Pub Date : 2023-05-09DOI: 10.3140/zpravy.geol.2023.04
Miloš René
Nb-Ta-Ti-bearing oxide minerals represent the most common hosts of Nb and Ta in high-F, high-P2O5, Li-mica granites from the Sauberg granite stock in the Krušné hory/Erzgebirge Mts. batholith (Figure 1). The stock hosts the Ehrenfriedersdorf ore deposit, representing the most significant Sn-W ore deposit in this area. This ore deposit was mined from the 13th century until the year 1990. Since July 2019, the Ehrenfriedersdorf mining landscape makes a significant part of the UNESCO world heritage site, the Montanregion ore mountains. Fine- to medium-grained granites of the Sauberg granite stock are composed by quartz, albite (An 0.1–0.5), K-feldspar (Or97–99, Ab1–3), Li-mica and topaz. Both feldspars are partly enriched in phosphorus (up to 0.52 wt. % P2O5). Apatite, zircon and monazite are accessory phases. The Nb-Ta-Ti-bearing oxide minerals – Nb-Ta-rich rutile, Fe-columbite, W-ixiolite occur in accessory amounts in ore-bearing structures together with cassiterite and wolframite. The main ore-bearing structures are represented by mineralised vein structures and metasomatic stringer zones, which are the most significant. The latter are characterised by numerous parallel to sub-parallel E-W striking en-echelon sets of ore veins. The Sauberg granite stock hosting the Nb-Ta mineralization is mostly formed by highly fractionated, highly peraluminous S-type granites (ASI = 1.2–1.4) with Nb/Ta ratio = 1.8–5.5 and depletion in CaO, MgO, Ba, Sr and high-field-strength elements. (Table 1, 2). The Nb-Ta-bearing rutile is the most common Nb and Ta carrier and occurs mostly as subhedral inclusions in Li-mica flakes. It has very low Mn/(Mn Fe) ratio (0.0–0.01) and low Ta/(Ta Nb) ratio (0.04–0.25) (Table 3). Columbite-group minerals are represented by columbite-(Fe) with a Mn/(Mn Fe) ratio varying from 0.11 to 0.14 and with relatively low Ta/(Ta Nb) values (0.08–0.26) (Table 4). The rare, W-ixiolite was observed as needle-like subhedral crystals and/or as inclusions in needle-like aggregates of wolframite. The W-ixiolite is Fe-rich with relatively low Mn/(Mn Fe) and Ta/(Ta Nb) values of 0.11–0.13 and 0.07–0.25, respectively (Table 5).
{"title":"Nb-Ta-Ti oxides in topaz granites of the Ehrenfriedersdorf tin-tungsten ore deposit (Krušné hory Mts., Germany)","authors":"Miloš René","doi":"10.3140/zpravy.geol.2023.04","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2023.04","url":null,"abstract":"Nb-Ta-Ti-bearing oxide minerals represent the most common hosts of Nb and Ta in high-F, high-P2O5, Li-mica granites from the Sauberg granite stock in the Krušné hory/Erzgebirge Mts. batholith (Figure 1). The stock hosts the Ehrenfriedersdorf ore deposit, representing the most significant Sn-W ore deposit in this area. This ore deposit was mined from the 13th century until the year 1990. Since July 2019, the Ehrenfriedersdorf mining landscape makes a significant part of the UNESCO world heritage site, the Montanregion ore mountains. Fine- to medium-grained granites of the Sauberg granite stock are composed by quartz, albite (An 0.1–0.5), K-feldspar (Or97–99, Ab1–3), Li-mica and topaz. Both feldspars are partly enriched in phosphorus (up to 0.52 wt. % P2O5). Apatite, zircon and monazite are accessory phases. The Nb-Ta-Ti-bearing oxide minerals – Nb-Ta-rich rutile, Fe-columbite, W-ixiolite occur in accessory amounts in ore-bearing structures together with cassiterite and wolframite. The main ore-bearing structures are represented by mineralised vein structures and metasomatic stringer zones, which are the most significant. The latter are characterised by numerous parallel to sub-parallel E-W striking en-echelon sets of ore veins. The Sauberg granite stock hosting the Nb-Ta mineralization is mostly formed by highly fractionated, highly peraluminous S-type granites (ASI = 1.2–1.4) with Nb/Ta ratio = 1.8–5.5 and depletion in CaO, MgO, Ba, Sr and high-field-strength elements. (Table 1, 2). The Nb-Ta-bearing rutile is the most common Nb and Ta carrier and occurs mostly as subhedral inclusions in Li-mica flakes. It has very low Mn/(Mn Fe) ratio (0.0–0.01) and low Ta/(Ta Nb) ratio (0.04–0.25) (Table 3). Columbite-group minerals are represented by columbite-(Fe) with a Mn/(Mn Fe) ratio varying from 0.11 to 0.14 and with relatively low Ta/(Ta Nb) values (0.08–0.26) (Table 4). The rare, W-ixiolite was observed as needle-like subhedral crystals and/or as inclusions in needle-like aggregates of wolframite. The W-ixiolite is Fe-rich with relatively low Mn/(Mn Fe) and Ta/(Ta Nb) values of 0.11–0.13 and 0.07–0.25, respectively (Table 5).","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135807548","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}
Pub Date : 2023-05-09DOI: 10.3140/zpravy.geol.2023.02
Radek Mikuláš
The collection of fossils in the abandoned limestone (? Lower Cambrian) quarry in Suchý Důl close to Dolní Albeřice (eastern margin of the Krkonoše Mts.) became practically impossible after the end of mining and modification of the pit for private recreational purposes. However, in the last phase of mining (2016), hundreds of blocks of these limestones with a weight of 200 to 500 kg were used to reinforce the banks of the Lysečiny and Albeřice brooks and the retention reservoir on the Lysečiny brook. After several years of natural weathering of the surfaces, the primary and secondary textures in the limestones are very well preserved and distinct when viewed with the naked eye or a hand lens. In the summer of 2022, I examined about 10 m2 of mostly oolitic limestone surfaces with a hand lens and found several structures which were probably of organic origin. The total area of studiable limestone is estimated at 100–250 m2. Due to weathering of the surfaces, the possibility of collection of fossils culminates in the current years and will become negligible within 5–10 years. Only cross-sections through the potential biogenic structures were observed. They have an ovoid, elliptical, or triangular shape. This could indicate their affiliation to the Archaeocyatha group, two individuals of which have been already found in the quarry. The comparison with the previous findings suggests that the findings depicted in Fig. 1A–1D can represent preserved fragments of Archaeocyatha. A little crest of an irregularly sinusoid shape in Fig. 1E shows preservation similar to the primary textures, i.e. ooids. This suggests its organogenic origin. The size and course of the crest indicates that it could represent, for example, a cross-section through a trilobite cephalon. For comparison, a usual way of weathering of veins of secondary origin in limestone block is shown in Fig. 1F. In addition to their sharp contact, they are tightly folded, which is typical of deformed rocks. On the other hand, during the field work in 2022, any deformed, flattened or elongated ooids (as known, e.g., from the Ordovician ferrite ooids of the Barrandian area) were observed. It is suggested that during deformation, the ooids (primarily build of magnesium carbonate) “floated” in the ductile matrix (primarily calcite) similar to, for example, raisins in leavened dough. Therefore, the deformation, judging from the shape of the ooids, is small or negligible; in reality, however, the shells of the vast majority of organisms were completely destroyed, “mixed up”. Acceptance of this idea then explains why the Albeřice carbonates are so poor in fossils, although the oolitic facies gives the impression of a rock that is not deformed or recrystallized at all and the carbonates point to a revived, climatically favourable, rather shallow marine environment. However, the results of a field research in August 2022 show that the search for fossils in the limestones around Albeřice is currently (and wi
{"title":"The current state of exposure of fossiliferous carbonates in Suchý Důl (Czech Republic, Bohemian Massif, Lusatia Region, Krkonoše-Jizera Mts. Crystalline Complex)","authors":"Radek Mikuláš","doi":"10.3140/zpravy.geol.2023.02","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2023.02","url":null,"abstract":"The collection of fossils in the abandoned limestone (? Lower Cambrian) quarry in Suchý Důl close to Dolní Albeřice (eastern margin of the Krkonoše Mts.) became practically impossible after the end of mining and modification of the pit for private recreational purposes. However, in the last phase of mining (2016), hundreds of blocks of these limestones with a weight of 200 to 500 kg were used to reinforce the banks of the Lysečiny and Albeřice brooks and the retention reservoir on the Lysečiny brook. After several years of natural weathering of the surfaces, the primary and secondary textures in the limestones are very well preserved and distinct when viewed with the naked eye or a hand lens. In the summer of 2022, I examined about 10 m2 of mostly oolitic limestone surfaces with a hand lens and found several structures which were probably of organic origin. The total area of studiable limestone is estimated at 100–250 m2. Due to weathering of the surfaces, the possibility of collection of fossils culminates in the current years and will become negligible within 5–10 years. Only cross-sections through the potential biogenic structures were observed. They have an ovoid, elliptical, or triangular shape. This could indicate their affiliation to the Archaeocyatha group, two individuals of which have been already found in the quarry. The comparison with the previous findings suggests that the findings depicted in Fig. 1A–1D can represent preserved fragments of Archaeocyatha. A little crest of an irregularly sinusoid shape in Fig. 1E shows preservation similar to the primary textures, i.e. ooids. This suggests its organogenic origin. The size and course of the crest indicates that it could represent, for example, a cross-section through a trilobite cephalon. For comparison, a usual way of weathering of veins of secondary origin in limestone block is shown in Fig. 1F. In addition to their sharp contact, they are tightly folded, which is typical of deformed rocks. On the other hand, during the field work in 2022, any deformed, flattened or elongated ooids (as known, e.g., from the Ordovician ferrite ooids of the Barrandian area) were observed. It is suggested that during deformation, the ooids (primarily build of magnesium carbonate) “floated” in the ductile matrix (primarily calcite) similar to, for example, raisins in leavened dough. Therefore, the deformation, judging from the shape of the ooids, is small or negligible; in reality, however, the shells of the vast majority of organisms were completely destroyed, “mixed up”. Acceptance of this idea then explains why the Albeřice carbonates are so poor in fossils, although the oolitic facies gives the impression of a rock that is not deformed or recrystallized at all and the carbonates point to a revived, climatically favourable, rather shallow marine environment. However, the results of a field research in August 2022 show that the search for fossils in the limestones around Albeřice is currently (and wi","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135807378","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}
Pub Date : 2023-05-09DOI: 10.3140/zpravy.geol.2023.05
Vladislav Rapprich, Eva Kadlecová, Zsolt Benkó, Miroslav Radoň, Markéta Chroustová, Zdeněk Dvořák
Fossilised remains of plants and animals can be found at many sites of volcaniclastic deposits and intravolcanic sediments (limestones, diatomites, lignite) of the České středohoří Volcanic Complex. Many of these localities have been known and studied since the 19th century. Some of these localities even gained international recognition due to abnormal abundance of fossil material. Collected and carefully stored paleontological material is still intensively studied with an aim to better understand the evolution of life but also environmental changes in Central Europe during Cenozoic. Combination of paleontology and volcanology has a potential to better constrain the paleo-environmental interpretations, as the two geological branches use different methods and gathered results can be confirmed by independent techniques. For this reason, our research focused on less-known paleontological locality at Starý Šachov, which provides interesting exposure documenting relations between volcanic activity, surrounding environment and biosphere during early stage of the České středohoří Volcanic Complex formation. The site Starý Šachov, also referred to as Malý Šachov (Radoň 2001), belongs to the basanitic Lower Oligocene Ústí Fm. of the České středohoří Volcanic Complex (sensu Cajz 2000) and is located at the northern margin of the České středohoří Mts. (Fig 1a). The Starý Šachov gorge exposes a sequence of pyroclastic rocks, capped with basanite lava (Fig. 1b), which was dated to 30.70 ± 0.45 Ma (K-Ar, bulk- rock). The pyroclastic sequence overlays redeposited volcaniclastic and intravolcanic sedimentary rocks (Fig. 1c). The volcaniclastic layers in the lower part of the sequence, where they alternate with intravolcanic sediments, consist of a mixture of basaltic epiclasts, and redeposited pyroclasts mixed with quartz and K-feldspar grains (Fig. 2a). This association suggests a short fluvial transport of volcaniclastic material from the growing volcanic complex, mixed with clastic material of the poorly solidified Merboltice Fm. sandstones representing the intimate bedrock of the locality. The pyroclastic sequence starts with deposits dominated by glassy non-vesiculated lapilli (Figs 1e and 2b, c) later replaced by deposits dominated by highly vesiculated lapilli (Figs 1d and 2d). The light-coloured sediments from the lower part of the succession contain abundant paleontological material. Clusters of white strongly flattened and crushed mollusc shells (Figs 3a, d, f, g) occur in whitish to light grey thinly bedded claystones. Together with molluscs, small cracked ostracod shells (Figs 4a–c) and caddisfly (Trichoptera) larval cases (Figs 4e, f ) are very abundant. Very rarely, twigs of plants from the Taxodiaceae family (Radoň 2001) and indeterminable leaf fragments were found. In dark coaly clays, undercut ostracod valves are abundant as well as in light coloured clays. Small rounded seeds of water lily-like plants (Fig. 4h) and fragments of frog bones (Fig.
{"title":"Reconstruction of Oligocene environment on the České středohoří volcanic complex northern periphery – integration of volcanology and paleontology","authors":"Vladislav Rapprich, Eva Kadlecová, Zsolt Benkó, Miroslav Radoň, Markéta Chroustová, Zdeněk Dvořák","doi":"10.3140/zpravy.geol.2023.05","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2023.05","url":null,"abstract":"Fossilised remains of plants and animals can be found at many sites of volcaniclastic deposits and intravolcanic sediments (limestones, diatomites, lignite) of the České středohoří Volcanic Complex. Many of these localities have been known and studied since the 19th century. Some of these localities even gained international recognition due to abnormal abundance of fossil material. Collected and carefully stored paleontological material is still intensively studied with an aim to better understand the evolution of life but also environmental changes in Central Europe during Cenozoic. Combination of paleontology and volcanology has a potential to better constrain the paleo-environmental interpretations, as the two geological branches use different methods and gathered results can be confirmed by independent techniques. For this reason, our research focused on less-known paleontological locality at Starý Šachov, which provides interesting exposure documenting relations between volcanic activity, surrounding environment and biosphere during early stage of the České středohoří Volcanic Complex formation. The site Starý Šachov, also referred to as Malý Šachov (Radoň 2001), belongs to the basanitic Lower Oligocene Ústí Fm. of the České středohoří Volcanic Complex (sensu Cajz 2000) and is located at the northern margin of the České středohoří Mts. (Fig 1a). The Starý Šachov gorge exposes a sequence of pyroclastic rocks, capped with basanite lava (Fig. 1b), which was dated to 30.70 ± 0.45 Ma (K-Ar, bulk- rock). The pyroclastic sequence overlays redeposited volcaniclastic and intravolcanic sedimentary rocks (Fig. 1c). The volcaniclastic layers in the lower part of the sequence, where they alternate with intravolcanic sediments, consist of a mixture of basaltic epiclasts, and redeposited pyroclasts mixed with quartz and K-feldspar grains (Fig. 2a). This association suggests a short fluvial transport of volcaniclastic material from the growing volcanic complex, mixed with clastic material of the poorly solidified Merboltice Fm. sandstones representing the intimate bedrock of the locality. The pyroclastic sequence starts with deposits dominated by glassy non-vesiculated lapilli (Figs 1e and 2b, c) later replaced by deposits dominated by highly vesiculated lapilli (Figs 1d and 2d). The light-coloured sediments from the lower part of the succession contain abundant paleontological material. Clusters of white strongly flattened and crushed mollusc shells (Figs 3a, d, f, g) occur in whitish to light grey thinly bedded claystones. Together with molluscs, small cracked ostracod shells (Figs 4a–c) and caddisfly (Trichoptera) larval cases (Figs 4e, f ) are very abundant. Very rarely, twigs of plants from the Taxodiaceae family (Radoň 2001) and indeterminable leaf fragments were found. In dark coaly clays, undercut ostracod valves are abundant as well as in light coloured clays. Small rounded seeds of water lily-like plants (Fig. 4h) and fragments of frog bones (Fig.","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135807379","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}
Pub Date : 2023-05-09DOI: 10.3140/zpravy.geol.2023.01
Karel Pátek, Jiří Bruthans
This study is focused on the base flow decrease due to surface water and groundwater evapotranspiration (ET) in wetlands of the Liběchovka catchment. Evapotranspiration in wetlands can significantly affect stream discharge, and its influence will probably still increase in the future due to the global rise of temperatures caused by climate change. The study site is located in the upper part of Liběchovka catchment (Fig. 1). This wetland hosts a small stream supplied by rather steady groundwater inflow, representing the favourable site for detection of the effect of ET. V notch weir and two piezometers were used to monitor stream discharge and wetland water table in 30 minute periods (Fig. 2). Diurnal periodical oscillations of water flow and water table caused by ET were observed (Fig. 3). They occurred in the summer part of the year, especially on sunny days without rain. The amplitude of water table level oscillation was increasing with increasing temperature (Fig. 4). Calculation showed that evapotranspiration reduced the water flow, on average, by 15 % on the warm sunny days. The maximum daily reduction was up to 32 %. Direct measurements were compared with the potential ET calculated using the Oudin’s method (Oudin 2005). The ET from the measurement was 45 % of the potential ET calculated by Oudin’s method. In the next step, the Oudin’s method was used to calculate the potential ET of all wetlands in Liběchovka catchment upstream from the Želízy village, where gauging station of ČHMÚ is situated. The original discharge not reduced by the wetland ET was defined as the sum of the wetland potential ET and the mean annual measured discharge. Due to the ET from wetlands (years 2015–2020), the discharge was reduced on average by 13 %. If only the summer months of July and August were considered, it was reduced, on average, by 26 % and by 39 % in the driest day recorded in this period. To estimate the role of groundwater abstraction on the Liběchovka stream during the period of 2015–2020, the sum of measured stream discharge, groundwater abstraction and wetland ET was calculated. From this sum, 71.5 % represented the directly measured water flow, 18.2 % was the groundwater abstraction, and 10.3 % was the wetland ET (Fig. 8).
{"title":"Base flow reduction due to surface water and groundwater evapotranspiration from wetlands of Liběchovka catchment: comparison of measurements and calculation by Oudin’s method","authors":"Karel Pátek, Jiří Bruthans","doi":"10.3140/zpravy.geol.2023.01","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2023.01","url":null,"abstract":"This study is focused on the base flow decrease due to surface water and groundwater evapotranspiration (ET) in wetlands of the Liběchovka catchment. Evapotranspiration in wetlands can significantly affect stream discharge, and its influence will probably still increase in the future due to the global rise of temperatures caused by climate change. The study site is located in the upper part of Liběchovka catchment (Fig. 1). This wetland hosts a small stream supplied by rather steady groundwater inflow, representing the favourable site for detection of the effect of ET. V notch weir and two piezometers were used to monitor stream discharge and wetland water table in 30 minute periods (Fig. 2). Diurnal periodical oscillations of water flow and water table caused by ET were observed (Fig. 3). They occurred in the summer part of the year, especially on sunny days without rain. The amplitude of water table level oscillation was increasing with increasing temperature (Fig. 4). Calculation showed that evapotranspiration reduced the water flow, on average, by 15 % on the warm sunny days. The maximum daily reduction was up to 32 %. Direct measurements were compared with the potential ET calculated using the Oudin’s method (Oudin 2005). The ET from the measurement was 45 % of the potential ET calculated by Oudin’s method. In the next step, the Oudin’s method was used to calculate the potential ET of all wetlands in Liběchovka catchment upstream from the Želízy village, where gauging station of ČHMÚ is situated. The original discharge not reduced by the wetland ET was defined as the sum of the wetland potential ET and the mean annual measured discharge. Due to the ET from wetlands (years 2015–2020), the discharge was reduced on average by 13 %. If only the summer months of July and August were considered, it was reduced, on average, by 26 % and by 39 % in the driest day recorded in this period. To estimate the role of groundwater abstraction on the Liběchovka stream during the period of 2015–2020, the sum of measured stream discharge, groundwater abstraction and wetland ET was calculated. From this sum, 71.5 % represented the directly measured water flow, 18.2 % was the groundwater abstraction, and 10.3 % was the wetland ET (Fig. 8).","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":"150 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135807380","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}
Pub Date : 2022-11-04DOI: 10.3140/zpravy.geol.2022.16
J. Valečka
The narrow, 40 km long belt of the Cretaceous sediments called „The Dlouhá mez“ has been preserved along the NW-SE-striking Železné hory fault within crystalline rocks in the Eastern Bohemia (Fig. 1). The youngest relic of this belt corresponds to the middle part of Jizera Fm. of middle Turonian age. In the southeastern part of the „Dlouhá mez“ belt, these deposits have fine-grained, glauconitic sandstone nature. Near the town of Ždírec nad Doubravou, the sandstone had been exploited for a long time in several presently abandoned quarries and used as a building material. The old quarry at the margin of Ždírec nad Doubravou was founded in the end of the 13th century, and it was replaced by new quarries between Ždírec nad Doubravou and the village of Nový Studenec in the second half of the 19th century. This sandstone was discovered in four gothic buildings in the wide surroundings of these quarries within the course of the macroscopic investigation by the author. To confirm this discovery, the author carried out microscopic investigation of ten sandstone samples taken both in the quarries and in the gothic buildings. Petrographic features of the sandstone were also specified. Microscopic study confirmed the identical character of all studied samples. The identity of sandstone exploited in the quarries and sandstones used in gothic buildings was also demonstrated by the analysis of total SiO2 content. The sandstone is fine-grained, with matrix-supported texture, variable content of glauconite grains and fragments of silicisponge spicules and rare foraminifera tests. Muscovite and feldspars occur in accessory amounts. The sandstone is silicified and exhibits a porosity from 6–8 to 20 %. The pores with very elongated, needle-like form originated by diagenetic dissolution of silicisponge spicules while the diagenetic quartz penetrated the original clayey and possibly also calcareous matrix. The foraminifera tests were also silicified during this process. Within subordinate thin layers in sandstone, the content of terrigenous quartz grains drops below 25 % (20–22 %) while the content of silicisponges fragments increases to 10–12 %. These layers can be classified as spiculitic, sandy silicite. The sandstone from Ždírec nad Doubravou was documented in two village churches (Krucemburk, Havlíčkova Borová), in a big church in the town of Havlíčkův Brod and in the chapel in the Lipnice Castle in the town of Lipnice nad Sázavou. These buildings originated in the last quarter of the 13th and in the 14th century. These localities are from 4 to 32 km away from the quarries near the town of Ždírec nad Doubravou (Fig. 1). The sandstones were used as ashlar masonry, window jambs and tracery, vault ribs and also in sculptures (figural corbels). A further investigation can probably reveal the Ždírec nad Doubravou sandstone in a higher number of medieval buildings.
窄的，40公里长的白垩纪沉积物带，称为“Dlouhámez”，沿着波西米亚东部结晶岩中的西北-东南走向的日勒锌内霍里断层保存下来（图1）。该带最年轻的遗迹对应于中土仑纪的吉泽拉组的中部“带，这些矿床具有细粒、海绿石砂岩性质。在日德雷克纳德杜布拉沃镇附近，这些砂岩在几个目前废弃的采石场被开采了很长一段时间，并被用作建筑材料。日德雷克nad杜布拉沃边缘的旧采石场建于13世纪末，在日德雷克纳德杜布拉之间被新采石场取代vou和NovýStudenec村。在作者宏观调查的过程中，在这些采石场周围广阔的四座哥特式建筑中发现了这种砂岩。为了证实这一发现，作者对采石场和哥特式建筑中采集的十个砂岩样本进行了微观调查。还详细说明了砂岩的岩石学特征。显微镜研究证实了所有研究样品的相同特性。通过对SiO2总含量的分析，也证明了采石场开采的砂岩和哥特式建筑中使用的砂岩的特性。砂岩细粒，基质支撑结构，海绿石颗粒和硅化海绵针状物碎片含量可变，罕见有孔虫测试。白云母和长石以副数量存在。砂岩硅化，孔隙率为6-8至20%。非常细长的针状孔隙源于硅化海绵针状物的成岩溶解，而成岩石英穿透了原始粘土，可能还有钙质基质。有孔虫测试也在这个过程中被硅化。在砂岩的次级薄层中，陆源石英颗粒的含量下降到25%以下（20–22%），而硅海绵碎片的含量增加到10–12%。这些层可归类为麻粒岩、砂质硅化岩。在两座乡村教堂（Krucemburk，Havlíčkova Borová）、Havlčkův Brod镇的一座大教堂和Lipnice nad Sázavou镇Lipnice城堡的小教堂中，都记录了来自于德雷克和杜布拉沃的砂岩。这些建筑起源于13世纪末和14世纪。这些地方距离茹dírec nad Doubravou镇附近的采石场4至32公里（图1）。砂岩被用作石灰质砖石、窗框和窗花、拱顶肋，也被用于雕塑（人像牛腿）。进一步的调查可能会发现，在更多的中世纪建筑中，都有杜布拉沃砂岩。
{"title":"Cretaceous sandstones near Ždírec nad Doubravou (Bohemian-Moravian Highlands) as material for gothic sacral buildings in large surroundings","authors":"J. Valečka","doi":"10.3140/zpravy.geol.2022.16","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2022.16","url":null,"abstract":"The narrow, 40 km long belt of the Cretaceous sediments called „The Dlouhá mez“ has been preserved along the NW-SE-striking Železné hory fault within crystalline rocks in the Eastern Bohemia (Fig. 1). The youngest relic of this belt corresponds to the middle part of Jizera Fm. of middle Turonian age. In the southeastern part of the „Dlouhá mez“ belt, these deposits have fine-grained, glauconitic sandstone nature. Near the town of Ždírec nad Doubravou, the sandstone had been exploited for a long time in several presently abandoned quarries and used as a building material. The old quarry at the margin of Ždírec nad Doubravou was founded in the end of the 13th century, and it was replaced by new quarries between Ždírec nad Doubravou and the village of Nový Studenec in the second half of the 19th century. This sandstone was discovered in four gothic buildings in the wide surroundings of these quarries within the course of the macroscopic investigation by the author. To confirm this discovery, the author carried out microscopic investigation of ten sandstone samples taken both in the quarries and in the gothic buildings. Petrographic features of the sandstone were also specified. Microscopic study confirmed the identical character of all studied samples. The identity of sandstone exploited in the quarries and sandstones used in gothic buildings was also demonstrated by the analysis of total SiO2 content. The sandstone is fine-grained, with matrix-supported texture, variable content of glauconite grains and fragments of silicisponge spicules and rare foraminifera tests. Muscovite and feldspars occur in accessory amounts. The sandstone is silicified and exhibits a porosity from 6–8 to 20 %. The pores with very elongated, needle-like form originated by diagenetic dissolution of silicisponge spicules while the diagenetic quartz penetrated the original clayey and possibly also calcareous matrix. The foraminifera tests were also silicified during this process. Within subordinate thin layers in sandstone, the content of terrigenous quartz grains drops below 25 % (20–22 %) while the content of silicisponges fragments increases to 10–12 %. These layers can be classified as spiculitic, sandy silicite. The sandstone from Ždírec nad Doubravou was documented in two village churches (Krucemburk, Havlíčkova Borová), in a big church in the town of Havlíčkův Brod and in the chapel in the Lipnice Castle in the town of Lipnice nad Sázavou. These buildings originated in the last quarter of the 13th and in the 14th century. These localities are from 4 to 32 km away from the quarries near the town of Ždírec nad Doubravou (Fig. 1). The sandstones were used as ashlar masonry, window jambs and tracery, vault ribs and also in sculptures (figural corbels). A further investigation can probably reveal the Ždírec nad Doubravou sandstone in a higher number of medieval buildings.","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46348178","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}
Pub Date : 2022-11-04DOI: 10.3140/zpravy.geol.2022.09
R. Mikuláš
The belt of dark carbonaceous rocks (shale and metamorphic limestone) near Koberovy (Krkonoše-Jizerské Mts. Crystalline Complex) is historically considered a record of the Silurian marine environment, due to the findings of poorly preserved but abundant fossils. Prantl (1948) considered them to be graptolites and, based on existing knowledge, classified the rocks as Silurian. Chlupáč (e.g. 1989) was of a similar opinion. However, later, the same author (Chlupáč 1993) re-interpreted all the remnants of the fauna found as traces of the activity of organisms, thus extending a possible stratigraphic interpretation to virtually entire Phanerozoic. Two different types of Koberovy fossils (two samples) were donated to me by prof. Chlupáč shortly before his death. These are two plates of graphitic calcareous shale, the metamorphism of which is revealed on foliation planes (parallel to bedding) for example by the presence of metamorphic minerals such as white mica (muscovite) and chlorite. The first of these has almost straight to slightly curved “strings” on the surface – probably the original bedding plane – in the left part (oriented according to Fig. 1A), which are dark under normal light; however, surface minerals have a pronounced luster, therefore under a particular illumination, the “strings” appear as light lines. The width of the lines is almost constant, about 0.6 mm. Another group of lines occurs in the centre of the sample. These show a “loop” pattern which can be compared to the double “e” in cursive writing. The width of these lines is around 0.6 mm again, with random fluctuations to lower values. A similar and final biogenic structure is in the top right of the Figure 1A. These are three semi-arcs, the estimated half of which is missing on the sample, probably representing an original 3-D spiral-like structure. Width of this structure is on average slightly larger than the previous two structures: it reaches about 0.8–1.0 mm. The second finding is preserved similarly: on the photograph (Fig. 1B), reflected light is used to highlight the dark fossil on the gray carbonaceous slate background. This sample contains four crescent-shaped segments, two in the “D” position and the remaining two in the “C” position. The next segment has an irregular oval shape and the last is a dashed line. The size of the structures is about 30 mm. Chlupáč (1993) withdrew from the original opinion that these poorly-preserved fossils are graptolites (Prantl 1948, Chlupáč 1953). Instead, he offered an interpretation that these were trace fossils. However, we cannot agree with this view for following reasons: 1. Ichnofossils, which have a similar contour as the spiral structures of the first finding, belong in particular to the ichnogenera Gordia Emmons, 1844 and Spirodesmos Andree, 1920. These fossils are surface grazing traces preserved in hyporelief or epirelief. Such ichnofossils have a small conservation potential during regional metamorphism, with movements and
{"title":"Reinterpretation of the fossil record in metamorphic rocks near Koberovy (Krkonoše-Jizera Crystalline Complex, Bohemian Paradise UNESCO Geopark, Czech Republic)","authors":"R. Mikuláš","doi":"10.3140/zpravy.geol.2022.09","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2022.09","url":null,"abstract":"The belt of dark carbonaceous rocks (shale and metamorphic limestone) near Koberovy (Krkonoše-Jizerské Mts. Crystalline Complex) is historically considered a record of the Silurian marine environment, due to the findings of poorly preserved but abundant fossils. Prantl (1948) considered them to be graptolites and, based on existing knowledge, classified the rocks as Silurian. Chlupáč (e.g. 1989) was of a similar opinion. However, later, the same author (Chlupáč 1993) re-interpreted all the remnants of the fauna found as traces of the activity of organisms, thus extending a possible stratigraphic interpretation to virtually entire Phanerozoic. Two different types of Koberovy fossils (two samples) were donated to me by prof. Chlupáč shortly before his death. These are two plates of graphitic calcareous shale, the metamorphism of which is revealed on foliation planes (parallel to bedding) for example by the presence of metamorphic minerals such as white mica (muscovite) and chlorite. The first of these has almost straight to slightly curved “strings” on the surface – probably the original bedding plane – in the left part (oriented according to Fig. 1A), which are dark under normal light; however, surface minerals have a pronounced luster, therefore under a particular illumination, the “strings” appear as light lines. The width of the lines is almost constant, about 0.6 mm. Another group of lines occurs in the centre of the sample. These show a “loop” pattern which can be compared to the double “e” in cursive writing. The width of these lines is around 0.6 mm again, with random fluctuations to lower values. A similar and final biogenic structure is in the top right of the Figure 1A. These are three semi-arcs, the estimated half of which is missing on the sample, probably representing an original 3-D spiral-like structure. Width of this structure is on average slightly larger than the previous two structures: it reaches about 0.8–1.0 mm. The second finding is preserved similarly: on the photograph (Fig. 1B), reflected light is used to highlight the dark fossil on the gray carbonaceous slate background. This sample contains four crescent-shaped segments, two in the “D” position and the remaining two in the “C” position. The next segment has an irregular oval shape and the last is a dashed line. The size of the structures is about 30 mm. Chlupáč (1993) withdrew from the original opinion that these poorly-preserved fossils are graptolites (Prantl 1948, Chlupáč 1953). Instead, he offered an interpretation that these were trace fossils. However, we cannot agree with this view for following reasons: 1. Ichnofossils, which have a similar contour as the spiral structures of the first finding, belong in particular to the ichnogenera Gordia Emmons, 1844 and Spirodesmos Andree, 1920. These fossils are surface grazing traces preserved in hyporelief or epirelief. Such ichnofossils have a small conservation potential during regional metamorphism, with movements and","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48036466","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}
Pub Date : 2022-11-04DOI: 10.3140/zpravy.geol.2022.12
Z. Šimůnek, Martin Lapacík, Václav Mencl
Three palaeontological localities (Ploužnice, Bradlecká Lhota and Bítouchov) were visited during the year 2022 in order to verify their condition and acquire a new palaeontological material. Ploužnice locality is a long-known Stephanian locality within the Ploužnice Horizon, where an interesting Cordaites-Calamites assemblage has been found. Bradlecká Lhota is a locality of the same age belonging to the Ploužnice Horizon, too. Besides Cordaites and Calamites, also Cyathocarpus cyatheus (Schlotheim) Mosbrugger and Odontopteris schlotheimii Brongniart have been found here. A thin layer containing small bones and fish scales, so-called „bone bed“, has been discovered on both localities. The last locality is Bítouchov, which is a Permian locality belonging to the Kalná Horizon. This locality is also frequently visited by collectors. Autunia conferta (Sternberg) Kerp has been found here.
{"title":"New palaeontological collections from the Krkonoše Piedmont Basin","authors":"Z. Šimůnek, Martin Lapacík, Václav Mencl","doi":"10.3140/zpravy.geol.2022.12","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2022.12","url":null,"abstract":"Three palaeontological localities (Ploužnice, Bradlecká Lhota and Bítouchov) were visited during the year 2022 in order to verify their condition and acquire a new palaeontological material. Ploužnice locality is a long-known Stephanian locality within the Ploužnice Horizon, where an interesting Cordaites-Calamites assemblage has been found. Bradlecká Lhota is a locality of the same age belonging to the Ploužnice Horizon, too. Besides Cordaites and Calamites, also Cyathocarpus cyatheus (Schlotheim) Mosbrugger and Odontopteris schlotheimii Brongniart have been found here. A thin layer containing small bones and fish scales, so-called „bone bed“, has been discovered on both localities. The last locality is Bítouchov, which is a Permian locality belonging to the Kalná Horizon. This locality is also frequently visited by collectors. Autunia conferta (Sternberg) Kerp has been found here.","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49065920","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}
Pub Date : 2022-11-04DOI: 10.3140/zpravy.geol.2022.11
T. Vorel, Z. Kvaček, P. Havlíček, P. Hradecký, M. Opletal, Josef Ševčík, Dalibor Mašek
Development cooperation projects implemented by the Czech Geological Survey in the area of Central America, focused on the evaluation of natural hazards, took place in the years 1997–2009. They started in Nicaragua (since 1997), continued in El Salvador (since 2003) and then also in Costa Rica (since 2006). The results of these projects were always handed over to local organizations (INETER, SNET and MINAE) in the form of final reports, and summarized last year in the book by Hradecký et al. 2021. As a supplement to this book, we present here some other findings of projects in El Salvador (from the years 2003–2005) that did not fit into its scope. They relate to the geology of Quaternary sediments and interesting findings of plant fossils preserved in the Neogene volcanosedimentary complexes. In the 2003 stage, work took place in the Gulf of Fonseca in south- -eastern part of El Salvador, with the dominant volcano Conchagua and the important port of La Unión. In addition to classic Quaternary sediments, the following phenomena were described: oyster hems (rims) around the islands of Periquito and Perico, volcaniclastic rocks (“tobas”) fallen into the lake environment near the Los Chorros lagoon (Břízová et al. 2004), and polygenetic sediments on the slopes of the formerly active volcano Conchagua, showing the existence of debris flows and lahars. Plant fossils have been found at one locality only, in fine-grained ash deposits of the maar sequence near El Naranjo (Figs 1 to 3). In the 2004 stage, work took place inland, in an area north of the capital city San Salvador, with the dominant volcano Guazapa. In addition to the classical Quaternary sediments, the following phenomena were described: polygenetic sediments of the depressions north of the town of Aguilares (Figs 4 to 9) and outcrops of lake sediments, exposed in the north of the studied territory on steep slopes near the Río Lempa dam (Fig. 10), south-east of the city of Colima (Havlíček – Vorel 2005). In the same area, on the bank of the dam near the town of San Cristobal, interesting consolidated (cemented) mudflows with the occurrence of fossil wood were also documented (Figs 11 and 12). In the year 2004, a paleontological expedition to the Río Sisimico canyon, about 40 km to the SE from the primarily studied area (Figs 13 to 16), was also carried out. The findings of plant remains from this locality are shown in Figs 17 to 22. Plant remains were further found at two localities in the primarily studied area: Suchitoto (Figs 23 to 29) and in the area south of El Molino (only indeterminable remains). Charred (and buried) tree trunks were also found in the white pumice tuffs called “Tierra Blanca” in several places of the studied area (Fig. 30). In the 2005 stage, the work took place in the north-western part of El Salvador, near the borders with Guatemala and Honduras, in the vicinity of the Metapán city. In addition to classic Quaternary sediments (Figs 31 and 32), the following phenomen
{"title":"Quaternary sediments and plant fossil findings in El Salvador, Central America","authors":"T. Vorel, Z. Kvaček, P. Havlíček, P. Hradecký, M. Opletal, Josef Ševčík, Dalibor Mašek","doi":"10.3140/zpravy.geol.2022.11","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2022.11","url":null,"abstract":"Development cooperation projects implemented by the Czech Geological Survey in the area of Central America, focused on the evaluation of natural hazards, took place in the years 1997–2009. They started in Nicaragua (since 1997), continued in El Salvador (since 2003) and then also in Costa Rica (since 2006). The results of these projects were always handed over to local organizations (INETER, SNET and MINAE) in the form of final reports, and summarized last year in the book by Hradecký et al. 2021. As a supplement to this book, we present here some other findings of projects in El Salvador (from the years 2003–2005) that did not fit into its scope. They relate to the geology of Quaternary sediments and interesting findings of plant fossils preserved in the Neogene volcanosedimentary complexes. In the 2003 stage, work took place in the Gulf of Fonseca in south- -eastern part of El Salvador, with the dominant volcano Conchagua and the important port of La Unión. In addition to classic Quaternary sediments, the following phenomena were described: oyster hems (rims) around the islands of Periquito and Perico, volcaniclastic rocks (“tobas”) fallen into the lake environment near the Los Chorros lagoon (Břízová et al. 2004), and polygenetic sediments on the slopes of the formerly active volcano Conchagua, showing the existence of debris flows and lahars. Plant fossils have been found at one locality only, in fine-grained ash deposits of the maar sequence near El Naranjo (Figs 1 to 3). In the 2004 stage, work took place inland, in an area north of the capital city San Salvador, with the dominant volcano Guazapa. In addition to the classical Quaternary sediments, the following phenomena were described: polygenetic sediments of the depressions north of the town of Aguilares (Figs 4 to 9) and outcrops of lake sediments, exposed in the north of the studied territory on steep slopes near the Río Lempa dam (Fig. 10), south-east of the city of Colima (Havlíček – Vorel 2005). In the same area, on the bank of the dam near the town of San Cristobal, interesting consolidated (cemented) mudflows with the occurrence of fossil wood were also documented (Figs 11 and 12). In the year 2004, a paleontological expedition to the Río Sisimico canyon, about 40 km to the SE from the primarily studied area (Figs 13 to 16), was also carried out. The findings of plant remains from this locality are shown in Figs 17 to 22. Plant remains were further found at two localities in the primarily studied area: Suchitoto (Figs 23 to 29) and in the area south of El Molino (only indeterminable remains). Charred (and buried) tree trunks were also found in the white pumice tuffs called “Tierra Blanca” in several places of the studied area (Fig. 30). In the 2005 stage, the work took place in the north-western part of El Salvador, near the borders with Guatemala and Honduras, in the vicinity of the Metapán city. In addition to classic Quaternary sediments (Figs 31 and 32), the following phenomen","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43937485","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}
Pub Date : 2022-11-04DOI: 10.3140/zpravy.geol.2022.13
Eliška Jurková, Pavlína Rybová, D. Matýsek, P. Skupien, L. Lenza
The rocks of the teschenite association form smaller scattered occurrences in the upper part of the Hradiště Formation of the Silesian Unit. The age of the igneous rocks corresponds to Berriasian to Barremian (Menčík et al. 1983). The teschenite association includes a relatively heterogeneous group of rocks with variable abundances of felsic and mafic minerals. Three outcrops of the teschenite association rocks (both typical teschenites and strongly altered ultramafic types) embedded in non- volcanic sediments were studied in the bed of the Pazderůvka River between Bruzovice and Žermanice (Bz1, Bz2, and Bz3; Fig. 1). At Bz1 and Bz2 outcrops, bodies of teschenite are hosted by sedimentary rocks affected by caustic metamorphism. The volcanic rocks at Bz3 are represented by strongly altered, markedly clayey dark green rocks with a macroscopically apparent high proportion of dark micas and pyroxenes. The bedrock of the outcrop is composed of calcareous claystone, limestone, and sandy limestone, likely representing Těšín Limestones. The phase composition of the volcanic rocks from the Bz1 and Bz2 localities is to a certain extent similar, which indicates that the same body was observed at both localities. Macroscopically, the rocks are medium- to coarse-grained with a variable proportion of dark minerals, indicating internal differentiation of the body. The very high proportions of natrolite (up to about 35 %, up to 54 % in the leucocratic type) are particularly notable. The volcanic rocks from the Bz3 locality are quite different. Their composition corresponds to strongly argilitised mafic rocks (and their volcaniclastic derivates), containing more than 50 % of clay component with a dominance of smectite, as documented by X-ray diffraction data. As for the primary components, pyroxene, biotite, plagioclase, and accessory amphibole were detected. Calcareous dinoflagellate cysts Cadosina semiradiata fusca, Colomisphaera vogleri, and Cadosina semiradiata representing the lower Valanginian to upper Barremian were identified in polished sections of the calcareous rock. Non-calcareous dinoflagellate cysts in Bz1 and Bz2 samples are almost black, reflecting the strong thermal effects of the teschenite intrusion at the contact with with the sediments. The dinoflagellate cysts in the Bz3 outcrop are very well preserved with no evidence of thermal alteration. The overlying body of the volcanic rock can be therefore considered as effusive. Circulodinium vermiculatum, Cymososphaeridium validum, Muderongia tabulata, Oligosphaeridium albertense, Oligosphaeridium asterigerum, Pseudoceratium pelliferum, Systematophora palmula from the Bz3 outcrop can be considered as stratigraphically significant. Based on the first occurrence of C. validum and the last occurrences of Circulodinium vermiculatum and Systematophora palmula, Leereveld (1995) delineates a dinoflagellate zone of Cymososphaeridium validum which represents the upper Valanginian to the lowermost Hauterivian
{"title":"Stratigraphy of the sediments accompanying the volcanic rocks of the teschenite association near Bruzovice village","authors":"Eliška Jurková, Pavlína Rybová, D. Matýsek, P. Skupien, L. Lenza","doi":"10.3140/zpravy.geol.2022.13","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2022.13","url":null,"abstract":"The rocks of the teschenite association form smaller scattered occurrences in the upper part of the Hradiště Formation of the Silesian Unit. The age of the igneous rocks corresponds to Berriasian to Barremian (Menčík et al. 1983). The teschenite association includes a relatively heterogeneous group of rocks with variable abundances of felsic and mafic minerals. Three outcrops of the teschenite association rocks (both typical teschenites and strongly altered ultramafic types) embedded in non- volcanic sediments were studied in the bed of the Pazderůvka River between Bruzovice and Žermanice (Bz1, Bz2, and Bz3; Fig. 1). At Bz1 and Bz2 outcrops, bodies of teschenite are hosted by sedimentary rocks affected by caustic metamorphism. The volcanic rocks at Bz3 are represented by strongly altered, markedly clayey dark green rocks with a macroscopically apparent high proportion of dark micas and pyroxenes. The bedrock of the outcrop is composed of calcareous claystone, limestone, and sandy limestone, likely representing Těšín Limestones. The phase composition of the volcanic rocks from the Bz1 and Bz2 localities is to a certain extent similar, which indicates that the same body was observed at both localities. Macroscopically, the rocks are medium- to coarse-grained with a variable proportion of dark minerals, indicating internal differentiation of the body. The very high proportions of natrolite (up to about 35 %, up to 54 % in the leucocratic type) are particularly notable. The volcanic rocks from the Bz3 locality are quite different. Their composition corresponds to strongly argilitised mafic rocks (and their volcaniclastic derivates), containing more than 50 % of clay component with a dominance of smectite, as documented by X-ray diffraction data. As for the primary components, pyroxene, biotite, plagioclase, and accessory amphibole were detected. Calcareous dinoflagellate cysts Cadosina semiradiata fusca, Colomisphaera vogleri, and Cadosina semiradiata representing the lower Valanginian to upper Barremian were identified in polished sections of the calcareous rock. Non-calcareous dinoflagellate cysts in Bz1 and Bz2 samples are almost black, reflecting the strong thermal effects of the teschenite intrusion at the contact with with the sediments. The dinoflagellate cysts in the Bz3 outcrop are very well preserved with no evidence of thermal alteration. The overlying body of the volcanic rock can be therefore considered as effusive. Circulodinium vermiculatum, Cymososphaeridium validum, Muderongia tabulata, Oligosphaeridium albertense, Oligosphaeridium asterigerum, Pseudoceratium pelliferum, Systematophora palmula from the Bz3 outcrop can be considered as stratigraphically significant. Based on the first occurrence of C. validum and the last occurrences of Circulodinium vermiculatum and Systematophora palmula, Leereveld (1995) delineates a dinoflagellate zone of Cymososphaeridium validum which represents the upper Valanginian to the lowermost Hauterivian","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46592912","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}
Pub Date : 2022-11-04DOI: 10.3140/zpravy.geol.2022.10
O. Pour, V. Rapprich, D. Matýsek, J. Jirásek
Magmatic origin of analcime has been discussed for decades (e. g., Karlsson and Clayton 1991, 1993; Pearce 1993). Despite the fact that analcime has been re-classified as zeolite and its secondary (post-magmatic) origin is globally accepted (e. g., Roux and Hamilton 1976, Giannetti and Masi 1989, Wilkinson and Hensel 1994), it is still commonly used in classification of alkaline rocks in the Czech Republic. In these rocks, analcime can be mostly found in the pseudomorphs after leucite (Fig. 1a; see Rapprich 2003), or as a homogeneous anhedral filling in the groundmass (Fig. 1b). In the second case, the boundaries of individual analcime crystals cannot be identified due to the isotropic optical properties of analcime. Therefore, origin and growth of analcime is difficult to reconstruct. For this contribution, we have studied samples of Mesozoic and Cenozoic alkaline rocks from three localities across the Czech Republic, where partly analcimized glass in the groundmass was preserved, with an aim to better understand the origin of analcime in alkaline rocks. Mesozoic augitite from the southwestern slope of the Petřkovice Mt. near Nový Jičín (sample TG05) displays small isometric colourless, optically isotropic domains (analcime) enclosed in originally glassy groundmass (Fig. 1c–f ). This texture suggests the analcime is replacing original glass in the groundmass, enclosing also microcrysts of the stable minerals in groundmass. Very similar texture was observed also in Oligocene augitite from Mětikalov in Doupovské hory Mts. (sample DR338, Fig. 2). In this rock, the analcime domains either mantle larger phenocrysts, or are distributed within the groundmass. The growth of the analcime domains on the edges of larger phenocrysts resembles growth of spherulites, which represent products of silica-rich glass recrystallization (e. g., Breitkreuz 2013). To further investigate this possibility, additional samples were collected from Kamenický vrch near Zákupy (Fig. 3). In individual samples, number and size of analcime domains vary, which suggests, that these domains represent various stages of a continuous growth. The X-ray elemental mapping of Al and Na (Fig. 4) then shows, that the analcime domains are represented by single grains of cubic analcime. As a result, we may conclude that analcime in groundmass of Mesozoic and Cenozoic alkaline rocks originates from devitrification of original glass. These rocks hence should not be classified as “analcimites” or “analcimic …” but rather as “analcimized …” according to Le Maitre et al. (2005).
岩浆岩成因已经讨论了几十年(如Karlsson和Clayton 1991,1993;皮尔斯1993)。尽管溶铝石已被重新归类为沸石，其次生(岩浆后)成因已被全球公认(如Roux and Hamilton 1976, Giannetti and Masi 1989, Wilkinson and Hensel 1994)，但在捷克共和国，溶铝石仍被广泛用于碱性岩石的分类。在这些岩石中，钙铝石主要存在于白晶石之后的假晶中(图1a;见Rapprich 2003)，或作为地体中的均匀面状充填体(图1b)。在第二种情况下，由于analcime的各向同性光学特性，单个analcime晶体的边界不能被识别。因此，很难重建钙的起源和生长过程。为了这一贡献，我们研究了捷克共和国三个地区的中新生代碱性岩石样本，其中保存了地面中部分分析化玻璃，目的是更好地了解碱性岩石中钙的来源。来自Nový Jičín附近Petřkovice山西南坡的中生代辉长岩(样品TG05)显示出小的等距无色、光学各向同性的结构域(analcime)，被包裹在原来的玻璃状地质体中(图1c-f)。这种结构表明，钙铝酸盐正在取代基质中的原始玻璃，同时也包围了基质中稳定矿物的微晶体。在doupovskrehory mt . m tikalov的渐新世辉长岩中也观察到非常相似的结构(样品DR338，图2)。在这种岩石中，铝质域要么是地幔较大的斑晶，要么分布在地块中。较大的现象晶体边缘的铝胺域的生长类似于球晶的生长，球晶代表了富硅玻璃再结晶的产物(例如，Breitkreuz 2013)。为了进一步研究这种可能性，从Zákupy附近的Kamenický vrch收集了额外的样本(图3)。在单个样本中，分析结构域的数量和大小各不相同，这表明这些结构域代表了连续生长的不同阶段。然后，Al和Na的x射线元素映射(图4)显示，解析域由立方解析矿的单颗粒表示。结果表明，中、新生代碱性岩中的钙铁矿来源于原始玻璃的脱硝作用。因此，根据Le Maitre等人(2005)的说法，这些岩石不应该被归类为“解析石”或“解析质”，而应该被归类为“解析化”。
{"title":"About the origin of analcime in meso- and cenozoic volcanic rocks of the Czech Republic and its role in rock classification","authors":"O. Pour, V. Rapprich, D. Matýsek, J. Jirásek","doi":"10.3140/zpravy.geol.2022.10","DOIUrl":"https://doi.org/10.3140/zpravy.geol.2022.10","url":null,"abstract":"Magmatic origin of analcime has been discussed for decades (e. g., Karlsson and Clayton 1991, 1993; Pearce 1993). Despite the fact that analcime has been re-classified as zeolite and its secondary (post-magmatic) origin is globally accepted (e. g., Roux and Hamilton 1976, Giannetti and Masi 1989, Wilkinson and Hensel 1994), it is still commonly used in classification of alkaline rocks in the Czech Republic. In these rocks, analcime can be mostly found in the pseudomorphs after leucite (Fig. 1a; see Rapprich 2003), or as a homogeneous anhedral filling in the groundmass (Fig. 1b). In the second case, the boundaries of individual analcime crystals cannot be identified due to the isotropic optical properties of analcime. Therefore, origin and growth of analcime is difficult to reconstruct. For this contribution, we have studied samples of Mesozoic and Cenozoic alkaline rocks from three localities across the Czech Republic, where partly analcimized glass in the groundmass was preserved, with an aim to better understand the origin of analcime in alkaline rocks. Mesozoic augitite from the southwestern slope of the Petřkovice Mt. near Nový Jičín (sample TG05) displays small isometric colourless, optically isotropic domains (analcime) enclosed in originally glassy groundmass (Fig. 1c–f ). This texture suggests the analcime is replacing original glass in the groundmass, enclosing also microcrysts of the stable minerals in groundmass. Very similar texture was observed also in Oligocene augitite from Mětikalov in Doupovské hory Mts. (sample DR338, Fig. 2). In this rock, the analcime domains either mantle larger phenocrysts, or are distributed within the groundmass. The growth of the analcime domains on the edges of larger phenocrysts resembles growth of spherulites, which represent products of silica-rich glass recrystallization (e. g., Breitkreuz 2013). To further investigate this possibility, additional samples were collected from Kamenický vrch near Zákupy (Fig. 3). In individual samples, number and size of analcime domains vary, which suggests, that these domains represent various stages of a continuous growth. The X-ray elemental mapping of Al and Na (Fig. 4) then shows, that the analcime domains are represented by single grains of cubic analcime. As a result, we may conclude that analcime in groundmass of Mesozoic and Cenozoic alkaline rocks originates from devitrification of original glass. These rocks hence should not be classified as “analcimites” or “analcimic …” but rather as “analcimized …” according to Le Maitre et al. (2005).","PeriodicalId":37965,"journal":{"name":"Geoscience Research Reports","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42919470","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}
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