Tonsteins: Altered Volcanic-Ash Layers in Coal-Bearing Sequences

Bohor, B. F.; Triplehorn, Don M.

doi:10.1130/spe285-p1

Cited by 119 publications

(104 citation statements)

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“…New Zealand; http://www.maf.govt.nz), results from 1.5 m (or more) of uncompacted tephra load. Following compaction, it is estimated (Bohor & Triplehorn 1993) this thickness can be reduced to about 1 / 2 and even 1 / 3 , which fits well with the 50-60 cm of the present-day Bělka thickness. Brousek above the Bělka is a complex of re-deposited volcanic ash with a siliciclastic admixture in the upper part of its thickness (Drábková 1986).…”

Section: B C D Esupporting

confidence: 64%

T0 peat-forming plant assemblage preserved in growth position by volcanic ash-fall: A case study from the Middle Pennsylvanian of the Czech Republic

Opluštil¹,

Pšenička²,

Bek³

et al. 2014

Bull. Geosci.

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A Middle Pennsylvanian tuff bed (the Bělka bed) in the roof of the Lower Radnice Coal bears T 0 peat-forming vegetation preserved in growth position. This vegetation has been studied in detail at the 12 hectares large Ovčín coal deposit in the southern part of the Radnice Basin. Documentation of the fossil record in six excavations and that previously collected in the former opencast mine allowed for a detailed reconstruction of the local peat-forming lepidodendrid-cordaitalean forest structured into well-developed stories. It consists of about 33 species, which colonized the occasionally flooded planar peat swamp precursor of the Lower Radnice Coal. The canopy story of this vegetation was dominated by Lepidodendron (Paralycopodites) simile, L. lycopodioides, Lepidophloios acerosus and Cordaites borassifolius. They formed a relatively dense canopy, locally interrupted with significant gaps allowing development of a rich groundcover that together with liana-like plants represents the most diverse part of the forest. A less diverse understory composed of calamites, medullosan pteridosperms and Psaronius tree ferns displays a patchy distribution pattern presumably related to density of the canopy. The minimal area that sufficiently represents the pattern of this forest phytocoenosis is estimated to be about 200 m 2 , although lower stories are well represented even within much smaller areas of about 60 m 2 . Slight heterogeneity in the population density of dominant taxa (Cordaites vs. lepidodendrid lycopsids) was documented across the Ovčín coal deposit. The fossil record of the Bělka tuff bed also indicates that the coal-forest colonizing the peat swamp prior the generation of forest killed by volcanic ash fall, was destroyed, presumably due to long-lasting flooding and thus suggests that catastrophic events were probably a relatively common part of the evolution of peat-forming Pennsylvanian successions.• Key words: Pennsylvanian, T 0 plant assemblage, coal forests, volcanic ash beds, Radnice Basin.

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Section: B C D Esupporting

confidence: 64%

T0 peat-forming plant assemblage preserved in growth position by volcanic ash-fall: A case study from the Middle Pennsylvanian of the Czech Republic

Opluštil¹,

Pšenička²,

Bek³

et al. 2014

Bull. Geosci.

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“…Such a mode of occurrence strongly suggests a parental rhyolitic magma. The above mentioned authors, following Bohor and Triplehorn (1993), believe that such "tonsteins" are altered tephra brought from distal sources. In our opinion, however, "tonsteins" could be better interpreted as bodily deposits of very dense ash clouds or even fluidized pyroclastic debris flowed from not too distant volcanic vents.…”

Section: Mineralogical and Petrographic Featuresmentioning

confidence: 99%

“…Such ovoids are found in core samples from bore holes 4, 6 and 7 and in outcrop A (Figure 3, b and c). Their appearance recalls the so-called "grapes" or "graupen", described by Bohor and Triplehorn (1993) as ovoidal or ellipsoidal kaolinite aggregates found in "tonstein" and believed to be altered volcanic ash. "Grapes" have been interpreted as modified pumice lumps, but no original textures have been detected.…”

Section: Sediment Compositionmentioning

confidence: 99%

Distribution, mineralogy, petrography, provenance and significance of Permian ash-carrying deposits in the Paraná Basin

Coutinho

Hachiro

2005

Geol. USP, Sér. cient.

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The study of thin sections taken from drill core samples and outcrops in southern Brazil has demonstrated the occurrence of repeated ash fall episodes during the Permian period between 280 and 245 Ma. Scattered or concentrated altered volcanic glass shards were detected in strata of Permian sedimentary rocks of the Rio Bonito and Tatui Formations. The shardcarrying sediment is usually a silty or cherty mudstone with variable amounts of calcrete calcite. Burial and alteration of unstable glass debris led to the development of analcite and less commonly, calcite, silica minerals, zeolites or montmorillonite. Sources of explosive Permian volcanism, responsible for ample ash falls have been sought in South Africa, in the Andean Cordillera and along the Paraná Basin margin. A swarm of rhyolitic centers described in the Cordillera Frontal and in the Central Argentinian Provincia de La Pampa (Patagonia) is here proposed as the most adequate Permian source. In that area, volcanoes must have expelled ashes that traveled thousands of kilometers before settling in deltaic or shallow marine environments. Twenty-three occurrences of Permian shard-carrying sediments have been plotted in a Paraná Basin map. The number of ash-carrying sediments decreases northeastward. The authors envisage dense clouds originated in Patagonia traveling NE, depositing progressively smaller quantities of ashes but reaching Australia in pre-drift Gondwana. Shard carrying sediments must be distinguished from "tonstein", ash fall or ash flow tuffs, also recorded in the Permian Gondwana, which would indicate closer ash source area.Palavras-chave: depósito de cinzas, mineralogia, origem, Gondwana permiano, Bacia do Paraná. RESUMOSecções delgadas de testemunhos de sondagem e afloramentos no sul do Brasil demonstraram a ocorrência de freqüentes quedas de cinzas vulcânicas durante o Permiano entre 280 e 245 Ma. Minúsculas (ca. 0,1mm) lascas de vidro vulcânico (glass shards) alterado, encontram-se dispersas ou concentradas nos sedimentos permianos das formações Rio Bonito e Tatuí, na Bacia do Paraná. O sedimento portador de glass shards é geralmente um lamito siltoso contendo em geral variável quantidade de calcita calcrete. Restos vítreos soterrados foram substituídos por analcita ou mais raramente calcita, sílica, zeólitas ou montmorilonita. Explosões vulcânicas são responsáveis por queda de cinzas em extensas áreas, e por isso, um possível vulcanismo permiano gerador foi procurado na África do Sul, na Cordilheira Andina e margens da Bacia do Paraná. Foi proposta como fonte mais adequada deste vulcanismo um enxame de centros riolíticos descritos na Cordilheira Frontal e na Província Argentina de La Pampa (Patagônia). Nesta área os vulcões devem ter expelido cinzas que caminharam milhares de quilômetros antes de se depositarem e se preservarem em ambientes deltaicos ou marinhos rasos. Vinte e três ocorrências conhecidas de sedimentos permianos contendo glass shards foram locados em mapa da Bacia do Paraná. Os relatos de ocorrência deste tipo de s...

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“…Tonstein presents distinct genetic type of clayey rocks, created in a peat bog from pyroclastic material, i.e. volcanic ash (Dopita and Kralik 1977;Gabzdyl 1984Gabzdyl , 1990Ryszka and Gabzdyl 1986;Ryka and Maliszewska 1991;£apot 1992;Bohor and Triplehorn 1993;Zhou et al 2000;Admakin 1995Admakin , 2001Dai et al 2011).…”

Section: Microscopic Observations Resultsmentioning

confidence: 99%

Petrographic and mineral variability of the rocks accompanying selected coal seams of the Poruba beds and their influence of the trace elements content / Zróżnicowanie Petrograficzno-Mineralogiczne Skał Współ Występujacych Z Wybranymi Pokładami Węgla Z Warstw Porębskich I Jego W Pływ Na Zawartość Pierwiastków Śladowych

Kokowska-Pawłowska¹

2015

Gospodarka Surowcami Mineralnymi

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Streszczenie Skały współwystępujące z węglem w wybranych pokładach warstw porębskich (610, 620, 630) reprezentowane są najczęściej przez iłowce oraz iłowce syderytyczne, a rzadziej przez mułowce i mułowce syderytyczmne. Sporadycznie występują piaskowce. Stwierdzono także występowanie przerostu z tonsteinem. Zależnie od odmiany petrograficznej skał stwierdzono w nich zróżnicowanie zawartości pierwiastków śladowych (Ba, Zn, Mn, V, Cr, Cu, Ni. Pb, As, Ga, B, Co, Ge, Be, Li, Cd, Ag, Sr - w kolejności malejącego udziału). Znaczna część pierwiastków wykazała wysoki i często dominujący udział w iłowcach. Stwierdzono także regionalne zróżnicowanie zawartości pierwiast- ków śladowych w skałach. Badania korelacji pomiędzy zawartością pierwiastków śladowych a zawartością głównych mine- rałów w skałach potwierdziły powinowactwo wielu pierwiastków śladowych z substancją organiczną, minerałami ilastymi i węglanami. Zwraca uwagę występowanie korelacji licznych pierwiastków śladowych z substancją organiczną (węglem) przy stosunkowo niewielkiej liczbie pierwiastków korelujących z minerałami ilastymi.

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Tonsteins: Altered Volcanic-Ash Layers in Coal-Bearing Sequences

Cited by 119 publications

References 0 publications

T0 peat-forming plant assemblage preserved in growth position by volcanic ash-fall: A case study from the Middle Pennsylvanian of the Czech Republic

T0 peat-forming plant assemblage preserved in growth position by volcanic ash-fall: A case study from the Middle Pennsylvanian of the Czech Republic

Distribution, mineralogy, petrography, provenance and significance of Permian ash-carrying deposits in the Paraná Basin

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