Systematic and stratigraphic palynology of Late Jurassic-earliest Cretaceous strata of the Eromanga Basin, Queensland, Australia: Part Two

Abstract

This second and concluding part of a comprehensive account of the Late Jurassic-earliest Cretaceous palynofloras of the Eromanga Basin includes systematic documentation of the trilete-zonate spores not included in Part One, together with monolete and hilate spores, pollen grains, and a few simple microphytoplankton cysts (which are minor constituents of a few samples). The 62 spore-pollen species described and illustrated herein are variously assignable among 36 genera. The following new species are instituted: Interulobites distogranulatus, Velosporites rugulatus, and Perinopollenites mckellarii. Three previously defined, stratigraphically successive Australian palynozones are recognizable through the interval examined. In ascending stratigraphic order, these are: Murospora florida Oppel Zone (signified mainly by the introductory presence of the eponymous species), middle Callovian to late Oxfordian; Retitriletes watherooensis Oppel Zone (also recognizable principally from the presence of its eponym), late Oxfordian to middle Tithonian; and Ruffordiaspora (Cicatricosisporites) australiensis Interval Zone (from the presence of its eponym), middle Tithonian to basal Valanginian. Notwithstanding some regional differences, the palynofloral sequence in the Upper Jurassic of the Eromanga Basin is very similar to that reported from the palynologically well documented Perth Basin sequence (specifically, Yarragadee Formation) in Western Australia.The Westbourne palynoflora is suggestive of a varied parental vegetation of mainly coniferophytes, pteridosperms (seed ferns), ferns, and bryophytes, as has been inferred previously from coeval palynofloras elsewhere in Australia. A warm, pluvial climate during the Late Jurassic-earliest Cretaceous is implied by the palaeofloristic evidence.