Wildfire during deposition of the \u201cIllinger Fl\xf6zzone\u201d (Heusweiler-Formation, \u201cStephanian B\u201d, Kasimovian\u2013Ghzelian) in the Saar-Nahe Basin (SW-Germany)

Dieter Uhl,André Jasper

doi:10.1007/s12549-020-00443-2

Abstract

Wildfires occurred more or less regularly in many Pennsylvanian ecosystems, not only in seasonally dry regions but also in the ever wet tropics. One of the reasons for this was probably the relatively high atmospheric oxygen conditions prevailing during this period. The present study reports evidence for the occurrence of wildfires during deposition of the Upper Pennsylvanian Heusweiler Formation (“Stephanian B”, Kasimovian–Gzhelian) in the intramontane Saar-Nahe (or Saar-Lorraine) Basin in SW-Germany. Based on anatomical features of the charcoal, as well as the co-occurring adpression flora, it seems possible that some of the fires occurred in an ecosystem inhabited by Cordaites. Some of the charcoal fragments exhibit traces of pre-charring decay by fungi, indicating either the consumption of litter by ground or surface fires, or of still standing (partly) dead trees by crown fires.

Highlights

Research on Carboniferous wildfires has largely focussed on occurrences of macro-charcoal from former “coal-swamps” of the tropical zone in Canada, Great Britain, Ireland, the U.S.A. and Poland (e.g. Nichols and Jones 1992; Scott and Jones 1994, Falcon-Lang 1998, 1999a, b, 2000; Zodrow et al 2010), some earlier studies mentioned the occurrence of charcoal as direct evidence of Pennsylvanian wildfires in other European coal fields of Pennsylvanian age
To add more information about the occurrence of palaeowildfires in the Saar-Nahe Basin during the Pennsylvanian, we provide a Scanning Electron Microscope (SEM)-analysis of macro-charcoal from clastic sediments as well as coals of the somewhat older, so-called “Illinger Flözzone” (Heusweiler Formation), providing evidence for the occurrence of palaeo-wildfires during the “Stephanian B” (Kasimovian–Gzhelian) of this particular basin, together with some ecological interpretations of these findings
The occurrence of charcoal as direct evidence of wildfire has first been suggested by Daubrée (1844, 1846), based on the physicochemical properties of this material which are the same as in charcoal, in a pioneering study on the pyrogenic origin of coal macerals of the inertinite group from this seam

Summary

Introduction

Research on Carboniferous wildfires has largely focussed on occurrences of macro-charcoal from former “coal-swamps” of the tropical zone in Canada, Great Britain, Ireland, the U.S.A. and Poland (e.g. Nichols and Jones 1992; Scott and Jones 1994, Falcon-Lang 1998, 1999a, b, 2000; Zodrow et al 2010), some earlier studies mentioned the occurrence of charcoal as direct evidence of Pennsylvanian wildfires in other European coal fields of Pennsylvanian age The occurrence of charcoal as direct evidence of wildfire has first been suggested by Daubrée (1844, 1846), based on the physicochemical properties of this material which are the same as in charcoal, in a pioneering study on the pyrogenic origin of coal macerals of the inertinite group from this seam. In this youngest workable Pennsylvanian (Gzhelian) coal-seam of the Saar-Nahe Basin (Cleal 2008), fusinite and semifusinite occur in distinct bands and lenses, reaching up to 9.5% of the total volume of the coalseam (Josten 1956). This flora is dominated by Sphenophyllum oblongifolium and Pecopteris polymorpha, as well as other members of plant groups adapted to more humid or even wet conditions, like sphenopsids, lycopsids and ferns (Boersma 1978)

Material and methods

Results and discussion

Conclusions

Compliance with ethical standards