Slavomír Nehyba

Seasonally and regionally determined indication potential of bioassays in contaminated river sediments.

River sediments are a dynamic system, especially in areas where floods occur frequently. In the present study, an integrative approach is used to investigate the seasonal and spatial dynamics of contamination of sediments from a regularly flooded industrial area in the Czech Republic, which presents a suitable model ecosystem for pollutant distribution research at a regional level. Surface sediments were sampled repeatedly to represent two different hydrological situations: spring (after the peak of high flow) and autumn (after longer period of low flow). Samples were characterized for abiotic parameters and concentrations of priority organic pollutants. Toxicity was assessed by Microtox test; genotoxicity by SOS-chromotest and green fluorescent protein (GFP)-yeast test; and the presence of compounds with specific mode of action by in vitro bioassays for dioxin-like activity, anti-/androgenicity, and anti-/estrogenicity. Distribution of organic contaminants varied among regions and seasonally. Although the results of Microtox and genotoxicity tests were relatively inconclusive, all other specific bioassays led to statistically significant regional and seasonal differences in profiles and allowed clear separation of upstream and downstream regions. The outcomes of these bioassays indicated an association with concentrations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) as master variables. There were significant interrelations among dioxin-like activity, antiandrogenicity and content of organic carbon, clay, and concentration of PAHs and PCBs, which documents the significance of abiotic factors in accumulation of pollutants. The study demonstrates the strength of the specific bioassays in indicating the changes in contamination and emphasizes the crucial role of a well-designed sampling plan, in which both spatial and temporal dynamics should be taken into account, for the correct interpretations of information in risk assessments.

Provenance analysis of the Permo-Carboniferous fluvial sandstones of the southern part of the Boskovice Basin and the Zöbing Area (Czech Republic, Austria): implications for paleogeographical reconstructions of the post-Variscan collapse basins

Abstract The provenance analyses of Permo-Carboniferous fluvial sandstones of the southern part of the Boskovice Basin and the Zöbing area are based on a wide spectrum of analytical techniques (petrography, heavy mineral assemblages, chemistry of garnet, rutile and spinel, zircon study, major and trace elements). The studied sandstones are poorly sorted and reveal a relatively immature composition implying short distance transport, rapid deposition, a high-relief source area, mainly physical weathering and the minor role of chemical weathering. Different source areas for the Boskovice Basin and the Zöbing area were proved. The Zöbing material was predominantly derived from crystalline units, mainly formed by metamorphic complexes, although the portions of magmatic and volcanic material were significant. The source area is supposed to be located in the Moldanubian Unit. The Boskovice Basin deposits, on the other hand, seem to be mainly derived from metamorphic complexes, corresponding especially to the Moravian Unit, with a relatively wider spectrum of metamorphites, together with the derivation of the detritus from pre-existing sedimentary rocks (especially from Moravo- Silesian Paleozoic deposits/Drahany Culm unit). The transport direction in the basin was more complex, both from the west and east. These results did not confirm the possibility of communication between the Boskovice Basin and the Zöbing area during the Late Paleozoic. The existence of “colinear” marginally offset half grabens with predominant transversal sources is here hypothesized. The general heavy mineral evolution in time does not indicate the successive exhumation of a simple structured orogen but may be interpreted as differences in the extent of the source areas.

Modern fluvial sediment provenance and pollutant tracing: a case study from the Dřevnice River Basin (eastern Moravia, Czech Republic)

Modern fluvial sediment provenance and pollutant tracing: a case study from the Dřevnice River Basin (eastern Moravia, Czech Republic) Modern fluvial deposits of a small fluvial system were studied in the area of eastern Moravia (Czech Republic) with the aim of determining the provenance of the deposits and weathering processes. Identification of the source rocks and their alongstream variations were used for the evaluation of the natural or anthropogenic source of the heavy metals. Paleogene flysch sandstones, flysch mudstones and Quaternary loesses represent source rocks and reflect both the role of recycling and local sources. Provenance from sandstones dominate upstream whereas mudstones represent dominant source rock in the downstream part of the fluvial system. The contents of Pb and Zn are highly enhanced when compared with the natural background in the entire study area. Their anthropogenic source is connected with the rubber/shoe manufacturing industry and traffic. The contents of Cr, Co, Cu, Ni and V are usually lower in modern deposits than in the identified source rocks.

Evolution of the passive margin of the peripheral foreland basin: an example from the Lower Miocene Carpathian Foredeep (Czech Republic)

Abstract The Karpatian deposits of the central part of the Carpathian Foredeep in Moravia, which are deeply buried under the Outer Western Carpathians, provide a unique opportunity to reconstruct the former evolutionary stages of this peripheral foreland basin and its paleogeography. A succession of three depositional units characterized by a distinct depositional environment, provenance, and partly also foreland basin depozone, have been identified. The first depositional unit represents a proximal forebulge depozone and consists of lagoon-estuary and barred coastline deposits. The source from the “local” crystalline basement played here an important role. The second depositional unit consists of coastline to shallow marine deposits and is interpreted as a forebulge depozone. Tidalites recognized within this unit represent the only described tide-generated deposits of the Neogene infill of the Carpathian Foredeep basin in Moravia. The source from the basin passive margin (the Bohemian Massif) has been proved. The third depositional unit is formed by offshore deposits and represents a foredeep depozone. The provenance from both passive and active basin margin (Silesian Unit of the Western Carpathian Flysch Zone) has been proved. Thus, both a stepwise migration of the foredeep basin axis and shift of basin depozones outwards/cratonwards were documented, together with forebulge retreat. The shift of the foreland basin depozones more than 50 km cratonward can be assumed. The renewed thrusting along the basin’s active margin finally completely changed the basin shape and paleogeography. The upper part of the infill was deformed outside the prograding thrust front of flysch nappes and the flysch rocks together with a strip of Miocene sediments were superposed onto the inner part of the basin. The width and bathymetric gradient of the entire basin was changed/reduced and the deposition continued toward the platform. The basin evolution and changes in its geometry are interpreted as a consequence of the phases of the thrust-sheet stacking and sediment loading in combination with sea-level change.

The Badenian parastratotype at Židlochovice from the perspective of the multiproxy study

Two shallow boreholes were drilled in 2010 into the Badenian (Langhian) parastratotype at Zidlochovice (Carpathian Foredeep, NN5 Zone, Czech Republic). Their profiles (26 m of sediment) were studied comprehensively (sedimentology, palaeontology-calcareous nannoplankton, red algae, palynology, Foraminifera, Bryozoa, Brachiopoda, Ostracoda, Mollusca, Teleostei and Elasmobranchii). The sedimentary succesion was biostratigraphically correlated with the NN5 Zone (14.9-13.9 Ma), namely with the initial time of the Middle Miocene Climatic Transition. Seven lithofacies representing multiple alternations of mudstone, sandstone and limestone facies were recognised within sedimentary succession. Fossils indicated a normal marine, warm to subtropical environment. The generally shallowing trend from the bottom (epibathyal/circalittoral) to the top (shallow infralittoral) of the sedimentary succession with repeated palaeobathymetric changes could be recognized in both boreholes. A mainly subtropical character of terrestrial flora was recorded. Within this framework, either warm wet conditions with seasonal increases, or cooler phases were observed. The abrupt change from mudstone deposited in a calm palaeoenvironment of the upper bathyal/circalittoral to the variegated deposits of shallow water represents the most significant event correlable with the FO of Orbulina (approximately 14.5-14.6 Ma). The interval below the FO of Orbulina can be characterized by mudstone facies and stable conditions of deposition, high nutrient input and a decrease of oxygen content at the bottom. Seasonal stratification of the water column is probable. Within this interval, cooling and an increase of seasonality were recorded. Above the FO of Orbulina, there is evidence of shallowing with a higher flow regime and higher sedimentation rate. The alternation of thick redalgal limestone bodies and variegated sandstone, mudstone and limestone interbeds possibly reflects orbitally forced climatic cyclicity.

The sedimentary environment of Devonian siliciclastics in the Babí lom locality (Brunovistulian Platform cover, Southern Moravia, Czech Republic)

Anchimetamorphosed sandstones and conglomerates of the so-called “Basal De vo nian Clastics”, that build a hill (ridge) named Babi lom, are considered to be of Lower to Middle Devonian age. Al though they are strongly tectonically affected, many sedimentary features are well-preserved and distinct. Both the facies and structures typical of alluvial fans and rivers were recognized in the sedimentary association at Babi lom. Among others, there are channel lags with imbricated grains, cross-bedding, and debrites. The way-up direction is clearly seen via repetitive coarsening-upwards sequences. Assuming a lack of rotation of the succession in the X–Y plane, the main palaeodrainage was towards the north and the major supply of material was from the east. The high maturity of the rocks suggests derivation from older deposits and/or highly weathered source rocks. The magmatic rocks of the Brunovistulicum are possibly the primary source of the sediments.

Lower Badenian coarse-grained Gilbert deltas in the southern margin of the Western Carpathian Foredeep basin

Abstract Two coarse-grained Gilbert-type deltas in the Lower Badenian deposits along the southern margin of the Western Carpathian Foredeep (peripheral foreland basin) were newly interpreted. Facies characterizing a range of depositional processes are assigned to four facies associations — topset, foreset, bottomset and offshore marine pelagic deposits. The evidence of Gilbert deltas within open marine deposits reflects the formation of a basin with relatively steep margins connected with a relative sea level fall, erosion and incision. Formation, progradation and aggradation of the thick coarse-grained Gilbert delta piles generally indicate a dramatic increase of sediment supply from the hinterland, followed by both relatively continuous sediment delivery and an increase in accommodation space. Deltaic deposition is terminated by relatively rapid and extended drowning and is explained as a transgressive event. The lower Gilbert delta was significantly larger, more areally extended and reveals a more complicated stratigraphic architecture than the upper one. Its basal surface represents a sequence boundary and occurs around the Karpatian/Badenian stratigraphic limit. Two coeval deltaic branches were recognized in the lower delta with partly different stratigraphic arrangements. This different stratigraphic architecture is mostly explained by variations in the sediment delivery and /or predisposed paleotopography and paleobathymetry of the basin floor. The upper delta was recognized only in a restricted area. Its basal surface represents a sequence boundary probably reflecting a higher order cycle of a relative sea level rise and fall within the Lower Badenian. Evidence of two laterally and stratigraphically separated coarse-grained Gilbert deltas indicates two regional/basin wide transgressive/regressive cycles, but not necessarily of the same order. Provenance analysis reveals similar sources of both deltas. Several partial source areas were identified (Mesozoic carbonates of the Northern Calcareous Alps and the Western Carpathians, crystalline rocks of the eastern margin of the Bohemian Massif, older sedimentary infill of the Carpathian Foredeep and/or the North Alpine Foreland Basin, sedimentary rocks of the Western Carpathian/Alpine Flysch Zone).

Výsledky vrtného průzkumu na lokalitě Holubice (spodnobadenské sedimenty karpatské předhlubně)

Early Badenian deposits of the Carpathian Foredeep were newly studied in the sedimentary successions from drill holes Holubice 1 and Holubice 2. Facies analysis together with study of grain size, the shape and roundness of the coarsest grains, the mineral compositions of selected heavy minerals (garnet, rutile) and the gamma-ray spectra, were all used for better understanding the depositional setting and provenance. Studied sediments were deposited in coastal and shallow marine environments. Six lithofacies was recognised in the sedimentary succession in the drill holes. They have been combined into two facies associations – lower clastic one and upper carbonate one, refl ecting deposition in shallow marine settings, upward shallowing trend and reduction of siliciclastic input. The primary source of the material is located mainly in the metamorphic rocks (gneisses, amphibolites and granulites). The spectral gamma-ray logs show vertical organization, which is consistent with the facies analysis and partly also grain-size. A significant reduction of terrigenous input is connected with deposition of carbonates (sandy limestones) in the upper part of the succession.

PÍSEČNÍK U JAVORNÍKU – DRUMLIN SE ZACHOVALOU SUKCESÍ SUBGLACIÁLNÍCH A SUPRAGLACIÁLNÍCH SEDIMENTŮ

Pisecnik Hill (288 m a. s. l.) is an isolated elevation located near the Javornik town close to the NE foothill of the main ridge of the Rychleby Mts. (Eastern Sudetes). It has a shape of a ridge elongated in the SE–NW direction, made of compacted Miocene sands covered by Pleistocene tills and glaciofl uvial sediments. These glacial sediments have been deposited during the Elsterian glaciation (MIS 12) according to the Northern European stratigraphical scale. The presented study is targeted on glacial deposits and the interpretation of the evolution of the Pisecnik Hill linked to continental glaciation. Facies description has been supplemented by petrographical analyses of the gravel fraction 16–64 mm. The glacial sequence is composed of five members. The first one is a lodgement till (Jk1) with a basal boulder lag, which followed the erosional phase producing elongated scours. Glacitectonic features, such as plucking of underlying Miocene sands and formation of rip-up clasts could be seen in the lodgement till unit. Boulder lag with boulders up to 2 m long originated by blocking of large clasts in compact, plastic, unlithifi ed basement. The second member (Jk2) is a massive to weakly stratifi ed gravely sand, which filled a shallow depression in the lodgement till. These sediments originated by reworking of underlying till material. Members Jk1–Jk2 have been deposited in subglacial environment. Both members are equivalent from the viewpoint of petrological composition – they both contain predominantly local Gieraltow gneiss. The third member (Jk3) is a coarse grained to bouldery gravel. The fourth member (Jk4) is made of a fi ne layer of laminated sand. The last member (Jk5) is a sandy gravel with gently sloping flat clasts. Members Jk3–Jk5 are interpreted as supraglacial sediments deposited with the ice-cored moraine environment. They are rather polymictic from petrological point of view, as they contain material of diverse provenance originating from different parts of the glacier. The clasts are also more variable in roundness with higher content of rounded to well-rounded clasts (“englacial egg gravel facies”). The Pisecnik Hill represents a drumlin with a core composed of plastic Miocene sand. Features described in the glacial sequence show on the active glacial movement (in subglacial environment), as well as the subsequent decay starting from the ice-cored moraine to the final disappearance of the dead-ice moraine. The drumlin orientation documents the ice sheet advance from the NE.

SEDIMENTÁRNĚ-GEOLOGICKÉ STUDIUM VYBRANÝCH KVARTÉRNÍCH SEDIMENTŮ V OKOLÍ BRNĚNSKÉ PŘEHRADY

Outcrops of Quaternary deposits are lining banks of the Brno dam. One of them is situated on the left bank ~ 250 m NW of the Osada pier. The sedimentary profile of Pleistocene deposits is composed of fluvial deposits of the Paleo – Svratka River covered by colluvial and eolian (loess) deposits. Alternation of various facies and various grain-size fractions reveals alternation of more or less arid conditions and also evolution of the surrounding landscape.