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Manganese concentrations in silver birch leaves were studied in the Ore Mountains and several reference localities in Czechia, both mountainous (up to 950 m MSL) and lowland (ca. 300 m MSL). The studied mountainous areas have been seriously damaged by acid rains in the last decades and forests there have still not recovered from that crisis. The aim of this study was to identify the major controls on the foliar Mn concentration variability, which was more than one order of magnitude, from 200 mg kg -1 (10th percentile) to 2000 mg kg -1 (90 th percentile) in the mountainous sites, that is, under uniform environmental conditions and for the same emission history of mountainous forests. The foliar Mn concentrations in the highest 5% samples were >3000 mg kg -1 which can be close to toxicity for persistent tree growth and thus indicate actual local geochemical stress in plants. Manganese uptake by plants has been enhanced by acid rain in the last decades, inferred from low foliar Mg (ca. 0.15%) and soil acidity (soil pH down to 4.0 in aqueous extracts). Certain bedrocks in the Ore Mountains, particularly local granitic porphyry and mafic lavas, have elevated Mn concentrations; however, in the mafic lavas, the soil Mn excess is compensated by elevated concentrations of soil Mg and pH. The highest foliar Mn concentrations were found in specimens growing in soils on granitic porphyry and on certain granites. The Mn concentration in birch leaves could be proposed as a proxy for the impact of soil acidification in central European mountain forests.

This study examines the early stages of clastic deposition above the main coal seam in the Most Basin (Ohře Rift, NW Czech Republic). Eight drill cores were subjected to chemical analysis by X-ray fluorescence spectroscopy (XRF) and cation exchange capacity determination (CEC) to corroborate the local chemostratigraphic scheme and extend its temporal and spatial ranges. Additionally, four drill cores were subjected to palaeomagnetic polarity analysis for magnetostratigraphic dating, and two cores were subjected to the frequency analysis of variations in elemental compositions to obtain cyclostratigraphic patterns and more detailed insight into depositional dynamics. We demonstrate that a local lake was present in the Bílina area from the end of palaeomagnetic chron C5Er through chron C5En (18.524-18.056 Ma according to the Astronomically Tuned Neogene Time Scale 2012) to the beginning of the C5Dr chrons. This finding extends the previous age models for the Most Formation by more than 0.5 My (18.6 to 17.9 Ma). The chemostratigraphic scheme, which is based on variations in the concentrations of K and the values of CEC, was successfully extended from the basin centre to its north-east periphery, which reflects the basin-wide environmental changes that terminated the peat accumulation (coal formation) in the basin. The basin-wide lacustrine body formed by the coalescence of local lakes and the flooding of the remaining peatlands ca. 17.8 Ma (during C5Dn), which is coeval with the substantial reduction of the Antarctic ice sheet prior to the onset of the Miocene climatic optimum (MCO). The Most Basin deposits are the most detailed (with respect to temporal resolution) continental sedimentary archive of the time period preceding the MCO that have not been described to date. • Key words: cyclostratigraphy, chemostratigraphy, lake sediments, climate forcing, Burdigalian. CR, v.v.i., 250 68 Řež, Czech Republic; grygar@iic.cas.cz, hosek@iic.cas.cz • Karel Mach, North Bohemian Mines, j.s.c., ul. 5. května 2013, 418 01, Bílina, Czech Republic; mach@sdas.cz • Petr Schnabl, Institute of Geology of the CAS, v.v.i., Prague, the Czech Republic; schnabl@gli.cas.cz • Mathieu Martinez, MARUM, Universität Bremen, Leobener Straße 8, D-28359 Bremen, Germany; mmartinez@marum.de • Magdaléna Koubová, Czech Geological Survey, Geologická 6, 152 00 Praha 5, Czech Republic; magdalena.koubova@geologycz Recent studies of sea level fluctuations during the Cretaceous highest sea level (Uličný et al. 2014) have shown that distinguishing between local/autogenic forcings (i.e. tectonic, palaeotopographic) and global/allogenic forcings (i.e. climatic, eustatic) in pre-Pleistocene sedimentary archives is difficult. Researchers mainly perform this intricate task (distinguishing between local and global controls in basin fills) to improve the temporal resolutions of environmental archives; this may be achieved with sediments that were deposited at higher sedimentation rates than in passive continental margins/ocean floors; however, these provid...

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