Wolframite deposition in a hydrothermal vein system; the Grey River tungsten prospect, Newfoundland, Canada

1985 ◽  
Vol 80 (5) ◽  
pp. 1297-1327 ◽  
Author(s):  
N. C. Higgins
Keyword(s):  
Hydrothermal Vein ◽  
Vein System

scholarly journals Sb-enriched association of Ni arsenides and sulfarsenides from the Zemberg-Terézia vein system near Dobšiná (Western Carpathians, Slovak Republic)

2020 ◽  
Vol 28 (1) ◽  
pp. 105-115
Author(s):  
Martin Števko ◽  
Jiří Sejkora
Keyword(s):  
Slovak Republic ◽  
Western Carpathians ◽  
Hydrothermal Vein ◽  
Vein System ◽  
Rich Variety ◽  
Different Types ◽  
Ore Minerals

An interesting association of Sb-enriched Ni arsenides and sulfarsenides was recently discovered in the carbonate-quartz (siderite type) hydrothermal vein in the Karol adit, at the Zemberg-Terézia vein system near Dobšiná, Slovak Republic. It is represented by nickeline and gersdorffite as main ore minerals accompanied by rammelsbergite, ullmannite, millerite, tetrahedrite-(Zn), chalcopyrite and bornite. The two distinct compositional types of nickeline are present, the Sb-poor (with up to 0.03 apfu of Sb) and Sb-rich variety (with up to 0.12 apfu of Sb). Gersdorffite is mostly replacing nickeline as rims or it forms aggregates, rims around or veinlets in tetrahedrite-(Zn). The three compositionally different types of gersdorffite are present: Sb-rich (with Sb reaching up to 0.31 apfu) and variable Ni/Co/Fe ratio, As-rich gersdorffite (with up to 1.32 apfu of As) also containing minor Co and Fe and the last one is Fe-rich gersdorffite (with up to 0.24 apfu) and nearly ideal As/S ratio. Rammelsbergite, ullmannite and millerite occur as abundant, microscopic inclusions in nickeline and gersdorffite. In tetrahedrite-(Zn), Zn (up to 1.52 apfu) is dominant over (Fe up to 0.82, Ni up to 0.12, Hg up to 0.04 and Pb up to 0.01 apfu) and Sb is considerably prevailing (2.96 - 4.01 apfu) over As (0.02 - 1.02 apfu). Both chalcopyrite and bornite were observed as inclusions in tetrahedrite-(Zn).

Hydrothermal subsilicic sodium gedrite from the Gåsborn area, West Bergslagen, central Sweden

1988 ◽  
Vol 52 (365) ◽  
pp. 193-200 ◽  
Author(s):  
A. Damman
Keyword(s):  
Electron Microprobe ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Compositional Variation ◽  
Crystallization Sequence ◽  
Hydrothermal Vein ◽  
Vein System ◽  
High Level

AbstractSubsilicic sodium gedrite has been found in a hydrothermal vein together with sekaninaite (Fe-cordierite), andalusite, plagioclase, topaz, sillimanite, quartz, biotite, magnetite, ilmenite, hercynite, wolframite, pyrrhotite, chalcopyrite and pyrite. This vein is part of a hydrothermal vein system consisting predominantly of quartz-feldspar veins, some of which contain andatusite, sekaninaite, biotite, muscovite, fluorite and accessory oxides and sulphides, which was formed during the later stages of crystallization of a high-level anorogenic Svecofennian granite. Petrographic observations suggest the following crystallization sequence for the quartz-feldspar veins: plagioclase-quartz-andalusite-sekaninaite-microcline-biotite-albite-oxides and sulphides-muscovite-fluorite, and for the subsilicic sodium gedrite-bearing vein: andalusite-sekaninaite-subsilicic sodium gedrite-biotite-quartz-albite-sillimanite-topaz-oxides and sulphides. Electron microprobe analysis revealed that all subsilicic sodium gedrite is relatively homogeneous with only the following compositional variation: Na(A) 0.57–0.81, Aliv 2.31–2.57, XMg 0.15–0.21. The temperature (T) for the formation of the hydrothermal vein system is estimated at 550–600°C and the pressure (P) is estimated to be less than 3 kbar.

scholarly journals Cellular remains in a ~3.42-billion-year-old subseafloor hydrothermal environment

2021 ◽  
Vol 7 (29) ◽  
pp. eabf3963
Author(s):  
Barbara Cavalazzi ◽  
Laurence Lemelle ◽  
Alexandre Simionovici ◽  
Sherry L. Cady ◽  
Michael J. Russell ◽  
...  
Keyword(s):  
South Africa ◽  
Low Temperature ◽  
Greenstone Belt ◽  
Early Life ◽  
Hydrothermal Fluid ◽  
Chemical Characteristics ◽  
Hydrothermal Vein ◽  
Vein System ◽  
Barberton Greenstone Belt ◽  
Hydrothermal Environment

Subsurface habitats on Earth host an extensive extant biosphere and likely provided one of Earth’s earliest microbial habitats. Although the site of life’s emergence continues to be debated, evidence of early life provides insights into its early evolution and metabolic affinity. Here, we present the discovery of exceptionally well-preserved, ~3.42-billion-year-old putative filamentous microfossils that inhabited a paleo-subseafloor hydrothermal vein system of the Barberton greenstone belt in South Africa. The filaments colonized the walls of conduits created by low-temperature hydrothermal fluid. Combined with their morphological and chemical characteristics as investigated over a range of scales, they can be considered the oldest methanogens and/or methanotrophs that thrived in an ultramafic volcanic substrate.

scholarly journals Spatial and Metallogenic Relationships between Different Hydrothermal Vein Systems in the Southern Arburèse District (SW Sardinia)

2021 ◽  
Vol 6 (1) ◽  
pp. 13
Author(s):  
Matteo Luca Deidda ◽  
Dario Fancello ◽  
Marilena Moroni ◽  
Stefano Naitza ◽  
Ignazio Scano
Keyword(s):  
Hydrothermal System ◽  
Ore Deposits ◽  
Early Permian ◽  
Italian Alps ◽  
Hydrothermal Vein ◽  
Vein System ◽  
Quartz Veins ◽  
Geological Processes ◽  
Host Rocks

The SW Sardinian basement hosts various ore deposits linked to geological processes active from Cambrian to post-Variscan times. In particular, the Southern Arburèse district hosts several granite-related W-Sn-Mo deposits and a 10 km-long system of Ni-Co-As-Bi-Ag ± Au bearing five-element veins. New investigations into the eastern and central parts of the district (Pira Inferida mine sector) were performed to understand the poorly documented spatial and metallogenic relationships between these systems. The granite-related deposits consist of massive wolframite-quartz (W-Bi-Te-Au) and molybdenite-quartz veins, linked to the early Permian (289 ± 1 Ma) Mt. Linas granite, that are cross-cut by the five-element veins. The wolframite-quartz veins, observed by optical and electron (SEM-EDS) microscopy, show abundant native Bi, Bi-Te phases and native Au suggesting a W-Bi-Te-Au hydrothermal system. The five-element veins exhibit breccia and cockade textures, enveloping clasts of the Ordovician host-rocks and locally small fragments of the earlier W-Mo-quartz veins. The five-element vein paragenesis includes three main stages, from older to younger: (1) native elements (Bi ± Au); (2) Ni-Co arsenides-sulfarsenides in quartz gangue; and (3) Pb-Zn-Cu ± Ag sulfides in siderite gangue. The mineralogical, geochemical and isotopic features of the five-element vein swarm are closely comparable to five-element deposits elsewhere in Europe (Germany, Switzerland, Italian Alps). While the source of Ni and Co is still unknown, the high Bi contents, as well as Au enrichment in the five-element veins, suggest selective remobilization of these elements, and perhaps others, from the granite-related W-Bi-Te-Au veins. The five-element vein system was likely formed during a post-289 ± 1 Ma and post-Variscan metallogenic event.

Basement aquifer evolution and the formation of unconformity-related hydrothermal vein deposits: LA-ICP-MS analyses of single fluid inclusions in fluorite from SW Germany

2021 ◽  
Vol 575 ◽  
pp. 120260
Author(s):  
Manuel Scharrer ◽  
Rebekka Reich ◽  
Tobias Fusswinkel ◽  
Benjamin F. Walter ◽  
Gregor Markl
Keyword(s):  
Fluid Inclusions ◽  
Hydrothermal Vein ◽  
Icp Ms ◽  
Vein Deposits

scholarly journals U–Pb geochronology of epidote by LA–ICP–MS as a tool for dating hydrothermal-vein formation

2020 ◽  
Author(s):  
Veronica Peverelli ◽  
Tanya Ewing ◽  
Daniela Rubatto ◽  
Martin Wille ◽  
Alfons Berger ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
A Priori ◽  
Swiss Alps ◽  
Hydrothermal Vein ◽  
Isotopic Compositions ◽  
Vein Formation ◽  
Icp Ms ◽  
Wide Range ◽  
Primary Reference

Abstract. Monoclinic epidote is a low-µ (µ = 283U / 204Pb) mineral occurring in a variety of geological environments, participating in many metamorphic reactions and stable throughout a wide range of pressure–temperature conditions. Despite containing fair amounts of U, its use as a U–Pb geochronometer has been hindered by the commonly high contents of initial Pb with isotopic compositions that cannot be assumed a priori. We present U–Pb geochronology of hydrothermal-vein epidote spanning a wide range of Pb (3.9–190 µg g−1), Th (0.009–38 µg g−1) and U (2.6–530 µg g−1) contents and with µ values between 7–510 from the Albula area (eastern Swiss Alps), from the Grimsel area (central Swiss Alps) and from the Heyuan fault (Guangdong province, China). The investigated epidote samples show appreciable fractions of initial Pb that vary to different extents. A protocol has been developed for in situ U–Pb dating of epidote by spot-analysis laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) with a magmatic allanite as primary reference material. The suitability of the protocol and the reliability of the measured isotopic ratios have been ascertained by independent measurements of 238U / 206Pb and 207Pb / 206Pb ratios respectively by quadrupole and multicollector ICP–MS applied to epidote micro-separates digested and diluted in acids. For age calculation, we used the Tera–Wasserburg (207Pb / 206Pb–238U / 206Pb) diagram, which does not require corrections for initial Pb and provides the initial 207Pb / 206Pb ratio if all intra-sample analyses are co-genetic. Petrographic and microstructural data indicate that the calculated ages date the crystallization of vein epidote from a hydrothermal fluid and that the U–Pb system was not reset to younger ages by later events. Vein epidote from the Albula area formed in the Paleocene (62.7 ± 3.0 Ma) and is related to Alpine greenschist-facies metamorphism. The Miocene (19.1 ± 4.0 Ma and 16.9 ± 3.7 Ma) epidote veins from the Grimsel area formed during the Handegg phase (22–17 Ma) of the Alpine evolution of the Aar Massif. Identical initial 207Pb / 206Pb ratios reveal homogeneity in Pb isotopic compositions of the fluid across ca. 200 m. Vein epidote from the Heyuan fault is Cretaceous in age (108.1 ± 8.4 Ma) and formed during the early movements of the fault. In situ U–Pb analyses of epidote returned reliable ages of otherwise undatable epidote-quartz veins. The Tera–Wasserburg approach has proven pivotal for in situ U–Pb dating of epidote and the decisive aspect for low age uncertainties is the variability in intra-sample initial Pb fractions.

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