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Mercury concentrations in the air and in forest crops

The January issue of Vesmír, the Czech popular science journal celebrating its 150 anniversary in 2021, published two papers authored by members of the Department of Environmental Geology and Geochemistry of the Institute of Geology. The first paper by Borovička, Roll and Nováková deals with the safety of collecting edible mushrooms and forest fruits at sites affected by historical mining of mercury-rich ores. The second paper by Navrátil and Rohovec brings news about the possibilities of using passive samplers to monitor mercury concentrations in the air.

Carboniferous eruption covered central and western Bohemia with up to 1 m thick ash layer

The famous Bělka tuff is an areally extensive pyroclastic layer preserved in the central and western Carboniferous late- to post-orogenic basins of central and western Bohemia. This tuff represents a unique stratigraphic marker documented from tens of boreholes and numerous black coal mines within a large area between the southern edge of the Pilsen Basin in western Bohemia and the eastern part of the Kladno-Rakovník Basin over a distance of 100 km. However, its volcanic source has been as yet enigmatic. In a new study by Tomek et al., published in International Geology Review, a multidisciplinary approach using the LA-ICP-MS U/Pb zircon dating, analysis of thickness and grain size distribution, and volume calculation suggested that the source volcano was the Altenberg–Teplice Caldera located at the Czech–German border in NW Bohemian Massif. In detail, this volcano underwent a major caldera-forming ignimbrite eruption with an estimated volcanic explosivity index 7 (out of 8) at 314 Ma. From the northern caldera margin, pyroclastic density currents travelled south over a distance of ca. 40 km towards the area of Oparno valley (Porta Bohemica). From here, northeasterly winds distributed the volcanic ash cloud towards the southwest, where the ash was deposited in the sedimentary basins. As indicated by an isopach reconstruction, the Regensburg area (Germany), for instance, was covered by a 10 cm thick ash layer that originated from the Altenberg–Teplice Caldera nearly 220 km away. For additional information click here.

Lampyrite

The Journal of Petrology, published by Oxford University, has recently published an extensive study by Czech and German researchers summarizing the results of their study of late-Variscan mantle-derived magmatic activity in the Bohemian Massif. Based on a combined research of radiogenic and non-radiogenic isotopes, the development of the composition of the upper mantle beneath the Bohemian Massif was reconstructed for a time span of 65 million years. The study was coordinated by Lukáš Krmíček of the Institute of Geology of the Czech Academy of Sciences and provides a recognition of a specific rock type described under a new term – lampyrite.

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