Geoscience Research Reports最新文献

{"title":"Langite from Mýtinka near Horní Halže in the Krušné hory Mts. (Czech Republic)","authors":"Jakub Vácha, D. Všianský","doi":"10.3140/zpravy.geol.2023.09","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2023.09","url":null,"abstract":"Horní Halže – Mýtinka is a mineral occurrence located near Mýtinka in the Krušné hory Mts. In the past, the area was intensively mined for iron (namely hematite in quartz veins). Quartz veins are located on complicated intersections of fault systems in mica schists and migmatites (Urban – Crkal 2021). Recently, Sejkora et al. (2021) described rich Cu mineralization found in the remains of old mine dumps. Sulfide mineralization is represented by pyrite, djurleite, roxbyite, anilite, spionkopite, bornite and covellite, supergene phases by malachite, brochantite, liebethenite and pseudomalachite. The studied material (thin blue coating on a part of a single sulfide grain 3 mm in size; Fig. 1) was found by the first author in 2021 at the old mine dump and matches the material described by Sejkora et al. (2021). The blue phase was identified as langite [Cu4(SO4)(OH)6 · 2H2O] using combination of EDS, Raman and pXRD. Chemical composition of examined mineral coating was analyzed using EDS, which detected presence of Cu, S and O contents only (with Cu significantly higher than S). Raman spectrum of langite from Mýtinka (Fig. 2, Tab. 1) was acquired using a HORIBA LabRam spectrometer and the data were processed using Systat PeakFit software. Proposed spectrum model is in very good agreement with empirical data (r2 = 0.992). Assignment of individual bands according to Martens et al. (2002, 2003) is proposed in Table 1. Raman spectrum of langite is similar to those of posnjakite [Cu4(SO4)(OH)6 · H2O] and wroewolfeite [Cu4(SO4)(OH)6 · H2O]. By combining (poorly and only partially presented) data of Frost et al. (2004) and Martens et al. (2002), following differences among these phases were identified. Bands at 155 and 258 (262 in this work) cm–1 are present in the Raman spectrum of langite but missing in that of posnjakite. The Raman spectrum of wroewolfeite is devoid of bands at 507 and 596 (500 and 598 in this work) cm–1, characteristic of langite, and at 511 and 596 cm–1, characteristic of posnjakite. About 15 fragments of the coating, 20–100 µm in size, were analyzed on Panalytical X’Pert powder XRD diffractometer. Only four diffraction maxima were obtained due to a very small amount of material available. Nevertheless, corresponding d-values are in a good agreement with data for langite (Tab. 2; Galy et al. 1984).","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140500127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydraulic parameters of Submenilite Formation of Ždánice Unit","authors":"Ondřej Janíček, Tomáš Kuchovský","doi":"10.3140/zpravy.geol.2023.13","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2023.13","url":null,"abstract":"This study aims to re-asses hydrodynamic tests of the Submenilite Unit of the Outer Carpathian Flysch Zone sediments, exposed at Přítlucká hora located near Rakvice village in South Moravian region, Czech Republic. We focused on four shallow, 6.0–7.6 m deep hydrogeological wells, drilled by Aqua Enviro s. r. o. company in 2005. The purpose of the drilling was a feasibility study for drainage of western part of Rakvice village. The sediments of the Submenilite Formation of the Ždánice unit that were drilled are dominated by compressed clays, claystones and siltstones, containing thin layers of sand and weathered sandstones. For the purpose of determining hydraulic parameters of underlying aquifer, the company conducted pumping and recovery tests on each of the wells. In this work, we used Jacob’s semilogarithmic method to interpret the measured groundwater level data. Hydraulic conductivity and transmissivity parameters were consequently calculated. The resulting transmissivity values range from 1.6 × 10–2 m2/d to 3.7 × 10–1 m2 /d and hydraulic conductivity value ranges from 3.6 × 10–3 m/d to 1.0 × 10–1 m/d. The calculated index of transmissivity Y corresponds to 4.32–4.57 and index of conductivity Z ranges between 5.80 and 6.27. The values of index of transmissivity Y from this study are generally comparable with results presented by previous authors and demonstrate very low transmissivity of the rocks of this unit mostly built by non-permeable pelitic rocks.","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140499797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New occurrences of Paseky Shale near Podlesí NW of Příbram and microfossils from the Nové Podlesí locality (Cambrian, Holšiny-Hořice Formation, Příbram-Jince Basin)","authors":"T. Vorel, Vojtěch Kovář","doi":"10.3140/zpravy.geol.2023.10","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2023.10","url":null,"abstract":"Previously unrecorded occurrences of the Paseky Shale were found in the course of geological mapping at three localities NW of Příbram near Podlesí (Fig. 1). This shale makes a part of the Cambrian Series 2, Holšiny-Hořice Formation in the Příbram-Jince Basin. The shale was documented ca. 250 m S and about 80 m NE of the Malá Dubová hora summit as abundant loose rock fragments (Fig. 2) and soil skeleton (Fig. 3), respectively. An outcrop of the Paseky Shale was found in a small quarry near Nové Podlesí (Figs 4 to 9). The Paseky Shale has a significant position within the geological record of the Barrandian area as it hosts the oldest macrofossil fauna in the Czech Republic, most notably the aglaspid-like arthropod Kodymirus vagans Chlupáč & Havlíček 1965 (Chlupáč – Havlíček 1965, Lamsdell et al. 2013). A microfossil analyses of samples from the quarry near Nové Podlesí has been carried out. The microfossils are relatively sparse and generally rather poorly preserved. The assemblage consists mostly of filaments belonging to the genus Siphonophycus Schopf 1968, emend. Knoll et al. 1991 (Fig. 10 A, D, E, F) ranging from ca. 8 to 50 µm in width. Less common are representatives of Leiosphaeridia minutissima Naumova 1949, emend. Jankauskas in Jankauskas et al. 1989 (Fig. 10 B, C). No other acritarchs were found. Residues further include poorly identifiable fragments of organic-walled microfossils, most likely representing degraded filaments (Fig. 10 G). The studied assemblage is consistent with findings from other localities of the Paseky Shale. However, further relatively rarer components of the microfossil assemblages known from other localities (see Fatka – Konzalová 1995, Kovář – Fatka 2023) are missing. This is most likely due to the low abundance and generally poor preservation of the microfossils at the locality. The general absence of a more diversified acritarch assemblage corresponds to an atypical, restricted marine environment, presumably represented by a lagoonal setting (see Fatka – Konzalová 1995).","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140500408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Indications of volcanic style of the Silurian Nová Ves Volcano (Hemrovy Rocks)","authors":"M. Stárková, Š. Mrázová, Stanislava Vodrážková","doi":"10.3140/zpravy.geol.2023.12","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2023.12","url":null,"abstract":"Studied locality of Hemrovy Rocks belongs to Nová Ves Volcanic Center, one of the Silurian volcanic centers of Prague Basin of Teplá-Barrandien area (lower Wenlock – lower Ludlow age). The aim of this work is to describe details of the volcanic rock structures and to contribute to the interpretation of the Silurian volcanic style. The macroscopic and microscopic structures of basaltic rocks in and close to the abandoned Kační Quarry in the southern part of Prague and at the adjacent locality – ridge of Hemrovy Rocks were studied. At these sites, volcaniclastics dominate over solid volcanic rocks and sediments. The volcanic rocks are represented by basalts, which form thin lava flows overlying both the volcaniclastics and sedimentary rocks. Massive fine-grained basalts pass to pillow lava facies, autobreccia or hyaloclastite breccia in-situ. These brecciated structures evolve into peperites or to unconsolidated volcaniclastic rocks of a previous eruption. Coarse-grained volcaniclastics with oversized subrounded to angular clasts of vesiculated lava or sediments within glassy matrix, sporadically with sediment admixture, are unsorted and thick-bedded. They were probably formed by gravity-driven mass flow. Basalt in the Kační Quarry probably represents a synvolcanic intrusion, as documented by its hyaloclastite rim and presence of clusters of resedimented volcaniclastics in the adjacent fine-grained sediments. Matrix of the volcaniclastics is mostly unsorted, formed mostly by quenched fragments of altered palagonitized and chloritized basaltic glass, locally scoriaceous, and fragments of chilled basaltic lava. Originally highly porous volcaniclastics, resp. hyaloclastites were secondarily cemented by calcite and silica. Secondary chlorite, calcite and silica also fill vesicles and cavities in fragments of glass and lava clasts. Dense vesicularity of lava fragments in volcaniclastics indicates an effective explosive interaction of lava with water. It is probable that much of the wet volcaniclastic material repeatedly slumped back down into the volcano’s crater to be re-ejected by subsequent phreato-magmatic explosions. Hydroclastic fragmentation was iniciated by repeated subaquatic eruptions in shallow subphotic marine zone. Unsorted crinoidal packstones mostly with trilobites, trepostomate bryozoan and volcaniclastic matrix were deposited in the vicinity of the Nová Ves Volcanic Center.","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140500360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Supergene mineral assemblage from sediments affected by contact and hydrothermal metamorphism, locality Dobrá – Staré Město near Frýdek-Místek (Czech Republic)","authors":"D. Matýsek, J. Jirásek","doi":"10.3140/zpravy.geol.2023.11","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2023.11","url":null,"abstract":"At locality Dobrá – Staré Město, series of outcrops occur on both banks of the Morávka River. The river cuts through the sediments on the tectonic contact between the Silesian and Subsilesian units of the Outer Western Carpathians. Clayey facies of the Hradiště Formation (Early Cretaceous, Valanginian to Aptian) contains numerous tectonic fragments reaching hundreds meters in size of strongly altered (carbonatized, smectitized) subaquatic volcanic rocks of the Teschenite Association. These volcanic rocks are dominated by fine-grained to aphanitic rocks, possibly of both effusive and intrusive origin. The host sediments affected by the contact metamorphism (contact adinole) also occur. Framboidal pyrite is abundant in majority of sediments of the studied area, giving rise to efflorescences of gypsum, baryte, celestine, and a mineral of alunite group (Figure 1). A more varied assemblage of supergene minerals was recognized on a small rock outcrop at GPS coordinates N 49° 39.992’ E 018° 23.810’ (Figure 2), where it developed relatively recently after the big floods in 2010 that washed away the previous mineralization. During the first years, only gypsum crusts were detectable, while in 2023, we recognized 4 macroscopic and 5 microscopic minerals forming thin botryoidal crusts. These crusts show faint zoning, with gooey, gel-like X-ray amorphous material in the humid upper part , middle zone with abundant fibroferrite and the lower part dominated by gypsum. Gypsum forms well-developed, but frequently corroded crystals with various habitus (Figure 4A, B). Fibroferrite is present as fibrous aggregates with individual crystals of up to ca. 100–150 µm long and <1 µm thick (Figure 4C). It forms directly from the gel-like substance (Figure 4D). Rhombohedral crystals and rossete aggregates of hydroniumjarosite vary from 2 µm to 5 µm in size (Figure 4E), but the most common are dust-like coatings on rock fissures with particle size <1 µm. Rusty coatings of schwertmannite (Figure 4F), in some places accompanied by gypsum, with Fe/S at. % ratios near 4–5 are common. In some cases, the Al/Fe at. % ratio exceed 1, which might indicate presence of yet undescribed Al-analogue of schwertmannite, ill-defined alumogel, or an amorphous precursor of aluminite. Presence of ferrihydrite is possible but not confirmed. The above-mentioned Fe-rich phases are frequently accompanied by diplobacilli-shaped bacteria (Figure 4F). Slavíkite, pickeringite-halotrichite, alunogen, copiapite group mineral, hexahydrite, and melanterite (Figure 5) were also recognized by EDS and PXRD. Slavíkite and copiapite group minerals seem to be alteration products of fibroferrite. Unit-cell parameters refined from the X-ray powder diffraction are presented for all recognized phases (Table 1). Surprisingly, secondary sulfates are present on the metasediments with abundant calcite (Figure 3), which should serve as a neutralization buffer. The reason is the restricted amount of calcite available on ","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140499520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Topaz quartzolite (greisen) in North Bohemia – potential source of the natural abrasive","authors":"Petr Martinec, Petr Hlaváček, L. Sitek, J. Foldyna, J. Klomínský, František Veselovský, Ferry Fediuk","doi":"10.3140/zpravy.geol.2023.14","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2023.14","url":null,"abstract":"Topazolite (greisen) is a rock formed essential by quartz and topaz, with accessory white mica, tourmaline, sulphides (molybdenite and arsenopyrite), wolframite and cassiterite. This rock was found in the Krkonoše and Jizera Mountains in the western Sudetes. In Poland, this metasomatic rock occurs at the contact between leucogranite and mica schist (associated with hydrothermal kaolinization) in a narrow zone between the settlements of Rebiszow and Gierałtówek. On Czech territory, similar topaz quartzolite (greisen rock), consisting of up to 65 % quartz and 32 % topaz, was found near the settlements of Růžek and Vítkov near Chrastava in association with orthogneiss. The high content of topaz in this rock offers the possibility of using it as an abrasive in high-speed abrasive water jet technology for cutting and surface treatment of hard metallic and non-metallic materials. In the crushed form, after being concentrated in a treatment plant, topaz could be a natural abrasive with a wide range of applications. However, the results of technological testing of the physical and mineralogical characteristics of the topaz concentrate indicate its unfavorable properties caused by the high fissility of topaz. This leads to losses of topaz during its technological adjustment to the required grain size or during recycling. It has been shown that abrasive concentrates with topaz content above 90 % are promising, especially for special applications of abrasive water jet technology. Mastering the technology for processing of the source raw material, i.e. topaz quartzolite, into a topaz-rich concentrate, and subsequent applied research on the use of topaz abrasives in industry are crucial.","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140500735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mineralogy of sulfide ores from the Měděná Adit in the Zlaté Hory Ore District","authors":"Stanislav Staněk, Jiří Zimák","doi":"10.3140/zpravy.geol.2023.07","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2023.07","url":null,"abstract":"Until 1993, sulfide ores of copper, lead and zinc, as well as native gold were mined in the Zlaté Hory ore district in the Jeseníky Mountains. These deposits occur in the Devonian volcano-sedimentary complex of the Vrbno Group, which consists of quartzites, phyllites, limestones and metamorphic igneous rocks of intrusive and extrusive nature. The main ore bodies are located in a quartzite horizon containing lenses of felsic metavolcanic rocks or in the underlying and overlying rocks (mainly phyllites). Sulfide mineralization of the Měděná Adit in the Zlaté Hory ore district concentrated in greenschists containing three mineral assembblages: i) chlorite + quartz + albite + barian feldspar + siderite + dolomite (ankerite) ± ilmenite, ii) chlorite + phlogopite + quartz + albite + siderite + dolomite (ankerite) ± magnetite ± ilmenite, iii) chlorite + muscovite + quartz + albite + ilmenite ± siderite ± magnetite. Micas have elevated barium contents (2.2 to 5.5 wt. % BaO in phlogopite, 2.6 to 4.6 wt. % BaO in muscovite) and represent the dominant carrier of this element in the rock. In the case that mica is absent in the rock, barium is bound in barian feldspar. When content of quartz in these greenschists is high, they pass into quartzite. Three types of sulfide ore were found in the Měděná Adit: A) banded copper ore in biotite-chlorite greenschist, which is formed dominantly by disseminated pyrite and pyrrhotite, accompanied by a small amount of chalcopyrite (the ore contains approx. 0.7 wt.% Cu), B) disseminated copper mineralization in quartz-rich bands or quartzite intercalations in chlorite greenschist, consisting mainly of pyrrhotite, less voluminous pyrite, and small amounts of chalcopyrite and galena (the ore contains approx. 0.3 wt.% Cu, the lead content is highly variable, up to 0.15 wt.% Pb), C) vein-like copper ore in greenschist with chalcopyrite dominating over pyrrhotite and pyrite (the ore has a very high copper content, 13.6 and 24.7 wt.% Cu in two analyzed samples). With its mineral composition, structural features and the character of the ore-bearing rocks, disseminated copper mineralization is similar to the Cyprus-type ores (so-called Cu-pyrite ores). The vein copper mineralization is probably a result of copper remobilization during regional metamorphism.","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135807376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lower and Middle Miocene sediments southwest of Brno in the light of new findings","authors":"Oldřich Krejčí","doi":"10.3140/zpravy.geol.2023.08","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2023.08","url":null,"abstract":"New knowledge on the occurrence of Lower and Middle Miocene sediments in the southwestern surroundings of Brno has been acquired through geological mapping and documentation work during the recent years. Specific work was focused on: • preparation of the publication on the local national history of the cadastral territory of the village of Bohutice; • salvage study of the former reserved bentonite deposit Ivančice – Réna, which is being gradually remediated and turned into a recreational area; • the area in the foreground of the New Ivančice viaduct, which is susceptible to long-term slope instability; • the western edge of the village of Němčičky near Židlochovice, where extensive construction of family houses is underway; • the area between the municipalities of Moravany, Nebovidy and Ostopovice, where the excavations for new extra-high voltage pylons were documented. The detailed mapping, petrographic and biostratigraphic studies allowed to refine the distribution, lithological characteristics and age of Miocene sediments; specifically, a more extensive occurrence of Lower Miocene sediments compared to previous findings was confirmed (localities Ostopovice, Moravské Bránice – locality 5). These findings support earlier results from the area N of the City of Brno, where the known extent of Ottnangian sediments was expanded at the expense of Badenian sediments. The documentation and sampling of the new excavations (for family houses and extra-high voltage pylons) and old mining pits enabled the description and further study of the sediments. The acquired litho- and biostratigraphic data were correlated with engineering geological findings. In a construction pit in Bohutice, a completely new occurrence of tuffitic sediments of the Ottnangian age was discovered and geochemically verified. Furthermore, the Ottnangian gravels in Němčičky were newly discovered. These contain a large proportion of granitoid pebbles probably derived from the Brno Massif. It was found that the weakly consolidated lithologically variable Lower Miocene sediments are prone to landslides. In the case of the New Ivančice viaduct, extensive suffusion doline were identified, resulting from the ingress of rainwater from the wider area of the railway embankment foreground. Biostratigraphy of the sediments was based on micropaleontological analysis of foraminiferas. Ottnangian sediments were usually fossil- free and/or they contained reworked Cretaceous foraminiferas. Lower Badenian sediments are characterized by occurrence of abundant and diversified fauna represented by foraminifera species such as Martinotiella karreri (Cush.), Globigerinoides bisphericus Todd, Vaginulina legumen (L.), etc.","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135807375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structure of the Kutiště rockslide developed in crystalline rocks of the Hrubý Jeseník Mts.","authors":"Martin Kašing, Zuzana Lenďáková, Jakub Jirásek, Michal Goldberger","doi":"10.3140/zpravy.geol.2023.06","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2023.06","url":null,"abstract":"Slope failures developed in crystalline rocks of the Hrubý Jeseník Mts. (Czechia) are quite sparse phenomenon. So far, only a few deep-seated landslides have been described from areas near Keprník Mt. and Červená hora Mt., while shallow flood- related flows are more frequent. The newly identified Kutiště rockslide (GPS 50.1437297N, 17.0563289E) is located in the village of Jindřichov (Šumperk District, the Olomouc Region, Czechia) about 1 km northeast of Štolný hřbet Mt. (883 m a. s. l.) within the Hrubý Jeseník Mts. The rockslide has been geomorphologically mapped and structural analysis and geophysical measurements using electrical resistivity tomography have been carried out to interpret surface and subsurface structure of the landslide. It is a planar rockslide developed in biotitic orthogneiss of the Keprník Nappe, covering an area of approximately 0.13 km2 (ca. 500 × 250 m) with a total altitude difference of about 140 m. The landslide is dominated by a morphologically very distinct amphitheatre-like headscarp. The approximately 300 m long and relatively compact transport zone of the slide is dissected by several transverse fissures and tension cracks, and it is delimited towards the bedrock by a planar sliding surface at depths of 10–17 m. The accumulation part of the landslide, about 150 m long, has further collapsed by gravity. The resistivity image in this part indicates a sliding surface at a depth of about 25 m. The structural data indicate that the slope failure was structurally predisposed by an orthogonal system of longitudinal (NNW-SSE) and transverse (ENE-WSW) brittle structures, and the hillslope-conformal metamorphic foliation of orthogneiss inclined at an angle of 11° towards N to NNW. The resistivity image of the rockslide does not exclude the presence of deeper sliding surfaces throughout the entire extent of the slope deformation, which would enable its further development. The morphologically fresh appearance of the landslide is not necessarily a result of low age, but rather of the strong resistance of the orthogneiss to weathering.","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135807377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrological diversity of leucocratic rocks at the sodium-potassium feldspar deposit Krásno – Vysoký kámen","authors":"Karel Breiter, Jaromír Tvrdý, Pavel Jedlička","doi":"10.3140/zpravy.geol.2023.03","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2023.03","url":null,"abstract":"The presented study aims to reevaluate the geological structure of the Krásno-Vysoký Kámen feldspar deposit and its relationship to the surrounding rocks using chemical and imaging methods. For this purpose, we have documented in detail all the preserved fragments of drill cores from the survey in the 1960s and 1970s years, and 21 exploratory boreholes of the KP series (Fig. 1) realized in 2021, including about 600 chemical XRF bulk-rocks analyzes of rocks from these drillings. The Krásno-Vysoký Kámen open pit is located about 1 km northwest of the Krásno village, western Bohemia. Subject of mining is a complex of leucocratic, feldspar-rich granitoids consisting of predominant medium-grained leucogranite with mainly subhorizontal intercalations of syenite, aplite-pegmatite and feldspar-rich metasomatites. Both the immediate bedrock and the exposed overburden of the leucogranite complex consist of biotite granites. The leucogranite complex forms a lenticular body, the lower boundary of which decreases from N and NW towards E and S (Fig. 5). Especially on the western side of the open pit, the contact of the two rocks is relatively steep, further to the east it flattens. Medium-grained leucocratic granite makes up most of the volume of the deposit. It has a magmatic texture (Fig. 2a) with euhedral, short columnar albite crystals, subhedral orthoclase grains, irregular late quartz grains and low mica content (Tab. 2); apatite and rare topaz and niobium rutile are also present. In the SW edge of the quarry, contact facies of the leucogranite with several layers of oriented crystallization of quartz is exposed. Locally, leucogranite changes to leucosyenite (Fig. 2b). The leucosyenite is still a medium-grained rock with a magmatic texture, but the quartz content decreases (<10%) and the mica is only accessory. Several flat veins of virtually mica-free aplite (Fig. 2c), from several dm to 5 m thick, are lined along the upper contact by a zone of oriented K-feldspar and quartz crystallization (i.e. stockscheider). Alkaline metasomatites (Fig. 2d) are medium to fine grained. Medium-grained varieties are macroscopically hardly distinguishable from igneous syenites; fine-grained varieties are similar to aplites. Feldspars in metasomatites already have a completely irregular worm-like shape, while the ratio of both feldspars fluctuates strongly. The underlying biotite granite is currently well exposed in the NW part of the quarry and was reached by wells KP4, KP5, KP6, and KP7. It is medium-grained granite with Li-biotite and topaz. The contact between this granite and the overlying leucocratic complex was interpreted as rapid transition in old boreholes (Pácal and Pavlů 1979), but sharp contact was found in the borehole KP4. The overlying biotite granite was exposed in the SW parts of the quarry and confirmed by 2 boreholes (KP2, KP3). Both types of biotite granite differ statistically in Fe, Na and K contents. The medians of the chemical composition of all ","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135807547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}