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Acta Musei Moraviae, Scientiae geologicae 95/2 2010

Obsah - Inhalt - Contents
 
KRMÍČEK, L.: Předmezozoické lamprofyry a související žilné intruze Českého masivu (Česká Republika, Polsko, Německo, Rakousko): komentovaný přehled Abstract5
 
ČOPJAKOVÁ, R.: Autigenní monazit-(Ce) až monazit-(Nd) v drobách kulmu Drahanské vrchoviny – vznik ve vztahu k chemickému složení drob a diagenetické teplotě Abstract63
 
FOJT, B., ŠKODA, R., DOLNÍČEK, Z.: Furutobeit a betechtinit z ložiska Horní Benešov v Nízkém Jeseníku Abstract81
 
ŠKODA, R., STANĚK, J.: Gayit z granitického pegmatitu od Cyrilova u Velkého Meziříčí, moldanubikum Abstract87
 

MÜCKE, A., FOJT, B., DOLNÍČEK, Z.: Petrography, mineralogy, geochemistry and genetic aspects of the Lahn-Dill type deposit of Malý Děd (= Leiterberg) in the Devonian Vrbno Group (Silesicum), Czech Republic Abstract95
 
BURIÁNEK, D.: Metamorfní vývoj metadioritové subzóny v brněnském batolitu Abstract131
 
BURIÁNEK, D.: Metamorfované horniny západní části brněnského batolitu Abstract151
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Abstract - Krmíček, L. (2010)
Předmezozoické lamprofyry a související žilné intruze Českého masivu (Česká Republika, Polsko, Německo, Rakousko): komentovaný přehled. – Acta Mus. Moraviae, Sci. geol., 2, 95, 3–61.
Pre-Mesozoic lamprophyres and associated dyke intrusions of the Bohemian Massif (Czech Republic, Poland, Germany, Austria): a review
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Abstract - Čopjaková, R. (2010)
Vznik autigenního monazitu v drobách kulmu Drahanské vrchoviny ve vztahu k diagenetické teplotě a chemickému složení drob. – Acta Mus. Moraviae, Sci. geol., 2, 95, 63–79.
Authigenic monazite-(Ce) to monazite-(Nd) in the greywackes of the Drahany Upland: formation related to the chemical composition of the greywackes and diagenetic temperature
Poikilitic monazite-(Ce) to monazite-(Nd), irregular in shape, enclosing variety of detrital and authigenic minerals, together with rounded, partly altered detrital monazite, were found in greywackes of the Protivanov Formation, Drahany Upland. Textural evidences suggest authigenic origin of poikilitic monazite. The most likely explanation is that the main source of REE (mainly LREE) in fluids was detrital monazite. Detrital monazite in greywackes of the Protivanov Formation is unstable and underwent a variety of replacement reactions during deep burial with maximal temperature close to 250 °C corresponding to very low-grade metamorphism. The products of the detrital monazite alteration reflect the whole-rock composition of greywackes. Newly-formed poikilitic monazite was observed only in greywackes with low Ca content in the whole-rock compositions. The CHIME dating revealed the precipitation of poikilitic monazite at 324 Ma (± 28 Ma), thus during high-temperature diagenesis. Chemical composition of lowgrade poikilitic monazite significantly differs from that of higher temperature magmatic or metamorphic detrital monazite. Poikilitic monazite shows low concentrations of Th, U, Ca, Y +HREE and weak Eu anomaly. Distribution of the REE in the poikilitic monazite grains shows typical trend. The central part is enriched in Nd, Sm and Gd, whereas the outer part is enriched in La and Ce. Some analyses from the central part yield Nd as dominant REE, therefore it corresponds to monazite-(Nd). Rarely, small core devoid of mineral inclusions with compositional characteristic typical of a high-temperature origin (high Th, U and Y content), interpreted as relict of detrital monazite, was found in central part of poikilitic monazite.
 
Key words: authigenic monazite; monazite-(Ce); monazite-(Nd); diagenesis; greywackes; Lower Carboniferous Drahany basin.
Renata Čopjaková, Czech Geological Survey, Leitnerova 22, 658 69 Brno, Czech Republic, e-mail: copjakova@sci.muni.cz
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Abstract - Fojt, B., .koda, R., Dolni.ek, Z. (2010)
Furutobeit a betechtinit z lo.iska Horni Bene.ov v Nizkem Jeseniku. . Acta Mus. Moraviae, Sci. geol., 2, 95, 81.86.
Furutobeite and betekhtinite from the ore deposit Horni Bene.ov in the Nizky Jesenik Mts. . Czech Republic
The occurrence of two rare Pb-Ag-Cu-Fe sulphides, furutobeite and betekhtinite, is described from the Devonian Zn-Pb stratiform deposit of Horni Bene.ov. Both minerals were found within post-metamorphic veinlets (cutting the pyrite-sphalerite-galena stratiform ore) associated with galena, digenite (both forming myrmekitic intergrowths), covellite, pearceite, stromeyerite, tennantite, quartz and barytocalcite. Aggregates of furutobeite, up to 0.4 mm, display significant substitution of Ag for Cu (0.21.1.05 apfu Ag), and slightly elevated content of Zn (0.09.0.17 apfu). Betekhtinite grains, up to X0 ƒĘm in diameter, exhibit also elevated Ag and Zn contents (0.09.0.11 and 0.01.0.08 apfu, respectively). The fluid inclusion study of associated quartz indicates the long-lasting fluid activity, which is manifested by the presence of three types of low-temperature (< 200 ‹C) aqueous fluids in primary fluid inclusions: 1) low-salinity Na-Mg-Cl .metamorphicg fluids; 2) high-salinity Ca-Na-Cl fluids with high NaCl/CaCl2 ratio; 3) high-salinity Ca-Na- Cl fluids with low NaCl/CaCl2 ratio. The role of high-salinity aqueous solutions for remobilization of heavy metals from the stratiform ores, is emphasized generativy giving rise to the Ag-Cu-enriched vein assemblage.
 
Key words: furutobeite, betekhtinite, mineralogy, fluid inclusions, genesis, stratiform ore deposit, Horni Bene.ov, Bohemian Massif, Czech Republic.
Bohuslav Fojt, Radek .koda . Institute of Geological Sciences, Masaryk University, 613 00 Brno, Kotla.ska 2, Czech Republic, fojt@sci.muni.cz, rskoda@sci.muni.cz
Zden.k Dolni.ek . Department of Geology, Palacky University, 771 46 Olomouc, T.ida 17. listopadu 12, dolnicek@prfnw.upol.cz 
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Abstract - Škoda, R., Stan.k, J. (2010)
Gayit z granitickeho pegmatitu od Cyrilova u Velkeho Mezi.i.i, moldanubikum. . Acta Mus. Moraviae, Sci. geol., 2, 95, 87.94 (with English summary).
Gayite from granitic pegmatite at Cyrilov near Velke Mezi.i.i, Moldanubicum
Gayite, a new dufrenite group mineral with Mn as dominant divalent cation was recently described by KAMPF et al. (2010) from beryl-columbite-phosphate type granitic pegmatite in Cordoba province, Argentina. Similar, Mn-dominant member of the dufrenite group occurs in association with natrodufrenite, mitridatite, fluorapatite and crandalite group minerals at the border of the Al-phosphate nodule from Cyrilov pegmatite, whereas its chemical composition differs from the type locality gayite. The elevated content of Ca (0.18.0.33 apfu; 1.20.2.13 wt. % CaO), Mg (. 0.15 apfu Mg (. 0.68 wt. % MgO), variable Al (0.01.1.03 apfu; 0.05.6.14 wt.% Al2O3) and ratio Mn/(Mn+Fe2+) 0.30.0.81 is typical for natrodufrenite to gayite form Cyrilov. Substitution trends are briefly discussed.
 
Key words: gayite, natrodufrenite, secondary phosphates, EMPA, Cyrilov pegmatite, Moldanubicum.
Radek .koda, Josef Stan.k . Institute of Geological Sciences, Masaryk University, Kotla.ska 2, 611 37 Brno, Czech Republic, email: rskoda@sci.muni.cz
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Abstract - Mücke, A., Fojt, B., Dolníček, Z. (2010)
Petrography, mineralogy, geochemistry and genetic aspects of the Lahn-Dill type deposit of Malý Děd (= Leiterberg) in the Devonian Vrbno Group (Silesicum), Czech Republic. – Acta Mus. Moraviae, Sci. geol., 2, 95, 95–129.
Petrografie, mineralogie, geochemie a genetické aspekty ložiska typu Lahn-Dill Malý Děd (= Leiterberg) v devonské vrbenské skupině (silesikum), Česká republika
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Abstract - Buriánek, D. (2010)
Metamorfní vývoj metadioritové subzóny v brněnském batolitu. – Acta Mus. Moraviae, Sci. geol., 2, 95, 131–150.
Metamorphic evolution metadiorite subzone in the Brno Batholith
Metadiorite subzone forms the western part of the Central basic belt of the Brno Batholith. It can be interpreted as relic of Neoproterozoic ophiolite complex. Cumulate gabbros, diorites and ultramafic rocks were obducted on to the Thaya terrane and subsequently deformed and/or metamorphosed. The mineral assemblage of rocks forming the metadiorite subzone and the mineral textures (zonation in amphibole, chromite) indicate polyphase metamorphic evolution. Three major metamorphic stages can be distinguished. The first stage comprises a regional metamorphism M1, which reached a greenschist facies grade. The second stage is represented by a contact metamorphism (M2) related to the intrusion of the Cadomian granitoids, with intensity reaching greenschist or up to amphibolite facies. The last stage is characterized by a regional Variscan metamorphism (M3) under prehnite–pumpellyite to greenschist facies conditions. Spinels from ultramafic rocks feature heterogeneous chemical zonation. The degree of chromite grains alteration depends on the chemical composition of coexisting silicates and on the P-T conditions of metamorphism. The individual alteration zones represent different steps of the prograde metamorphism (M2) that affected primary chromitites. The estimated thermal metamorphic conditions for the metadiorites and metagabbros are in agreement with the data obtained from metamorphic assemblage of the ultramafic rocks.
 
Key words: Brno Batholith, metadiorite subzone, cumulate, chromite, ultramafic rocks, P-T conditions, metamorphic overprint.
David Buriánek,Czech Geological Survey, Leitnerova 22,65859,Brno;CzechRepublic; david.burianek@geology.cz
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Abstract - Buriánek, D. (2010)
Metamorfované horniny západní části brněnského batolitu. – Acta Mus. Moraviae, Sci. geol., 2, 95, 151–170.
Metamorphic rocks western part Brno batholith
Biotite and amphibole biotite granitoids of the northern part of Thaya terrane (western part of the Brno batholith) contains large enclaves of polyphase-metamorphosed sedimentary and igneous rocks. The enclaves, up to several km long, consist mainly of biotite to muscovite-biotite gneisses (Qtz + Pl + Bt ± Ms ± Sil ± Ky), biotite to cordierite-biotite migmatites (Qtz + Pl + Bt ± Kfs ± Ms ± Sil ± Crd), metagabbros (Amp + Pl ± Px), calc-silicate rocks (Amp + Pl + Px + Qtz ± Cal ± Grt ± Qtz and Cpx ± Grt ± Ves ± Wo ± Cal ± Qtz ± Pl ± Kfs ± Czo) and amphibolites (Amp + Pl ± Qtz). Three metamorphic events with different P-T conditions are distinguished in the studied rocks. The first stage M1 was marked by regional metamorphism under amphibolite facies conditions (700 °C and 6–7 kbar). Regional metamorphism was followed by a decompression stage and intrusion of Cadomian granitoids of the Thaya terrane (Tetčice suite). P-T estimates for low-pressure contact metamorphism M2 correspond to approximately 700–800 °C and 3–5 kbar. The metamorphic assemblage (Pl + Cpx ± Grt ± Ves ± Wo ± Cal ± Qtz ± Kfs ± Czo) of skarnoid layers from enclaves of calc-silicate rocks indicates high water activity (XCO2 < 0.03) during this metamorphic event. The subsequent Variscan metamorphic overprint (M3) was characterized by regional hydrothermal alteration under prehnite-pumpellyite facie (2–3 kbar and >300 °C ).
 
Key words: Brno massif, P-T conditions, enclaves, migmatites, metagabbros, calc-silicate rocks, skarnoids.
David Buriánek,Czech Geological Survey, Leitnerova 22,65859,Brno;CzechRepublic; david.burianek@geology.cz   
 
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