GA AV

The project aims to enhance our understanding of the prehistoric landscape used and cultivated by man, to identify key stages in its long-term evolution and to study individual processes that cause it to change. The landscape's historic evolution is a highly complex process that can be studied only by using an interdisciplinary approach – one of the most efficient being the application of archaeology closely combined with palaeoecological techniques (like palynology, analysis of plant macroremains, palaeomalacology). The questions we ask have both historical and methodological focus. They deal with: spatial structure of settlement areas and the possibilities of its depiction in the landscape, the identifiability and form of prehistoric farming systems (including the importance of pastures and the role of forest in the prehistoric economy), the regeneration capacity of natural ecosystems and the reliability of pollen analysis in tracing settlement history.

This is an interdisciplinary project integrated palaeobotanical and palynological methods of investigation of Carboniferous plants from the North American coalfields stored in large collections in the United States.The aim of the project is to study fructifications and in situ spores released from spore-bearing organs and attempt to correlate isolated plant organs to parent plants. Resulting data will not only improve our knowledge on the North American Carboniferous compression flora and its diversity in different basins and stratigraphic levels but also provide reliable platform for comparative analysis of American and European floras in term of their similarity and diversities either as a whole or within particular plant groups and in various stratigraphic levels. Such data are of the key- importance for mapping of floristic changes within the Euramerican province during the Pennsylvanian and consequently for better understanding to the controls responsible for them (climate/tectonics).

Fossil and recent organisms with accretionary skeletons show growth rhythms recognized as a record of changing seasons, days and nights, lunar cycles, and other changes gives a count of days per year and thus the rate of the Earth's rotation in the geological past. Measured data will be compared to astronomically computed ones and differences will be correlated with geotectonic events. The goal of the project is also to reconstruct the weather in the Palaeozoic: coral colonies were moved through storms or hurricanes, and their corallites then assumed different growth direction. As the year's growth periods are manifested as light and dark bands, we plan to compute the length of the periods between successive storms, and to determine the frequency of such events. The measurements can show the pattern of successive longer or shorter increments corresponding to favorable or less favorable conditions. Comparing of such patterns can lead to local sclerochronometry.

Karst functions as trap of the geological past. Karst sediments (surface and cave) conserve unique records, which can miss outside the karstland. Caves mostly contain record of the last infilling (fossilisation) events, in favourable conditions record of more events. Resulting from polycyclicity of most of karsts, karst sediments can cover long time-spans. The application of broad variety of geochronologic methods (magnetostratigraphy, magnetosusceptibility stratigraphy, standard paleontology and biostratigraphy, stable isotopes, isotopic dating methods) can therefore represent a tool for the reconstruction of Cenozoic history in respective karst region. The karst record includes not only data for solution of geomorphic evolution itself (speleogenesis, karst landscape evolution), but also for reconstruction of tectonic events in mobile regions. Karst regions for the test of such kind of reconstructions were carefully selected (Czechia, Slovakia, Poland, Hungary, Slovenia).

The aim of the project is to characterize the magnetostratigraphy of Cenozoic volcanics of the Bohemian Massif, integrated with bio- and lithostratigraphy. A comparison with previous paleomagnetic results from sediments of the Tertiary basins and volcanics from areas outside the territory of the Czech Republic will provide a complete paleomagnetic picture to extend the knowledge of the post-Variscan development. Pilot paleomagnetic profiles will be measured in rocks of the České středohoří Mts. and the Doupovské hory Mts. and complemented with data from solitary volcanoes. Application of well established paleomagnetic methods, supported by other methods used in volcanic rocks, will provide a set of complex and reliable results relevant for the paleomagnetic and stratigraphic development of Cenozoic volcanism of the Bohemian Massif.

The region of the Ohře Rift in the northwestern part of the Bohemian Massif attracts attention of scientists due to the exceptional geological phenomena: contacts of geological units, significant faults, large granitic massifs, sedimentary basins with lignite deposits, Tertiary and Quaternary volcanism, mineral springs and seismic swarms. The project will yield a three-dimensional anisotropic model of seismic velocities to a depth of about 15 km with a specification of the boundaries of the geological bodies. The derivation of the model will be based on seismic tomography. The following seismic data will be used: refraction data from international profiles, measurements of local earthquakes and industrial shots. Geological maps, data from boreholes, physical parameters of rocks and gravity data will be used as well. The model will facilitate the solution of the problems of tectonic evolution of the rift, depth range of geological bodies, origin of mineral springs and earthquakes.

The youngest and more than 1,000 m thick sequence of the Central and Western Bohemian Basins is represented by the Líně Formation. There are up to 10 often fossiliferous lacustrine horizons and the Horizon of Conglomerates with carbonate pebbles. Comparison of interpreted facies with ichnologic and paleontologic data enable to assign the corresponding paleoenvironments and paleoclimates near the Carboniferous/Permian boundary. The paleocurrent, facies, and fossil communities analyses can clarify paleogeographic situation of the tropical zone of Pangea. Provenance of the unique marine carbonate Paleozoic pebbles will be solved with help of micropaleontology. Large scale tectonic elements will be studied with help of GIS analysis of remote sensing data and digital elevation model. The Ichnofabric Index will be determined in continuous profiles and drill cores. The vertebrate assemblages (obtained also by chemical way) integrated with correlation of well logs can solve stratigraphy.

The main aim of the project is to study flowers, inflorescences and pollen in situ at fossil plants of the Peruc-Korycany Formation within the Bohemian Cretaceous Basin. Methodology which have not yet been applied, will be used. The project is focused on detailed study of flowers and their pollen ncluding study of exina sculptation (using high resolution SEM) and pollen ultrastructures (using TEM). The project follows up with results of previously finished projects on infructescences, fruits and seeds. Another aim of the project is to compare pollen grains known from dispersed pollen spectra with pollen found in situ. This will help to determine systematical affinity of pollen grains classified till now only by names of formal palynomorph nomenclature. New data on Cretaceous plants and their pollen in situ will be used for palaeoecological interpretations and reconstructions for purposes of exhibition of the National Museum and lectures on palaeontology in the Charles University.

Highly siderophile elements (Os, Ir, Ru, Rh, Pd, Pt, Re, Au) and Re-Os isotopic system provide new unique insights into Earth`s geochemistry. This is mainly because of different behaviour of these elements during mantle melting and metasomatism. Pyroxenites plays very significant role in processes of mantle refertilization and enrichment. Therefore, their study provide direct insights into these processes, which are, in turn, very important for genesis of numerous mantle-derived melts. This project is focused on distribution and fractionation of highly siderophile elements and Re-Os geochemistry of upper mantle pyroxenites representing different mantle sources (oceanic vs. subcontinental) and on study of peridotite-pyroxenite interaction (mixing).