Geochemistry of highly saline fluids in siliciclastic sequences: genetic implications for post-Variscan fluid flow in the Moravosilesian Palaeozoic of the Czech Republic

Kučera, Jan; Muchez, Philippe; Slobodník, Marek; Prochaska, Walter

doi:10.1007/s00531-008-0387-z

Cited by 14 publications

(5 citation statements)

References 57 publications

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“…According to [98] the origin of this type of fluid responsible for the genesis of some post-Variscan mineralization in Sardinia is mainly from evaporated seawater, with a possible small contribution from halite dissolution. Post-Variscan brine associated to the deposition of dolomite in Zn-Pb-Cu veins at the Nızky Jesenık Mountains and the Upper Silesian Basin (Czech Republic) are also interpreted as evaporated sea-water [103]. Whereas, [96] suggested that the mixing of post-Variscan NaCl-CaCl2-bearing basinal brines with low-temperature sulphate-rich formation waters can explain the temperature/salinity features of fluid inclusions from post-Variscan mineralization of the Harz (Germany) mining district.…”

Section: Discussionmentioning

confidence: 99%

Factors Controlling Hydrothermal Nickel and Cobalt Mineralization—Some Suggestions from Historical Ore Deposits in Italy

et al. 2019

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We compare three poorly known, historical Ni–Co-bearing hydrothermal deposits in different geological settings in Italy: The Ni–Co–As–Sb–Au-bearing Arburese vein system (SW Sardinia), the Co–Ni–As-rich Usseglio vein system (Piedmont), and the small Cu–Ag–Co–Ni–Pb–Te–Se stockwork at Piazza (Liguria). These deposits share various (mineralogical, chemical, thermal, and stable isotopic) similarities to the Five Element Vein-type ores but only the first two were economic for Co–Ni. The Sardinian Ni-rich veins occur in Paleozoic basement near two Variscan plutons. Like the Co-rich Usseglio vein system, the uneconomic Piazza deposit is hosted in an ophiolite setting anomalous for Co. The Sardinian and Usseglio deposits share a polyphasic assemblage with Ni–Co–As–Sb–Bi followed by Ag-base metal sulfides, in siderite-rich gangue, whereas Piazza shows As-free, Ag–Pb–Te–Se-bearing Co–Ni–Cu sulfides, in prehnite–chlorite gangue. Fluid inclusions indicated Co–Ni arsenide precipitation at ≈170 °C for Usseglio, whereas for the Sardinian system late sulfide deposition occurred within the 52–126 °C range. Ore fluids in both systems are NaCl-CaCl2-bearing basinal brines. The chlorite geothermometer at Piazza provides the range of 200–280 °C for ore deposition from CO2-poor fluids. Enrichments in Se and negative δ13C in carbonates suggest interaction with carbonaceous shales. These deposits involve issues about source rocks, controls on Co/Ni and possible role of arsenic and carbonate components towards economic mineralization.

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Section: Discussionmentioning

confidence: 99%

Factors Controlling Hydrothermal Nickel and Cobalt Mineralization—Some Suggestions from Historical Ore Deposits in Italy

et al. 2019

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“…The 'basement brines' are H 2 O-Ca-NaCl-dominated fluids with high salinities up to halite saturation due to evaporation in a marine environment. Homogenisation temperatures of B200°C are distinctly lower as compared to the metamorphic Variscan fluids (Behr et al 1987;Heijlen et al 2001;Kucera et al 2010).…”

Section: Regional Geology and Fluid Evolutionmentioning

confidence: 95%

Fluid evolution at the Variscan front in the vicinity of the Aachen thrust

Синдерн

Meyer

Lögering

et al. 2011

Int J Earth Sci (Geol Rundsch)

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Quartz-carbonate-chlorite veins were studied in borehole samples of the RWTH-1 well in Aachen. Veins formed in Devonian rocks in the footwall of the Aachen thrust during Variscan deformation and associated fluid flow. Primary fluid inclusions indicate subsolvus unmixing of a homogenous H 2 O-CO 2 -CH 4 -(N 2 )-Na-(K)-Cl fluid into a H 2 O-Na-(K)-Cl solution and a vapour-rich CO 2 -(H 2 O, CH 4 , N 2 ) fluid. The aqueous end-member composition resembles that of metamorphic fluids of the Variscan front zone with salinities ranging from 4 to 7% NaCl equiv. and maximum homogenisation temperatures of close to 400°C. Pressure estimates indicate a burial depth between 4,500 and 8,000 m at geothermal gradients between 50 and 75°C/26 MPa, but pressure decrease to sublithostatic conditions is also indicated, probably as a consequence of fracture opening during episodic seismic activity. A second fluid system, mainly preserved in pseudo-secondary and secondary fluid inclusions, is characterised by fluid temperatures between 200 and 250°C and salinities of \5% NaCl equiv. Bulk stable isotope analyses of fluids released from vein quartz, calcite, and dolomite by decrepitation yielded dD H2O values from -89 to -113 %, d 13 C CH4 from -26.9 to -28.9% (VPDB) and d 13 C CO2 from -12.8 to -23.3% (VPDB). The low dD and d 13 C range of the fluids is considered to be due to interaction with cracked hydrocarbons. The second fluid influx caused partial isotope exchange and disequilibrium. It is envisaged that an initial short lived flux of hot metamorphic fluids expelled from the epizonal metamorphic domains of the Stavelot-Venn massif. The metamorphic fluid was focused along major thrust faults of the Variscan front zone such as the Aachen thrust. A second fluid influx was introduced from formation waters in the footwall of the Aachen thrust as a consequence of progressive deformation. Mixing of the cooler and lower salinity formation water with the hot metamorphic fluid during episodic fluid trapping resulted in an evolving range of physicochemical fluid inclusion characteristics.

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“…Numerous, well-known hydrothermal veins, occurring in the Nízký Jeseník Mts., are a record of fluid influence on the Culm rocks. These polymetallic veins are concentrated in historical mining districts, where mainly silver and lead and also gold were mined (Fojt and Vecera, 2000;Kuèera and Slobodnik, 2002;Zimák et al, 2002;Kuèera et al, 2010;Dolníèek et al, 2014;Janiková et al, 2015). Common ore minerals are galena, sphalerite, chalcopyrite, pyrite and marcasite, whilst quartz, Mg, Fe-carbonates, calcite and barite represent gangue minerals.…”

Section: Thermal Evolution Of the Moravo-silesian Fold And Thrust Beltmentioning

confidence: 99%

“…Previous studies on fluid inclusions in the Culm Basin (Zimák et al, 2002;Kuèera et al, 2010;Dolníèek et al, 2014) focused on veins associated with ore mineralisation. Their homogenisation temperatures are considerably lower than those of samples CZ9, CZ74 and SV.…”

Section: Fluid Inclusionsmentioning

confidence: 99%

Thermal history of the lower Carboniferous Culm Basin in the Nízký Jeseník Mts. (NE Bohemian Massif, Czech Republic and Poland)

Botor

Toboła

Jelonek

2017

ASGP

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Raman microspectroscopy of organic matter, vitrinite reflectance and fluid inclusion data were used to reconstruct the thermal history in the lower Carboniferous accretionary prism of the Culm Basin in the Nízký Jeseník Mts. (NE Bohemian Massif). The model involves the Variscan (mid-late Carboniferous) burial diagenesis, which was overprinted by a post-Variscan, probably Permian and/or early Mesozoic, thermal pulse(s) in its central and western parts. The latter may have been related to advective heat transport and the circulation of hot fluids. In the siliciclastic rocks of the Culm Basin, the maximum palaeotemperatures varied from~200 ± 30°C in the E (in the Hradec-Kyjovice Formation) to~350 ± 30°C in the NW (in the Andìlská Hora Formation).

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Geochemistry of highly saline fluids in siliciclastic sequences: genetic implications for post-Variscan fluid flow in the Moravosilesian Palaeozoic of the Czech Republic

Cited by 14 publications

References 57 publications

Factors Controlling Hydrothermal Nickel and Cobalt Mineralization—Some Suggestions from Historical Ore Deposits in Italy

Factors Controlling Hydrothermal Nickel and Cobalt Mineralization—Some Suggestions from Historical Ore Deposits in Italy

Fluid evolution at the Variscan front in the vicinity of the Aachen thrust

Thermal history of the lower Carboniferous Culm Basin in the Nízký Jeseník Mts. (NE Bohemian Massif, Czech Republic and Poland)

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