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.

“Without taking notice, we got accustomed to the use of light laptops, thin mobile phones, and small electronics. We are no longer surprised by the possibility of recharging and discharging the battery repeatedly, and we take it for granted that the energy stored in this ‘can’ is easily available. The word lithium has penetrated the dictionary of the general public.” This is an introduction to a new popular-science article by our colleagues Jan Rohovec and Tomáš Navrátil, recently published in the Vesmír magazine, where you can find more details.

The Violet Crown Cup, Sarcosphaera coronaria, is a nicely coloured spring mushroom. In earlier days, the mushroom was considered edible, but several poisonings were reported in the early 20th century. The reason for the sporadic toxicity of S. coronaria is still unknown. The presence of arsenic could be a possible explanation, since Crown Cups can take up high amounts of this toxic element. Arsenic concentration and speciation were investigated in S. coronaria with inductively coupled plasma mass spectrometry (ICPMS) and HPLC coupled to ICPMS and revealed incredible maximum values of 0.9 % As (dry mass). Most of it was present in the form of methylarsonic acid (MA), a less toxic form of this element. However, low concentrations of the highly toxic methylarsonous acid (MA [III]) were also detected. The amounts were too low to pose an acute risk for consumers but the concentration of MA (III) significantly increased during simulated gastric digestion. We could not unambiguously identify arsenic as the toxic constituent of S. coronaria but we demonstrated that the extremely toxic MA (III) can be formed under certain circumstances, which should be carefully investigated in the future. This international research was conducted in co-operation of two Czech Academy of Sciences institutes (Institute of Geology, Nuclear Physics Institute) and the Austrian University of Graz.

Insect borings, unique in the fossil record, were found in fossil wood from a thin lignite seam of lowermost Cretaceous age, exposed in cliffs of the southwestern shore of the Isle of Bornholm (Denmark). The find consists of six thin, roughly parallel, short passages connected with a remnant of a long straight tunnel running along a mechanically-induced fissure just below the wood surface. This find is not fully analogous with the presently most common feeding insect borings as the passages are situated in an oblique fissure of the wood sample (instead of the usual position below the bark). Nevertheless, the best modern analogues of the borings found in Bornholm still come from the insect forestry pests such as the Scolytidae (bark beetles). The find shows that ecological predecessors of bark beetles probably first inhabited random mechanic cracks; later, they occupied the most devastating niche at the boundary between the bark and the wood. More in the paper (Journal Ichnos).