First palynological evidence from the Upper Devonian of Armenia (northern Gondwanan margin): biostratigraphic implications

Abstract

Diverse and abundant terrestrial palynomorphs are recovered from a Frasnian–Famennian (F-F) succession of shales in the Ertych section, situated in central Armenia. They represent the first discovery of spores from the F-F shallow marine sedimentary sequences of the South Armenian Block, which at that time was part of the northern Gondwanan continental margin. Their taxonomic assessment recognizes 37 spore taxa assigned to 22 genera. Notably, the presence of Teichertospora torquata allows us to assign the entire studied succession to the torquata–gracilis zone, indicating a late Frasnian to early Famennian age. In addition, the occurrence of Acinosporites lindlarensis, which corresponds to the spores of the herbaceous lycophyte Leclercqia, suggests that the age of the studied succession should be further restricted to the late Frasnian. The presence of chitinozoans (i.e., Angochitina mourai) in the studied interval argues for marine deposition. Our biostratigraphic results provide a more coherent picture for the sedimentary evolution of this Frasnian–Famennian sequence arguing for a rather uninterrupted sedimentation close to the critical boundary interval. The identified spore assemblage highlights the close affinity of the Frasnian vegetation preserved in Armenia with other parts of the Northern Gondwana and southern Laurentia. We provide the first evidence of the occurrence of Kraeuselisporites ollii outside Canada and extend its known age range to the late Frasnian.