ASGP (2023), vol. 93: 195–210
CHROMIUM-RICH ILLITE/SMECTITE IN THE BASAL BALINKA CONGLOMERATE OF THE UPPER CARBONIFEROUS-PERMIAN BOSKOVICE BASIN (BOHEMIAN MASSIF)
Pavla HRŠELOVÁ (1*), Stanislav HOUZAR (1), David BURIÁNEK (2), Dalibor VŠIANSKÝ (3), Marek SZCZERBA (5), Zuzanna CIESIELSKA (5), Jindřich ŠTELCL (3, 4) & Slavomír NEHYBA (3)
1) Department of Mineralogy and Petrography, Moravian Museum, Zelný trh 6, 659 37, Brno, Czech Republic; e-mails: phrselova@mzm.cz, shouzar@mzm.cz
2) Czech Geological Survey, branch Brno, Leitnerova 22, 602 00 Brno, Czech Republic; e-mail: david.burianek@geology.cz
3) Department of Geological Sciences, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic; e-mails: dalibor@sci.muni.cz, stelcl@sci.muni.cz, slavek@sci.muni.cz
4) Department of Biology, Faculty of Education, Masaryk University, Poříčí 7, 603 00 Brno, Czech Republic; e-mail: stelcl@sci.muni.cz
5) Institute of Geological Sciences, Polish Academy of Sciences, Senacka 1, 31-002 Kraków, Poland; e-mails: m.szczerba@ingpan.krakow.pl, z.ciesielska@ingpan.krakow.pl
*) Corresponding author
Hršelová, P., Houzar, S., Buriánek, D., Všianský, D., Szczerba, M., Ciesielska, Z., Štelcl, J. & Nehyba, S., 2023. Chromium-rich illite/smectite in the basal Balinka Conglomerate of the Upper Carboniferous-Permian Boskovice Basin (Bohemian Massif). Annales Societatis Geologorum Poloniae, 93: 195–210.
Abstract: The Upper Carboniferous polymictic Balinka Conglomerate was deposited along the western margin of the Boskovice Basin (eastern part of the Bohemian Massif). Angular aggregates of deep-green chromium-rich interstratified clay mineral R1-illite(0.8)/smectite (I/S) are present exclusively in the basal part of this unit. The textural position of chromium-bearing I/S (0.77–2.88 wt.% Cr2O3; 0.040–0.153 apfu Cr) in the conglomerate matrix indicates a genetic link with the highly altered chromium spinel, which is preserved in the relics. The source of Cr-rich spinelides was serpentinized peridotites in the adjacent Moldanubicum (Gföhl Unit). The formation of I/S is related to diagenetic processes in the conglomerate matrix. The fluids would have relatively high fugacity of CO2 and activity of K+. K/Ar ages of 284.1 ± 7.7 and 276.3 ± 7.4 Ma (lower Permian – Kungurian/Artinskian age) confirmed the diagenetic origin of this I/S.
Manuscript received 15 June 2022, accepted 16 February 2023
