Hydrothermal mineralization in rocks of the Soláň Formation in the western part of Chřiby Hills

Hydrothermal mineralization sporadically occurs in the western part of Chřiby Hills in a form of thin carbonate veins and veinlets hosted by sedimentary rocks of the Lukov Member of the Soláň Formation. These veins were found in old quarries and slope debris nearby Koryčany, Cetechovice, and Roštín. The mineral filling of studied veins is formed by calcite or rarely calcite and barite. Based on the investigation of fluid inclusions, hydrothermal calcite crystallized from low-temperature (Th = 70–187 °C) and on average low-salinity (0.2–5.6 wt. % NaCl equiv.) hydrothermal solutions. Hydrothermal veins filling crack systems with the direction NNW–SSE or W–E in quarries Holý kopec near Koryčany and Roštín-Chapel are probably post-tectonic. Their origin can be connected to young tectonic events after the termination of main phase of the Alpine Orogeny. Diagenetic origin cannot be excluded in case of calcite vein which fills a bed joint between layers of conglomerate in old quarry 3.5 km south–southeast from the town Koryčany. The source fluids can be derived from mixing of seawater with diagenetic waters. In case of post-tectonic veins, a contribution of meteoric waters is also possible. In addition, UV-fluorescence microscopy reveals a sporadic presence of inclusion with higher hydrocarbons which exhibits strong blue-white fluorescence. These inclusions document a migration activity of higher hydrocarbons in the northwestern part of the Rača Unit in Chřiby Hills.Hydrothermal mineralization sporadically occurs in the western part of Chřiby Hills in a form of thin carbonate veins and veinlets hosted by sedimentary rocks of the Lukov Member of the Soláň Formation. These veins were found in old quarries and slope debris nearby Koryčany, Cetechovice, and Roštín. The mineral filling of studied veins is formed by calcite or rarely calcite and barite. Based on the investigation of fluid inclusions, hydrothermal calcite crystallized from low-temperature (Th = 70–187 °C) and on average low-salinity (0.2–5.6 wt. % NaCl equiv.) hydrothermal solutions. Hydrothermal veins filling crack systems with the direction NNW–SSE or W–E in quarries Holý kopec near Koryčany and Roštín-Chapel are probably post-tectonic. Their origin can be connected to young tectonic events after the termination of main phase of the Alpine Orogeny. Diagenetic origin cannot be excluded in case of calcite vein which fills a bed joint between layers of conglomerate in old quarry 3.5 km south–southeast from the town Koryčany. The source fluids can be derived from mixing of seawater with diagenetic waters. In case of post-tectonic veins, a contribution of meteoric waters is also possible. In addition, UV-fluorescence microscopy reveals a sporadic presence of inclusion with higher hydrocarbons which exhibits strong blue-white fluorescence. These inclusions document a migration activity of higher hydrocarbons in the northwestern part of the Rača Unit in Chřiby Hills

Petrography of xenoliths of igneous rocks in neovolcanites from the quarry Bučník near the Komňa village

Neovolcanites from the Uherský Brod area sporadically enclose cm to dm large xenoliths of plutonic rocks. This paper focuses on characterization of xenoliths from the Bučník hill which are enclosed in trachyandesites by using classic petrographic methods. Based on mineral composition and textural features of main rock-forming minerals, the studied xenoliths can be classified as fine- to coarse-grained pyroxenic-amphibolic gabbros or diorites, respectively. They consist mainly of intermediate polysynthetically twinned plagioclase (andesine to labradorite; An44–55) and yellow-brown pleochroic magnesiohastingsite to pargasite (XMg = 0.64–0.75; Si = 6.09–6.29 apfu; Ti = 0.30–0.42 apfu). Relicts of diopside (XMg = 0.70–0.80; Ti = 0.01–0.03 apfu; Na = 0.03–0.04 apfu), brown strongly pleochroic phlogopite leaflets (XMg = 0.58–0.65; Si = 5.51–5.60), apatite columns (predominantly fluorapatite; F = 0.43–0.77 apfu) and K-feldspar (Ab16–17Or82–84An00–01) grains are less frequent. Amphiboles sporadically enclose round or tabular inclusions of labradorite to bytownite (An64–72) and subhedral olivine (Fo64). Xenoliths are similarly to host trachyandesites affected by superimposed hydrothermal alteration. Secondary minerals represent acid plagioclase (An05–10), chlorites (clinochlore; XMg = 0.55–0.67; Si = 3.13–3.29 apfu), carbonates (calcite and siderite), Ti-minerals (ilmenite, rutile and titanite), sulphides (pyrite and chalcopyrite) and less frequently quartz. The genetic affinity of xenoliths and the host neovolcanites is evidenced by the similarity in mineral composition and whole-rock chemistry. Xenoliths can be interpreted either as material from deeper parts of the magma chamber, or more probably as crystal cumulates (i.e. equivalents of cumulate gabbros).Neovolcanites from the Uherský Brod area sporadically enclose cm to dm large xenoliths of plutonic rocks. This paper focuses on characterization of xenoliths from the Bučník hill which are enclosed in trachyandesites by using classic petrographic methods. Based on mineral composition and textural features of main rock-forming minerals, the studied xenoliths can be classified as fine- to coarse-grained pyroxenic-amphibolic gabbros or diorites, respectively. They consist mainly of intermediate polysynthetically twinned plagioclase (andesine to labradorite; An44–55) and yellow-brown pleochroic magnesiohastingsite to pargasite (XMg = 0.64–0.75; Si = 6.09–6.29 apfu; Ti = 0.30–0.42 apfu). Relicts of diopside (XMg = 0.70–0.80; Ti = 0.01–0.03 apfu; Na = 0.03–0.04 apfu), brown strongly pleochroic phlogopite leaflets (XMg = 0.58–0.65; Si = 5.51–5.60), apatite columns (predominantly fluorapatite; F = 0.43–0.77 apfu) and K-feldspar (Ab16–17Or82–84An00–01) grains are less frequent. Amphiboles sporadically enclose round or tabular inclusions of labradorite to bytownite (An64–72) and subhedral olivine (Fo64). Xenoliths are similarly to host trachyandesites affected by superimposed hydrothermal alteration. Secondary minerals represent acid plagioclase (An05–10), chlorites (clinochlore; XMg = 0.55–0.67; Si = 3.13–3.29 apfu), carbonates (calcite and siderite), Ti-minerals (ilmenite, rutile and titanite), sulphides (pyrite and chalcopyrite) and less frequently quartz. The genetic affinity of xenoliths and the host neovolcanites is evidenced by the similarity in mineral composition and whole-rock chemistry. Xenoliths can be interpreted either as material from deeper parts of the magma chamber, or more probably as crystal cumulates (i.e. equivalents of cumulate gabbros)

Vznik metamorfní minerální asociace granátovců z desenské jednotky silezika

The usually medium-grained garnetites form up to several cm thick layers in quartz-magnetite mineralizations of the Desná Unit in the Silesicum. The garnetite mineral assemblage consists of epidote, quartz, garnet, magnetite, biotite, ilmenite, apatite and retrograde chlorite. The mineralogical and petrological results demonstrate that garnetites are metamorphosed submarine exhalites. Garnet from the garnetites has compositions with nearly equal amounts of spessartine and almandine components and can by interpreted as result metamorphic reactions partially consuming of the Mn-rich epidote. Thermobarometric calculations from the garnetites yielded peak amphibolite facie metamorphic conditions ca. 540–600 °C and up to 3 kbar. Chemical composition of fluids estimated for this metamorphic event is H2O = 82 až 95 mol. %, CO2 = 4 až 17 mol %, NaCl = 1 až 2 mol. %. The biotite was partially replaced by chlorite during younger retrograde metamorphic event under greenschist facie

Ultrabasic rocks of the teschenite association in the western part of the Silesian Unit

The teschenite association occurring in southwest part of the Silesian Unit (Carpathian Flysch Belt) consists of several types of predominantly alkaline basic to ultrabasic intrusive and extrusive igneous rocks. Ultrabasic rocks such as peridotites and picrites represent geochemically relatively primitive melt. Primary magmatic mineral assemblages of ultrabasic rocks are characterized by a large amount of olivine (Fo 81–86 mol. %), clinopyroxene (predominantly diopside: XMg = 0.65–0.85, Na = 0.02–0.04 apfu; aegirine-augite sometimes forms small rims around diopside: XMg = 0.00–0.14, Na = 0.40–0.98 apfu) and rare chrome spinel to chromite with Cr/(Cr+Al) values 0.55–0.62 in peridotite or 0.26–0.69 in picrites. Olivine, linopyroxenes or spinelides in these rocks appear as suitable for calculation of PT conditions. The temperatures obtained using the olivine-clinopyroxene thermobarometry (1 294–1 322 °C; 8–11 kbar) are consistent with the appearance of these two minerals in the crystallization sequence of peridotite. However, the temperatures calculated for spinelide inclusions in olivine are ~ 500 °C lower than the experimentally derived liquidus for ultrabasic melt. This difference can be explained by subsolidus re-equilibration during cooling. Younger mineral assemblage in peridotite consists of phlogopite, pargasite, and magnetite.The teschenite association occurring in southwest part of the Silesian Unit (Carpathian Flysch Belt) consists of several types of predominantly alkaline basic to ultrabasic intrusive and extrusive igneous rocks. Ultrabasic rocks such as peridotites and picrites represent geochemically relatively primitive melt. Primary magmatic mineral assemblages of ultrabasic rocks are characterized by a large amount of olivine (Fo 81–86 mol. %), clinopyroxene (predominantly diopside: XMg = 0.65–0.85, Na = 0.02–0.04 apfu; aegirine-augite sometimes forms small rims around diopside: XMg = 0.00–0.14, Na = 0.40–0.98 apfu) and rare chrome spinel to chromite with Cr/(Cr+Al) values 0.55–0.62 in peridotite or 0.26–0.69 in picrites. Olivine, linopyroxenes or spinelides in these rocks appear as suitable for calculation of PT conditions. The temperatures obtained using the olivine-clinopyroxene thermobarometry (1 294–1 322 °C; 8–11 kbar) are consistent with the appearance of these two minerals in the crystallization sequence of peridotite. However, the temperatures calculated for spinelide inclusions in olivine are ~ 500 °C lower than the experimentally derived liquidus for ultrabasic melt. This difference can be explained by subsolidus re-equilibration during cooling. Younger mineral assemblage in peridotite consists of phlogopite, pargasite, and magnetite

PETROGRAFIE A GEOCHEMIE SEDIMENTÁRNÍCH HORNIN V OKOLÍ KÓTY OBŘANY V HOSTÝNSKÝCH VRŠÍCH

The Obřany Hill is situated in the Hostýn Hills which are formed by the Raèa Unit of the Magura Nappe. Local sedimentary rocks (sandstone, conglomerate, shale, rare limestones) have been characterized petrographically and geochemically in this paper. Quartz sandstones dominate at the Hill. Detrital plagioclase occurring within sandstone is pure albite. The first investigated limestone was according to Dunham classification determined as a lime mudstone. Geochemically, it is rich in SiO2. The second limestone sample was determined as chemically very pure packstone. It is probably a boulder from local conglomerates. Clay (i.e., weathered claystone) is of various colour, exhibits high contents of Al2O3 and Fe2O3 and contains concretions of pelosiderite

Ultrabasic rocks of the teschenite association in the western part of the Silesian Unit

The teschenite association occurring in southwest part of the Silesian Unit (Carpathian Flysch Belt) consists of several types of predominantly alkaline basic to ultrabasic intrusive and extrusive igneous rocks. Ultrabasic rocks such as peridotites and picrites represent geochemically relatively primitive melt. Primary magmatic mineral assemblages of ultrabasic rocks are characterized by a large amount of olivine (Fo 81–86 mol. %), clinopyroxene (predominantly diopside: XMg = 0.65–0.85, Na = 0.02–0.04 apfu; aegirine-augite sometimes forms small rims around diopside: XMg = 0.00–0.14, Na = 0.40–0.98 apfu) and rare chrome spinel to chromite with Cr/(Cr+Al) values 0.55–0.62 in peridotite or 0.26–0.69 in picrites. Olivine, linopyroxenes or spinelides in these rocks appear as suitable for calculation of PT conditions. The temperatures obtained using the olivine-clinopyroxene thermobarometry (1 294–1 322 °C; 8–11 kbar) are consistent with the appearance of these two minerals in the crystallization sequence of peridotite. However, the temperatures calculated for spinelide inclusions in olivine are ~ 500 °C lower than the experimentally derived liquidus for ultrabasic melt. This difference can be explained by subsolidus re-equilibration during cooling. Younger mineral assemblage in peridotite consists of phlogopite, pargasite, and magnetite.The teschenite association occurring in southwest part of the Silesian Unit (Carpathian Flysch Belt) consists of several types of predominantly alkaline basic to ultrabasic intrusive and extrusive igneous rocks. Ultrabasic rocks such as peridotites and picrites represent geochemically relatively primitive melt. Primary magmatic mineral assemblages of ultrabasic rocks are characterized by a large amount of olivine (Fo 81–86 mol. %), clinopyroxene (predominantly diopside: XMg = 0.65–0.85, Na = 0.02–0.04 apfu; aegirine-augite sometimes forms small rims around diopside: XMg = 0.00–0.14, Na = 0.40–0.98 apfu) and rare chrome spinel to chromite with Cr/(Cr+Al) values 0.55–0.62 in peridotite or 0.26–0.69 in picrites. Olivine, linopyroxenes or spinelides in these rocks appear as suitable for calculation of PT conditions. The temperatures obtained using the olivine-clinopyroxene thermobarometry (1 294–1 322 °C; 8–11 kbar) are consistent with the appearance of these two minerals in the crystallization sequence of peridotite. However, the temperatures calculated for spinelide inclusions in olivine are ~ 500 °C lower than the experimentally derived liquidus for ultrabasic melt. This difference can be explained by subsolidus re-equilibration during cooling. Younger mineral assemblage in peridotite consists of phlogopite, pargasite, and magnetite

Petrographic variability of a body of teschenite from the site Bludovice near Nový Jičín (Silesian Unit, Outer Western Carpathians)

A petrographically complex teschenite sill occurs 800 m south-eastern from the village of Bludovice near Nový Jičín. The rocks are composed mainly of chemically zonal clinopyroxene (diopside core – Fe-rich diopside or Mg-rich hedenbergite rim) and clinoamphibole (kaersutite or ferrokaersutite core – hastingsite or ferropargasite rim) phenocrysts which range up to few cm in size, apatite, biotite, opaque minerals and bright gray to pinkish matrix. Main constituents of the matrix are alkali feldspars and analcime which are accompanied by secondary minerals (titanite, chlorite, prehnite, carbonates, epidote, and hydrated iron oxide-hydroxides). In this paper, we characterize various rock types of analcime-rich teschenites and thus try to elucidate petrographic variability of the teschenite body from Bludovice. Based on the mineral composition, texture, and geological position, four types of teschenites were distinguished: (I) leucocratic (M´ = 28–35) medium- to coarse-grained teschenites with pyroxene and amphibole phenocrysts; (II) mesocratic to melanocratic (M´ = 46–66) fine- to medium-grained pyroxene-amphibole to amphibole-pyroxene teschenites; (III) nests of leucocratic (M´ = 20–21) fine-grained pyroxene teschenite; and (IV) dykes of leucocratic to mesocratic amphibole-pyroxene to amphibole (M´ = 22–38) teschenite. Large petrographic variability resulted from processes of magmatic differentiation (fractional crystallisation, gravitational differentiation, and irregular distribution of volatile components) and subsequent hydrothermal alteration. Leucocratic nests and dykes represent most differentiated parts of the teschenite body.A petrographically complex teschenite sill occurs 800 m south-eastern from the village of Bludovice near Nový Jičín. The rocks are composed mainly of chemically zonal clinopyroxene (diopside core – Fe-rich diopside or Mg-rich hedenbergite rim) and clinoamphibole (kaersutite or ferrokaersutite core – hastingsite or ferropargasite rim) phenocrysts which range up to few cm in size, apatite, biotite, opaque minerals and bright gray to pinkish matrix. Main constituents of the matrix are alkali feldspars and analcime which are accompanied by secondary minerals (titanite, chlorite, prehnite, carbonates, epidote, and hydrated iron oxide-hydroxides). In this paper, we characterize various rock types of analcime-rich teschenites and thus try to elucidate petrographic variability of the teschenite body from Bludovice. Based on the mineral composition, texture, and geological position, four types of teschenites were distinguished: (I) leucocratic (M´ = 28–35) medium- to coarse-grained teschenites with pyroxene and amphibole phenocrysts; (II) mesocratic to melanocratic (M´ = 46–66) fine- to medium-grained pyroxene-amphibole to amphibole-pyroxene teschenites; (III) nests of leucocratic (M´ = 20–21) fine-grained pyroxene teschenite; and (IV) dykes of leucocratic to mesocratic amphibole-pyroxene to amphibole (M´ = 22–38) teschenite. Large petrographic variability resulted from processes of magmatic differentiation (fractional crystallisation, gravitational differentiation, and irregular distribution of volatile components) and subsequent hydrothermal alteration. Leucocratic nests and dykes represent most differentiated parts of the teschenite body

Petrographic variability of a body of teschenite from the site Bludovice near Nový Jičín (Silesian Unit, Outer Western Carpathians)

A petrographically complex teschenite sill occurs 800 m south-eastern from the village of Bludovice near Nový Jičín. The rocks are composed mainly of chemically zonal clinopyroxene (diopside core – Fe-rich diopside or Mg-rich hedenbergite rim) and clinoamphibole (kaersutite or ferrokaersutite core – hastingsite or ferropargasite rim) phenocrysts which range up to few cm in size, apatite, biotite, opaque minerals and bright gray to pinkish matrix. Main constituents of the matrix are alkali feldspars and analcime which are accompanied by secondary minerals (titanite, chlorite, prehnite, carbonates, epidote, and hydrated iron oxide-hydroxides). In this paper, we characterize various rock types of analcime-rich teschenites and thus try to elucidate petrographic variability of the teschenite body from Bludovice. Based on the mineral composition, texture, and geological position, four types of teschenites were distinguished: (I) leucocratic (M´ = 28–35) medium- to coarse-grained teschenites with pyroxene and amphibole phenocrysts; (II) mesocratic to melanocratic (M´ = 46–66) fine- to medium-grained pyroxene-amphibole to amphibole-pyroxene teschenites; (III) nests of leucocratic (M´ = 20–21) fine-grained pyroxene teschenite; and (IV) dykes of leucocratic to mesocratic amphibole-pyroxene to amphibole (M´ = 22–38) teschenite. Large petrographic variability resulted from processes of magmatic differentiation (fractional crystallisation, gravitational differentiation, and irregular distribution of volatile components) and subsequent hydrothermal alteration. Leucocratic nests and dykes represent most differentiated parts of the teschenite body.A petrographically complex teschenite sill occurs 800 m south-eastern from the village of Bludovice near Nový Jičín. The rocks are composed mainly of chemically zonal clinopyroxene (diopside core – Fe-rich diopside or Mg-rich hedenbergite rim) and clinoamphibole (kaersutite or ferrokaersutite core – hastingsite or ferropargasite rim) phenocrysts which range up to few cm in size, apatite, biotite, opaque minerals and bright gray to pinkish matrix. Main constituents of the matrix are alkali feldspars and analcime which are accompanied by secondary minerals (titanite, chlorite, prehnite, carbonates, epidote, and hydrated iron oxide-hydroxides). In this paper, we characterize various rock types of analcime-rich teschenites and thus try to elucidate petrographic variability of the teschenite body from Bludovice. Based on the mineral composition, texture, and geological position, four types of teschenites were distinguished: (I) leucocratic (M´ = 28–35) medium- to coarse-grained teschenites with pyroxene and amphibole phenocrysts; (II) mesocratic to melanocratic (M´ = 46–66) fine- to medium-grained pyroxene-amphibole to amphibole-pyroxene teschenites; (III) nests of leucocratic (M´ = 20–21) fine-grained pyroxene teschenite; and (IV) dykes of leucocratic to mesocratic amphibole-pyroxene to amphibole (M´ = 22–38) teschenite. Large petrographic variability resulted from processes of magmatic differentiation (fractional crystallisation, gravitational differentiation, and irregular distribution of volatile components) and subsequent hydrothermal alteration. Leucocratic nests and dykes represent most differentiated parts of the teschenite body

Fluid inclusions and chemical composition of analcimes from Řepiště site (Outer Western Carpathians)

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 SiO2/Al2O3 mole ratios from 2.08 to 3.12. Increasing SiO2/Al2O3 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.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 SiO2/Al2O3 mole ratios from 2.08 to 3.12. Increasing SiO2/Al2O3 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

New occurrence of the Menilite Formation near Dřevohostice

The Menilite Formation is an important lithostratigraphic member of the Krosno-menilite Unit in the Carpathian Flysch Belt. The rocks of the Menilite Formation occur as small bodies also within Sub-Silesian Unit on the geological map sheet 25-13 Přerov. In this paper, we present new occurrence of chert layers of the Menilite Formation at ground elevation 275 which is situated 1.2 km easternlyof the village Dřevohostice. The rock body is formed of layers of laminated gray-white to gray-brown menilite chert interlayered by thin interpositions of weathered gray-green non-calcareous claystones. The menilite cherts consist of brownish-yellow and gray opal laminae with limonite and chalcedony streaks. Opal laminae have thickness mostly in range of 1–10 mm. Rock matrix is cut by numerous veins formed by opal and chalcedony which originated during at least two diff erent events. Menilite cherts sporadicallyenclose small siliceous chalcedony geodes. Claystones have pelitic texture with a clotted inner structure and contain siliceous sponge spicules and other non-specified microfossils (probably planktonic diatoms). The cherty layers documented in a dug probe have WNW–ESE direction with inclination to SSW under the angle of 25°. The sediments were folded during the overthrust of the Sub-Silesian Nappe on the Carpathian Foredeep in the Karpatian and during subsequent late-tectonic rotations towards NW.The Menilite Formation is an important lithostratigraphic member of the Krosno-menilite Unit in the Carpathian Flysch Belt. The rocks of the Menilite Formation occur as small bodies also within Sub-Silesian Unit on the geological map sheet 25-13 Přerov. In this paper, we present new occurrence of chert layers of the Menilite Formation at ground elevation 275 which is situated 1.2 km easternlyof the village Dřevohostice. The rock body is formed of layers of laminated gray-white to gray-brown menilite chert interlayered by thin interpositions of weathered gray-green non-calcareous claystones. The menilite cherts consist of brownish-yellow and gray opal laminae with limonite and chalcedony streaks. Opal laminae have thickness mostly in range of 1–10 mm. Rock matrix is cut by numerous veins formed by opal and chalcedony which originated during at least two diff erent events. Menilite cherts sporadicallyenclose small siliceous chalcedony geodes. Claystones have pelitic texture with a clotted inner structure and contain siliceous sponge spicules and other non-specified microfossils (probably planktonic diatoms). The cherty layers documented in a dug probe have WNW–ESE direction with inclination to SSW under the angle of 25°. The sediments were folded during the overthrust of the Sub-Silesian Nappe on the Carpathian Foredeep in the Karpatian and during subsequent late-tectonic rotations towards NW