Petrology and dating of the Permian lamprophyres from the Malá Fatra Mts. (Western Carpathians, Slovakia) (original) (raw)
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Journal of the Czech Geological Society
Electron microprobe analyses were made on micas, amphiboles, feldspars, chlorites and accessory minerals in lamprophyric dykes (kersantites, minettes, spessartites), and in associated mafic diorite to tonalite porphyries (porphyrites) of the Kruné hory (Erzgebirge) area and Mariánské Láznì region in Western Bohemia (Czech Republic). All studied rocks are altered to various degrees during deuteric and/or postmagmatic stages of evolution. The only primary mafic mineral preserved in all rock types is Mg-biotite to phlogopite, in spessartites and some diorite porphyries also Ti-rich hornblende corresponding to titanian magnesiohastingsite to kaersutite. Magmatic biotites are relatively rich in Ti with limited variations in their Mg/Fe ratios, evidently re-equilibrated during cooling or re-heating. Olivine is totally replaced by pilitic pseudomorphs and by biotite-actinolite clots. Phenocrystic clinopyroxene is completely uralitized, often in well-preserved original shapes. The secondary amphiboles correspond to Si-rich magnesiohornblende to actinolite. Chlorite and epidote are rather scarce and their important occurrences are restricted to limited number of samples. Instead of chloritization typical of lamprophyres in other parts of the Bohemian Massif, most samples are affected by secondary biotitization. Effects of greisenization sensu stricto were observed in some lamprophyres from Krupka where Li-bearing dark micas rich in Si and Mg originated.
Geologica Carpathica, 2014
We studied representative samples from a peridotite body situated NE of Sedlice village within the Central- Carpathian Paleogene sediments in the Central Western Carpathians. The relationship of the peridotite to the surrounding Paleogene sediments is not clear. The fractures of the brecciated peridotite margin are healed with secondary magnesite and calcite. On the basis of the presented bulk-rock and electron microprobe data, the wt. % amounts of mineral phases were calculated. Most of calculated “modal” compositions of this peridotite corresponds to harzburgites composed of olivine (∼70-80 wt. %), orthopyroxene (∼17-24 wt. %), clinopyroxene ( < 5 wt. %) and minor spinel ( < 1 wt. %). Harzburgites could originate from lherzolitic protoliths due to a higher degree of partial melting. Rare lherzolites contain porphyroclastic 1-2 mm across orthopyroxene (up to 25 wt. %), clinopyroxene (∼ 5-8 wt. %) and minor spinel ( < 0.75 wt. %). On the other hand, rare, olivine-rich dunit...
Geologica Carpathica
Turonian to Maastrichtian exotics-bearing deposits from the Pieniny Klippen Belt (Klape and Kysuca units) and from the Považský Inovec Mts. (Western Carpathians) were analyzed for heavy minerals and compared with similar, yet older Albian-Cenomanian deposits. The Turonian to Maastrichtian deposits are petrographically more variable in composition in the entire range, from quartz arenites to litharenites. Percentages of the main heavy minerals are similar on both stratigraphic levels, i.e., they are dominated by chrome-spinels, zircon, tourmaline, apatite, and rutile. Garnet is more common in the Turonian to Maastrichtian samples, while titanite, kyanite, monazite, hornblende, blue amphibole, pyroxenes, epidote, staurolite, and sillimanite are quite rare. Statistical factor analysis indicates dominance of ophiolites and older sediments in the source areas. One important factor is an influx of garnet, with the weakest factor being related to the influx of tourmaline and apatite, which may indicate low-grade metamorphics. Spinels were derived from harzburgites (supra-subduction peridotites). The majority of tourmalines were derived from metasediments, Fe 3+-rich quartztourmaline rocks, calc-silicate rocks, and metapelites and granitoids. Some had complex zonation with two phases of tourmaline (schorl-dravite and bosiite), or tourmaline intergrown with quartz. These were likely derived from ophiolitic sources. Garnets are predominantly almandinic and derived from rocks that had been metamorphosed up to the amphibolite facies, or magmatic rocks. Common pyrope-almandinic garnets indicate their source from granulites and eclogites. The main change after the Albian-Cenomanian period is the more expressed presence of the continental crust segments in the source area in comparison with ophiolites.
Geologica Carpathica, 2009
According to earlier concepts, the Czorsztyn Unit (Oravic Superunit, Pieniny Klippen Belt, Western Carpathians) sedimented on the isolated Czorsztyn Swell which existed in the Middle Jurassic-Late Cretaceous time in the realm of the Outer Western Carpathians. This paper brings new data providing an alternative interpretation of its Cretaceous evolution. They are based on heavy mineral analysis of the Upper Aptian/Lower Albian sediments of the Czorsztyn Unit. They rest upon a karstified surface after a Hauterivian-Aptian emersion and are represented by condensed, red marly organodetritic limestones with some terrigenous admixture (Chmielowa Formation). The heavy mineral spectrum is dominated by spinels, followed by garnet, with lesser amounts of zircon, rutile and tourmaline. The composition of the majority of the detrital garnets shows that they were derived from primary HP/UHP parental rocks which were recrystallized under granulite and amphibolite facies conditions. The garnets were most probably derived directly from the magmatic and metamorphic rocks of the Oravic basement, as the high-pyrope garnets are known to be abundant in Mesozoic sediments all over the Outer Western Carpathians. The presence of spinels is surprising. According to their chemistry, they were mostly derived from mid-oceanic ridge basalts (MORB) peridotites, supra-subduction zone peridotites (harzburgites) and transitional lherzolite/harzburgite types. Only a lesser amount of spinels was derived from volcanics of BABB composition (back-arc basin basalts). The presence of this ophiolitic detritus in the Czorsztyn Unit is difficult to explain. Ophiolitic detritus appeared in the Aptian/Albian time only in the units which were considered to be more distant, because they were situated at the boundary between the Central and the Outer Western Carpathians (Klape Unit, Tatric and Fatric domains). The hypothetical Exotic Ridge which represented an accretionary wedge in front of the overriding Western Carpathian internides was considered to be a source of the clastics. In previous paleogeographical reconstructions, the Czorsztyn Unit was situated north of the Pieniny Trough (considered to be one of the branches of the Penninic-Vahic Ocean). In the trough itself, the ophiolitic detritus appeared as late as in the Senonian and there was no way it could reach the Czorsztyn Swell which was considered to be an isolated elevation. The new results presented herein show that these reconstructions do not fit the obtained data and infer a possibility that the Czorsztyn sedimentary area was not isolated in the Cretaceous time and it was situated closer to the Central Carpathian units than previously thought. A new paleogeographical model of the evolution of the Pieniny Klippen Belt is presented in the paper: Oravic segment was derived from the Moldanubian Zone of the Bohemian Massif by the Middle Jurassic rifting which caused block tilting where most of the Oravic units were arranged north of the Czorsztyn Swell. The Oravic segment was situated in the lateral continuation of the Central and Inner Western Carpathians from which it was detached by later clockwise rotation. The Oravic segment was then laterally shifted in front of the Central Western Carpathians, together with remnants of the Meliatic suture zone which represented a source for the exotics to the Klape, Tatric, Fatric and Oravic units.
Journal of Geosciences, 2008
Metabasic rocks form an important constituent of the Chýnov and Český Krumlov units belonging to the Varied Group (Moldanubian Zone, south Bohemia). The amphibolites are dominated by amphibolite-facies mineral assemblages of mainly tschermakitic amphibole and plagioclase. Hornblendes show compositional variation with Si ~ 6.5 apfu, Mg/(Mg + Fe) ~ 0.5 and (Na + K) A ~ 0.5 apfu. Garnet with clinopyroxene are subordinate and occur in a few samples only. No relics of previous greenschist-or granulite-facies assemblages have been observed, most likely due to the relatively simple metamorphic history. The petrology indicates rather close correlation of the Chýnov and Český Krumlov units. The similarities include presence of dolomite in carbonate bodies, graphite schists, rocks with marialitic scapolite, locally also Ti-andradite (± magnetite, epidote) oxidic assemblages and thin layers of Mn-rich garnet-quartz rocks. However, there is a major difference in the oxidation state. Most Chýnov amphibolites have Fe 2 O 3 /FeO = 0.70-1.00 and their protolith probably experienced an early incipient oxidation. Great deal of the parental basalts thus could have been effusive. The Český Krumlov amphibolites have Fe 2 O 3 /FeO ≤ 0.4, perhaps because they show much closer association with graphite schists that could have been responsible for the reduction of the adjacent rock units. The dataset is dominated by EMORB-like tholeiite basalts interpreted as having been derived by Early Palaeozoic melting of a strongly depleted mantle source (ε 50 Nd 0 = +8.6 to +9.4; T D Nd M = 0.43-0.50 Ga). This argues stoutly against Precambrian age of the Varied Group in south Bohemia. The composition of the remaining samples reflects contamination by upper continental crust (ε 50
Western Carpathian mid-Permian Magmatism: Petrographic, geochemical, and geochronological data
Data in Brief, 2021
This study presents geochemical and geochronological data from rock samples collected from the Western Carpathian mountains, eastern Slovakia. Granite assemblages that intrude the Gemeric and Veporic Superunits were imaged using a petrographic microscope to determine rock textures and their mineral assemblages. Zircon grains from seven individual portions of the Gemeric granites (Hnilec, Betliar, Elisabeth Mine, Popro č plutons) and one from the Veporic unit (Klenovec pluton) were dated using Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) and Secondary Ion Mass Spectrometry (SIMS). Eight individual portions of the Gemeric unit's Betliar pluton and seven from the Klenovec granite were analyzed for major and trace elements using Fusion Inductively Coupled Plasma (ICP) and Fusion ICP-mass spectrometry. We also report detrital zircon
Mineralogy and Petrology, 1992
The Alcsutdoboz-2 (AD-2) core contains 12 magmatie dykes which belong to the Late Cretaceous lamprophyric-carbonatitic association of NE Transdanubia, Hungary. Petrographically, 11 dykes can be considered alkaline lamprophyre (mainly monchiquite), and the remainder might be called carbonatite. The lamprophyre dykes are similar to both alkaline lamprophyres and ultramafic lamprophyres in major element composition, whereas the carbonatite dyke has some features that are similar to carbonatites but others that are dissimilar. Nevertheless, both of the two types of AD-2 dykes possess higher LILE content than the ultramafic lamprophyres and kimberlites, but strongly differ from average earbonatite. Based on the REE pattern, crystal fractionation (mainly of olivine) and separation of a carbonate phase from the parental lamprophyric magma are proposed for genesis of the carbonatite dyke. These characteristics and the compositional zoning of clinopyroxene and mica suggest a complex crystallization history for these dykes. The likeliest origin for the parental lamprophyric melt is through a very small degree of partial melting of metasomatized mantle.
Journal of GEOsciences, 2014
Variscan lamprophyres occur in the greisen tin-, tungsten-and molybdenum-ore district of Krupka in the Eastern Krušné hory/Erzgebirge (KHE). They belong to a bimodal dyke suite of aplites, felsic porphyries, microgranites and mafic dykes associated with late Variscan tin-bearing granites and include minettes, kersantites and spessartites, while vogesite reported earlier has not been confirmed. One altered mafic dyke is interpreted as original microdiorite. All lamprophyres are basic to intermediate rocks (47.3-56.9 wt. % SiO 2 ) with shoshonitic to ultrapotassic composition (3.1-7.5 wt. % K 2 O). The high concentrations of MgO (4.7-11.4 wt. %), molar Mg/(Mg + Fe) ratios (0.56-0.74) and abundances of compatible elements (350-800 ppm Cr, 130-360 ppm Ni) indicate that lamprophyres represent primary mantle melts that underwent no or little fractionation or contamination, and high LREE/HREE ratios point to magma formation in the stability field of garnet peridotite. In addition, high contents of potassium and LILE (50-370 ppm Li, 150-920 ppm Rb, 750-3100 ppm Ba) indicate metasomatic enrichment of the upper mantle prior to partial melting. The LILE-HFSE-REE patterns indicate involvement of slab components (subducted siliciclastic and carbonate sediments). Strong enrichment in U (6-29 ppm) and Th (17-75 ppm) is another characteristic feature of lamprophyres from the Eastern KHE and elsewhere in central Europe, and it is consistent with the metasomatic transport via oxidized saline fluids from the slab to the mantle wedge. The lamprophyres in the Krupka district were variably greisenized in the vicinity of granite greisens and Sn-W hydrothermal veins and their original minerals were replaced by an assemblage of lithian phlogopite, topaz, fluorite, apatite and titanium-bearing phases. During alteration, they were strongly depleted in Na 2 O, CaO, Sr and Ba, moderately depleted in REE, and enriched in Li, Rb, Cs, Sn and F. By contrast, Al and Zr behaved as immobile elements and their abundances indicate overall mass loss of 10-18 % during greisenization consistent with the increase of porosity, which facilitated the hydrothermal dissolution-precipitation reactions. The spatial association of greisens and lamprophyres suggests that the greisenizing fluids migrated along similar geological structures, which were previously accessible to the mantle-derived media (melts and/or fluids). On a local scale, the lamprophyre dykes intersected by greisen veins provided geochemical or lithological barrier, which favoured the cassiterite deposition. The timing of lamprophyre dykes also indicates that the mantle metasomatism beneath the KHE area occurred before the late Variscan granitic magmas were generated.
Geologica Carpathica
In situ U-Pb zircon dating by the ICP-MS technique from tonalite located in the southern margin of the Kriváňska Malá Fatra granite massif records a Concordant age of 353 ± 3 Ma for zircon cores, 342 ± 3 Ma for their rims but the zircons from granodiorite on the northern margin of the massif show only coeval Concordant age of 342 ± 3 Ma from both cores and rims. The obtained ages establish successive Tournaisian and Visean magmatic events in the Variscan Malá Fatra crystalline basement and an intimate relationships between two Early Carboniferous intrusions. The Th/U ratio from zircon cores of Tournaisian tonalite shows a magmatic value of 1.0, whereas the ratio with value of 0.2 from zircon rims most likely represent the thermal imprint from emanated hydrothermal fluids from identified Visean granodiorite intrusion with similar Th/U zircon ratio of 0.4. The short time span of about 11 Ma for the origin of these two granitoid intrusive phases in the Malá Fatra Mountains advocates a relatively rapid Variscan convergence from a probably terminated Tournaisian arc magmatic regime to Visean collisional setting.