GACR

Lacustrine sediments and largely also coal seams are sensitive indicators of palaeoenvironmental changes. Lake metabolism is very responsive not only to global climatic and geotectonic changes, but also to local climatic, vegetation, erosional and tectonic changes. These processes are frequently linked by reciprocal feedbacks and resulting system behavior is usually non-linear. Understanding a global climatic influence on a paleolake evolution, and filtering off local controls, requires  multidisciplinary approach. Proposed project is focused on the detailed study of 200 m thick succession of lacustrine Cypris Formation and underlying Antonín Coal Seam in the Sokolov Basin (Miocene), where depositional rhytmicity of several orders were observed. Project has strong multidisciplinary nature integrating sedimentological, cyclostratigraphical, magnetostratigraphical, petrological, petrophysical, geochemical and palaeontological approaches. Aim of the proposed project is paleonvironmental and paleoclimatic reconstruction of the Miocene paleolake and comparison of results with data from other Miocene lakes in Europe. Integrated methodological approach will contribute to our understanding of Miocene climate changes and mechanisms of their record to sedimentary rocks.

Aim of this project is the utilization of the chemical composition of magmatic quartz to better understand the genesis of Variscan granites and rhyolites in the Bohemian Massif.Quartz is the relatively most stable rock-forming mineral during majority of post-magmatic processes. Quartz, its internal texture and chemical composition, provide detail information about pT and chemical evolution of silicic magma. Internal texture of quartz crystals visualised by cathodoluminiscence (CL) and in-situ determination of trace element using laser-ablation ICP MS will be combined with existing data of whole-rock chemistry, accessory mineral assemblage, isotopic geochemistry, and eventual also melt inclusions study to reconstruct evolution of several contrasting types of  Variscan granitoid magma in the Bohemian Massif.Another significance of this project is to support methodological development of a new ICP-MS instrument equipped with laser-ablation, which will be installed at the Institute of Geology AS CR,v.v.i. in autumn 2009. Quartz is the simplest matrix among geological materials and thus represents the optimal target for establishment of methodical procedures in a new laboratory.

A complex and spatially extensive study of lithospheric upper mantle of the Bohemian Massif is based on peridotite xenoliths and their host basalts. Chemical, Pb-Sr-Nd isotopic, and microfabric analyses performed on large suite of samples will show the 3-D or 4-D variation of composition, metasomatic transformation, deformation, and seismic properties of the upper mantle beneath the 500km long zone of Cenozoic neovolcanics. The results will bring basic knowledge on physico-chemical properties of the upper mantle in the Bohemian Massif, which is largely missing. The neovolcanic zone studied includes two tectonic domains with clear differences of their lithospheric structures: the Ohře Rift and the Labe/Odra Zone. The proposed research is expected to shed light on processes which led to quasi-synchronous volcanism in such contrasting regions. The spatial variations of the studied parameters of the basalts and xenoliths can indicate the interference between the Variscan terrane architecture, upper mantle structure/composition and neovolcanism.