The Lower Carboniferous Culm Basin of the Czech Republic represents the most easterly and southerly part of the European Variscan foreland basin system. The NNE–SSW-trending basin is exposed along the eastern flank of the Bohemian Massif. It contains up to 7.5 km of deep marine sediment deposited as an axial turbidite system sourced from south/southwest of the basin. Heavy mineral data and clast types indicate that for much of the Viséan, sediment was sourced from a predominantly low-grade metamorphic terrane and Viséan limestones. In the latest Viséan, a progressive change in source material is recorded by an increase in high-grade metamorphic detritus. Studies of Variscan nappe pile emplacement along the eastern flank of the Bohemian Massif allow an assessment of the relationship between basin development and nappe emplacement. Basin initiation coincided with underthrusting of high grade metamorphic (Moldanubian) nappes at 340 Ma. Sedimentation was synchronous with nappe emplacement throughout the Viséan which resulted in uplift and erosion of a low grade metamorphic terrane. Moldanubian nappes were exhumed at approximately 330 Ma when high grade metamorphic detritus entered the basin. Two phases of northward-directed sediment progradation are recognized. Sediment progradation is considered to be related to changes in drainage basin size and/or climatic fluctuations within the Variscan Orogen, since sediment is inferred to have been supplied to the basin axially rather than laterally and subsidence curves show no significant change in subsidence rates. In contrast to many models of foreland basin sediment distribution, filling of the Culm Basin was largely independent of tectonic activity adjacent to the basin margin and/or of subsidence rate changes. Sedimentation in the Culm Basin commenced 10–15 Ma earlier than the rest of the Variscan foreland, and records the first impact of the northwardly propagating Variscan Orogen in northern Europe.

Abstract. Organic and clay indicators were measured to characterise the burial and thermal history of Devonian through Upper Carboniferous siliciclastic and carbonate rocks in the Rheno-Hercynian zone of the Variscan orogeny in Moravia (eastern Czech Republic). The very low-grade metamorphism is documented by the illite crystallinity (IC) and vitrinite reflectance (R r ) in the inner part of the thrust and fold belt in the NNW. Application of forward thermal modelling suggests maximum palaeo-temperature of 240-360 • C and burial depth of 4-9 km. In the Variscan foreland in the SSE the IC and R r values are typical of diagenetic conditions with maximum palaeo-temperature of 80-130 • C. The distribution of both clay and organic maturity parameters is interpreted as a result of pre-and syn-tectonic thermal exposure of the rocks due to burial by a wedge-shaped body of thrust sheets thinning towards the Variscan foreland where only sedimentary burial was effective. The amount of uplift and denudation increases from the foreland to the RhenoHercynian thin-skinned thrust and fold belt.

Development of new stratigraphic techniques has led to better understanding of the compositional variability and quantity of dust-related impurity components in pure marine limestones, with a considerable impact on stratigraphic resolution and explanation of causality. The early Middle Frasnian (E-MF, punctata Zone) stratigraphic interval was selected for this study in order to assess the contribution of atmospheric dust and to distinguish between the robust climatically driven anomalies and the potential distant effect of the Alamo impact. The location of the study in the Moravian Karst area has two advantages: there are no mixed carbonate-siliciclastic sediments, only the pure limestone of a platform reef complex, and the authors have access to voluminous survey and drilling reports. The methodology employed for undertaking the most recent research was based on succession and combination of the following steps: biostratigraphy and facies analysis, magnetic susceptibility (MS), gamma-ray spectrometry (GRS), instrumental neutron activation analysis (INAA), and finally, separation and assessment of rare non-carbonate particles. The natural atmospheric dust burden, deposition, and embedding in pure carbonate traps were, most likely, threefold higher during the Frasnian in the Upper Devonian in comparison with Quaternary platform reef counterparts. Variation of 10-100 ka averages is medium in terms of the Frasnian ranges of MS-GRS values, and the base and top of the E-MF interval are manifested by robust elevations of these values. Forced anomalies in MS, GRS and geochemical signals that defy the normal sequence of rhythms were found: two anomalies disturb the broad middle part of the E-MF interval and one is superimposed on the upper part of the punctata-hassi zones strata. The most significant disturbance was found near the mid-punctata Zone level. In spite of the relatively low magnitude, it shows features that are usually related to major environmental crises which occured in the Devonian, such as the Choteč, Kačák or Kellwasser events. These include a large depression in MS and dust-particle concentration values coupled with a period of sea level lowstand and calm atmospheric conditions (stage A), and an abrupt shift to high MS that has a comb-like pattern that gradually fades upward, developed together with a forced flooding surface, increased detritism, and stormy conditions (stage B). It is a reverse of the normal cyclicity in pure limestone when the high impurity corresponds to lowstands. A very small amount of particulate material of an exotic nature was found at the A-B stage interface and assessed: it contained iron-rich silicate microspherules and drops, devitrified glasses, tiny mineral/rock clasts of hyperbasite compositions, as well as pellets and clumps of glasses and phlogopites. The silt-sized particles show ablated and striated surfaces, flow deformation of devitrified glasses, and layered onion-like structures. Iron-rich lamellae with meshwork crystal patterns occur among decrepitated crystalli...

As so ci ate Ed i tor-Anna Wysocka The en trenched Odra palaeovalley, cut into the bed rock of the dis tal mar gin (forebulge basal un con formity) of the Moravian Carpathian Foredeep (pe riph eral fore land ba sin) is filled with an al most 300 m thick pile of Mio cene de pos its. The directon of the val ley (NW-SE to NNW-SSE) has been con trolled by faults subparallel with the sys tem of sudetic faults". The sed i mentary suc ces sion con sists of 5 fa cies as so ci a tions/depositional en vi ron ments, which are in ter preted (from bot tom to top, i.e. from the old est to the youn gest) as: 1-col lu vial de pos its to de pos its of al lu vial fan, 2-de pos its of al lu vial fan, 3-fan-delta de pos its, 4-shal low wa ter delta to nearshore de pos its and 5-open ma rine de pos its. This fin ing-up and deep en ing-up succes sion re veals the fol low ing: the for ma tion of the new flex ural shape of the ba sin; deep ero sion con nected with up lift and tilting of the forebulge and re ac ti va tion of the NW-SE trending base ment faults; the Early/Mid dle Mio cene sea level fall; al lu vial de po si tion mostly driven by tec ton ics and mor phol ogy; forebulge flex ural re treat; Mid dle-Mio cene sea level rise; back-stepping of val ley infill; ma rine in va sion dur ing the Early Badenian with shift of the coast line fur ther land ward of the pallaeovalley. Tec ton ics re lated to con tem po rary thrust ing pro cesses in the West ern Carpathians are as sumed to be the dom i nat ing fac tor of the stud ied de po si tion at the ex pense of eustatic sea level changes. Prov e nance stud ies have proven that the pre-Neogene base ment (i.e. the Early Car bon if er ous clastic "Culmian fa cies" of the Moravian-Silesian Pa leo zoic) rep re sents an impor tant source for the con glom er ates and sands, which vol u met ri cally dom i nate in the palaeovalley infill. How ever, they also showed, that the de pos its of the ear lier Carpathian Foredeep Ba sin sed i men tary stage (Karpatian in age?) cov ered the area un der study and were eroded and resedimented into the palaeovalley infill.

Abstract:Recently two new trilobite occurrences were discovered during geological mapping of fossiliferous shales of the Březina Formation around the village of Březina in the Moravian Karst (Czech Republic). The newly discovered localities are extraordinary because of the unexpected occurrence of articulated trilobite exoskeletons associated with brachiopods including supporting spines. The new atheloptic association of Mississippian trilobites is described for the first time from the Moravian Karst.