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Wyszukujesz frazę "mineralisation" wg kryterium: Temat


Wyświetlanie 1-6 z 6
Tytuł:
Geochemistry and tectonic setting of the volcanic host rocks of VMS mineralisation in the Qezil Dash area, NW Iran : implications for prospecting of Cyprus-type VMS deposits in the Khoy ophiolite
Autorzy:
Imamalipour, Ali
Barak, Samaneh
Powiązania:
https://bibliotekanauki.pl/articles/2058590.pdf
Data publikacji:
2019
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
geochemistry
massive sulphide mineralisation
IAT
ophiolite
Khoy
Iran
Opis:
The uppermost part of the Khoy ophiolite includes submarine volcanic lavas. These rocks are found as two different types including basaltic pillow lavas and andesitic to andesitic basalt massive-sheet lavas known as the Qezil Dash unit. These last rocks host volcanogenic massive sulphide mineralisation (VMS). Concordant small lenticular massive sulphides associated with widespread stockworks, extensive wall rock alteration and simple mineralogical parageneses are characteristic of this mineralisation. The Qezil Dash lavas are characterized by HFSE depletion (such as in Nb, Zr, and Hf) and LILE enrichment, low Yb, Y and Ni contents and low Zr/Hf and Nb/Ta ratios. These rocks have low Ti contents and are of LKT type. These geochemical characteristics can be interpreted as indicating SSZ magmatism and suggesting that the Qezil Dash rocks belong to an early stage of island arc formation. Geochemically, this host rock is comparable with the Lasail unit, part of a volcanic sequence within the Oman ophiolite. In the Troodos and Oman ophiolites VMS mineralisation has occurred at the contacts of MOR-basalt and island arc tholeiite (IAT) lavas, so prospecting for VMS deposits in the Khoy area should be estabilished based on geochemical investigations of the volcanic rocks and recognition of their field boundaries.
Źródło:
Geological Quarterly; 2019, 63, 3; 435--448
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Isotopic Re-Os age of molybdenite from the Szklarska Poręba Huta Quarry (Karkonosze, SW Poland)
Autorzy:
Mayer, W.
Creaser, R. A.
Mochnacka, K.
Oberc-Dziedzic, T.
Pieczka, A.
Powiązania:
https://bibliotekanauki.pl/articles/2059392.pdf
Data publikacji:
2012
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Karkonosze granite
hydrothermal mineralisation
Re/Os isotopic age
Opis:
New Re/Os isotopic data for molybdenite from the Szklarska Poręba Huta Quarry provide ages of 307 ± 2 Ma and 309 ± 2 Ma, respectively. The quarry is dominated by the porphyritic (“central”) and equigranular (“ridge”) varieties of the Karkonosze granite. Ore mineralisation hosted in aplogranite includes an assemblage of sulphides, sulphosalts, oxides and various rare phases. The molybdenite ages obtained are consistent with a previously published isotopic age of leucogranite (aplogranite?) from the same quarry and are only slightly older than a recently published, refined 2 6Pb/238U age of untreated zircons from the Szklarska Poręba Huta porphyritic granite. The age of the molybdenite corresponds moderately well to the younger stage of post-magmatic, pneumatolitic/hydrothermal activity of the Karkonosze granite (about 312 Ma).
Źródło:
Geological Quarterly; 2012, 56, 3; 505--512
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The auriferous ore mineralisation and its zonal distribution around the Variscan Kłodzko–Złoty Stok granitoid pluton in the Sudetes (SW Poland) – an overview
Autorzy:
Mikulski, S. Z.
Speczik, S.
Powiązania:
https://bibliotekanauki.pl/articles/2059951.pdf
Data publikacji:
2016
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
gold
ore mineralisation
skarn
Variscan granitoids
Kłodzko–Złoty Stok pluton
Sudetes
Opis:
Due to a low level of erosion the Variscan (Carboniferous–Mississippian) Kłodzko–Złoty Stok (KZS) granitoid pluton and its metamorphic rock cover are unique examples of the ore mineralisation distribution pattern around a pluton. The KZS pluton formed from I-type magmas. It is composed mostly of high-K, metaluminous, biotite- and hornblende-rich granitoids of various compositions ranging from granodiorite to monzonite. The ore mineralisation in the KZS shows specific zonation that reflects interaction between post-magmatic mineralising fluids and country rocks of different composition. In the KZS pluton and its surroundings the mineralisation reveals high-temperature Ti-W oxides and As-Fe sulphide-arsenides plus Fe-oxides which are replaced outwards by Cu-Fe-Pb-Zn sulphides and subsequently, in the marginal parts of the pluton, by the Pb-Sb-Fe sulphide mineralisation. The specific elements and the isotopic composition of sulphur in ore minerals indicate that the metal-bearing postmagmatic-metamorphic hydrothermal fluids, despite their strong affinities to the KZS hybrid magmatic fluids, show also an influence of variable composition of country rocks. Variable alteration processes: hornfelsitisation, skarnisation, dolomitisation, serpentinitisation, pyroxenisation, biotitisation, K-feldspatisation, silicification, berezitisation, carbonatisation, prehinitisation, chloritisation, epidotisation, sericitisation, albitisation and sulphidisation developed along contacts of various rock types within the country rocks. In more fractured zones, transported elements were preferentially trapped by calcareous (Ca-rich) metamorphic rocks. Moreover, along the direct contact between granitoids and calcareous rocks a high temperature auriferous skarns with magnetite-pyrrhotite or/and löllingite-arsenopyrite mineralisation were formed. There are positive correlations between organic matter and Fe2O3 and MgO contents in skarns, suggesting remobilization of organic matter by hydrothermal fluids released during serpentinisation. The organic matter and carbonate samples have very variable δ13C and δ18O values. Most probably these are the result of isotopic re-equilibration between minerals under high temperatures. On the intimate contact of granitoids with less permeable amphibolitic hornfelses a high temperature titanite-scheelite mineralisation of veinlet-impregnation type occurred, while thermal and metasomatic alteration of the enveloping more permeable sandstones developed away from direct contact with granites, causing the formation of pyrite-rich beresites. As a rule, different types of sulphide ore mineralisation contain refractory gold captured by arsenopyrite, löllingite and/or pyrite. Moreover, the formation of contact-metasomatic ore mineralisation was accompanied by ore precipitation in veins and stockworks at a wide temperature range from 480 to 150°C during early and late fracturing stages. The younger stages also revealed variable concentration of gold. All those observations strongly indicate that the whole KZS pluton and its aureole was fertile in gold.
Źródło:
Geological Quarterly; 2016, 60, 3; 650--674
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Organic and inorganic geochemical study of the Lower Permian Walchia shale of the Intrasudetic Basin (SW Poland)
Autorzy:
Bilkiewicz, E.
Pieczonka, J.
Piestrzyński, A.
Powiązania:
https://bibliotekanauki.pl/articles/2060412.pdf
Data publikacji:
2018
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Intrasudetic Basin
Walchia shale
organic matter
uranium
base metal mineralisation
Opis:
The Lower Permian Walchia shale of the Intrasudetic Basin is lacustrine sediment enriched in organic matter and base metals. Rock-Eval geochemical analysis was conducted on 110 drill-core rock samples of the Walchia shale in order to characterize the quantity, genetic type and maturity of dispersed organic matter. Concentrations of U, Th, Cu, Ni, V, Pb, Zn, Co, Mo, Cr, P, S and Fe were determined and microscopic studies to recognize mineral composition were performed on selected samples. Organic matter of the Walchia shale is immature and dominated by terrestrial type III kerogen with an admixture of planktonic type II kerogen. The Walchia shale is generally poor source rock, but some parts of the profile exhibit good and even excellent hydrocarbon potential. The average concentrations of analysed metals are higher than the average reported for black shales. The concentrations of base metals do not correlate with TOC contents, suggesting that their presence is associated with inorganic features of the Walchia shale or they could have been related primarily to organic matter which was subsequently oxidized and altered. Uranium may be partly associated with phosphates. Results of microscopic investigations revealed the lack of detectable radioactive minerals, abundance of framboidal pyrite, and prevalent galena, sphalerite and chalcopyrite.
Źródło:
Geological Quarterly; 2018, 62, 3; 631--643
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Neoproterozoic flood basalts of the upper beds of the Volhynian Series (East European Craton)
Autorzy:
Białowolska, A.
Bakun-Czubarow, N.
Fedoryshyn, Y.
Powiązania:
https://bibliotekanauki.pl/articles/2059908.pdf
Data publikacji:
2002
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Volhynian Series
Ratno Beds
flood basalts
fractional crystallisation
liquation
palagonite
copper mineralisation
Opis:
The effusive rocks of the Ratno Beds of the Volhynian Series known from the western slope of the Ukrainian Shield are represented by lower Vendian flood basalts whose normative composition is that of quartz tholeiites. These are plagioclase-pyroxene basalts displaying intergranular, intersertal, doleritic, ophitic and amygdaloidal textures; they range from aphanitic to medium-grained and contain about 7 vol. % of palagonite - an altered glass with a high iron and considerable magnesium content. The range in composition of plagioclases (andesine-bytownite) and clinopyroxenes (augite-ferropigeonite) suggests that the Ratno Beds basalts formed by fractional crystallisation of a parent magma. Residual magma underwent liquation, producing a separate acid glass (69-73 wt. % of SiO2) phase within a basic one considerably poorer in SiO2 but rich in iron and magnesium. The Ratno Beds basalts are relatively rich in silica, iron, titanium and vanadium as well as in REE and LREE in particular but poor in Ni, Co and Cr. Normative composition, geochemical characteristics and tectonic position suggest classification as continental quartz tholeiites. Hydrothermal solutions are responsible for rich native copper mineralisation in basalts of certain parts of Volhynia (Ivance and Policy). The Vendian volcanism of the Volhynian Series lithologically correlated with the Sławatycze Series of eastern Poland, can be related to continental rifting accompanying the breakup of Rodinia, with crustal fractures mainly running concordantly with the suture zone between Fennoscandia and Sarmatia, thus almost perpendicular to the Tornquist rift; other fracture trends may also have controlled Vendian volcanism.
Źródło:
Geological Quarterly; 2002, 46, 1; 37-58
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evidence of oxidation of the Kupferschiefer in the Lubin-Sieroszowice deposit, Poland: implications for Cu-Ag and Au-Pt-Pd mineralisation
Autorzy:
Oszczepalski, S.
Nowak, G. J.
Bechtel, A.
Zak, K.
Powiązania:
https://bibliotekanauki.pl/articles/2059920.pdf
Data publikacji:
2002
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Lubin-Sieroszowice
Kupferschiefer
Rote Fäule
copper deposit
oxidation
organic matter
stable isotopes
Cu-Ag ores
Au-Pt-Pd mineralisation
Opis:
In the western part of the Lubin-Sieroszowice mining district, processes of secondary oxidation of the Kupferschiefer sediments have led to the formation of the Rote Fäule hematitic footwall alteration and resulted in a unique Kupferschiefer profile clearly comprising reduced, transitional and oxidised rocks. Redox zones were identified by petrographic, geochemical and stable isotope studies of selected core and mine sections. The vertical petrographic and geochemical zonation of the Kupferschiefer sections implies that this variation is the result of an ascending flow of hydrothermal oxidising fluids through the basal part of the Zechstein sediments. The upward, cross-formational flow and water-rock interaction resulted in the oxidation of the initially reduced Kupferschiefer shales that led to the destruction and leaching of unstable components, leaving only refractory and immobile constituents behind within the Rote Fäule. The oxidised rocks are characterised by an abundance of ferric Fe oxides, the presence of gold in association with hematite, high concentrations of aromatic hydrocarbons and asphaltenes, the lowest delta13 C and delta18 O values in carbonates and the highest delta 34 S values in disseminated sulfides. The residual organic matter is significantly depleted in bitumen and hydrogen, and characterised by the absence of alginite and sporinite, low collinite and bituminite contents, and a high relative proportion of solid bitumen. A considerable loss of pyrite and base metals coincides with organic matter degradation. The association of Au-Pt-Pd mineralisation with the oxidised rocks, and Cu-Ag ores with the reduced sediments implies that the processes forming the Rote Fäule were paralleled by sulfide mineralisation. The Rote Fäule/ore system developed as post-sedimentary event caused by large-scale flow of metal-bearing fluids from the underlying Rotliegend aquifer.
Źródło:
Geological Quarterly; 2002, 46, 1; 1-24
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

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