Permian sedimentary sequence containing analcimolite and authigenic aegirine from the Boskovice Basin (Bohemian Massif, Czechia)
- 1Department of Geology, Faculty of Science Palacký University Olomouc Olomouc Czechia
- 2Department of Geological Engineering, Faculty of Mining and Geology VŠB—Technical University of Ostrava Ostrava‐Poruba Czechia
Abstract
The Early Permian freshwater lacustrine sedimentary sequence in the vicinity of Bačov (Czechia) is world‐famous for its rich fossiliferous content, including amphibians, actinopterygians and insects. The detailed sampling of two quarries and nearby outcrops (129 samples) focused on the reasons for this sequence's extraordinary paleontological content. The mineral composition of all samples was determined by powder X‐ray diffraction analysis, accompanied by FESEM and WDS analysis, heavy mineral analysis and bulk geochemical analysis of selected samples. In both quarries, the rock‐forming minerals include quartz, albite, microcline, illite, chlorite and carbonates. The steady content of analcime (average 10 and 6 wt% in both quarries) and aegirine (average 4 and 5 wt% in both quarries) is surprising. The extreme enrichment of the 40‐cm‐thick layer in Quarry No. III in analcime (average 35 wt%, max. 56 wt%) indicates its transition to analcimolite, sedimentary rock with over 50% analcime, known from less than two dozen localities worldwide. The presence of authigenic aegirine, NaFe3+ clinopyroxene, in the sedimentary sequences makes them even more unique, as it has been reported from only about five localities. The combination of several clues, including the presence of analcimised glass shards, layers rich in microcline (up to 58 wt%), well‐developed prismatic apatite crystals, the presence of smectites and the geochemical signature of alteration‐resistant elements, indicates the presence of low‐temperature tephra systems altered during burial diagenesis at temperatures <240°C. The presence of aegirine could be explained by the reaction of Na+ and (SiO4)4− partially expelled during glass decomposition with Fe3+ brought to the basin from extrabasinal source areas during arid to semi‐arid weather periods, as evidenced by the accompanying hematite. Ashfall of rather intermediate volcanic rock source fits the synsedimentary volcanism of at least two European volcanic complexes. There is a direct link between ashfalls and fossil accumulations (Konzentrat‐Lagerstätten).
Related
- Sedimentology and geochemistry of the Pleistocene-Holocene fluvial-lacustrine colluvial sedimentary sequence in the Pegalan River section, NW Borneo: Implications for regional tectono-climatic conditions and landscape evolution
- The Sedimentary Archives of Ancient Purandarapura
- Efficient measurement of marine sedimentary porewater pH and oxygen concentrations using optical sensors
- Sedimentary characterization of the carbonate source rock of upper kimmeridgian parnac formation of the aquitaine basin (Quercy area)
- Sedimentary controls on pyrite sulfur isotopes in euxinic settings
BibTeX
@article{jirasek2026permian,
title = {{Permian sedimentary sequence containing analcimolite and authigenic aegirine from the Boskovice Basin (Bohemian Massif, Czechia)}},
author = {Jakub Jirásek and Dalibor Matýsek and Martin Kašing and Daniel Šimíček},
journal = {The Depositional Record},
year = {2026},
month = oct,
doi = {10.1002/dep2.70095},
url = {https://doi.org/10.1002/dep2.70095},
note = {CC BY},
}
RIS
TY - JOUR
TI - Permian sedimentary sequence containing analcimolite and authigenic aegirine from the Boskovice Basin (Bohemian Massif, Czechia)
AU - Jakub Jirásek
AU - Dalibor Matýsek
AU - Martin Kašing
AU - Daniel Šimíček
PY - 2026
DA - 2026/10/30
JO - The Depositional Record
DO - 10.1002/dep2.70095
UR - https://doi.org/10.1002/dep2.70095
AB - The Early Permian freshwater lacustrine sedimentary sequence in the vicinity of Bačov (Czechia) is world‐famous for its rich fossiliferous content, including amphibians, actinopterygians and insects. The detailed sampling of two quarries and nearby outcrops (129 samples) focused on the reasons for this sequence's extraordinary paleontological content. The mineral composition of all samples was determined by powder X‐ray diffraction analysis, accompanied by FESEM and WDS analysis, heavy mineral analysis and bulk geochemical analysis of selected samples. In both quarries, the rock‐forming minerals include quartz, albite, microcline, illite, chlorite and carbonates. The steady content of analcime (average 10 and 6 wt% in both quarries) and aegirine (average 4 and 5 wt% in both quarries) is surprising. The extreme enrichment of the 40‐cm‐thick layer in Quarry No. III in analcime (average 35 wt%, max. 56 wt%) indicates its transition to analcimolite, sedimentary rock with over 50% analcime, known from less than two dozen localities worldwide. The presence of authigenic aegirine, NaFe3+ clinopyroxene, in the sedimentary sequences makes them even more unique, as it has been reported from only about five localities. The combination of several clues, including the presence of analcimised glass shards, layers rich in microcline (up to 58 wt%), well‐developed prismatic apatite crystals, the presence of smectites and the geochemical signature of alteration‐resistant elements, indicates the presence of low‐temperature tephra systems altered during burial diagenesis at temperatures <240°C. The presence of aegirine could be explained by the reaction of Na+ and (SiO4)4− partially expelled during glass decomposition with Fe3+ brought to the basin from extrabasinal source areas during arid to semi‐arid weather periods, as evidenced by the accompanying hematite. Ashfall of rather intermediate volcanic rock source fits the synsedimentary volcanism of at least two European volcanic complexes. There is a direct link between ashfalls and fossil accumulations (Konzentrat‐Lagerstätten).
SN - 2055-4877
ER -