Buried Triassic rocks and vertical distribution of ores in the giant Jiaodong gold province (China) revealed by apatite xenocrysts in hydrothermal quartz veins

We performed a detailed analysis of hydrothermal quartz at the Mokrsko gold deposit (Čelina, Mokrsko-East, and Mokrsko-West deposits). Twenty-one samples were studied by scanning electron microscopy cathodoluminescence (CL) imagining, CL emission spectra and trace elements were measured on six selected samples. Four quartz growth generations Q1 to Q4 were described. Homogeneous early blue CL Q1 with initial emission spectra at 380 and 500 nm was observed at the Čelina deposit with typical titanium concentrations in the range of 20–50 ppm. Hydrothermal quartz at Mokrsko-West, which also includes early Q1, late subhedral faces of yellow CL Q2, and microfissures of greenish CL Q3 (both 570 nm), is characterized by titanium depletion. The titanium concentration is comparable to previous studies of crystallization temperatures proving titanium concentration in quartz as a good geothermal indicator. Q4, developed in microfissures only at Čelina, has no visual CL effect. Mokrsko-West is specific in comparison to Mokrsko-East and Čelina by germanium enrichments in hydrothermal quartz (up to 17 ppm) and the presence of fluorite. Tectonic (sheeted veinlets system, regional tectonic setting) and geochemical (germanium in quartz, the presence of fluorite) characteristics of the quartz veins link the late mineralization stages at the Mokrsko-West deposit to the temporally related Blatná intrusive suite.

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Archaean precious-metal hydrothermal systems, Dome Mine, Abitibi Greenstone Belt. II. REE and oxygen isotope relations

Canadian Journal of Earth Sciences ◽

10.1139/e79-041 ◽

1979 ◽

Vol 16 (3) ◽

pp. 440-458 ◽

Cited By ~ 122

Author(s):

R. Kerrich ◽

B. J. Fryer

Keyword(s):

Oxygen Isotope ◽

Greenstone Belt ◽

Precious Metal ◽

Igneous Rocks ◽

Lode Gold ◽

Quartz Veins ◽

Hydrothermal Quartz ◽

Abitibi Greenstone Belt ◽

Chemical Sediments ◽

Gold Bearing

The Porcupine District, Abitibi Greenstone Belt, is one of the most extensive areas of Archaean auriferous mineralisation. At least two stages of lode-gold emplacement are recognised: the first stage involves gold-bearing carbonate–chert chemical sediments within the lower mafic volcanic sequence; the second stage is represented by auriferous hydrothermal quartz veins which postdate deformation of the greenstone assemblage and transect diverse host rocks.Rare-earth element (REE) concentrations in the stratiform carbonates are typical of the distinctive patterns recorded for Archaean chemical sediments. Chert in these rocks has a δ18O value averaging 17.1‰, implying exchange from heavier 18/16 ratios during diagenesis and metamorphism. Metabasic volcanic rocks and quartz–feldspar porphyry stocks with background gold abundances have mean whole-rock δ18O values of 9.1‰ and 10.7‰ respectively. This enrichment in 18O relative to primary igneous rocks is attributed to oxygen isotope exchange with seawater at low temperatures during fluid transport through the oceanic crust.Quartz in all of the five hydrothermal vein systems present has a δ18O of 14‰ to 15‰, and quartz-muscovite fractionations are 3.4‰ to 3.8‰. Ambient temperatures of mineralisation are estimated to have been 400 °C to 450 °C, from oxygen isotope thermometers, fluid inclusion filling temperatures, and metamorphic mineral assemblages. The calculated δ18O of the mineralising solutions is~10‰, implying fluids of metamorphic origin. REE patterns in hydrothermal quartz veins suggest that they have been derived from high-temperature solutions in equilibrium with source rocks having relatively flat (chondrite normalised) REE distributions, such as tholeiitic and komatiitic volcanics. Adjacent to hydrothermal veins, quartz in igneous rocks approaches isotopic equilibrium with vein quartz, at 15‰, and whole-rock δ18O values for metabasalts shift to ~11‰, implying extensive water-rock interaction. Strong depletions in heavy REE of metabasic schists adjacent to veins provides further evidence for pervasive hydrothermal alteration. The Eu enrichment of all lode gold deposits analysed at Dome Mine is consistent with the reduced state of the solutions involved in their deposition, as recorded by the predominance of Fe2+. The gold-bearing veins are believed to have formed by focussed flow of fluids outgassed at the greenschist–amphibolite transition. Source volumes for Au in the Porcupine District exceed 600 km3, the carrier fluid volume for mineralisation was 60–90 km3, the Au solute concentration in the low nanogram mL−1 range, and transport distances were of the order of 10 km. Such veins may be the precursors of precious-metal-bearing chemical sediments if fluids debouche into the hydrosphere.

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Primary Minerals and Age of The Hydrothermal Quartz Veins Containing U-Mo-(Pb, Bi, Te) Mineralization in the Majerská Valley near Čučma (Gemeric Unit, Spišsko-Gemerské Rudohorie Mts., Slovak Republic)

Minerals ◽

10.3390/min11060629 ◽

2021 ◽

Vol 11 (6) ◽

pp. 629

Author(s):

Štefan Ferenc ◽

Martin Števko ◽

Tomáš Mikuš ◽

Stanislava Milovská ◽

Richard Kopáčik ◽

...

Keyword(s):

Electron Microprobe ◽

Slovak Republic ◽

Mineral Phase ◽

Quartz Veins ◽

Hydrothermal Quartz ◽

Ti Oxides ◽

Mineral Phases ◽

Gemeric Unit ◽

Primary Minerals

An occurrence of vein U-Mo mineralization is located in the Majerská valley near Čučma, about 7 km to the NNE of the district town of Rožňava (Eastern Slovakia). Mineralization is hosted in the acidic metapyroclastics of the Silurian Bystrý Potok Fm. (Gemeric Unit), and originated in the following stages: (I.) quartz I, fluorapatite I; (II.) quartz II, fluorapatite II, zircon, rutile chlorite, tourmaline; (III.) uraninite, molybdenite, U-Ti oxides; (IV.) pyrite I, ullmannite, gersdorffite, cobaltite; (Va.) galena, bismuth, tetradymite, joséite A and B, Bi3(TeS)2 mineral phase, (BiPb)(TeS) mineral phase, ikunolite; (Vb.) minerals of the kobellite–tintinaite series, cosalite; (VI.) pyrite II; (VII.) titanite, chlorite; and (VIII.) supergene mineral phases. The chemical in-situ electron-microprobe U-Pb dating of uraninite from a studied vein yielded an average age of around 265 Ma, corresponding to the Guadalupian Epoch of Permian; the obtained data corresponds with the age of Gemeric S-type granites. The age correlation of uraninite with the Gemeric S-type granites and the spatial connection of the studied mineralization with the Čučma granite allows us to assume that it is a Hercynian, granite-related (perigranitic) mineralization.

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Hydrotermálny bastnäsit-(Ce) zo štôlne Elisabeth pri Gemerskej Polome (Slovenská republika)

Bulletin Mineralogie Petrologie ◽

10.46861/bmp.28.001 ◽

2020 ◽

Vol 28 (1) ◽

pp. 1-8

Author(s):

Martin Števko ◽

Jiří Sejkora ◽

Zdeněk Dolníček

Keyword(s):

Infrared Spectra ◽

Rare Metal ◽

Coarse Grained ◽

Unit Cell Parameters ◽

Cell Parameters ◽

Quartz Veins ◽

Hydrothermal Quartz ◽

Magmatic Fluids ◽

Type Granite ◽

Pale Green

Bastnäsite-(Ce), ideally CeCO3F, was recently found at the dumps of the Elisabeth adit near Gemerská Poloma, Rožňava Co., Košice Region, eastern Slovakia. It forms orange-brown aggregates up to 2 × 1 cm with vitreous to greasy lustre, which occur in the hydrothermal quartz veins crosscutting the coarse-grained, porphyritic rare metal S-type granite. Bastnäsite-(Ce) is closely associated with white, pale-green to purple fluorite, siderite and minor pyrite. It is hexagonal, space group P-62c with refined unit-cell parameters: a 7.1354(1) Å, c 9.7954(2) Å and V 431.90(1) Å3. The empirical formula of bastnäsite-(Ce) from the Gemerská Poloma based on sum of all cations = 1 apfu is (Ce0.49 La0.22Nd0.15Pr0.05Sm0.03Th0.02Ca0.02Gd0.01Y0.01)Σ1.00(CO3)1.00F0.83(OH)0.17. The Raman and infrared spectra of bastnäsite-(Ce) as well as tentative assignment of observed bands are given in this paper. Bastnäsite-(Ce) and associated minerals were formed from the early-hydrothermal post-magmatic fluids related to the adjacent granite.

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EXAMINATION OF CRYSTAL GROWTH AND FLUID HISTORY IN HYDROTHERMAL QUARTZ VEINS USING VEIN PETROGRAPHY, FLUID-INCLUSION MICROTHERMOMETRY, AND SEM-CL: EXAMPLES FROM THE PENNSYLVANIA VALLEY AND RIDGE PROVINCE

10.1130/abs/2017ne-291270 ◽

2017 ◽

Author(s):

Corbin B. MacDonald ◽

◽

Mark A. Evans

Keyword(s):

Crystal Growth ◽

Fluid Inclusion ◽

Quartz Veins ◽

Hydrothermal Quartz ◽

Valley And Ridge Province

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Shock effects and pre-shock microstructures in hydrothermal quartz veins from the Rochechouart impact structure, France

Journal of Structural Geology ◽

10.1016/j.jsg.2009.06.017 ◽

2009 ◽

Vol 31 (10) ◽

pp. 1183-1196 ◽

Cited By ~ 5

Author(s):

C.A. Trepmann

Keyword(s):

Impact Structure ◽

Quartz Veins ◽

Hydrothermal Quartz

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Fluid chemistry and evolution of hydrothermal fluids in an Archaean transcrustal fault zone network: the case of the Cadillac Tectonic Zone, Abitibi greenstone belt, Canada

Canadian Journal of Earth Sciences ◽

10.1139/e06-130 ◽

2007 ◽

Vol 44 (6) ◽

pp. 745-773 ◽

Cited By ~ 12

Author(s):

P Neumayr ◽

S G Hagemann ◽

D A Banks ◽

B WD Yardley ◽

J -F Couture ◽

...

Keyword(s):

Hydrothermal Fluid ◽

Gold Mineralization ◽

Shear Zones ◽

Wall Rock ◽

Higher Order ◽

Hydrothermal Fluids ◽

Tectonic Zone ◽

Quartz Veins ◽

Hydrothermal Quartz ◽

Lower Fluid

Detailed fluid geochemistry studies on hydrothermal quartz veins from the Rouyn-Noranda and Val-d'Or areas along the transcrustal Cadillac Tectonic Zone (CTZ) indicate that unmineralized (with respect to gold) sections of the CTZ contained a distinct CO2-dominated, H2S-poor hydrothermal fluid. In contrast, both gold mineralized sections of the CTZ (e.g., at Orenada #2) and associated higher order shear zones have a H2O–CO2 ± CH4–NaCl hydrothermal fluid. Their CO2/H2S ratios indicate H2S-rich compositions. The Br/Cl compositions in fluid inclusions trapped in these veins indicate that hydrothermal fluids have been equilibrated with the crust. Oxygen isotope ratios from hydrothermal quartz veins in the CTZ are consistently 2 more enriched than those of associated higher order shear zones, which are interpreted to be a function of greater fluid/rock ratios in the CTZ and lower fluid/rock ratios, and more efficient equilibration of the hydrothermal fluid with the wall rock, in higher order shear zones. An implication from this study is that the lower metal endowment of the transcrustal CTZ, when compared with the higher metal endowment in higher order shear zones (ratio of about 1 : 1000), may be the result of the lack of significant amounts of H2O–H2S rich fluids in most of the CTZ. In contrast, gold mineralization in the higher order shear zones appear to be controlled by the high H2S activity of the aqueous fluids, because gold was likely transported in a bisulfide complex and was deposited during sulfidation reactions in the wall rock and phase separation in the quartz veins.

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