scholarly journals The Buenaventura Sector of the San Finx W–Sn Deposit (NW Spain): Ore Mineralogy, Host Rocks and Associated Hydrothermal Alteration

2021 ◽  
Vol 6 (1) ◽  
pp. 11
Author(s):  
David Garófano-Medina ◽  
Mercedes Fuertes-Fuente ◽  
Antonia Cepedal ◽  
Agustín Martin-Izard
Keyword(s):  
Hydrothermal Alteration ◽  
Nw Spain ◽  
Ore Deposit ◽  
Main Host ◽  
Ore Minerals ◽  
Ore Mineralogy ◽  
Native Bismuth ◽  
Host Rocks ◽  
Spanish Province

The San Finx W–Sn ore deposit is located in the Spanish province of A Coruña (Galicia, NW Spain). Geologically, it occurs in the Galicia-Trás-os-Montes zone which is one of the innermost zones of the Iberian Variscan collisional belt. This ore deposit is characterized by NE–SW trending quartz-dominated veins with centimeter-size hübnerite and cassiterite. This research focuses on one sector of this deposit known as Buenaventura. The aim of this work is to present a mineralogical and petrological characterization of the ore-bearing veins, their host rocks and associated hydrothermal alteration. The vein mineralogy is mainly quartz, muscovite, K-feldspar, apatite and scarce fluorite. The ore minerals are hübnerite, scheelite and cassiterite with columbite and ilmenorutile-struverite inclusions, together with sulfides, mainly chalcopyrite and arsenopyrite, and, in less abundance, molybdenite, löllingite, pyrrhotite, sphalerite, stannite, pyrite, Bi-Pb-Ag sulfosalts and native bismuth. The main host-rocks are micaschist and paragneiss and two types of pegmatites, homogeneous pegmatites and banded aplite-pegmatites with columbite. The host rocks are affected by four types of hydrothermal alterations: tourmalinization, greissenization, feldspathization and silicification. The more widespread alteration is the feldspathization in which the protolith is replaced by massive albite and K-feldspar with fibrous habit, accompanied by apatite, chlorite, rutile, magnetite, hematite, chalcopyrite and sphalerite. In addition, there are highly deformed areas with a complex alteration rich in K-feldspar and sulfides, mainly chalcopyrite, minerals of the stannite group and sphalerite and, in less abundance, bismuthinite, native bismuth, galena and pyrite. This deposit shares features in terms of geological setting, hydrothermal alteration and ore assemblages with exogreisen systems formed in the cupolas of highly fractionated granites in collisional settings.

Ore Mineralogy of the Louvem Copper Deposit Val d'Or, Quebec

1972 ◽  
Vol 9 (12) ◽  
pp. 1596-1611 ◽  
Author(s):  
Jayanta Guha ◽  
Richard Darling
Keyword(s):  
Copper Deposit ◽  
Wall Rock ◽  
Textural Features ◽  
Ore Deposit ◽  
Ore Body ◽  
Ore Minerals ◽  
Wall Rock Alteration ◽  
Ore Mineralogy ◽  
Rock Alteration ◽  
Host Rocks

Microscopic study of samples from the Louvem copper deposit shows that the principal ore minerals are pyrite, chalcopyrite, and sphalerite and the accessory ore minerals are rutile, tetradymite, two unidentified tellurides, cobaltite, molybdenite, galena, and four optically distinct phases having compositions along the digenite–bornite tie line.The Louvem ore body is a pipe-shaped mass of mineralized rhyolitic tuff and agglomerate that is conformable with enclosing volcanic and pyroclastic rocks. The ore body is zoned, with a copper-rich core and pyrite-rich margins. Wall-rock alteration spatially related to the ore deposit suggests that it was formed by replacement of porous tuffaceous host rocks by a hydrothermal fluid. Textural features of the ore indicate that it was subjected to post-emplacement thermal metamorphism.

scholarly journals Mineralogical and Fluid Inclusions Study of Epithermal Type Veins Intruding the Volcanic Rocks of the Kornofolia Area, Evros, NE Greece.

2019 ◽  
Vol 55 (1) ◽  
pp. 202
Author(s):  
Foteini Aravani ◽  
Lambrini Papadopoulou ◽  
Vasileios Melfos ◽  
Triantafillos Soldatos ◽  
Triantafillia Zorba ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Fluid Inclusion ◽  
Hydrothermal Alteration ◽  
Fluid Inclusions ◽  
Volcanic Rocks ◽  
The Other ◽  
Calc Alkaline ◽  
Ft Ir ◽  
Host Rocks

The volcanic rocks of Kornofolia area, Evros, host a number of epithermal-type veins. The host rocks are Oligocene calc-alkaline andesites to rhyo-dacites. The andesites form hydrothermal breccias and show hydrothermal alteration. The veins comprise mainly silica polymorphs such as quartz, chalcedony and three types of opal (milky white, transparent and green). Amethyst also forms in veins at the same area. Apart from the silica polymorphs, the veins are accompanied by calcite and zeolites. The main aim of this study is the characterization of the silica polymorphs. Using FT-IR analyses, variations in the crystal structure of the three opals were recognized. The green opal is found to be more amorphous than the other two types. Fluid-inclusion measurements were performed in calcite and were compared with amethyst from previous studies. The Th is between 121-175 °C and the Te between -22.9 and -22.4 °C. The salinities range from 0.9 to 4.5 wt % NaCl equiv.

scholarly journals Geochemistry, Hydrothermal alteration and Ore mineralogy of Skarn Mineralization at Wethey-Pheshey area, Thabeikkyin Township, Mandalay Region, Myanmar

2016 ◽  
Vol 1 (2) ◽  
pp. 53
Author(s):  
Toe Naing Oo ◽  
Lucas Donny Setijadji ◽  
I Wayan Warmada ◽  
Than Than Oo
Keyword(s):  
Rare Earth ◽  
Hydrothermal Alteration ◽  
Inductively Coupled Plasma ◽  
Xrd Analysis ◽  
Granitic Rocks ◽  
Magmatic Differentiation ◽  
Heavy Rare Earth Element ◽  
Inductively Coupled ◽  
Ore Minerals ◽  
Host Rocks

Wethey-Pheshy area is located 80 km north of Mandalay at Thabeikkyin Township, Mandalay Region. X-ray Diffraction (XRD) Analysis and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) were applied in this study. Geochemical studies on the host rocks indicate that major and minor oxides compositions of metamorphicrocks show some degree of variation. CaO, MgO, FeO, TiO2 and P2O5 concentration of the metamorphic rock samples show a coherent negative correlation with SiO2 whereas Na2O is positively correlated with SiO2. The metamorphic rocks are strongly enriched in light rare earth elements (LREE) and relatively depleted in heavy rare earth element (HREE). The depleted Eu-nomalies in the chondrite-normalized REE diagrams indicate a plagioclase-depleted Eu crustal source or fractionation during magmatic differentiation. Intrusion of granitic rocks in the diopside marble caused the base metal ore mineralization and associated skarn alterations. Granite shows the sub-alkaline nature and peraluminous character. It is identified as I-type granite (magnetite series) developed in the volcanic arc setting. Hydrothermal alteration types associated with gold and skarn mineralization in the study area include calc-silicate alteration, propylitization, sericitization (argillitization) and hematization. Based on the nature and characteristics of host rocks, mineralization and alteration style and geochemical characteristics in the study area is identified as intrusion-related skarn mineralization. Common ore minerals include chalcopyrite, galena, sphalerite, pyrite, gold and Fe-oxides. 

CHARACTERIZATION OF PALEOPROTEROZOIC STRUCTURES, AURIFEROUS QUARTZ VEINS, AND HOST ROCKS, FISHER PROPERTY, SEABEE GOLD OPERATION, SASKATCHEWAN, CANADA

2019 ◽  
Author(s):  
Courtney Carol Onstad ◽  
◽  
Kevin M. Ansdell ◽  
Camille A. Partin ◽  
Anders Carlson
Keyword(s):  
Quartz Veins ◽  
Host Rocks

Mineralization of the South Pennine Orefield, UK—A Review

2016 ◽  
Vol 61 (1) ◽  
pp. 55-86 ◽  
Author(s):  
T.D. Ford ◽  
N.E. Worley
Keyword(s):  
Wall Rock ◽  
Hydraulic Gradient ◽  
Mississippi Valley ◽  
The South ◽  
The North ◽  
East Midlands ◽  
Ore Minerals ◽  
Placer Deposits ◽  
Fractured Limestone ◽  
Host Rocks

This review of the South Pennine Orefield (SPO) draws together the findings from many years of underground field observations and petrographical study. Mineralization is of the Mississippi Valley-type (MVT) and is concentrated within an area of some 200 km2, mainly along the eastern margins of a large inlier, the Derbyshire High, in Carboniferous platform carbonate host rocks. The inlier covers some 390 km2, forms an up-dip promontory of a larger structure, the East Midlands Shelf, and is surrounded by shales and sandstones of the Millstone Grit and Pennine Coal Measures groups. Mineralization probably began during the late Westphalian (Moscovian, Mid Pennsylvanian), when subsidence due to thermal sag resulted in the limestone being buried to depths of c. 4 km beneath younger strata. A palaeohydraulic reconstruction is presented from analysis of mineralized palaeokarst features, which are interpreted as representing hypogenic or deep-seated karst formed by the interstratal circulation of hydrothermal water in a mostly confined hydrodynamic setting. It is reasoned that Variscan inversion of N–S faults to the east of the SPO resulted in erosion of Namurian and Westphalian (Upper Mississippian–Middle Pennsylvanian) rocks and created a hydraulic gradient inclined towards the south-west. Acidic F-Ba-Pb-Zn enriched fluid evolved in the Namurian basinal rocks and migrated into fractured limestone. The resultant wall-rock dissolution along existing wrench faults led to the formation of a maze of stratiform mineral deposits (flats) and more irregular spongework-shaped structures (pipes). The presence of hydrocarbon accumulations in the limestones and evidence from fluid inclusions indicates that the mineralizing fluids were chloride/fluoride-rich and compositionally typical of oilfield brine. Isotope evidence demonstrates a sulphate evaporite source of sulphur, mainly from the Chadian (Visean, Middle Mississippian) Middleton Anhydrite Formation. By the late Cenozoic, karstification of exposed carbonate rocks began and the current pattern of epigenic karst drainage started to develop as the regional hydraulic gradient reversed, assuming its present eastward inclined attitude. The mineralized hypogenic karst was overprinted by later drainage systems as the hydraulic gradient changed, and placer deposits were formed from the erosion of existing mineralization. This was accompanied by circulation of meteoric water and resulted in the supergene weathering of the sulphide ore minerals. Eastward underflow of meteoric groundwater also exploited the same mineralization flow paths. There is evidence that pre-mineralization hypogenic karst was also significant in the formation of orebodies in the North Pennine Orefield and the Halkyn–Minera Orefield of NE Wales.

scholarly journals Minerály kontaminovaných granitových pegmatitů z lomu Pohled u Havlíčkova Brodu (moldanubikum), část II: prvky a sulfidy

2021 ◽  
Vol 29 (1) ◽  
pp. 90-107
Author(s):  
Zdeněk Dolníček ◽  
Jana Ulmanová ◽  
Karel Malý ◽  
Jaroslav Havlíček ◽  
Jiří Sejkora
Keyword(s):  
Raman Spectrum ◽  
Metamorphic Rocks ◽  
Mineral Association ◽  
Ore Minerals ◽  
Ore Mineralization ◽  
Mineralogical Study ◽  
Native Bismuth ◽  
Polymetallic Ore ◽  
Hydrothermal Veins ◽  
Cobalt And Nickel

In the Pohled quarry near Havlíčkův Brod town (central part of Czech Republic), texturally and mineralogically simple contaminated anatectic pegmatites form dikes or irregular bodies cementing breccia of host metamorphic rocks (paragneisses, amphibolites) belonging to the Monotonous (Ostrong) Group of the Moldanubicum of the Bohemian Massif. They exhibit signs of intense hydrothermal overprint and also the presence of abundant disseminations, nests and veinlets of ore minerals. A detailed mineralogical study revealed the presence of an extraordinary rich ore assemblage (20 species in total, including one unnamed phase). The oldest minerals are sphalerite (rich in Fe), löllingite, Fe-Co-Ni sulphoarsenides (cobaltite, glaucodot, arsenopyrite, gersdorffite), pyrrhotite, galena and chalcopyrite, in later portion accompanied by inclusions of Bi-minerals (native bismuth, bismuthinite, joséite-A, joséite-B, ikunolite and a Pb-Bi sulphosalt). The composition of the Pb-Bi sulphosalt is equal to Ag,Fe-substituted eclarite; its identity was confirmed also by Raman spectrum. Pyrite is very abundant phase, present probably in several generations. The Fe-Co-Ni thiospinels disseminated in younger chlorite, and represented by siegenite, violarite, grimmite and an unnamed NiFe2S4 phase, are the youngest ore minerals. The mineral association as well as chemical composition of most ore minerals are well comparable to those of local polymetallic ore veins and Alpine-type veins, which give evidence for identical origin of all these ore mineralizations. The formation of pegmatite-hosted ore assemblage was long-lasting multiphase process, which took place at temperatures between ca. 350 and <120 °C during changing fugacities of sulphur, tellurium and oxygen. A distinct enrichment in cobalt and nickel of ore mineralization hosted by pegmatites (in comparison with hydrothermal veins) is explained in terms of pronounced interactions of fluids with amphibolites and serpentinites.

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