GA AV

Spatial and temporal changes of sandstone provenance in the Krkonoše Piedmont Basin and their tectonosedimentary implications
The Krkonoše Piedmont Basin formed as part of system of extensional/transtensional basins during the late phases of the Variscan orogeny and early post-orogenic period. Shifting of depocentres at the Stephanian B/C and Autunian/Saxonian boundary show to a distinctive changes of basin configuration. Driving mechanisms of these changes are poorly understood so far. This project intends to decipher these mechanisms based on the provenance investigations using heavy mineral analysis, U/Pb age of detrital zircon and fission track analysis of detrital apatite and zircon on several stratigrafhic levels and lateral areas of the basin. Obtained data will be compared to the potential source areas. This work will result in establishing a model of tectonosedimentary development of the basin including reconstruction of sediment dispersal pathways and a model of erosional history and tectonostratigraphical development of surrouding crystalline units.

We propose to undertake an analysis of the effect of Basal Choteč event (early Eifelian, Middle Devonian) on faunistic communities in the Prague Basin based on synthesis of paleontological, geochemical, petrographical and geophysical data. The Basal Choteč event was documented from several areas of the Europe and the North Africa. The Prague Basin provides a number of appropriate sections for studies on the Basal Choteč event in different environments. Thus, the detailed evaluation of changes of biotic and abiotic parameters across the Basal Choteč event can provide scope for an interesting study capable of shedding light not only on the effect of the Basal Choteč event on faunistic communities, but also on the evolutionary changes and stability of Devonian faunas, and their reactions to changes of some environmental factors, and subsequently to bring a contribution to our better understanding of basic evolutionary mechanisms.

Salt karst was intensively studied on Mt. Sedom (Israel) by Dr. Frumkin in 90's. Till this time, it is the only place with detailed study of salt karst all over the World. In the Zagros Mountains and Iranian coast of Persian Gulf, there are several tens of salt plugs with well-developed salt karst. These salt plugs show very various conditions (precipitation amount, position above the erosion base, thickness of the cap rock, development of exo and endokarst). Six expeditions performed to the area shown great potential for research of salt karst and fruitful cooperation with Shiraz University. Grant project is focused on evolution and development of the salt karst on selected plugs in Zagros Mts. There are two objectives: Describe and explain the influence of different factors on shape and evolution of exo- and endo-karst forms in salt karst and quantify the rate of speleogenesis in various conditions (erosion rate of salt outcrops and caprock, age of caves).

This project aims to study speciation and mobility of arsenic (As) in soil and waters affected by medieval mining dump - located in the NW part of the Jáchymov ore district (NW Bohemia). Analysis of arsenic speciation in pore water, ground water, surface water, and solids in soil and waste dump will be integrated with detailed mineralogical and geochemical observation and speciation modelling. Results of complex research will provide information on long-term As behaviour in the oxidation zone and mobility-limiting factors of As in the field conditions.

The proposed project is aimed at the deciphering of polyphase metamorphism and especially at the dating of particular metamorphic events in the course of the HP-HT evolution of granulite-facies rocks. Several zircon populations in granulites of the southern part of the Bohemian Massif are indicative of varied processes of its growth or modification. Since the zircon dating is the most often used tool for dating of the metamorphic rock and metamorphic processes, assigning discrete zircon populations to a specific metamorphic event appears to be crucial in modern metamorphic petrology and geochemistry. For a more robust and reliable interpretations of zircon ages we will try to introduce a new methods for distinguish individual zircon populations – besides conventional methods as are external habit, internal structure or chemistry of trace elements, we will use EBSD structural observations and Hf isotopic analyses in conjunction with precise in-situ laser ablation ICPMS U-Pb dating.

The main objective of the proposed project is to carry out detailed comparative study of Hg distribution and mobility in soil at 3 contrasting sites. The sites have been selected according to topsoil Hg concentration. The study will include the determination of Hg concentration and speciation in individual horizons of selected soil profiles and sediments. Additionally Hg concentration will be determined in vegetation to evaluate the actual input flux of Hg to ecosystems. Analysis of total Hg will be performed by the AMA-254 Mercury Analyzer. Mercury speciation will be analyzed by means of Hg pyrolysis technique. The proposed project should extend the present knowledge of Hg contamination in the Czech Republic and broaden the research methodology, especially with respect to the Hg speciation in soil. Comparable study has not been recently realized in the CR, although understanding of Hg speciation and migration in environment is essential for assesing the environmental risks for human.

The purpose of the project is to fill the substantial gaps in early Devonian stratigraphy of Central Bohemia with new biostratigraphical (conodont) data and to perform their detailed correlation with other faunal groups. Biostratigraphic data will be correlated with magnetic susceptibility (MS) and gamma-ray spectrometry (GRS) logs. The arrangement of these records into the main composite section of the Lower Devonian of the Barrandian area in combination with bio- and chemostratigraphic data, in terms of integrated stratigraphy, will strongly enhance the potential of the Barrandian area for interregional correlation purposes. The results of the project to be most welcomed in international scale are the long expected proposals for a novel revision of global early Devonian stratigraphy.

Highly siderophile character of platinum-group elements gives a powerfull tool for the study of upper mantle, magmatic intrusions and volcanic flows differentiation. Strongly differentiated intrusions shows an excellent possibility for the study of trace element behaviour during magmatic differentiation and fractionation. This project is focused on behaviour of platinum-group elements during differentiation of gabbro-peridotite and gabbro-diorite intrusions (as will be demonstrated on the Ransko, Kdyně, Poběžovice, Mutěnín and Drahotín intrusions from the Bohemian Massif) on the basis of their distribution in particular rock types and mineral phases (silicates, oxides and sulphides).

Geochemical charakteristics of the AFC processes resulting in evolved trachyte/phonolite derivates of alkaline magmas: (a) serie nephelinite/tephrite-phonolite/trachyte-(carbonatite), and (b) serie olivine nephelinite/basanite - trachyandesite - trachyte/phonolite - (rhyolite) will be investigated. Petrochemical modeling for evaluation of parental magma source is proposed. On basis of the Sr-Nd isotopic data, the magmatic source and a level of crustal magma contamination will be established. For detailed geochemical evaluation of sample set, the great number of indicative elements is needed; it will be ensured by the sensitive analytical mathods of instrumental neutron and gamma(photon)-activation analyses (INAA + IGAA). The determination of radiogenic Ar and K by means of NAA would contribute to the more precise geochronological dating.

The proposed project is focused on the complex paleoecologic and stratigraphic study of fauna from the Šárka Formation (Middle Ordovician of the Prague Basin, Czech Republic). The aim of the project is to revise available published data, to collect new material from natural and temporary outcrops and, above all, to make a modern investigation of the fossil associations of the Šárka Formation. Interpretations of stratigraphical-paleoecological position of regions ("segments") of the Prague Basin where the Šárka Formation occurs is another goal of the project. Revisions of the main index groups of graptolites, trilobites and ichnofossils are also planned. Paleogeographic correlations, especially with other regions of peri-Gondwana, will be studied. Results will be published in a scientific journal. The project is a contribution to the IGCP 497 "The Rheic Ocean".