralogía, Facultad
de Ciencias Naturales, Universidad Nacional de Salta, 4400 Salta, Argentina. E-mail:
sureda@sinectis.com.ar 3 – Department of Applied Geosciences,
Mineralogy and Petrology Group, Universiy of Leoben, A-8700 ABSTRACT: Merenskyite, PdTe2, in the selenium, copper and silver ores from Las Asperezas mine,
Sierra de Umango mining district, La An exotic mineralogy is typical for several selenide
occurrences in the Cerro Cacho-Sierra de Umango mining district. The deposits
are small and uneconomic. The assemblages are dominated by selenides of
copper (umangite, klockmannite, berzelianite), mercury (tiemannite) and lead
(clausthalite) associated with eucairite, fischesserite, native gold and
platinum group minerals. The host rocks of this vein-type mineralization
belong to the Precambrian basement of the Western Sierras Pampeanas. At Las
Asperezas mine, merenskyite occurs as minute inclusions within an
umangite-klockmannite-eukairite assemblage. We report here the second
reference in Keywords: merenskyite, Cu-Ag-Hg selenide ores, W.
Sierras Pampeanas, La Rioja, Argentina. |
|
ELEMENTOS DEL GRUPO DEL PLATINO
EN EL COMPLEJO MAFICO-ULTRAMÁFICO DE CERRO LA COCHA, DEPARTAMENTO DE PUNILLA,
PROVINCIA DE CÓRDOBA PUGLIESE,
Luis Eduardo*, VILLAR, Luisa María ** *Geólogo Consultor, E-mail.
lpugli@yahoo.com.ar **CONICET, Instituto de
Recursos Minerales, SEGEMAR, e-mail lvillar@arnet.com.ar ABSTRACT: PGE´S
ELEMENTS IN THE MAFIC AND ULTRAMAFIC COMPLEX OF CERRO LA COCHA, PUNILLA DEPARTMENT, PGE analysis of ultramafic rocks of the La Cocha
mafic- ultramafic Complex shows the complete spectre of these elements. Their
spiders normalized to chondrite show primitive patterns consistent with a
mantle origin for these rocks. Keywords: PGE,
layered mafic-ultramafic series
|
LA PARAGÉNESIS Pb-Zn-Sb DEL DISTRITO EL QUEVAR, SALTA
ROBL, K. * *ILF Consulting Engineers, Innsbruck,
Austria e-mail:
Klaus.Robl@utanet.at ABSTRACT: THE Pb-Zn-Sb PARAGENESIS OF EL QUEVAR DISTRICT, SALTA.
The epithermal system present in the Incahuasi
Valley is situated on the SW side of the Quevar Stratovolcano Complex, Puna
of Salta, Argentina. During the Upper Miocene K-rich dacitic to andesitic
volcanism in the form of huge caldera eruptions followed by large
stratovolanoes occur. The ores precipitated into small veinlets, irregular
bodies and disseminated in the host rock. All known Pb-Zn-Sb mineralizations
appear along a NW fault and are
characterized by Pb-Zn-Sb sulfides and sulfosalts like galena, sphalerite,
geocronite/jordanita and boulangerita. Electron microprobe analyses showed a variety of
additional Pb-Sb sulfosalts including the unknown phases X 4 and X 10. Keywords:
Pb-Zn-Sb paragenesis –epithermal – El Quevar – Salta |
|
ANÁLISIS COMPARATIVO DE EVAPOCRISTALES DE BÓRAX NEÓGENO Y RECIENTE
(LOMA BLANCA Y TURI LARI, JUJUY) RUIZ, Teresita del V.*, QUIROGA,
Alicia G.* y ALONSO, Ricardo N.** * Cátedra de Mineralogía, Universidad Nacional de Salta. E-mail:
ruiz@unsa.edu.ar y gquiroga@unsa.edu.ar ** CONICET – Cátedra de Mineralogía, Universidad Nacional de Salta. E-mail:
rnalonso@sinectis.com.ar ABSTRACT: COMPARATIVE
ANALYSIS OF BORAX EVAPOCRYSTALS FROM NEOGENE AND QUATERNARY BORATE DEPOSITS
(LOMA BLANCA AND TURI LARI), In this
study we made a comparison between borax (or tincal) evapocrystrals that
occurs in Loma Blanca (Miocene) and Turi Lari (Quaternary) borate deposits in
the Puna of Jujuy ( Key words: Puna, borax, Miocene, borate
deposits, evapocrystals. |
|
PRESENCIA DE ESFALERITA RICA EN
INDIO EN EL YACIMIENTO EL PELADAR; PROVINCIA DE JUJUY ZAPPETTINI,
Eduardo O. (*), BRODTKORB, Milka K. de (**),
GODEAS, Marta(*) y
BERNHARDT Heinz J. (***) (*) SEGEMAR. Julio A. Roca 651 – 8° piso – Buenos
Aires. e-mail: ezappe@secind.mecon.gov.ar (**) CONICET- UBA. e-mail:
milkabro@gl.fcen.uba.ar (***) Ruhr Universität Bochum. Alemania |
|
|
|
METALOGENIA |
|
|
|
EL DOCUMENTO COLONIAL DE FILIBERTO DE MENA (1791) Y SUS ASUNTOS
GEOLOGICOS Y MINEROS ALONSO, Ricardo N.* * CONICET – Cátedra de Mineralogía, Universidad Nacional de Salta. E-mail:
rnalonso@sinectis.com.ar ABSTRACT: FILIBERTO
DE MENA AND HIS MINING AND GEOLOGICAL DOCUMENT FROM 1791. A manuscript dated in 1791 and
signed by Philiberto de Mena, is analyzed. The manuscript contains
information about gold and silver mines, pegmatite, saltpans, lime, gypsum,
alum, sulfur, meteoritic iron, Key words: Filiberto de Mena, Mining,
History of Mining, |
|
METALOGENIA DE LA PUNA DE JUJUY EN LA COMARCA DEL RÍO GRANDE DE
CORANZULÍ ALONSO, Ricardo N.*, RUIZ,
Teresita del V.** y QUIROGA, Alicia G.** * CONICET – Cátedra de Mineralogía, Universidad Nacional de Salta.
E-mail: rnalonso@sinectis.com.ar ** Cátedra de Mineralogía, Universidad Nacional de Salta. E-mail:
ruiz@unsa.edu.ar y gquiroga@unsa.edu.ar ABSTRACT: METALLOGENY OF The Puna
of northwestern Key words: Puna, Gold, Borate,
Magnesiocopiapite, Kalinite
|
|
EL DEPÓSITO DE ESTAÑO LA DESCUBRIDORA, SIERRA DE MAZÁN, LA RIOJA,
ARGENTINA AVILA,
Julio1,2 y FOGLIATA, Ana1 1 Facultad de Ciencias Naturales, U.N.T., 2 CONICET jcavila@csnat.unt.edu.ar, fogliat@csnat.unt.edu.ar ABSTRACT: LA DESCUBRIDORA TIN
DEPOSIT, SIERRA DE MAZÁN, LA RIOJA, ARGENTINA. La Descubridora tin deposit is located on the
northeastern slope of Sierra de Mazán. Greisenization affected to the Mazán
porphiric granite of lower Paleozoic age that constituted the country rock.
The mineralization (mostly cassiterite) is developed in quartz veins with muscovite. It is
proposed that the deposit was formed during the late magmatic hydrothermal
stage genetically linked to La Quebrada granite of possible Carboniferous
age. Mining was developed in two sectors but the lower is most important.
There are about 500 m of galleries in
different levels according to the topography of the area. Keywords: Sierra de Mazán-
Tin- Geology- Mining |
|
Mineralized Dissolution/Collapse Breccias of the
Gualcamayo Mining District, BRUNO, Natalia Edith 1,2 1CONICET, 2INGEO-FCEFN,
UNSJ. E-mail: nbruno@unsj-cuim.edu.ar ABSTRACT:
MINERALIZED DISSOLUTION/COLLAPSE BRECCIAS OF THE GUALCAMAYO MINING DISTRICT, The studied
breccias out crop in the Quebrada del Diablo area which is located in the
Eastern Precordillera, Gualcamayo Mining District, San Juan province. The zone
is characterized by Upper Tremadocian-Early Llanvirnian dolomitic limestone
and marbles of San Juan Formation, and a dacite porphyry of tertiary age. NW
reverse faults and WSW tear faults are the most important structures. The
limestone are affected by hydrothermal alteration as decarbonatization,
carbon enrichment, dolomitization, silicification and pyritization. The
disseminated mineralization consists of gold, arsenian rich-pyrite, pyrite,
marcasite, cinnabar, realgar-orpiment, galena, sphalerite, chalcopyrite and
pyrrhotite. Pre-ore dissolution/collapse breccias are characterized by
predominant fragment-supported textures, irregular shape of fragments and
lentiform to tabular breccia bodies interbedded with carbonate units with the
same strike of limestone. Fragments consists of: limestone, marble and
locally, dacite porphyry, calcite, chert and skarn. The matrix is composed of
the same comminuted materials of the clasts, carbonaceous materials and iron
oxides and it is cemented by calcite, quartz, and locally barite and gypsum.
Intensely decarbonatized zones were formed by continued removal of carbonates
by acidic fluids which principally percolated through bedding plane. As
carbonates were removed the altered rocks were unable to support the overlying
load and collapse. The hydrothermal alteration of carbonate rocks and the
associated brecciation phenomenon played a critical rol in a deposition of
gold mineralization. Dissolution/collapse breccias and associated
decarbonatized and carbon enrichment rocks remained highly permeable,
allowing migration of large volumes of gold-bearing fluids. Mineralized
fluids moved through NW reverse faults and WSW tear faults. Keywords: limestone, hydrothermal alteration, breccias, gold
|
|
GEOLOGIA Y MINERALOGIA DE LA PEGMATITA
YATASTO-SAN BERNARDO, SAN LUIS, ARGENTINA CADILE, Sebastián1, OYARZABAL, Julio1
y ROQUET, M. Belén2 1 Cátedra de Mineralogía, Proy. 349001, UNSL.
e-mail: joyar@unsl.edu.ar 2 Cátedra de Mineralogía, Proy. 349001, UNSL,
CONICET. e-mail: maber@unsl.edu.ar ABSTRACT: GEOLOGY AND MINERALOGY OF THE YATASTO-SAN
BERNARDO PEGMATITE, SAN LUIS, ARGENTINA. Yatasto and San Bernardo
deposits comprise an only body classified here as a rare element class,
complex type and spodumene subtype pegmatite. This deposit is located in the
north of the San Luis ranges, at 32º 24´ 34´´ S and 65º 42´ 44´´ W, and
hosted within a fertile LCT pegmatitic granite intruded in
Qtz-Bt-Pl-Ms±Tur-Ap-Zrn schists. The pegmatite has N25-35ºE
strike and 45-60º NW dip, it is tabular, with 260 m long and 14 m maximum
wide in the central segment. Its internal structure is complex and
asymmetric, and is possible to recognize the following units: border zone
(Ab-Qtz-Ms±Tur-Grt-Ap), wall zone (Qtz-Mc-Ms-Ab-Brl±Srl-Elb-Ap-Grt), outer
intermediate zone (Mc-Qtz-Ms±Ap), inner intermediate zone
(Qtz-Spd-Lpd-Amb±Elb-Ap) and core (Qtz). A tabular replacement unit of
saccharoidal albite, and several smaller replacement-filling units have been
recognized. A mineral of the varulite-hagendorfite series (probably varulite)
has been identified and studied, constituting this one, the first occurrence
in Argentina. In the outer intermediate zone,
K-feldspar presents a high Al:Si order (≈1), and muscovite shows 2M1
polytypic form; lepidolite of the inner intermediate zone has different
structural packing, according to 1M polytype. The geochemistry of K-feldspar
and muscovite shows a marked differentiation process and the probable
derivation form the granite. The pegmatite emplacement shows forced character,
with displacement of the host rock from a physical discontinuity, generated
by operating tensional efforts during the cooling period of the fertile
granite, in semi-fragile reologic conditions. Keywords: Yatasto-San Bernardo
pegmatite, geology, mineralogy. |
|
LA ALTERACION HIDROTERMAL DEL ARROYO AUQUEN, NO DE NEUQUÉN: ¿UN ESTILO SIMILAR A LA
ALTERACIÓN DEL DEPÓSITO EPITERMAL DE ALTA SULFURACIÓN? CASÉ, Ana M*, IMPICCINI, Agnes**, FRANCHINI, Marta***., DANIELI, Juan
C*. SCHALAMUK,
Isidoro****. *Dirección de Minería de la Provincia del Neuquen.
Asentamiento Universitario Zapala. Facultad de Ingeniería. Universidad
Nacional del Comahue. dgm_geologia@neuquen.gov.ar **CIMAR. Facultad de Ingeniería. U.N.Comahue *** CIMAR. CONICET. AUZa-
U.N.Comahue **** Universidad Nacional de la Plata. INREMI. ABSTRACT: HIDROTHERMAL ALTERATION ALONG AUQUEN STREAM,
NW NEUQUEN PROVINCE, ¿AN EPITHERMAL HIGH SULFIDATION ALTERATION MODEL? The aim of this
contribution is to show the development of an hydrothermal alteration
area analogous to those with advanced argillic alteration that identified
hig-sulfidation systems. The area is placed in the beggining and midle course
of Auquen stream, Neuquén province (36º 47'18''-36º 48' 14'' SL y 70º37'23''
y 70º34'30'' WL) distributed in two focus where the leached volcanic rocks
belongs to Grupo Choiyoi (low Permic-Low Triasic age). There's a relictic
vuggy quarz body with traces of pirite, chalcopirite and gold, sourrounded by
a pyrophyllite halo and the advance argillic alteration composed by
pyrophyllite, illite, chlorite, kaolinite and interestratified
chlorite/smectite and illite/smectite. Key words: argilic
alteration, pyrophylite, Kübler index, Choiyoi Group. |
|
DACITA EL ARRIERO
EXPONENTE DEL MAGMATISMO Y METALOGÉNESIS GONDWÁNICA EN LA SIERRA DE LA
HUERTA, PROVINCIA DE SAN JUAN: ALTERACIÓN HIDROTERMAL Y MINERALIZACIÓN CASTRO de MACHUCA, Brígida1,2,3 y
MEISSL, Estela2,3 1 Consejo
Nacional de Investigaciones Científicas y Técnicas. e-mail:
bcastro@unsj-cuim.edu.ar 2 Departamentos de Geología y de Geofísica,
FCEFN, Universidad Nacional de San Juan. 3 INGEO,
FCEFN, Universidad Nacional de San Juan. e-mail: emeissl@unsj-cuim.edu.ar ABSTRACT: EL ARRIERO DACITE EXPONENT OF THE GONDWANIC
MAGMATISM AND METALLOGENESIS IN LA HUERTA RANGE, PROVINCE OF SAN JUAN:
HYDROTHERMAL ALTERATION AND MINERALIZATION The
porphyritic dacite of El Arriero (DEA), placed in the eastern flank of La
Huerta Range, Western Pampean Ranges, province of San Juan, is characterized
by intense propylitic alteration and silicification that also affect the
metamorphic host rocks. Evidences of minor phyllic and potassic (biotite
facies) alteration are also recognized. Metallic mineralization in the DEA as
well as in a surrounding breccia appears disseminated, in quartz±calcite veinlets and/or in
drusy aggregates. The main hypogene ore minerals are pyrite, magnetite and
chalcopyrite, plus minor pyrrhotite, ilmenite and native gold. Radiometric
K/Ar and 40Ar/39Ar dating, permit assigning the DEA to
the Gondwanic magmatic-metallogenic cycle.
The economical perspectives of the area are restricted due to the magnitude
of such occurrence.
Keywords: El Arriero Dacite * Hydrothermal
alteration * Mineralization * Gondwanic magmatic-metallogenic cycle |
|
ESTUDIO
DE ISÓTOPOS ESTABLES APLICADO A LOS DEPÓSITOS DE FLUORITA DEL BATOLITO CERRO
ÁSPERO, CÓRDOBA Coniglio, Jorge*, Perez
Xavier, Roberto**, Pinotti, Lucio***, D`Eramo,
Fernando***, *Departamento de Geología,
UNRC, email: jconiglio@exa.unrc.edu.ar;
**Instituto
de Geociências, UNICAMP, Brasil; ***Departamento de Geología
UNRC-CONICET ABSTRACT: STABLE ISOTOPE STUDY APPLIED TO THE VEIN-TYPE
FLUORITE DEPOSITS, CERRO ASPERO BATHOLITH. CENTRAL ARGENTINA Stable
isotopic data, in conjunction with fluid inclusion and geological evidences
indicate that highly exchanged meteoric water was the single fluid reservoir
involved in the formation of the Cretaceous epithermal vein fluorite deposits
hosted in Devonian granites of the Cerro Áspero batholith, southern Sierras
Pampeanas. The ores zones consist mainly of fluorite and chalcedony, which
deposited in three successive stages of mineralization. The evolution of the
epithermal system is marked by a systematic decrease in the calculated d18O fluid composition from 10.7‰ to -9.5‰ accompanied by
relatively constant dD values from -48.5‰ to -53.3‰.
The vein-filling occurred driven by a regime of progressive increase in the
water/rock ratio and decreasing temperature (220 - 116ºC) giving rise to
early muscovite and later to clay minerals-bearing alteration assemblages.
This work also confirms the relevant
role of fluid-rock
interactions as the main
mechanism for the
geochemical evolution of the
ore-forming fluids in the fluorite veins. Keywords: Fluorite veins, stable isotopes, fluid
inclusions, metallogeny, Sierras Pampeanas |
|
COMPOSICIÓN Y
CONDICIONES P-T DE LOS FLUIDOS HIDROTERMALES EN VETAS SEMICIRCULARES Y
RADIALES DEL DISTRITO WOLFRAMÍFERO CERRO ÁSPERO, CÓRDOBA CONIGLIO, Jorge*, PEREZ XAVIER, Roberto**,
PINOTTI, Lucio***, D`ERAMO, Fernando***, PETRELLI, Hugo**** y DUCART, Diego** *Departamento de Geología, UNRC, email:
jconiglio@exa.unrc.edu.ar; **Instituto de Geociências, UNICAMP, Brasil;
***Dpto de Geología UNRC-CONICET; ****Dpto de Geología UNRC-Segemar ABSTRACT: COMPOSITION AND P-T CONDITIONS OF THE HYDROTHERMAL FLUIDS IN RADIAL
AND SEMICIRCULAR W-Mo VEINS. CERRO ASPERO
DISTRICT, CÓRDOBA. In this work the composition and P-T conditions of
the hydrothermal fluids responsible for the formation of semicircular and
radial W-Mo veins in the Cerro Áspero District, Sierras Pampeanas, are
determined. Primary aquocarbonic and aqueous coexistent fluid inclusions are
related to the earliest evolution of the mineralizing fluids. Most fluid
inclusions homogenize in the range
310 –140ºC and have a salinity of 8.5-2.3 eq.wt.% NaCl. They display
Th-salinity covariation consistent with a hypothesis of dilution of magmatic
water by influx of meteoric water. The hydrogen isotope data suggest
contributions to the ore forming fluids of D-depleted meteoric waters that
have reacted extensively with metasedimentary rocks. Chlorite geothermometry
combined with fluid inclusion data indicate precipitation of mineralized
veins at estimated pressures lower than 1.5 kb. Keywords:
Hydrothermal fluids, W-Mo-F veins, metallogeny, Sierras Pampeanas. |
|
DEFORMACIÓN Y METAMORFISMO EN LA
MINA TÍO, CÓRDOBA: UN DEPÓSITO VOLCANOGÉNICO EXHALATIVO SUBMARINO MODIFICADO DI
MARCO, Alejandro* y MUTTI, Diana* * Dpto. de Ciencias Geológicas, Universidad de
Buenos Aires. E-mail:
geoecono@gl.fcen.uba.ar ABSTRACT: STRAIN AND
METAMORPHISM IN THE TIO MINE, CÓRDOBA: A MODIFIED VOLCANOGENIC EXHALATIVE
SUBMARINE DEPOSIT. The Tío mine is a
modified volcanogenic exhalative submarine deposit with massive sulphide
levels. In this paper, the morphology, mineralogy and texture of the deposit
are described and analysed, in order to discriminate the effects of the
metamorphism and ductil strain of the Pampean tectonic cycle (M2 - D2), and
the shearing dinamic metamophism of the Famatinian tectonic cycle (M4 - D4) Keywords: strain,
metamorphism, volcanogenic exhalative
submarine deposit. |
|
FLUORITA EN LAS
VETAS DE CUARZO AURÍFERO DE LA ESTANCIA LA PALOMA PROV. DE SANTA CRUZ DOMÍNGUEZ, Eduardo***, GOMEZ, Cristina**, GARRIDO,
Mirta* y ALIOTTA, Guida** ***Cátedra
de Yacimientos, Universidad Nacional del Sur. CONICET. e-mail: edomin@criba.edu.ar ** Cátedra de Geología General, Universidad Nacional del Sur. e-mail: mcgomez@criba.edu.ar ; galiotta@criba.edu.ar * Cátedra de Geología de Yacimientos. e-mail: mgarrido@criba.edu.ar ABSTRACT: FLUORITE IN THE AURIFEROUS QUARTZ VEINS OF
“ESTANCIA LA PALOMA”, PROV. DE SANTA
CRUZ. This paper informs about the finding of fluorite
in the auriferous lode Ea° La Paloma at the “Macizo del Deseado”. The lode
system belongs to the quartz – adularia type containing some basic sulfides
and variable gold tenors. In the lode the fluorite outcrops along 15 m with a
thickness of 50 cm, together with quartz of several generations. The wall
rocks are jurassic andesites of the Bajo Pobre Formation included in the
Chon-Aike effusive volcanic event. The lode textures are hydrothermal
breccias and fissure fillings. The fluorite appears only as fissure fillings
and in an intermediate stadium after a very fine banded quartz-chalcedony and
it is followed by a new quartz generation. The fluorite has ghosts of lattice
bladed textures (barite-calcite ??) pseudomorphycally replaced by fine
adularia and quartz. Gold precipitation is associated with this
quartz-adularia arrangement. These findings reinforce the genetic link with
mineralizations found in the jurassic riolites at the “Macizo Norpatagónico”
and permit to extend with more confidence the auriferous exploration to the
entire area. The spatial and temporal
relationships between gold and fluorite still remain to be confirmed with
more data.
Keywords: fluorite,
auriferous quartz vein, Macizo Norpatagónico, Macizo del Deseado. |
|
LOS
MINERALES MAGNÉTICOS DEL CUERPO BÁSICO-ULTRABÁSICO DE LAS ÁGUILAS, SAN LUIS GEUNA, Silvana*, ESCOSTEGUY,
Leonardo**, y CLARK, David*** * CONICET-
Universidad de Buenos Aires. e-mail: geuna@gl.fcen.uba.ar ** Servicio
Geológico Minero Argentino *** CSIRO
Division of Exploration and Mining ABSTRACT:
MAGNETIC PROPERTIES OF THE BASIC-ULTRABASIC BODY OF LAS AGUILAS, SAN LUIS. Rock
magnetic properties of the basic-ultrabasic Early Palaeozoic body of Las
Águilas and its country rocks have been investigated. Monoclinic pyrrhotite
is the main magnetic mineral in the igneous body, differing clearly from
hosting gneisses which carry mainly magnetite. Las Aguilas body
and its country rocks might not be distinguishable by magnetic prospecting,
as they are both magnetic. Moreover, the presence of pyrrhotite may be a
source of complexity in the interpretation of magnetic anomalies, because
this mineral is capable of carrying important magnetic remanence. Keywords: Pyrrhotite, magnetite, rock
magnetism, basic-ultrabasic rocks. |
|
MINA MARTHA: UN YACIMIENTO
EPITERMAL ARGENTIFERO EN EL MACIZO DEL DESEADO, PROVINCIA DE SANTA CRUZ GONZÁLEZ
GUILLOT, Mauricio *; de BARRIO, Raúl * y GANEM, Fernando * *Instituto de Recursos Minerales (INREMI), FCNyM,
UNLP (instituto@inremi.unlp.edu.ar) ABSTRACT: MARTHA MINE, AN ARGENTIFEROUS
EPITHERMAL DEPOSIT IN THE DESEADO MASSIF, SANTA CRUZ PROVINCE. Martha mine, located in
Bacon area, consist of epithermal breccias with multiple brecciation stages,
vein filling and mineralisation. Mineralogy and a high Ag/Au (900-1000:1) are
typical from gold and silver bearing epithermal deposits of intermediate
sulfidation type. Mineralisation is essentially argentiferous .and
include mainly pyrargyrite, miargyrite, freibergite, native silver and minor
argentite, polybasite (and/or stephanite) and chlorargyrite. Mineralisation is related to several pulses which
represents changes in the fluid physico-chemical conditions. Many of the
products of these changes are overprinted due possibly to fault
reactivations, lifting and increase in permeability with a shifting to
conditions of minor temperature. Subsequent erosion would be responsible for
exposure of deep levels of the system. Keywords: Martha mine,
Macizo del Deseado, mineralogy, intermediate sulfidation. |
|
MINERALIZACIÓN EPITERMAL EN EL SECTOR EL BARRIL, MACIZO DEL DESEADO,
PROVINCIA DE SANTA CRUZ. GONZÁLEZ GUILLOT, Mauricio1;
DEL BLANCO, Miguel1; GUIDO, Diego1-2; GANEM, Fernando1 y
CÁBANA, Cecilia1-3. 1: Instituto de Recursos Minerales (INREMI).
E-mail: instituto@inremi.unlp.edu.ar 2: CONICET – Consejo Nacional de Investigaciones
Científicas y Técnicas. 3: CICBA – Comisión de Investigaciones Científicas
de la provincia de Buenos Aires. ABSTRACT: EPITHERMAL MINERALIZATION IN EL BARRIL AREA,
DESEADO MASSIF, SANTA CRUZ PROVINCE. Two sets of mineralizations were
identified in El Barril property (San Jorge Minera S. A.). The northernmost
one is located in the same structure that contains Mina Martha epithermal
vein (Ag-Au), five kilometers to the east. This set is also divided into two
zones (eastern and western) on the basis of metallogenical and textural
characteristics. The western zone has higher grades in Au, Ag, Cu, Pb and As,
whereas the eastern zone is richer in Hg and carbonates (or its pseudomorphs).
This facts would reflect a structural higher position within the system for
the western zone compared to the eastern one, and for both when compared with
the neighboring Martha vein, thus increasing the mining potential for El
Barril. The presence of adularia as a gangue mineral and carbonate
pseudomorphs, the scarcity of sulfides observed and textures suggest a low
sulfidation model for this deposit.
Keywords: Macizo del Deseado, El Barril, epithermal mineralization
|
|
MINERALIZACIONES DE Pb - Zn EN VALCHETA, PROVINCIA DE RÍO NEGRO GOZALVEZ,
Martín* y HERRMANN, Carlos** *CONICET – Servicio Geológico Minero Argentino.
e-mail: mgozal@secind.mecon.gov.ar ** Servicio Geológico Minero Argentino. e-mail:
cherrm@secind.mecon.gov.ar ABSTRACT: MINERALIZATION OF Pb
- Zn IN VALCHETA, PROVINCE OF RIO NEGRO. In Valcheta area, located at NE of Northpatagonian
Massif, Rio Negro province, mineralizations of Pb - Zn occur hosted by a low
grade metamorphic basement, a plutonic complex (Neopaleozoic) and a volcanic
complex (Jurassic). The deposits are of vein type. In this paper, the
mineralogy of three deposits were determined on the basis of calcographic
studies and show a typical paragenesis of Pb-Zn deposits. Keywords: lead, zinc, mineralization, Northpatagonian
Massif. |
|
CARACTERIZACIÓN DE LOS FLUIDOS
HIDROTERMALES EN EL ÁREA CHISPAS, ESTE DEL MACIZO DEL DESEADO, PROVINCIA DE
SANTA CRUZ GUIDO,
Diego CONICET - FCNyM (UNLP), Instituto de Recursos
Minerales (INREMI). La Plata. E-mail: instituto@inremi.unlp.edu.ar ABSTRACT: HYDROTHERMAL FLUID
CHARACTERIZATION AT CHISPAS AREA, EAST OF THE DESEADO MASSIF, SANTA CRUZ
PROVINCE. Hydrothermal fluids of the
Chispas area were characterized with fluid inclusions and oxygen and sulphur
stable isotopes from the Stockwork quartz veinlets. These studies point out
that the composition of the mineralising fluids in the Chispas area had
formed in an H2O-NaCl system, without CO2 in the vapour
face, at an estimated temperature (Th) of 285°C and a 4.86 NaCl eq. wt% salinity. The oxygen
isotope composition (δ18OSMOW=-5.05‰) shows that fluids had an
important meteoric input, with affinities to local meteoric waters (-6 to
-11‰). Sulphur isotope (δ34Sfluid=0,02‰) indicates that S source is related with middle to upper Jurassic volcanism (Bahía Laura Group
and Bajo Pobre Formation). The low content of δ18O, together
with the high Th of Chispas, allow to interpret that this deposit is relatively
deep if compared with the rest of the known Deseado Massif epithermal
deposits. Also a deepness estimation of 800 m below surface was done.
Considering salinities of Chispas and Deseado Massif epithermal deposits, it
can be concluded that hydrothermal fluids of the Deseado Massif are
characterized by a higher salinity than classic low sulfidation deposits. Keywords: Deseado
Massif, Chispas, hydrothermal fluids, epitermal deposits
|
|
MANIFESTACIONES EPITERMALES
AUROARGENTÍFERAS EN LA ESTANCIA EL ÁGUILA, SECTOR ORIENTAL DEL MACIZO DEL
DESEADO, PROVINCIA DE SANTA CRUZ GUIDO,
Diego* y TIBERI, Pedro** * CONICET - FCNyM (UNLP), Instituto de Recursos Minerales (INREMI). La
Plata. E-mail: instituto@inremi.unlp.edu.ar ** La Manchuria 50 (9400) Río Gallegos. ABSTRACT: AUROARGENTIFEROUS EPITHERMAL OCCURRENCES IN
THE EL AGUILA FARM, EASTERN DESEADO MASSIF, SANTA CRUZ PROVINCE. El Águila area shows precious metal-rich
mineralization, associated with four vein zones (El Águila, Sur, Negra and
del Stockwork). These veins are hosted in volcanic rocks of the Bahía Laura
Group and they are composed by quartz and chalcedony with typical epithermal
textures. Ore minerals are pyrite and chalcopyrite disseminated in the veins,
together with some Fe-Mn oxides. Hydrothermal alteration is restricted to
veins and shows mainly silicification and argillization. Geochemical analysis
evidence important anomalies in precious metals, very rich in Au (Ag:Au
<17), with values up to 30.5ppm Au and 51ppm Ag. Oxygen isotope composition
from El Águila vein quartz is -3.18‰ (δ18OFLUID),
indicating a mixture of meteoric and magmatic waters in the hydrothermal
fluids. The El Águila mineralization is interpreted as a low sulfidation
epithermal system and can be included in the Auroargentiferous Deseado
Province. Keywords: Deseado Massif, El Águila, epithermal mineralization
|
|
CERRO LEON, UNA VARIACION DEL
MODELO EPITERMAL DE BAJA SULFURACION DEL MACIZO DEL DESEADO JOVIC
Sebastián1, GUIDO Diego 1-2; TIBERI Pedro 3
y SCHALAMUK Isidoro 1-2 1 Instituto de Recursos Minerales (INREMI). La Plata. E-mail:
instituto@inremi.unlp.edu.ar 2 CONICET y Facultad de Ciencias Naturales y Museo (UNLP) 3 La Manchuria 50 (9400) Río Gallegos. ABSTRACT: CERRO LEON, A VARIATION FROM THE LOW
SULFIDATION EPITHERMAL MODEL OF THE DESEADO MASSIF. Cerro León area presents base metal and precious
metal-rich mineralization, associated with structurally controlled (El
Tranquilo fault) quartz veins. The veins are hosted in volcaniclastic rocks
(Roca Blanca Formation) and continental sedimentary rocks (El Tranquilo
Group), and they are spatially associated with a basic-intermediate volcanism
(Bajo Pobre and Cerro Leon Formations). This multiple mineralization stage
veins are characterised by epithermal temperatures, between 155.87° and
245.7°C (calculated from sulphur isotopes). They have low sulfidation
characteristics (structural control, quartz textures and hydrothermal
alteration). On the other hand, base metal content (up to 0.08% Cu, 1.2% Pb
and 0.11% Zn in average.), the proportion of sulphides (20 to 90% in volume),
the complex mineralogy and the differences in magmatic and host rock
settings, are indicating the presence of variations in the low sulfidation
epithermal model from the Deseado Massif. This increases the potential to
find different epithermal deposits with other metallogenical associations,
and must be considered during future prospecting duties in the Deseado
auroargentiferous province. Keywords:
Deseado Massif, Cerro León, metalliferous mineralization, epithermal model
|
|
ALTERACIÓN HIDROTERMAL Y
PETROGRAFÍA DE INCLUSIONES FLUIDAS APLICADAS A LA EXPLORACIÓN DEL PÓRFITO
CUPRÍFERO BAJO SAN LUCAS, CATAMARCA KORZENIEWSKI,
Lidia Inés* y GODEAS, Marta C.* (*) IGRM – Servicio Geológico Minero Argentino.
Julio A. Roca 651 – piso 8, sector 9. 1322. Ciudad de Buenos Aires mgodea@secind.mecon.gov.ar;
ikorze@secind.mecon.gov.ar ABSTRACT: HIDROTERMAL ALTERATION AND FLUID INCLUSIONS
PETROGRAPHY APPLIED TO YHE EXPLORATION OF BAJO SAN LUCAS PORFHYRY COPPER,
CATAMARCA. Fluid inclusions petrography and hydrothermal alteration are
useful to define the setting of porphyry copper hydrothermal systems, and
identify sectors and zones in this kind of system. It is emphasized the
importance these methods have in mining exploration as a simple, quick and
cheap tool; they provide also useful information for programming their mining
exploitation. Keywords: fluid inclusions, porphyry copper, early stage,
late stage, potassic alteration. |
|
EL LINEAMIENTO DE TUCUMÁN COMO GUÍA DE PROSPECCIÓN PARA DEPÓSITOS
MINERALES. LAZARTE,
José E. Fac. de Ciencias Naturales e Instituto Lillo, UNT. CONICET Miguel Lillo 205, (4000) Tucumán
(jelazar@csnat.unt.edu.ar). ABSTRACT: THE LINEAMENT OF TUCUMÁN AS A GUIDE FOR PROSPECTING
OF ORE DEPOSITS. In this paper the lineament of Tucumán as a guide to
prospecting of ore deposits is proposed. On the basis of structural intersections
and the location of many ore deposits (Cu, Au, Ag, W, Sn, etc.), the
lineament of Tucumán appear as a fertile guide for poorly exposure terrains. Key words: tectonic lineaments, ore deposits,
prospecting guide, magmatism. |
|
ISOTOPOS ESTABLES DE
LAS MANIFESTACIONES EPITERMALES DEL AREA LA JOSEFINA, MACIZO DEL DESEADO,
PROVINCIA DE SANTA CRUZ MOREIRA Pilar*, FERNÁNDEZ Raúl**,
ECHEVERRY Ricardo* y SCHALAMUK Isidoro A*. *Instituto de Recursos Minerales-UNLP-CONICET.
e-mail: pilimoreira@yahoo.es **Instituto de Recursos Minerales-UNLP-CICBA. ABSTRACT: STABLE ISOTOPES FROM EPITHERMAL OCCURRENCES OF
LA JOSEFINA AREA, MACIZO DEL DESEADO, SANTA CRUZ PROVINCE. Oxygen isotope results on quartz samples and oxygen
and carbon isotopes on calcareous stromatolites samples from epithermal
occurrences of La Josefina of the Deseado Massif are presented here. The d 18
OSMOW values of the quartz vein range from 3 to 8.1 ‰ and of the
silica superficial occurrences is 10.1 ‰. The d18O and the d13C values of the calcite range from 16.12 to 22.25 ‰
and -2.7 to 4.7 ‰. The calcareous and silica shallow precipitates are clearly
enriched in 18O from quartz of deeper veins. Keywords: stable isotopes, Au-Ag epithermal
occurrences, calcareous stromatolites, La Josefina, Deseado Massif. |
|
CARACTERIZACIÓN DE LA ESFALERITA DE LAS
MANIFESTACIONES EPITERMALES DEL AREA LA JOSEFINA, MACIZO DEL DESEADO,
PROVINCIA DE SANTA CRUZ MOREIRA
Pilar*, FÉRNANDEZ Raúl**, RÍOS Francisco J.*** y SCHALAMUK Isidoro B.**** *Instituto
de Recursos Minerales-UNLP-CONICET.e-mail: pilimoreira@inremi.unlp.edu.ar ** Instituto de Recursos Minerales-UNLP-CICBA.
e-mail:rfernand@inremi.unlp.edu.ar ***CDTN- Comissão Nacional de Energia Nuclear,
Brasil: e-mail: javier@cdtn.br **** Instituto de Recursos Minerales-UNLP-CONICET.
e-mail:ischala@inremi.unlp.edu.ar ABSTRACT: SPHALERITE
CHARACTERIZATION FROM EPITHERMAL OCURRENCES OF LA JOSEFINA AREA, MACIZO DEL
DESEADO, SANTA CRUZ PROVINCE.
Fluid inclusions and % molar SFe content in
sphalerite from La Josefina, Santa Cruz province, were studied.
Homogenization temperatures reached 190 to 200 oC and salinities
are 1.7-3.39% (NaCl equiv.). Content of Fe in sphalerite ranges from 3 to 5.2
% molar SFe indicating that the sulfidation state of the gold-rich fluids in
La Josefina is intermediate to low. Keywords: epithermal deposit, sulfidation state,
sphalerite SFe % molar content, fluid inclusions, Macizo del Deseado. |
|
INCLUSIONES FLUIDAS E ISÓTOPOS ESTABLES DE
ESTRUCTURAS VETIFORMES, ESTANCIA LA ESPERANZA, MACIZO DEL DESEADO, SANTA CRUZ MYKIETIUK, Karina * y CURCI, Marcela ** *CONICET-INREMI, Fac. de
Ciencias Naturales y Museo, UNLP. e-mail: mykietiuk@yahoo.com **INREMI, Fac. de Ciencias
Naturales y Museo, UNLP. e-mail: marcecurci@yahoo.com ABSTRACT: FLUIDS INCLUSIONS AND STABLE ISOTOPES OF VEINS
STRUCTURES, LA ESPERANZA FARM, DESEADO MASSIF, SANTA CRUZ. Fluid inclusion and stables isotopes studies are
made in the La Esperanza area (central part of the Deseado Massif, Santa
Cruz) in a sector called Vetas del Sur, where is well developed a quartz
veins and veinlets epithermal system. The salinity of primary fluid
inclusions ranges between 3.39 to 6.45wt% NaCl equivalent, while secondary
fluid inclusions rise up to 9.21 to 12.16wt% NaCl equivalent. Temperatures
were 180°and 270°C, respectively. The δ 18OSMOW
(‰) calculated values for the fluid in equilibrium with quartz were
approximately –8.5‰, values really closed related to the meteoric circulated
water in Jurassic times at the Deseado Massif. This study revealed a
structurally high position inside the epithermal system with an important
meteoric water contribution. Keywords: epithermal, fluid
inclusions, stable isotopes |
|
DEPÓSITOS JURÁSICOS DE UN LAGO
GEOTERMAL EN EL CERRO TORNILLO, MACIZO DEL DESEADO, SANTA CRUZ MYKIETIUK, Karina * y
LANFRANCHINI, Mabel ** *CONICET-INREMI, Facultad
de Ciencias Naturales y Museo, UNLP. e-mail: kmykietiuk@inremi.unlp.edu.ar **CONICET-INREMI, Facultad de
Ciencias Naturales y Museo, UNLP. e-mail: mlanfranchini@inremi.unlp.edu.ar ABSTRACT: JURASSIC GEOTHERMAL LAKE DEPOSITS IN THE
TORNILLO HILL, DESEADO MASSIF, SANTA CRUZ. The Tornillo hill is located in the central part of
the Deseado Massif, Santa Cruz province, Argentina. Their outcropping rocks
were formed in a volcanic environment related to lake sediments. The main
hydrothermal alteration recognized is silicification. Geochemical analysis
show anomalies in Hg, As, Sb and Mn, indicating a strong participation of
magmatic volatiles. The stable isotopes δ 18O values in quartz are very close to meteoric waters
values calculated for Jurassic times. Indeed, the Tornillo hill was
interpreted as a geothermal lake, with an associated sinter deposit. This
paper is devoted to the geological characterization, stable isotopes analysis
and geochemistry of hydrothermal alteration at Tornillo hill. Keywords: stable isotopes,
acid lake, sinter, geothermal system. |
|
IDENTIFICACIÓN DE ALTERACIÓN HIDROTERMAL EN LA FORMACIÓN CHON
AIKE MEDIANTE LA APLICACIÓN DE ESPECTROMETRÍA DE RAYOS GAMMA, SECTOR CENTRAL
DEL MACIZO DEL DESEADO, PROVINCIA DE SANTA CRUZ PEÑALVA,
Gabriela A.*, CHERNICOFF Carlos J.*, FERNÁNDEZ, Raúl R.** y PALACIO, Belén*** *CONICET
- SEGEMAR. e-mail: gpenia@minproduccion.gov.ar ; jchern@secind.mecon.gov.ar **
INREMI - CICBA. e-mail: rfernand@inremi.unlp.edu.ar ***SEGEMAR. e-mail: mapala@minproduccion.gov.ar ABSTRACT: A
study of the radioelement content (K, U y Th measured by gamma ray
spectrometry) of the Chon Aike Formation in the area comprised between 47º44’
- 48º09’ S and 70º - 69º15’ W is
presented, and its relationship with hydrothermal alteration processes is
established. High concentrations of Th and U in ignimbrites are associated
with metamict accessory minerals. Silicified zones are characterized by K and
Th depletion, with unchanged or increased U content. Finally, hydrothermal
alteration indicators such as low Th/K ratio and high K anomalies, as well as
anomalous values of the empirical parameters “F” and “Kd”, delimit targets
characterized by argillic alteration and potassic metasomatism. Keywords: gamma-ray
spectrometry, Chon Aike Formation, hydrothermal alteration. |
|
CARACTERISTICAS DE LAS ROCAS ÍGNEAS DEL C° LAS
MINAS Y SU VINCULACIÓN CON LOS SKARNS (Fe) DE VEGAS PELADAS, CORDILLERA
PRINCIPAL, SO DE MENDOZA Pons, M. Josefina.*, Franchini, Marta.**, Schalamuk,
Isidoro. B., ***, Ulbrich, Mabel.**** *CONICET-INREMI-CIMAR, Universidad Nacional del
Comahue. josepons74@yahoo.com.ar **CONICET-CIMAR, Universidad Nacional del Comahue.mfranchi@uncoma.edu.ar ***CONICET-INREMI, Universidad Nacional de La Plata.
ischala@museo.unlp.edu.ar ****Instituto
de Geociencias, Universidad de Sao Paulo, Brasil. mulbrich@usp.br ABSTRACT: CHARACTERISTICS OF THE CERRO LAS MINAS IGNEOUS
ROCKS AND THEIR RELATION TO THE VEGAS PELADAS (Fe) SKARN, CORDILLERA
PRINCIPAL, SW MENDOZA. At Vegas Peladas, four Neogene igneous
units with a wide compositional range (gabbrodiorite to granite) intruded the
Jurassic sediments causing a widespread metamorphic aureole, hydrothermal
alteration (skarnification) and Fe mineralization. District-scale mapping of
hornfels and skarn mineralogical zonations has identified gabbrodioritie as
the parental pluton to the Fe skarn of the area. This pluton exhibits low SiO2,
K2O and incompatible elements, but high MgO, compatible elements
and magnetite contents, similar to igneous rocks associated with world- class
Fe skarns. Keywords: igneous rocks, iron skarns, argentine |
|
GÉNESIS DEL TALCO VINCULADO A
LAS ROCAS ULTRABASICAS DE LA FORMACIÓN CORTADERAS. PREVILEY,
Lorena (1) y SIMON, Wilko(2). (1) Instituto de Geología (INGEO) de la U.N.S.J. y CONICET (2)Cátedra de Yacimientos Minerales y Prospección Geoquímica Departamento
de Geología, U.N.S.J. ABSTRACT:
GENESIS AND EVOLUTION OF TALC RELATED TO ULTRABASIC
ROCK OF THE CORTADERAS FORMATION.
This paper explains the genesis and evolution of talc related to
ultrabasic rock cropping out in the Quebrada de los Pozos, a locality in the
Nortwestern part of the Precordillera of the province of Mendoza (Argentina).
These rocks belong to the Cortaderas Formation (Fig. 1b). In this zone exist
two types of talc. The first one, yellowish buff, stained y iron oxides, with
fibrous habit, occurs in bancs not surpassing 0.50 meters in thickness,
interbedded with the ultrabasic rocks and black phillites. The second type of
talc is silvery white in colour, scaly, with greasy luster, very soft to the
touch, and is found in 0.90 metres thick and 24 metres long veins. The first
type was originated simultaneously with the serpentinization, by hydrothermal
and metamorphic processes that acted jointly on the ultrabasic rocks during
the evolution of an oceanic rift. The second one was formed by a later
hydrothermal event, the solutions of which circulated through strike slip
faults of a system running along the Quebrada de los Pozos and which affected
the serpentinized rocks. Keywords: Precordillera, Talc, Ultrabasic Rocks, Serpentinization. |
|
COMPOSICIÓN Y ENRIQUECIMIENTO DE LOS FOSFATOS SEDIMENTARIOS MARINOS EN
FORMACIONES CRETÁCICAS. PALEÓGENAS Y NEÓGENAS DE PATAGONIA, ARGENTINA TOURN,
Selvia1, CASTRO, Liliana1 y SCASSO, Roberto 1,2 1Departamento de Geología, Facultad de Ciencias Exactas y Naturales,
Universidad de Buenos Aires, Argentina; 2CONICET. selvia@fl.fcen.uba.ar;
lilianacastro@fibertel.com.ar; rscasso@gl.fcen.uba.ar. ABSTRACT: COMPOSITION AND ENRICHMENT OF CRETACEOUS, PALEOGENE
AND NEOGENE SEDIMENTARY MARINE PHOSPHATES IN PATAGONIA ARGENTINA. Major and trace elements composition is studied from
phosphatic concretions of three ocurrences in Patagonia (Lefipan, Rio Claro
and Gaiman Fms). The major-element
chemistry of phosphorites reflects both the composition of francolite and
that of the associated minerals such us calcite, glauconite and goethite. Carbonate-fluorapatite is the main mineral phase
occurrence in phosphatic levels. According to chemical analyses the
level of substitution shown by francolite decreases progressively with
increasing ages, which promotes a transition towards fluorapatite. The
elevated SiO2 and, to a lesser extent, Al2O3
and NaO2 contents indicate the higher proportions of quartz and
minor clay minerals in Patagonian deposits. The open apatite structure
facilitates trace elements substitution promoting an enrichment in Sr, U, Y
and REE, and depletion of Co, Sn and Ga. Keywords: sedimentary phosphates – francolite- Patagonia
|
|
|
|
PETROLOGÍA |
|
|
|
METASOMATISMO MODAL Y CRÍPTICO EN XENOLITOS DE MANTO DEL
NORTE DE SANTA CRUZ, ARGENTINA ALIANI, Paola
1, BJERG, Ernesto 1 y NTAFLOS, Theodoros 2 1. CONICET - Departamento de
Geología, Universidad Nacional del Sur, San Juan 670, B8000ICN Bahía Blanca,
Argentina. E-mail: geoauto@criba.edu.ar 2.
Department of Geological Sciences, University of Vienna, Althanstrasse 14, A-1090 Wien, Austria.
E-mail: theodoros.natflos@univie.ac.at ABSTRACT: MODAL AND
CRYPTIC METASOMATISM IN MANTLE XENOLITHS FROM THE NORTH OF SANTA CRUZ,
ARGENTINA. Ultramafic
xenoliths from Estancia Poklepovic, Santa Cruz province, Argentina, comprise
lherzolites, harzburgites and wehrlites, hosted by alkaline lavas and cinder
cones. Most of the samples carry glass veins and/or melt
pockets and most of them also bear amphibol, mica or both. Criptic
mestasomatism is demonstrated by enrichment of light rare earth elements in
bulk rock analyses of samples devoid of hydrous phases, melt pockets and
glass veins. Modal metasomatism is evident in samples carrying hydrous
phases, melt pockets and glass veins, which led to high contents of
incompatible elements in bulk rock analyses. Textural evidences suggest that
two metasomatic events affected this part of the mantle. One event allowed
the crystallization of amphibol and mica, and the second is responsible for
the melt pockets. The presence of glass veins (± carbonate) in samples devoid
of melt pockets is a strong evidence in favour of a third metasomatic
episode. Textural evidences demonstrate that at least part of the carbonate
was precipitated from meteoric water rich in carbonates. Keywords: mantle, xenoliths, metasomatism,
petrography, chemistry. |
|
LOS NÓDULOS DE CORDIERITA-Na EN LOS ESQUISTOS DE LA FORMACIÓN TUCLAME,
SIERRAS PAMPEANAS DE CÓRDOBA BALDO, Edgardo G. A.* y
VERDECCHIA, Sebastián O.**
* Escuela de
Geología, Fac. Cs. Ex. Fís y
Nat., UNC – CONICET. ebaldo@com.uncor.edu.ar ** Escuela
de Geología, Fac. Cs. Ex. Fís y Nat. – UNC. ABSTRACT: THE NODULES OF Na-CORDIERITE IN
THE TUCLAME FORMATION SCHISTS, SIERRAS PAMPEANAS DE CÓRDOBA. The
Lower Cambrian schists of the Tuclame Formation in the NW of the Sierras de
Córdoba have pre-tectonic porphyroblasts of andalucite and cordierite. The
last one forms ovoid nodules differentiated in two sectors, an internal one
with an isopoikilitic blast of Na-Crd1 (0.17-0.25 cpfu of Na and
Xmg = 0.65) and an external one with a decussate texture of Bt + Ms and Pl
(An22) ± St + Qtz + xenoblastic Crd2 (0,08 cpfu
of Na and Xmg = 0,70). The
porphyroblasts are mainly surrounded by a lepidoblastic and
lepidogranoblastic texture with Ms + Bt + Qtz + Pl. The nodules of cordierite
represents a static grew during M-1 metamorphism of medium grade at low
pressure (530ºC and 2-3 kb) and the external foliated matrix represent a new
stage of grew and deformation overprinted to the M-1 event. In this case the
Na concentrations in cordierite would be not depend only the temperature and the high Na in the
Crd1 would depend on the presence of an extra pelitic components like Li and Be coming from the
protolith composition.
Keywords: Na-Cordierite; Low Pressure
Metamorphism; Pampean Orogen; Sierra de Córdoba. |
|
SEGUNDO REPORTE DE CORDIERITAS RICAS EN Na-Be EN ARGENTINA,
SIERRA DE VELASCO DAHLQUIST, Juan* y ALASINO, Pablo** *CRILAR – CONICET, ANPCyT, Anillaco, La Rioja.
e-mail: jdahlquist@crilar-conicet.com.ar **CRILAR – CONICET, Anillaco,
La Rioja. e-mail: palasino@crilar-conicet.com.ar
ABSTRACT: SECOND REPORT OF Na-Be CORDIERITES IN
ARGENTINA, FROM SIERRA DE VELASCO. Na-Be cordierites (Na2O = 15 -1.58% and
estimated BeO = 0.92 - 0.94%) occur in peraluminous granitoid outcrops in
northeastern sierra de Velasco. This
is the second report from Argentina (and probably from world?) of this type
of cordierite founded in granitoids. Based on bulk analysis of the
cordierite, we provisionally argue that Na and Be were introduced through the
substitution 2Na(channel)+2Be(VI-IV) --- Mn(VI)+Si(IV)
and propose a way to estimate the Be content in Na-cordierite. The
crystallization of Na-Be cordierites would have been supported by the
composition of the parental magma, which was derived by melting of
metapelites with a distinctive alkali and Be content and lack of cordierite. Keywords: Na-Be cordierites, peraluminous
granitoid, sierra de Velasco
|
|
Termobarometría Anfíbol-plagioclasa en un
cuerpo ígneo del complejo de las Peñas, Sierra Pampeanas orientales Demichelis, Alejandro1, Hernández,
Laura2, Rabbia, Osvaldo2 y Tibaldi, Alina.2,3 1 Dpto. de Geología, Universidad Nacional de Río Cuarto, Enlaces Rutas
8 y 36, km 601. (5800) Río Cuarto, Argentina.
e-mail: ademichelis@exa.unrc.edu.ar 2 Intituto GEA, Universidad de Concepción, Chile 3
CONICET ABSTRACT:
AMPHIBOLE-PLAGIOCLASE THERMOBAROMETRY OF AN IGNEOUS BODY FROM SIERRA
DE LAS PEÑAS, EASTERN SIERRAS PAMPEANAS. Electron microprobe chemical analyses of amphibole
and plagioclase are presented. Analyzed sample corresponds to a non-deformed
igneous rock in the northern part of Sierra de Las Peñas (southern Sierras
Pampeanas Orientales) and were assigned to the Famatinian cycle. The amphiboles are classified and barometric
(Al-in amphibole) and thermometric (amphibole-plagioclase pair) conditions of
crystallization are determined. Results are discussed in a regional context. Keywords: geothermometry,
geobarometry, igneous rocks, Famatinian cycle, Sierra de Las Peñas |
|
METAMORFISMO, DEFORMACIÓN Y
MAGMATISMO ASOCIADOS EN EL TRAMO MEDIO DE LA SIERRA DE COMECHINGONES,
PROVINCIA DE CÓRDOBA. FAGIANO, Marcelo*, PINOTTI, Lucio.** y
ESPARZA, Ana* *Dpto. de Geología.
Universidad Nacional de Río Cuarto. e-mail: mfagiano@exa.unrc.edu.ar ** CONICET- Universidad
Nacional de Río Cuarto. e-mail: lpinotti@exa.unrc.edu.ar ABSTRACT: METAMORPHIC, DEFORMATION AND ASSOCIATED
MAGMATIC EVENTS IN THE HALF TRACT OF THE SIERRAS DE COMECHINGONES, CÓRDOBA. The Monte Guazú
complex comprise the southern half part of the Sierra de Comechingones,
Córdoba, Argentina. It is constituted by stromate and discreet nebulitic
nuclei, amphibolites and gneisses generated during the Pampean orogeny. These
rocks were transformed during the Famatinian deformation, generating the
Guacha Corral shear zone that was active from the late Ordovician to the
middle Devonian. Finally, the late to post-orogenic intrusion of the Cerro
Aspero batolith, truncated the earlier structures and developed a metamorfic
contact aureole. In this paper we describe a migmatic area affected at
western boundary by the Guacha Corral shear zone, with a transitional zone
between them. This limit separates a Pampean domain at East from a Famatinian
domain at West. It is also inferred that a great part of the Sierra de
Comechingones was affected by Famatinian deformation processes. Keywords: Metamorphic, deformation-magmatic, Comechingones, Argentina
|
|
CROMO ESPINELOS DE LAS AGUILAS,
PROVINCIA DE SAN LUIS, como indicadores tectónicos Ferracutti,
Gabriela1; Bjerg, Ernesto1 y
Mogessie, Aberra2 1 CONICET– Universidad
Nacional del Sur, Departamento de Geología, San Juan 670, B8000ICN Bahía
Blanca, Argentina. E mail: ferracut@criba.edu.ar 2
Institute of Earth Sciences, University of Graz, Universitaetsplatz 2, A8010
Graz, Austria. ABSTRACT: CHROME Spinels from Las Águilas
mafic-ultramafic ROCKS, San Luis, as tectonic tracers The
mafic-ultramafic rocks of the Las Águilas deposit occur 30 km. NE of San Luis
city, Central Argentina. Two groups of spinels were
identified. Both have homogeneous chromian-alumina cores, with one of them
generally displaying cores with higher Al/(Cr+Al) and chromian-aluminian
chromite rims, associated to orthopyroxenites, while the other group occur in
dunites with ferritchromites and chromian-magnetite rims. Based
on spinel chemical features and comparison with spinels from ophiolites, the
Las Aguilas deposit is considered to belong to the worldwide well defined
group of mafic-ultramafic layered continental intrusives. Keywords: spinels, continental layered
intrusions, mafic-ultramafic rocks, Argentina. |
|
DISCUSIÓN
PETROGENÉTICA DE LAS ANATEXITAS DE VILACATO Y EL QUEBRACHO, SIERRA CHICA SUR,
CORDOBA, ARGENTINA GOZALVEZ,
Martín Ricardo(1) y BONALUMI, Aldo Antonio(2) (1)CONICET – Servicio Geológico Minero Argentino. e-mail:
mgozal@secind.mecon.gov.ar (2)Cátedra de Petrología Ígnea y Metamórfica, Facultad de Ciencias
Exactas, Físicas y Naturales, Universidad Nacional de Córdoba. Gerencia de
Minería Córdoba. e-mail:
abonalumi@gtwing.efn.uncor.edu ABSTRACT: PETROGENETIC DISCUTION OF THE VILACATO AND EL QUEBRACHO ANATEXITES,
SOUTHERN SIERRA CHICA, CÓRDOBA, ARGENTINA. The basament of the Vilacato-El Quebracho consists
of inhomogeneous and homogeneous diatexites, stromatitic metatexites and
metasomatic rocks. Four metamorphic events have been recognized. The oldest
is represented by the metamorphic foliation of the resisters (calcosilicate
gneisses) in the diatexites. Second event reached the conditions of
high-grade metamorphism and partial melting, and produced stromatitic
metatexites and diatexites with the following mineral paragenesis: Qtz2+Pl+Bt1+Grt+Kfs.
A cooling + hydration event followed the metamorphic peak is made evident by
biotite coronas around garnet. The last hydration event developed a low
temperatures mineral alteration. The granoblastic and porphyroblastic units
are diatexites whose texture and modal composition were changed by incipient
metasomatism related to infiltration of anatectic fluids. Keywords: diatexites; metatexites; metasomatism;
metamorphic events. |
|
GEOTERMOMETRÍA
DE LOS BASALTOS DE GASTRE, CHUBUT HALLER, Miguel J.* y MASSAFERRO, Gabriela I.* * Universidad Nacional de
la Patagonia San Juan Bosco y CENPAT-CONICET. e-mail: haller@cenpat.edu.ar;
gim@cenpat.edu.ar ABSTRACT: Geothermometric
results in Basalto Crater Volcanic Field, Chubut. The crystallization temperatures of basalts from the
Crater Basalt have been calculated using microprobe data from pairs of
minerals in equilibrium. The pairs used are olivine-liquid, olivine-spinel, olivine-diopsidic pyroxene and ilmenite-magnetite. The olivine-liquid temperature is about 1137°C and
represents the beginning of crystallization of magma, while the lowest
temperatures obtained from ilmenite-magnetite, point out the crystallization
of the groundmass, at about 960°C. Keywords: Geothermometers;
Basalts; Patagonia; Chubut. |
|
Caracterizacion Geologica y Geofisica de los Basaltos de la Sierra de
Queupuniyeu, Provincia de Río Negro Kostadinoff,
Jose, Bjerg, Ernesto, Labudía, Carlos y Ntaflos, Theodoros Abstract: GEOLOGICAL
AND GEOPHYSICAL CHARACTERIZATION OF THE BASALTS OF THE SIERRA DE QUEUPUNIYEU,
RIO NEGRO PROVINCE. Dimension and geometry of
the volcanic conguits feeding the basaltic lavas of the Sierra de Queupuniyeu
was estimated based on rock densities and magnetic susceptibilities. Our
results indicate that volcanism took place along several parallel narrow
conduits, coincident with regional faults recognized in this area. The
magnitude of the magnetic anomalies reflects the high magnetic susceptibility
of the basaltic rocks, with values exceding 0.040 SI. Low values of gamma
radioactivity reflect the mantle origin of the basaltic rocks constituing the
Sierra de Queupuniyeu. Keywords: basalts- gravimetry- magnetometry- density |
|
NÓDULOS
LHERZOLÍTICOS ESPINÉLICOS EN BASALTOS ALCALINOS DEL NORTE DE LA SIERRA DE LOS
CÓNDORES (CÓRDOBA) LAGORIO, Silvia* y
MONTENEGRO, Teresita**
*Departamento de Ciencias Geológicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires; e-mail: lag@gl.fcen.uba.ar ** CONICET y Departamento de Ciencias Geológicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires; e-mail: mon@gl.fcen.uba.ar ABSTRACT: SPINEL
LHERZOLITIC NODULES IN ALKALI BASALTS FROM NORTHERN SIERRA DE LOS CÓNDORES (CÓRDOBA). In the
eastern peninsula of Embalse Río
Tercero, to the east of Cerro
Rumipalla, alkali basalts carrying upper mantle xenoliths crop out. They
are mainly spinel-bearing Cr-diopside lherzolites, with modal composition: Ol
53-65%, Opx 15-30%, Cpx 15-25% and Sp 0-2%. Texture is tabular equigranular to porphyroclastic.
Olivine (Fo89) carry fluid
inclusions with CO2 (L) and glass inclusions. CO2 phase
is pure and homogenization temperature is congruent with high densities, between
0,785 and 0,8699 g/cm3. Trapping pressure for this density range
is 0,57 kb, pointing out a minimum depth of 20km at 1200°C. Inclusions are
primary because of the absence of any linear arrangement. Nevertheless, some
scarce low density inclusions would indicate that a period of residence at
intermediate pressures during
transport can not be ruled out. Keywords: spinel lherzolite, alkali basalt, fluid
inclusions, glass inclusions, Sierra de los Cóndores |
|
MINERALES ACCESORIOS
DIAGNÓSTICOS EN LAS TOBAS MIOCENAS DE LA FORMACIÓN TAMBO, VALLE DEL CURA,
PROVINCIA DE SAN JUAN LITVAK, Vanesa D.* y POMA, Stella* *CONICET – Universidad de Buenos Aires Facultad de Ciencias Exactas y Naturales, Departamento de Ciencias
Geológicas Ciudad Universitaria, Pabellón II, email: vane@gl.fcen.uba.ar,
stella@gl.fcen.uba.ar ABSTRACT: DIAGNOSTIC ACCESORY MINERALS IN THE MIOCENE TUFFS
OF TAMBO FORMATION, VALLE DEL CURA, SAN JUAN PROVINCE. A detalied petrographycal analisis of the
crystalline tuff included in the Tambo Formation of Middle Miocene is
presented in this contribution. This tuffs have a diagnostic mineral
assemblage that differenciate them from the rest of the pyroclastic rocks of
the area; they consist of dacitic crystalline tuffs interpreted as distal
pyroclastic flows. They are formed by a high proportion of crystalline
fragments, shards, and volcanic ash; vitroclast of pumice, and low abundace
of lithics fragments. Plagioclase and quartz are the main crystalline phases;
biotite and amphibole are the characteristic accesory minerals, while
titanite is present as a minor phase. The presence of amphibole and titanite
as accesory phases are diagnostic features of these tuffs. This paragenesis
reflects oxidazing conditions, high pressure and the presence of water during
the formation of the tuffs. Keywords: tuffs, pyroclastic flows, titanite,
amphibole, Valle del Cura |
|
LOS FLUJOS LAVICOS MIOCENOS AL SUR DE LA LAGUNA SOCOMPA, SALTA MAISONNAVE, E. Beatriz* y POMA
Stella M. N**. *Departamento de Cs. Geológicas, FCEyN, UBA. e-mail:
beatriz@gl.fcen.uba.ar ** Departamento de Cs. Geológicas, FCEyN, UBA. y CONICET. e-mail:
stella@gl.fcen.uba.ar ABSTRACT: MIOCENE
LAVA FLOWS TO THE SOUTH OF LAGUNA SOCOMPA, SALTA A new petrographic and
geochemical data set of volcanic rocks of Miocene age are shown. These rocks
are grouped into the Volcanosedimentary Complex Quebrada del Agua, located in
the west of Puna (province of Salta). Two units of flow have been recognized
on which Pliocene volcanic rocks lean. They are grey in colour and their
chemical composition varies between basaltic andesite to trachyandesite of
calcalkaline trend. These rocks correspond to continental arc setting and
they are interpreted as the last expression of arc volcanism in the region,
because the later effusions demonstrate participation of intraplate
components. Key words:
Puna, volcanism, Miocene, continental arc |
|
Manifestación
Geotérmica El Humazo, Volcán Domuyo, Argentina Mas, G.R.1, Bengochea, L.1
y Mas, L.C.2 1 Dep. de Geología. UNS–CONICET.
B. Bca. email: gmas@criba.edu.ar; lbengo@criba.edu.ar 2 EPEN. Gcia. de Ingeniería. Dir. de Energías Alternativas. Nqn. email: lucarmas@yahoo.es Abstract: El Humazo
Geothermal Manifestation, Domuyo Volcan, Argentina This geothermal
manifestation is characterized by water-vapor mixed type fluids, above 200°C
of the geochemical geothermometer, and belongs to an area of high gravity
anomaly with points of local low gravity anomalies. The alteration minerals at
El Humazo have been studied by means of XRD, SEM-EDAX and optical microscopy.
This zone is characterized by the presence of cristobalite, with tridimite
and quartz subordinate. Some zeolites, specially mordenite, stilbite and
heulandite, appear close to and over the fumaroles. These minerals are
arranged in a zonation of alteration around the center of the geothermal
manifestation. Keywords: alteración,
silicificación, zeolitas, El Humazo, Domuyo |
|
condicionES
de emplazamiento de la granodiorita Valle Fértil y su comparación con el
batolito los llanos - ulapes MURRA, Juan A. F.* y BALDO, Edgardo G. A.* *Cátedra de Geología General. Universidad Nacional
de Córdoba. CONICET. jmurra@com.uncor.edu;
ebaldo@com.uncor.edu ABSTRACT: EMPLACEMENT CONDITIONS IN THE GRANODIORITE
VALLE FÉRTIL AND COMPARISON WITH THE LOS LLANOS - ULAPES BATHOLITH. Low Ordovician granodiorite with Qtz - Pl -
Bt - Kfs - Hbl - Ep - Ttn and no deformational texture has been recognized in
the eastern border of the Sierra de Valle Fértil (western margin of
Famatinian Orogen). Thermo-barometric data have been obtained on these rocks
in order to establish crystallization and emplacement conditions. The Hbl -
Pl geothermometer combined with the Al in Am geobarometer is a minimal
P-Tvalue of ~ 750 ºC and 5.5- 6.5 kb. These minimal P-T conditions are higher
than those obtained in rocks of similar composition and age located in the
Sierra de Chepes, Las Minas y Los Llanos, (the central part of Famatinian
Orogen) indicating westwards increasing of magmatism emplacement depth of 10
to 18 km. Keywords:
Valle Fértil; Famatnian Orogeny; thermobarometry; Chepes-Las Minas-Los
Llanos. |
|
Texturas
coroníticas en las rocas ultramáficas de las sierras de La Huerta y Las
Imanas: descripción Y ESTIMACIONes P-T MURRA, Juan A. F.* y BALDO, Edgardo G. A.* *Cátedra de Geología General. Universidad Nacional
de Córdoba. CONICET. jmurra@com.uncor.edu;
ebaldo@com.uncor.edu ABSTRACT: CORONITIC TEXTURES IN ULTRAMAFIC
ROCKS IN THE SIERRA DE LA HUERTA AND LAS IMANAS: description AND P-T CONDITIONS. In the sierra of
Valle Fértil - La Huerta, located in the central - western sector of the
Sierras Pampeanas, small bodies of ultramafic rocks have been recognized constituted
by Opx - Cpx - Pl - Am - Spl, they exhibit
development of concentric and kelifític coronitic textures, attributed
to subsolid reactions in post-magmatic events. The P-T conditions of the
coronitic event was calculated to be ~ 720 ºC and 4.1 kb. These conditions
are lower than those atributed to the M2 metamorphic pick of the region (~
760 ºC and 6 - 7.5 kb), and suggest that the magmatic associations were
retrograded, producing the coronitic textures in the pyroxenites. The
coronitic reaction texture is generated during M4 metamorphic event. Keywords:
Valle Fértil-La Huerta; ultramafic; pyroxenite; coronitic textures. |
|
MINERALOGÍA MAGNÉTICA DE GRANITOIDES DE LAS SIERRAS DE CÓRDOBA PINOTTI,
Lucio*, D’ ERAMO Fernando*, Vegas
Néstor***, TUBÍA José M.****, CONIGLIO, Jorge** * CONICET- Departamento de Geología,
FCEFQy NAT. Universidad Nacional de Río Cuarto. e-mail: lpinotti@exa.unrc.edu.ar.
fjderamo@exa.unrc.edu.ar ** Departamento de Geología, FCEFQy NAT.
Universidad Nacional de Río Cuarto. e-mail: jconiglio@exa.unrc.edu.ar *** LMTG,
Equipe de Pétrophysique, Université Paul Sabatier, 38, rue des 36-Ponts,
31400 Toulouse, France. E-mail: gobvetun@lg.ehu.es. ****
Dpto. Geodinámica UPV, Apartado 644, Bilbao, España. E-mail: gpptuxxj@lg.ehu.es ABSTRACT:
MAGNETIC MINERALOGY OF GRANITES, SIERRAS DE CÓRDOBA Magnetic
studies were perfomed in the Alpa Corral, El Talita and El Hongo plutons
(Sierras Pampeanas de Córdoba). The K values reveal a correlation with
different petrographic facies. Thermomagnetic curves and coercitivity spectra
revealed that coarse-grained early crystallized magnetite is the main
ferromagnetic mineral in these rocks. Keywords: magnetic mineralogy, granites,
anisotropy of remanent magnetization. |
|
UN FLUJO PIROCLÁSTICO
DEL TRIÁSICO EN LA FORMACIÓN PARAMILLO, PROVINCIA DE MENDOZA POMA, Stella*, QUENARDELLE, Sonia*
y KOUKHARSKY, Magdalena* Laboratorio de Petrología,
Departamento de Ciencias Geológicas, FCEN (UBA) y CONICET stella@gl.fcen.uba.ar; sonia@gl.fcen.uba.ar;
mkou@gl.fcen.uba.ar ABSTRACT:
A TRIASSIC PYROCLASTIC FLOW FROM PARAMILLO FORMATION, MENDOZA PROVINCE. A succession of thin
greyish green color levels with sandy appearance is interpreted as a
pyroclastic flow. Detailed studies based on a 50 meters thick stratigraphic
profile and petrographic studies, allow us to identify an hydromagmatic
eruption. That process originated a fast succession of diluted volcaniclastic
flows. The vent zone could have been to the northwest of the profile surveyed. Keywords:
Precordillera, Triassic, pyroclastic deposit, Paramillo Formation |
|
IDENTIFICACION DE
PROTOLITOS DEL BASAMENTO GNEISICO DE LAS SIERRAS DE LA HUERTA Y VALLE FERTIL,
SIERRAS PAMPEANAS OCCIDENTALES, PROVINCIA DE SAN JUAN, MEDIANTE CRITERIOS
GEOQUIMICOS. PREVILEY,
Lorena1,2 y CASTRO de MACHUCA, Brígida1,2,3 1Consejo
Nacional de Investigaciones Científicas y Técnicas (CONICET). e-mail: lpreviley@unsj-cuim.edu.ar
/ bcastro@unsj-cuim.edu.ar 2 INGEO,
FCEFN, Universidad Nacional de San Juan. 3 Departamento
de Geofísica, FCEFN, Universidad Nacional de San Juan. ABSTRACT: IDENTIFICATION OF PROTOLITHS OF BASEMENT GNEISSES
FROM LA HUERTA AND VALLE FERTIL RANGES, WESTERN PAMPEAN RANGES, PROVINCE OF
SAN JUAN, USING GEOCHEMICAL CRITERIA. In La Huerta and Valle Fertil ranges, Western
Pampean Ranges, province of San Juan, a medium to high-grade metamorphic
basement crops out. It is composed mainly of Grt-Bt±Sil gneisses, amphibolites and marbles. The
combination of petrographical and geochemical (whole-rock major elements)
analyses of the gneisses indicate that they derived from a sedimentary source
comprising a succession of pelites and semipelites and minor greywackes, that
was part of an active margin sequence. The comparison of bulk rock
compositions of the gneisses with the rock data base provided by the Ancomp
program (Röhr, 1997) confirms the nature of the protoliths. Keywords: gneisses * petrography
and geochemistry * sedimentary protoliths * sierra de La Huerta * sierra de
Valle Fértil |
|
EL GRANITO PRIMAVERA (SIERRA DE FIAMBALÁ)
CONSIDERACIONES SOBRE SU EDAD QUENARDELLE, Sonia M.* y POMA,
Stella* *Departamento de Ciencias Geológicas,
FCEN (UBA) y CONICET email: sonia@gl.fcen.uba.ar;
stella@gl.fcen.uba.ar ABSTRACT: LA
PRIMAVERA GRANITE (SIERRA DE FIAMBALA), CONSIDERATIONS ABOUT ITS AGE.
The goal of this paper is to present the lithology, the
geologic relationships and a geocronologic data of one of the numerous
granitoids of the connection between Northern Pampean Ranges – Puna geologic
provinces. The La Primavera Granite is located in the northern block of the
Sierra de Fiambalá, in the province of Catamarca (Argentina). This is
monzogranitic in composition and it has green schists metamorphism
overimposed. Their mineralogic paragenesis and geologic characteristics
compare it with the so called "La Puntilla orthogneiss". Both bodies
are located in the same block of the mountain range but La Primavera has less
deformation. The biotite K/Ar age obtained in this step of the research
points out the closing age of the last metamorphism that would had affected
the zone. And this is concordant with the timing of intrusion represented by
the postectonic granitoids of the Carboniferous time. Keywords: La Primavera Granite, Sierra de Fiambalá, La Puntilla
orthogneiss, metamorphism, Carboniferous. |
|
TERMOBAROMETRIA DE LAS CORNEANAS GRANATIFERAS DEL FLANCO SUDOCCIDENTAL
DE LA SIERRA DE VELASCO. LA RIOJA, ARGENTINA ROSSI,
Juana N.H y TOSELLI, Alejandro J.H HFacultad Ciencias Naturales -
Universidad Nacional de Tucumán – ajtoselli@infovia.com.ar ABSTRACT: THERMOBAROMETRY OF THE GARNET – BEARING
HORNFELSES IN THE SOUTHWESTERN MARGIN OF THE SIERRA DE VELASCO, LA RIOJA,
ARGENTINA. Small, long-shaped biotite – bearing
granodiorite and tonalite granitoids can be observed in the
southwestern margin of the Sierra de Velasco (29º 21' - 29º 24 ' S and
67º11'- 67º 16' W). They
display an approximately 6 km long Northwest-Southeast trending, with a
probable Lower Ordovician age representing marginal facies of major
porphyritic two-mica monzogranite plutons. Tonalites and granodiorites
display scarce remnants of the metasedimentary country rock, as septa and
enclaves, ranging from several centimeters to 15 meters in size. The latter
are metamorphized in massive fine-grained dark hornfelses, someones
quartz–plagioclase-biotite rich type, while others, metapelitic with
alkali-feldspar (pertite), quartz, biotite, cordierite, sillimanite and
garnet as dispersed granular masses. This first record of high
temperature paragenetic garnet-
bearing hornfelses found with cordierite-alkali feldspar and biotite in
granites of the Batholitic Central Area, implying deeper intrusion levels for
the granitoids of the southwestern margin of the Sierra de Velasco.
Thermobarometric data indicate that hornfelses equilibrated at a pressure of
4.8 Kbar and a temperature of 640º C. Key words: Sierra de Velasco – granitoids –
garnet-cordierite hornfelses – thermobarometry. |
|
ORIGEN DE LOS ANFÍBOLES Y
TERMOMETRÍA ANFÍBOL-PLAGIOCLASA EN LAS ROCAS MÁFICAS DEL COMPLEJO SUYA TACO,
SIERRA DE COMECHINGONES, PROVINCIA DE CÓRDOBA. TIBALDI,
A. M.1,2, OTAMENDI, J.E1,2 y DEMICHELIS, A.H.1 1 Departamento de Geología Universidad Nacional de Río Cuarto, 5800 Río
Cuarto, Argentina. e-mail:
atibaldi@exa.unrc.edu.ar 2 CONICET ABSTRACT: ORIGIN DE LOS ANPHIBOLES AND ANPHIBOL-PLAGIOCLASE
THERMOMETRY IN THE MAFIC ROCKS FROM SUYA TACO COMPLEX, SIERRA DE
COMECHINGONES, PROVINCE OF CÓRDOBA. Some mafic rocks in the
Suya Taco complex (Sierra de Comechingones) have an important concentration
of amphiboles. These minerals have been classified like calcic amphibole.
Pargasite is the predominant amphibole whereas edenite and actinolite are in
less proportion. The amphibole solid-solution is dominated by pargasite
end-member with variable substitution of tschermak exchange component.
Occasionally, pargarsite-actinolite assemblage is affected by glaucophane
exchange. The equilibrium temperatures computed from amphibole-plagioclase
thermometry are 836-1023 °C, 802-870 °C and 702-720 °C when using
edenite-plagioclase, pargasite-plagioclase and actinolite-plagioclase,
respectively. These conditions were obtained for pressures ranging from 4 to
7 Kbar that are representative of the emplacement of the mafic magmas.
Moreover, textural relations together with estimated P-T conditions suggest
that the amphiboles did not form in equilibrium with the mafic magma. Keywords:
amphibole, thermometry, barometry, mafic rocks, Sierra de Comechingones. |
|
LOS ESQUISTOS CON
NÓDULOS CORDIERÍTICOS DE LA FORMACIÓN TUCLAME, SIERRAS PAMPEANAS DE CÓRDOBA:
RELACIONES DE BLÁSTESIS – DEFORMACIÓN VERDECCHIA,
Sebastián O.* y BALDO, Edgardo G. A. **
* Escuela
de Geología, Fac. Cs. Ex. Fís y Nat. – UNC ** Escuela
de Geología, Fac. Cs. Ex. Fís y Nat., UNC – CONICET.
ebaldo@com.uncor.edu.ar ABSTRACT:
THE CORDIERITE NODULAR SCHISTS IN THE TUCLAME FORMATIONS, SIERRAS PAMPEANAS
DE CÓRDOBA: BLASTESIS-DEFORMATIONS RELATIONS.
The metapelitic schists
of the Tuclame Formation at the NW of the Sierra de Córdoba have ovoid
porphiroblasts of cordierite, xenoblasts of andalucite with an isopoikilitic
inclusions pattern, and a relic decussate fabric. All of them represent a
first static grew during a M-1 metamorphic event at low pressure and medium
grade. The probable age of M-1 is Lower Cambrian. The ovoid shape of cordierite porphiroblasts and the relic Sn+1
foliation in the porphiroblasts would be related with a first deformational
event post M-1 (D-1 event). The external lepidoblastic texture surrounds the nodules usually at an angle
of < 70º to the Sn+1 suggesting a second stage of deformation
and recrystallisation (D-2, M-2). The last one retrogrades the M-1
paragenesis at low grade metamorphic conditions.
Keywords: Low pressure
metamorphism; Pampean Orogeny;
Formación Tuclame; Sierras de Córdoba. |