Hlavnim cilem předkladane disertacni prace bylo komplexně popsat vývoj hydrotermalnich fluid ve slezske a podslezske jednotce Vnějsich Zapadnich Karpat. Mineralni asociace byly studovany za použiti těchto metod: mikrotermometrie a analýza výluhů fluidnich inkluzi, studium stabilnich izotopů (O, C, H a S) a stopových prvků v hydrotermalni fazi, analýza mineralů na elektronove mikrosondě, polarizacni mikroskopie, katodova a UV-fluorescence. Studovane projevy hydrotermalni mineralizace se važi ve slezske jednotce zejmena na magmaticke horniny těsinitove asociace asociovane s jilovci těsinsko-hradisťskeho souvrstvi a v podslezske jednoce byl jejich výskyt zjistěn zejmena ve vapnitých jilovcich frýdeckeho a frýdlantskeho souvrstvi. Hydrotermalni mineralizace byla na zakladě jejich vzniku rozdělena do jednotlivých genetických typů (postmagmaticka, diageneticka, syntektonicka, posttektonicka). Postmagmatický typ hydrotermalni mineralizace byl zjistěn ve vsech druzich magmatických hornin těsinitove asociace (těsinit, pikrit, monchiquit) ve dvou zakladnich morfologických typech: 1) výplň miarol a mandli a 2) výplň žil. Miaroly zjistěne v těsinitech jsou vyplněny zejmena analcimem, v mensi miře i kalcitem. Na mineralni výplni mandli a žil v efuzivnich typech magmatických hornin (monchiquit-pikritova skupina) se podili karbonaty (zejmena kalcit, misty take dolomit, siderit, magnezit), chlority (delessit až pennin), sulfidy (pyrit, markazit, vzacně take sfalerit, millerit a molybdenit), glaukonit, křemen, chalcedon a/ nebo opal. Syntektonicka mineralizace s. s. je v magmatitech reprezentovana jako pravidelne subhorizontalně uložene tenzni žily, jejichž orientace odpovida směru maximalni tektonicke komprese (SSZ-JJV). Tyto žily, klasifikovane jako kompozicně složene unitaxialně syntaxialni a jednoduse unitaxialně syntaxialni typ vlaknitých žil, jsou vyplněny zejmena vlaknitým kalcitem, meně chloritem (pennin), křemenem a pyritem. Syntektonicka hydrotermalni mineralizace vyplňujici pukliny v sedimentech je zastoupena pouze kalcitem. Posttektonicke hydrotermalni žily byly zjistěny v sedimentech i magmatitech. Tento system je zastoupen pravidelnými subvertikalně uloženými (sklon 70 až 90°) extenznimi žilami, ktere maji směr ZSZ-VJV, ZJZ-VSV a nevykazuji genetickou vazbu ke strukturnim prvkům horninoveho prostředi. Diageneticke hydrotermalni žilky v obou tektonických jednotkach kopiruji průběh struktur duktilnich deformaci. V mineralni výplni je zastoupen kalcit, ojediněle i kaolinit. Zminěne interpretace vývoje fluid jsou pro hydrotermalni asociace zjistěne v magmatitech těsinitove asociace slezske jednotky i ve flysových sedimentech srovnatelne, což ukazuje na obdobný zdroj hydrotermalnich roztoků v obou horninových prostředich. Existujici data navic naznacuji kontinualni vývoj fluidniho systemu ve Vnějsich Zapadnich Karpatech na uzemi Ceske republiky a to od sedimentace a postmagmaticke alterace souvisejici s intruzi magmatitů do nezpevněných sedimentů, přes diagenezi a deformaci hornin během alpinske orogeneze až po post-orogenni tektoniku.
Studied locality is situated in western part of the Silesian Unit of the Outer Western Carpathians. Analcime was found in magmatic rock of the teschenite association which was subject of extensive analcimization. Th e analcime crystals, filling the veins and cavities (amygdules, miaroles), have a size up to 5 mm and composite structure: a milky white core shows irregular shape, up to 1 mm in size, and a vitreous transparent rim showing euhedral crystals. The vitreous transparent analcime from veins forms either euhedral crystals or white-pink spherulitic aggregates (size up to 5 mm). Their composition is not close to stoichiometry, with the SiO 2 /Al 2 O 3 mole ratios from 2.08 to 3.12. Increasing SiO 2 /Al 2 O 3 molar ratios of analcimes are consistent with decreasing crystallization temperatures. Analcime contains abundant primary fluid inclusions, less secondary fluid inclusions. Fluid inclusions are one-phase (L-only) or two-phase (L+V) with essentially constant liquid-vapour ratios (gaseous phase takes ca. 10 vol. %). The homogenization temperatures of two-phase inclusions range between 122 and 180 °C (analcime from veins) and between 219 and 295 °C (analcime from cavities - amygdules, miaroles). Inclusions freeze at temperatures of -38 to -49 °C. The last ice melts at temperatures between -0.6 and -3.7 °C. The eutectic temperature was not possible to measure due to the small size of the inclusions. The hydrothermal analcime formed from fluids causing the pervasive post-magmatic hydrothermal alteration of the host magmatic rock. The parent fluids were low-salinity (0.7 to 3.2 wt. % NaCl equiv.) aqueous solutions that were progressively cooled during mineral precipitation. This mineral phase represents a transitional stage between the high-temperature and low-temperature stages of post-magmatic hydrothermal activity in the study area.
Abstract Heavy rare earth elements (HREE) are dominantly mined from the weathering crusts of granites in South China. Although weathering processes occur globally, no economic HREE resources of this type have yet been found outside China. Here, we report the occurrence of unidentified REE minerals in the granites from South Chinese deposits. They contain high levels of both HREE and light REE, but are strongly depleted in Ce, implying high oxidation state. These REE minerals show higher initial Nd isotope than primary REE-rich minerals ( ɛ Nd( t )=0.9±0.8 versus −11.5±0.5). The mineralized weathering crusts inherited REE signature of the granites, but show more Ce depletion and more overall concentration of the REE. We propose, therefore, that highly oxidized, REE-rich fluids, derived from external, isotopically depleted sources, metasomatized the granites, which resulted in Ce depletion as Ce 4+ and enrichment of the remaining REE, especially the HREE, contributing to formation of a globally important REE resource.
Abstract Fluorcaphite [SrCaCa 3 (PO 4 ) 3 F] is a rare strontium-calcium member of the apatite supergroup which was previously known only from the Khibiny and Lovozero alkaline complexes. This paper presents evidence of a third fluorcaphite occurrence. It was found in hydrothermally altered Lower Cretaceous teschenite, which forms an intrusive body (probably a sill) in the Lower Cretaceous siliciclastic flysch sediments at Tichá near Frenštát pod Radhoštěm, Silesian Unit, Outer Western Carpathians (Czech Republic). Fluorcaphite occurs as an accessory mineral in hydrothermal veins and in an adjacent alteration zone within the host teschenite. Vein-hosted fluorcaphite forms euhedral crystals and skeletal crusts enclosed in analcime while the teschenite-hosted fluorcaphite forms small overgrowths on older phenocrysts of magmatic apatite. Fluorcaphite from Tichá contains 0.50–1.97 Sr apfu, 2.96–4.49 Ca apfu, 0.59–1.09 F apfu and significantly lower Na (0.01–0.05 apfu) and LREE contents (up to 0.07 apfu). Fluorcaphite formed under hydrothermal conditions after solidification of the host teschenite during post-magmatic hydrothermal activity at temperatures probably between ∼150 and 300°C. The initial 87 Sr/ 86 Sr ratio of vein-hosted analcime +fluorcaphite (0.7063) is significantly higher than those of the host teschenite (0.7041). We therefore suggest a mix of strontium sources in the vein analcime+fluorcaphite: (1) from the host teschenite plus (2) from external source(s) including the Lower Cretaceous seawater and/or surrounding sedimentary rocks of the Silesian Unit. These data indicate an open-system fluid regime and the participation of various fluid sources during the alteration event giving rise to fluorcaphite.
Studied locality Choryně is situated in the Silesian Unit of the Outer Western Carpathian’s flysch. Hydrothermal veins up to 1.5 cm thick are present in greyish blue Lower Cretaceous claystones belonging to the Lhota Formation. The studied mineralization is mineralogically very simple, being composed only of calcite. Hydrothermal veins are apparently deformed. Homogenization temperatures of primary aqueous fluid inclusions present in calcite vary between 110 and 147 °C. The fluids have generally low salinities (0.5 to 3.1 wt. % NaCl equiv.), positive δ18O values between +3.5 and +7.0 ‰ SMOW and δ13C around –8 ‰ PDB. Chondrite-normalized REE pattern of calcite is different from those of the host claystone (MREE-enriched calcite vs. LREE-enriched claystone) and shows a negative Eu and Ce anomalies. The origin of the mineralization was probably related to the diagenetic processes that took place in the host rocks.
Post-magmatic hydrothermal mineralization associated with Cretaceous picrite (Outer Western Carpathians, Czech Republic): interaction between host rock and externally derived fluid Mineralogy, fluid inclusions, C, O, S, Sr isotopes and trace elements have been studied in amygdule and vein mineralization hosted by the Lower Cretaceous effusive picrite at Hončova hůrka (Silesian Unit, Flysch Belt of the Outer Western Carpathians). Besides dominating dolomite, magnesite, siderite, quartz, calcite, chlorite, glauconite, fluorite, barite, pyrite and millerite were also identified. The parent fluids are characterized by low temperatures (<50-170°C), low salinities (0.4 to 3.7 wt. % NaCl eq.), low content of strong REE-complexing ligands, δ 18 O, δ 13 C and δ 34 S ranges of 0/+ 14 ‰ SMOW, 0/-9 ‰ PDB and ~0 ‰ CDT, respectively, and initial 87 Sr/ 86 Sr ratios much more radiogenic (0.7060 to 0.7068) than those of host picrite (0.7042 and 0.7046). The fluids are interpreted to be predominantly of external origin, derived from mixing of seawater with diagenetic waters produced by dewatering of clay minerals in the associated flysch sediments. The isotope and REE signatures indicate interaction of at least a part of fluids with sedimentary carbonates. The interaction of fluids with host picrite led to strong alteration of rock-forming minerals and leaching of some elements (Mg, Ni, S, partly also REE) that widely participated during precipitation of vein- and amygdule-hosted mineral phases.
Studied locality is situated in western part of the Silesian Unit of the Outer Western Carpathians. In an abandoned monchiquite quarry at Žilina village near Nový Jicin NW–SE -trending calcite veinlet containing ferrierite-Mg has been found. Ferrierite-Mg forms colorless to red aggregates of acicular crystals about 400 μm in size. Fluid inclusions hosted by younger vein calcite showed low both homogenization temperatures (90–130 °C) and salinities (0.5–2.6 wt. % NaCl eq.). These data are consistent with vein formation during the later stage of postmagmatic hydrothermal alteration. The hydrothermal solutions represented mixed heated seawater and diagenetic water pointing to an open-system hydrothermal circulation during this stage.
Abstract Hydrothermal mineralization hosted by the Lower Cretaceous igneous rock of the teschenite association at Jasenice (Silesian Unit, Flysch Belt, Outer Western Carpathians) occurs in two morphological types - irregular vein filled by granular calcite and regular composite vein formed by both fibrous and granular calcite and minor chlorite, quartz, and pyrite. Crosscutting evidence indicates that the granular veins are younger than the composite vein. The composite vein was formed by two mechanisms at different times. The arrangement of solid inclusions in the marginal fibrous zone suggests an episodic growth by the crack-seal mechanism during syntectonic deformation which was at least partially driven by tectonic suction pump during some stages of the Alpine Orogeny. Both the central part of the composite vein and monomineral veins developed in a brittle regime. In these cases, the textures of vein suggest the flow of fluids along an open fracture. The parent fluids of both types of vein are characterized by low temperatures (Th=66-163 °C), low salinities (0.4 to 3.4 wt. % NaCl eq.), low content of strong REE-complexing ligands, and δ 18 O and δ 13 C ranges of + 0.2/+12.5 %. SMOW and -11.8/-14.1 %. PDB, respectively. The parent fluids are interpreted as the results of mixing of residual seawater and diagenetic waters produced by dewatering of clay minerals in the associ-ated flysch sediments. The flow of fluids was controlled by tectonic deformation of the host rock.
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