GACR

Cryogenic cave carbonate is a rare type of secondary cave carbonate, which was formed in caves as a result of water freezing. The dissolved load of karst water was concentrated in the residual solution during formation of ice, and upon complete water freezing it was segregated as a carbonate precipitate. The existence of this carbonate type in caves of Central Europe was recognized only several years ago. Samples of cryogenic cave carbonate from localities in the Central European countries will be documented in the field, dated by U-series method and studied both mineralogically and geochemically, using C and O stable isotopes. Based on position of the dated samples, minimum permafrost depth during the Last Glacial Maximum will be estimated. The study will be complemented by experimental laboratory freezing of calcium bicarbonate water, followed by mineralogical and geochemical study of the formed carbonate phases.

The project concerns late Silurian (Ludlow-Přídolí) conodont and graptolite faunas, their taxonomic revisions and biostratigraphic applications. Pending problems in global conodont biostratigraphy and taxonomy caused considerable difficulties in inter-regional correlations. Progress in the worldwide correlation of classic sections of the Prague Synform would be attained by integration of all available and newly obtained stratigraphic data considering different paleoenvironmental conditions with special emphasis on detailed correlation of conodont and graptolite faunas. Paleoenvironmental interpretations will be based especially on changes in the composition of benthic and nektonic faunas. The entire succession of the Upper Silurian in its type area will be supported by a complete and detailed carbon isotope log, and detected local and/or global events will be precisely dated by high-resolution stratigraphy. The goal of the proposed project is to fill blank spots in the stratigraphy of the late Silurian in the classic area near Prague and enhance the correlation potential of the sections that may have crucial implications for the precision of global late Silurian stratigraphy.

The main objective of this project is clarification of the contribution of pores space on physical and mechanical properties of highly porous rocks, i.e. rocks in which pores make important part of bulk rock fabric. The study will be focused on the following research tasks:- relationship between shape of solid rock constituents (clasts) and shape of pore space, their contribution to the bulk symmetry of rock fabric, and validation of the presumption of the transversal isotropy symmetry of clastic sedimentary rocks;- influence of the shape of pore space (in 3-dimensions) on the physical (gas and water permeability, water absorption, capillarity) and mechanical (deformation, strength) properties;- research on the possible determination of pore space and 3D approximation using direct methods (optical microscopy equipped with the image analysis, electron microscopy, diagnostic colouration of pores) and indirect methods (anisotropy of magnetic susceptibility using suction of magnetic fluid in

The late Aeronian Sedgwickii Event belongs is one of the most dramatic global extinctions among planktic graptolites and roughly coincides with one of the most significant carbon isotope excursions so far recorded through the Silurian System. Carbon isotopic data, combined with stratigraphic distribution of oxic beds or gaps in sedimentation, account for sea-level drawdown, tentatively attributed to glacial interval recorded in the Amazon Basin. In the Barrandian area, the mass extinction has been recorded in the latest convolutus-early sedgwickii Biozone along with mottled oxic beds in a generally black-shale succession. In some Barrandian sections, however, this interval is missing due to an offshore gap in sedimentation. A section, temporarily exposed in the Radotin tunnel, provided a unique opportunity for a detailed multidisciplinary study of the whole Sedgwickii Event interval. The Radotin section data will be supplemented with that from other partial sections and correlated with El Pintado section of SW Spain. Detailed analysis of the graptolite mass extinction and recovery, palynomorph abundance and diversity fluctuation, Corg isotope excursion, and facies changes aims to elucidate scenarios, relative timing and causal links of these chemical, biotic and sedimentary proxies of the early Silurian climatic and sea-level fluctuations.

The former Komořanské jezero Lake formed the largest and therefore the most important natural water body in the area of the Czech Republic. The absolute majority of unique lake sediments was destroyed due to the progress in coal mining in the last century. The principal aim of the proposed project is to save the paleolimnological information hidden in four rediscovered sediment profiles gathered in 1980s in order to reconstruct climatic events throughout Late Pleistocene and Holocene by means of multi-proxy approach. Tracking human impacts on the lake ecosystem belongs also to the main objects of the research. Immediate action is necessary on account to stop and prevent further biological decay of the profiles found after almost 25 years of inappropriate stocking.

The existing evidence for different palaeoecological interactions between primary producers and their primary consumers, as well as between primary and higher consumers are only partly established in Lower Palaeozoic communities. The goal of the proposed project is to study, describe and evaluate the already existing extensive materials of Cambrian to Middle Ordovician findings preserving palaeoecological interactions in different parts of the trophic web. Several thousand specimens of microscopical and macroscopical fossils (both skeletal and soft-bodied) have been collected from Cambrian to Middle Ordovician of the Barrandian area in the last 150 years. Obvious but poorly studied and thus unsufficiently established changes in frequence and proportion of different trofic levels within the "middle" Cambrian - Middle Ordovician interval will be evaluated in detail. Such evaluation of existing and new materials provides an exceptional possibility to follow the agronomic revolution and changes of the complex benthic food web from Cambrian to Ordovician in comparable facies.

Good knowledge of soil hydraulic properties is required for successful solution of pollutant transport, hydrological modeling of catchments and prediction of the plant production in soil. The submitted project is aimed at experimental, analytical and numerical investigation of theory that multimodal character of soil pore size distribution and hierarchical pore composition influence not only the shape of soil hydraulic properties, but also total character of water flow and solute transport in soil porous media. In many cases, the soil porous system cannot be treated as one continuum (usual approach), but as two continuums assuming either appearance of zones with immobile water and zones with mobile water or two continuums with different soil hydraulic properties characterizing preferential flow. Another objective of this project is evaluation of agricultural management impact on soil properties and consequently on water flow and contaminant transport. The research will provide complex view on transport processes in soils that is important especially for ground water protection.

Mercury is considered to be one of the most important pollutants due to its ecotoxicological effects. Elevated Hg contents in the environment are closely related to industrialization of developed countries, which began at the end of the 18th century. Recent studies show that current anthropogenic emissions have exceeded those from the natural sources. Geochemical archives such as peat bogs, tree rings or lake sediments are widely used for reconstruction of historical trends of environmental pollution. Although the environment of the Czech Republic is bearing several loads originating in its past, only few studies have dealt with atmospheric Hg deposition. The proposed project aims to evaluate historical change in Hg deposition recorded in tree rings and bark pockets. Obtained data allows us to observe the magnitude of environmental change resulting mainly from industrial activities and evaluate the present day situation. Moreover it could help us in understanding of Hg biogeochemical cycle in the forest ecosystems.

Prague Basin (PB) has become worldwide known area of Lower Palaeozoic due to extensive palaeontological and biostratigraphical investigations. However, disproportional palaeomagnetic and geochemical research does not permit the interpretation of PB palaeosetting and its development. The proposed project is focused on study of volcanic rocks within the Late Ordovician-Early Devonian sequences of the PB. At first, we intend to biostratigraphically establish ages of volcanic phases and use data on petrology, mineral and whole-rock geochemistry and Nd-Sr-Pb isotopes to constrain the character, petrogenesis and geotectonic setting of volcanites of the PB. At second, we intend to define and build new palaeomagnetic database with additional information of palaeomeridians, palaeolatitudes and of the approximate ages. Finally, by integration of the palaeomagnetic position development and geotectonic setting evolution of volcanites, we will determine the PB palaeosetting and its development; improve the location of peri-Gondwanan terranes and contribute to the Early Palaeozoic palaeogeography.

Aim of this project is to define contents of Ga and Ge and establish the Al/Ga- and Si/Ge-ratios in different types of natural silicate melts (granitoids) representing partial melting and following evolution (fractional crystallization, mixing, reaction with fluid) in different positions in the Earth crust. The contents of Ga and Ge will be studied in whole-rock samples and in major rock-forming minerals - quartz, feldspars, micas, and amphiboles etc. We expect to find differences in the Al/Ga- and Si/Ge-ratios not only between different rock series (differences in pT-conditions of melting and fractionation), but also among individual mineral species )differences in crystal structure). Evolution of Al/Ga- and Si/Ge-ration will be compared with the K/Rb, Zr/Hf, Nb/Ta and Y/Ho of analysed rocks. Model of Ga and Ge behaviour in magmatic process will be developed. Chemical analyses will be performed with quadrupole ICP-MS spectrometer Agilent 7500ce equipped with laser ablation system UP213.