Spore assemblages from Lower Devonian ‘Lower Old Red Sandstone’ deposits of Spitsbergen

Charles H. Wellman

Dept. of Animal & Plant Sciences, University of Sheffield, Alfred Denny Building, Western Bank, Sheffield S10 2TN, UK

E-mail: c.wellman@sheffield.ac.uk

The Lower Devonian deposits of Spitsbergen consists of typical terrestrial-fluviatile-lacustrine ‘Lower Old Red Sandstone’ facies. They accumulated within the Euramerica (Old Red Sandstone) continent, in a tectonically active region associated with the Caledonian Mountains. At the time of deposition Spitbergen is considered to have been located near the equator within the arid climate belt. Dispersed spore assemblages have been recovered from Lower Devonian deposits from Spitsbergen from two locations: (i) the Mimerdalen area of Dickson Land collected on a 2010 expedition; (ii) the Forkdalen area of Andrée Land resampled from historical collections of the Harland Svalbard Geological Collections (curated by CASP, Cambridge). Samples from both areas yield dispersed spore assemblages. The spore assemblages are variable in terms of abundance, preservation and thermal maturity. They vary from rich assemblages of well preserved spores of low thermal maturity (pale yellow) to low abundance assemblages of poorly preserved spores of high thermal maturity (black). Presumably this variability relates to the complex syn- and post-depositional tectonic activity characteristic of the area. Dispersed spore assemblages from the Lower Devonian of Spitsbergen are important because: (i) They are from near the palaeoequator and, along with co-occurring plant megafossils, provide a rare insight into Lower Devonian equatorial floras; (ii) They provide evidence (age dating and stratigraphical correlation) facilitating interpretation of the stratigraphy of these deposits, which is vital for understanding the complex tectonic history of this region; (iii) Spitsbergen spore assemblages were important in establishing taxonomy in the fledgling days of Devonian spore research (Allen 1965) and re-examination of this material is helping to resolve various taxonomic issues that have arisen during the subsequent half century.

References

Allen, K. C. (1965). Lower and Middle Devonian spores from North and Central Vestspitsbergen. Palaeontology 8, 687-748.