Water column euxinia and wildfire evidence during deposition of the Upper Famennian Hangenberg event horizon from the Holy Cross Mountains (central Poland)

Abstract

A palynological study of the uppermost Famennian section from Kowala Quarry (Holy Cross Mountains, central Poland) allowed recognition of two miospore zones: LV (Retispora lepidophyta–Apiculiretusispora verrucosa) and LN (Retispora lepidophyta–Verrucosisporites nitidus). Based on palynology and sedimentology, the black shale within the upper part of the section is identified as equivalent to the Hangenberg Black Shale, which is known globally. This black shale contains compounds characteristic of photic zone euxinia, including isorenieratane and its derivatives. Such compounds are absent in the organic-poor marls and shales occurring below the LN Zone, and are present only as traces in the layers just above the black shale, indicating fluctuations in the oxygen minimum zone during uppermost Famennian sedimentation. Palynofacies show high amounts of amorphous organic matter and prasinophyte concentrations in the black shale, and a subsequent significant decrease of amorphous organic matter concomitant with a rapid increase of terrestrial input (mainly miospores with common tetrads) in the layers above the black shale. This supports the relatively rapid change in the taxonomic composition of phytoplankton caused by fluctuations of the chemocline. The whole succession corresponds to one sea-level rise and fall. The presence of high concentrations of peri-condensed polycyclic aromatic hydrocarbons and large amounts of small charcoal particles at the Hangenberg event horizon indicate the occurrence of wildfires. Such observations suggest that atmospheric O22 levels had exceeded the critical threshold of 13 %, above which wildfires may occur, by latest Famennian time.

The Devonian/Carboniferous boundary in the Holy Cross Mountains (Poland)

“…In the Chêciny-Zbrza intrashelf ba sin of the Kielce re gion sev eral black bi tu mi nous beds as signed to the Mid dle Famennian through the De vo nian-Car bon if er ous bound ary have been re corded (Filipiak and Racki, 2005;Racki, 2006;Rakociñski, 2011). They cor re spond to the Famennian Annulata, Dasberg, Kowala Black Shale and Hangenberg Black Shale of global and lo cal ex tent (Walliser, 1996;House, 2002;Marynowski and Filipiak, 2007;Filipiak and Racki, 2010;Racka et al, 2010;Marynowski et al, 2010Marynowski et al, , 2012aKaŸmierczak et al, 2012).…”

“…De pos its from the De vo nian/Car bon if er ous bound ary in terval in Kowala have also been sub ject to microfloral anal y sis (Filipiak, 2004(Filipiak, , 2005Marynowski and Filipiak, 2007). Five miospore zones (LV, LE, LN, VI, HD), char ac ter is tic of the Devo nian/Car bon if er ous bound ary in ter val have been dis tinguished (Filipiak, 2004).…”

“…The thin Kowala Black Shale layer (Marynowski and Filipiak, 2007) has been cor re lated with a 30 cm thick bi tu mi nous black shale bed that oc curs in a study trench lo cated about 300 m toward NW (Malec, 1993b). The lat ter (Fig.…”

“…The lat ter (Fig. 3, bed 51) lies in the lower part of the Mid dle expansa condont Zone, about 11.5 m be neath top of the Wocklumeria lime stones, whereas the Kowala Black Shale, dis tin guished in the quarry, oc curs about 7.8 m be neath this lime stone top in the Up per expansa Cono dont Zone (Marynowski and Filipiak, 2007;Filipiak and Racki, 2010;Marynowski et al, 2010). The 30 cm thick bi tu mi nous shale that oc curs in the study trench seems rather to rep re sent a lo cal ho rizon sit u ated be tween the Dasberg shales and Kowala Black Shale, about 1.8 m above the top of the for mer ones (re fer to Devleeschouwer et al, 2013).…”

Geomicrobial functional groups: A window on the interaction between life and environments

“…In the Phanerozoic, euxinic oceans also occurred frequently, and interrupted the normal oxic oceanic sedimentation. The main intervals known with euxinic conditions in the Phanerozoic are Late Cambrian [171], the transition from Ordovician to Silurian [172], Late Devonian [173], late Permian to early Triassic [55,174] and several intervals in the Cretaceous known as the Anoxic Ocean Events [175]. It remains unclear whether these euxinic oceans were global, or caused by local restricted sedimentary basin conditions (e.g.…”