While the final manifestations of caldera-forming eruptions can be easily observed on the Earth’s surface and are thus relatively well studied, the physical conditions and causes of caldera collapse and the mechanisms of brittle failure of the underlying rocks are still a mystery. The aim of a long-standing project by a joint team from the Faculty of Science of the UK and the Czech Technical University in Prague was to understand under what conditions the gravitational collapse of calderas occurs and what effect the shape of the underlying magma mantle, its size and depth in the Earth’s crust has. New research has shown, using a combination of geological data and mathematical modelling, that magma pressure oscillations lead to intense brittle failure in places, and therefore to a reduction in the strength of the magma crust ceiling, but that collapse and caldera formation can only occur under specific conditions.
Somr M., Žák J., Kabele P., Tomek F. (2023): Analysis of fracturing processes leading to caldera collapse. Earth-Science Reviews241, 104413 (DOI)
On April 27, 2023, we had a PhD conference of the Center with intimate and friendly atmosphere and excellent students’ presentations. The program and the book of abstracts can be downloaded from here. Thanks to the organizers!
On Monday March 20, 2023, Kateřina Němečková associated to the Center for Geosphere Dynamics successfully defender her PhD thesis entitled „Detecting biomarkers of expremophiles in Martian analogues“ under the supervision of prof. Jan Jehlička. On the photo with her supervisor and one of the reviewers, prof. Peter Vandenabeele from Ghent University (Belgium) and other members of the comittee. Congratulations!
On December 14, 2022, Rafael Baieta successfully defended his PhD thesis entitled “A study of the behavior of selected metals in affected environments using isotopic approach” completed under supervision of prof. Martin Mihaljevič. On the photo you find Rafael with the external reviewers Dr. Tomáš Navrátil (left) and Dr. Václav Tejnecký (right). Congratulations, Rafael!
You are cordially invited to an autumn meeting of the Center with four lectures given by the junior researchers (Václav Špillar, Jakub Trubač, Filip Scheiner and Jaroslav Semerád). The detailed program is available in the leaflet.
Evaporation from rocks is a poorly understood, yet important process. In the recent study, an evaporation rate from 10 lithologies, including sedimentary, igneous, and metamorphic granular rocks, was measured and calculated. The measured evaporation rate varied over four orders of magnitude (0.4–2447 mm/year), and the calculations reasonably followed the measured values. Within the range of observed values, the evaporation rate was mostly influenced by the vaporization plane depth below the rock surface (by up to 2.2 orders of magnitude), which was followed by: lithology (up to 1.1 order of magnitude), local climate (up to 1.0 order of magnitude), and climate seasonality (up to 0.8 order of magnitude). Thus, our study shows the key role of the vaporization plane depth in the evaporation rate. This approach can find employment in a large number of investigations such as in the evaporation estimates and hydrologic balance in rock landforms and rocky slopes, hydrologic processes in the shallow rock subsurface, living conditions of endolithic and epilithic organisms, weathering processes, and in the protection of carved or rock constructed cultural heritage.
Slavík M., Bruthans J., Schweigstillová J. (2018): Evaporation rate from surfaces of various granular rocks: Comparison of measured and calculated values. Science of the Total Environment856, 159114. (DOI)
On Thursday 22nd September 2022, Magdaléna Peřestá (née Knappová) successfully defended her PhD thesis entitled “Speciation of arsenic under reducing conditions of organic-rich soil“, supervised by Dr. Petr Drahota. On the photo you will see Magdaléna with her supervisor and both reviewers, Prof. Edgar Hiller (Comenius University, Bratislava) and Dr. Barbora Doušová (University of Chemistry and Technology Prague). Congratulations!
Cobalt is one of the most important critical metals which could be potentially extracted from the old metallurgical slags in the Zambian Copperbelt. The slags from Luanshya, the oldest mining and smelting site in the Copperbelt, contain up to 5990 ppm Co (median: 2370 ppm). The detailed mineralogical investigation combined with the sulfuric acid leaching simulating hydrometallurgical recovery indicated that up to 67% of Co can be extracted from slag in a short period of time (24 h). However, despite the dramatic increase of Co prices on the global market, its recovery from the Luanshya slags appears to be non-economical due to the high costs of the mechanical and chemical processing of the slag materials. The paper is freely available via open access:
Ettler V., Mihaljevič M., Drahota P., Kříbek B., Nyambe I., Vaněk A., Penížek V., Sracek O., Natherová V. (2022): Cobalt-bearing copper slags from Luanshya (Zambian Copperbelt): Mineralogy, geochemistry, and potential recovery of critical metals. Journal of Geochemical Exploration237, 106987. (DOI)
Cristian Quinones, geologist-geostatistician from Chile will stop in Prague during his lecture tour at European universities and will give a one-day workshop on “Practices for Mineral Resources Statement and Study Cases”. The course will take place on 3rd May 2020 (9-17h) in Ložiskové sbírky room, Faculty of Science, Charles University, Albertov 6 building. Topics covered include International Codes, Audits, QAQC, Geological Models, Exploratory Data Analyses. For registration, ask the organizer Dr. Jiří Zachariáš (e-mail). This workshop is partly supported by the Center for Geosphere Dynamics.