Preliminary results of stratigraphic investigations of the Jura at Hády Hill near Brno

Small remnant of Jurassic sediments at Hády Hill near Brno in Moravia (Czech Republic) comprises 8 m thick conglomerates and detritic limestones and 5 m thick cherty limestones. Pebbles of greenish radiolaria-bearing claystones and marls within the conglomerate are evidence of older Jurassic sedimentation. The detritic limestones contain bivalves Pteroperna sp., Cardita sp., Oxytoma inaequivalvis while the cherty limestones are rich in brachiopods, belemnites, and ammonites assigned to the Transversarium zone by earlier authors. Recorded benthic foraminifers Paalzowella feifeli, Spirillina kuebleri, S. andreae and Trocholina nodulosa indicate the Middle Oxfordian what contradicts the presence of planktonic Globuligerina oxfordiana considered to be Lower Oxfordian marker.Small remnant of Jurassic sediments at Hády Hill near Brno in Moravia (Czech Republic) comprises 8 m thick conglomerates and detritic limestones and 5 m thick cherty limestones. Pebbles of greenish radiolaria-bearing claystones and marls within the conglomerate are evidence of older Jurassic sedimentation. The detritic limestones contain bivalves Pteroperna sp., Cardita sp., Oxytoma inaequivalvis while the cherty limestones are rich in brachiopods, belemnites, and ammonites assigned to the Transversarium zone by earlier authors. Recorded benthic foraminifers Paalzowella feifeli, Spirillina kuebleri, S. andreae and Trocholina nodulosa indicate the Middle Oxfordian what contradicts the presence of planktonic Globuligerina oxfordiana considered to be Lower Oxfordian marker

LIMONITOVÁ MINERALIZACE V NĚMČICKÉM KRASU

Limonite occurrences are hosted by the Devonian limestones belonging to Němčice-Vratíkov belt. This belt can by interpreted as NNW–SSE trending tectonic slice between the granodiorites Brno massif and Lower Carboniferous Culm sediments. Mineralization is localized along faults in limestone and filling small caves belonging to the Němčice Karst. According to mineralogical and textural features are studied ores interpreted as product of limestones interaction with acid solutions generated during weathering of pyrite-rich Creatacerous sediments. Two main stages evolution can be recognized. During first stage circulate iron rich solutions along pre-existing narrow fractures and faults. Under reduction conditions crystallize pyrite and replaced of the host rock and fossils. During second oxidation stage was empty caves partially filling by limonite sometimes with small intercalations clastic sediments. During this stage limonite ore was partial silicificated and calcificated

Carbonate concretions “donuts” from the Nové Dvory by Suchdol site in the Moravian Karst (Czech Republic)

Nové Dvory “donuts” are globular to elongated concretions, up to 10 cm in diameter, with remarkable radial structure. They were described from sandstone and limestone cavities in the Moravian karst. Microscopic analyses indicate that these nodules consist of about 45 mod. % of elongated calcite crystals (Ca0,999–0,998 Mg0,002–0,001 CO3). Angular to subrounded quartz grains form the dominant clast type. K-feldspar, strongly weathered plagioclase grains and muscovite are present in small amount. Mineralogical composition of the translucent heavy fraction of “donuts” and surrounding sandstones is interpreted as result of mixing of the detritus coming from the typical Cretaceous (Cenomanian) sediments and of detritus coming from local sources (such as Devonian clastic sediments). Translucent heavy mineral assemblage typical for the Cretaceous clastic sediments includes staurolite, kyanite, tourmaline, rutileand sillimanite, while the local material (Devonian) is characterized by a dominance of epidote and/or zircone. The Nové Dvory “donuts” can be interpreted as a product of precipitation of calcium carbonate in sand that filled the karst cavities (paleo-sinkholes or paleo-cave). Nové Dvory “donuts” are globular to elongated concretions, up to 10 cm in diameter, with remarkable radial structure. They were described from sandstone and limestone cavities in the Moravian karst. Microscopic analyses indicate that these nodules consist of about 45 mod. % of elongated calcite crystals (Ca0,999–0,998 Mg0,002–0,001 CO3). Angular to subrounded quartz grains form the dominant clast type. K-feldspar, strongly weathered plagioclase grains and muscovite are present in small amount. Mineralogical composition of the translucent heavy fraction of “donuts” and surrounding sandstones is interpreted as result of mixing of the detritus coming from the typical Cretaceous (Cenomanian) sediments and of detritus coming from local sources (such as Devonian clastic sediments). Translucent heavy mineral assemblage typical for the Cretaceous clastic sediments includes staurolite, kyanite, tourmaline, rutileand sillimanite, while the local material (Devonian) is characterized by a dominance of epidote and/or zircone. The Nové Dvory “donuts” can be interpreted as a product of precipitation of calcium carbonate in sand that filled the karst cavities (paleo-sinkholes or paleo-cave)

ORIENTAČNÍ STANOVENÍ RECENTNÍ MÍRY DENUDACE FLYŠOVÉHO PÁSMA VNĚJŠÍCH ZÁPADNÍCH KARPAT NA PŘÍKLADU POVODÍ BYSTŘIČKY VE VSETÍNSKÝCH VRŠÍCH

Dating and quantifying of denudation rates is still quite difficult task for any terrestrial setting at a local scale. We realized a rough analysis of recent denudation rate within a small catchment of the Bytřička River in the Czech part of the Flysch Belt of Outer West Carpathians near Vsetín by balancing the dam clastic sediments with the area of the catchment above. The recent denudation rate of the flysch rocks within the catchment is assumed to be between 0.0821 mm and 0.0287 mm per year. However, we must respecta fact that we omitted many important factors and unknowns and thus, the results are just an estimation

Revision of the geological documentation in the Křtiny Valley adits, Moravian Karst

Four adits excavated in the Křtiny Valley in the early fifties were documented and sampled especially from the viewpoint of structural geology and of genesis and origin of the sedimentary infi llings. The studied localities include limestones of the Macocha Formation (Givetian of the Býčí skála cycle), Devonian clastics and granitoids of the Brno Massif (Neoproterozoic). Relativelly monotonous fold structure of the limestones is disrupted by a thrust zone imbedding sandstone and granodiorite tectonic slices into the limestone sequence. NW–SE striking thrust zone bears N–S trending striae suggesting its strike-slip character. The shear sense was not yet determined. This thrust zone was rejuvenated and extremely altered during younger faulting, so nowadays it has a clayish appearance. Most of the psammites sampled in limestone cavitties display a typical „Ottnangian“ or „Cenomanian“ translucent heavy mineral assemblage (staurollite, kyanite, tourmaline, rutil) which proves redeposition (vertical transport) from Ottnangian and Cretaceous sands.Four adits excavated in the Křtiny Valley in the early fifties were documented and sampled especially from the viewpoint of structural geology and of genesis and origin of the sedimentary infi llings. The studied localities include limestones of the Macocha Formation (Givetian of the Býčí skála cycle), Devonian clastics and granitoids of the Brno Massif (Neoproterozoic). Relativelly monotonous fold structure of the limestones is disrupted by a thrust zone imbedding sandstone and granodiorite tectonic slices into the limestone sequence. NW–SE striking thrust zone bears N–S trending striae suggesting its strike-slip character. The shear sense was not yet determined. This thrust zone was rejuvenated and extremely altered during younger faulting, so nowadays it has a clayish appearance. Most of the psammites sampled in limestone cavitties display a typical „Ottnangian“ or „Cenomanian“ translucent heavy mineral assemblage (staurollite, kyanite, tourmaline, rutil) which proves redeposition (vertical transport) from Ottnangian and Cretaceous sands

Revision of the geological documentation in the Křtiny Valley adits, Moravian Karst

Four adits excavated in the Křtiny Valley in the early fifties were documented and sampled especially from the viewpoint of structural geology and of genesis and origin of the sedimentary infi llings. The studied localities include limestones of the Macocha Formation (Givetian of the Býčí skála cycle), Devonian clastics and granitoids of the Brno Massif (Neoproterozoic). Relativelly monotonous fold structure of the limestones is disrupted by a thrust zone imbedding sandstone and granodiorite tectonic slices into the limestone sequence. NW–SE striking thrust zone bears N–S trending striae suggesting its strike-slip character. The shear sense was not yet determined. This thrust zone was rejuvenated and extremely altered during younger faulting, so nowadays it has a clayish appearance. Most of the psammites sampled in limestone cavitties display a typical „Ottnangian“ or „Cenomanian“ translucent heavy mineral assemblage (staurollite, kyanite, tourmaline, rutil) which proves redeposition (vertical transport) from Ottnangian and Cretaceous sands.Four adits excavated in the Křtiny Valley in the early fifties were documented and sampled especially from the viewpoint of structural geology and of genesis and origin of the sedimentary infi llings. The studied localities include limestones of the Macocha Formation (Givetian of the Býčí skála cycle), Devonian clastics and granitoids of the Brno Massif (Neoproterozoic). Relativelly monotonous fold structure of the limestones is disrupted by a thrust zone imbedding sandstone and granodiorite tectonic slices into the limestone sequence. NW–SE striking thrust zone bears N–S trending striae suggesting its strike-slip character. The shear sense was not yet determined. This thrust zone was rejuvenated and extremely altered during younger faulting, so nowadays it has a clayish appearance. Most of the psammites sampled in limestone cavitties display a typical „Ottnangian“ or „Cenomanian“ translucent heavy mineral assemblage (staurollite, kyanite, tourmaline, rutil) which proves redeposition (vertical transport) from Ottnangian and Cretaceous sands

MOBILIZACE CHEMICKÝCH SLOŽEK STRUSKOVÉ DEPONIE V NÁRODNÍ PŘÍRODNÍ REZERVACI RUDICKÉ PROPADÁNÍ

The Rudice swallow hole (Rudické propadání) National Nature Monument is a locality affected by occasional mass movements and landslides. During exceptional rainfall events, the slag material from the slopes of a small valley called “Ve struskách” (“In the Slags”) slides into an episodic stream, which enters the local karst system near the swallow hole of the Jedovnice Creek (Jedovnický potok).The slag was dumped in the locality in consequence of the past processing of iron ore in blast furnaces, which had been built near Jedovnice by the princely Salm family in the 19th century. Even though the blast furnaces were closed down a hundred years ago, the slag components leaking into the Rudice stream sink cave system still demonstrably damage the speleothems. This was the majorimpulse for us to have a closer look at the geochemical properties of the slag.The chemical composition was determined by silicate analyses carried out in the Institute of Geological Sciences at the Faculty of Sciences of the Masaryk University in Brno and in the ACME laboratories in Canada. The ACME laboratories determined heavy metal contents by atomic absorption spectroscopy (AAS) and by inductively coupled plasma mass spectrometry (ICP-MS). The petrographic characterization of the slag and its enclosures was conducted based on point analyses by a wavelength dispersive X ray (WDX) electron microprobe. Predictions regarding the geochemical behavior of the slag components in an aqueous environment were made using the sequential extraction analysis (SEA) according to Tessier (1979).We have found the expected spatial variability of the basic chemical composition of the slag dumps, as well as the presence of heavy metals (cadmium and especially zinc are present at high concentrations).The slag material exhibits a glassy amorphous structure containing occasional mineral crystals, droplets of pure or oxidized iron and fragments of other materials (such as charcoal or blast furnace bricks). The ongoing weathering of the slag is accompanied by oxidation of crude iron and formation of limonite. Apart from that, the material is not subject to signifi cant secondary transformations. The results of the sequential extraction analyses of slag and soil samples suggest that Cd and Zn are chemically bound to the “carbonate fraction”, which, in general, tends to dissolve under acidic conditions. Even though the environment of the carbonate rock cave systems is typically alkaline, there is a persisting risk of mobilization of heavy metals by acid soil solutions. From the environmental point of view, the slag deposition primarily represents a source of clastic material, which contaminates the cave system and damages speleothems by mechanical abrasion

Underground spaces in Bosonožský hájek Nature Reserve and their geoeducation importance

Bosonožský hájek Natural Reserve (Brno, South Moravia) is a very important site from the Earth Science point of view, however, its geodiversity values have been rather overlooked and omitted in the past (the object of legal protection is the occurrence of well-preserved forest ecosystems and endangered species). In the last decades, a series of field work and geophysical measurements has been carried out and the Earth Science phenomena have been identified and described here. These are represented by a dense network of gullies that developed in Pleistocene loess and that are both of natural and anthropogenic origin (some gullies probably developed along the old paths) and specific underground spaces (so called dugouts). Until now, the dugouts in South Moravia have been investigated mainly by archaeologists and those in Bosonožský hájek NR have not been described in detail yet. This brief contribution brings new information about three underground landforms and their possible relationship to the age and development of the gullies. The possibility of different interpretations of the origin of these specific landforms can be considered an opportunity in the field of Earth Science (geosciences) education and as an interesting complement of tourist and recreational activities on site.Published Versio

Geochemické interakce horninového prostředí s plošnými kontaminanty - využití indikačních horizontů 137Cs ke studiu distribuce‚ vazeb a významu vybraných radionuklidů a kovových prvků v horninách oblasti Moravskoslezských Beskyd

Ve druhém roce řešení projektu byly odběry profilů půd a zemin (kopané sondy) na dalších 38 lokalitách ve východní části CHKO Moravskoslezské Beskydy až po hranici se SR. Na stejných bodech zajistily pracovníci Geominu družstvo Jihlava odběry materiálu pro analýzy šlichů, které byly již dokončeny pro celé území. Specialisté z firmy GEORADIS s.r.o. realizovali měření terénní gamaspektrometrie (K, Th, U, 137Cs) podle speciální metodiky. Ta byla užita i na dalších bodech v zájmové oblasti s cílem pokrýt s větší hustotou území pro následné regionální interpretace radiogenní zátěže. Celkem bylo v terénu proměřeno během etap 2005 a 2006 v místech kopaných sond 117 lokalit (B1 až B117) a pro zahuštění sítě měření dalších 113 lokalit (B200 až B 312). Měření byla rovněž provedena na vzorcích sedimentů z jader odebraných potápěči v etapě 2005 z nádrží Šance a Morávka (celkem 19 jader, 79 vzorků). Na všech vzorcích byl aplikován laboratorní gamaspektrometrický výzkum, část z nich (celkem 47 vzorků) byla analyzována v loňském roce na široké spektrum 41 prvků (laboratoře ACME v Kanadě) a menší část z nich (14 vzorků) i na obsahy signifikantních organických látek (Zkušební laboratoře ČGS Brno). Dokončena již byla i gamaspektrometrická měření šlichových frakcí (GEOMIN, GEORADIS). Značný díl laboratorních prací představovala gamaspektrometrická měření vzorků odebraných v profilech kopaných sond (přes 350 analyzovaných vzorků). Série vybraných sedimentů (103 vzorků) byla dále podrobena zrnitostním analýzám (Geodrill s.r.o.). Pro potřeby porovnání gamaspektrometrických dat z terénních a laboratorních měření s přirozeným geologickým pozadím byly sestaveny mapy distribuce minerálů a radioaktivních prvků ve šlichových koncentrátech. Veškeré informace jsou obsaženy v dílčích zprávách, které jsou nedílnou součástí závěrečné zprávy za rok 2006. Bylo provedeno pilotní srovnání výsledků terénních měření gamaspektrometrie mezi dosud hodnocenými regiony (CHKO Moravskoslezské Beskydy, oblast Jeseníků, Králického Sněžníku a Orlických hor)

Geochemické interakce horninového prostředí s plošnými kontaminanty - využití indikačních horizontů 137Cs ke studiu distribuce‚ vazeb a významu vybraných radionuklidů a kovových prvků v horninách oblasti Moravskoslezských Beskyd

Výzkum je zaměřen na vymezení plošného rozsahu, úrovně a vertikální distribuce vybraných kontaminantů v půdách rozdílné kultivace (les, pastvina, pole) v oblasti Moravskoslezských Beskyd. Konkrétně jde hlavně o radiogenní 137Cs a další vybrané prvky (těžké kovy). Posouzeny budou vazby těchto kontaminantů na zrnitost, jílovitou a organickou složku půd. Analyzován bude též možný ekologický dopad kontaminace zemin s ohledem na možný vstup antropogenních látek do potravinového řetězce. Dále budou zkoumány sedimenty přehradních nádrží Morávka a Šance, které v hloubkových profilech dokumentují sedimentační historii oblasti. Pozornost bude věnována také indikaci atmosférické depozice v oblasti a výzkumu imisí z průmyslových oblastí. V prvním roce řešení projektu byly provedeny odběry profilů půd a zemin na 89 lokalitách. Na stejných místech byl zajištěn odběr šlichtů. Podle speciální metodiky bylo provedeno měření terénní gamaspektroskopie. Ta byla aplikována i na dalších bodech v zájmové oblasti CHKO Moravskoslezské Beskydy s cílem pokrýt s větší hustotou území pro následné regionální interpretace radiogenní zátěže. Pomocí potápěčů a zarážených sond byly provedeny odběry jader sedimentů z nádrží Šance a Morávka (19 jader). Z nich se vydělilo na následné analýzy 79 vzorků. Na všech bude postupně proveden laboratorní gamaspektrometrický výzkum (K, Th, U, 137Cs), jejich část byla zadána na analýzy širokého spektra více než 40 prvků. Série vybraných 45 vzorků byla dále podrobena zrnitostním analýzám. Pro potřeby porovnání gamaspektrometrických dat z terénních a laboratorních měření s přirozeným geologickým pozadím provedena komplexní rešerše využitelných starších informací