Acid-free palynological processing: a Permian case study

Acid-free palynological processing was performed on Permian material from a borehole of the southern Galilee Basin, eastern Australia, to test the efficacy compared to standard processing techniques. Both techniques yielded well-preserved assemblages of terrestrial and aquatic palynomorphs. The proportion of phytoclasts was much higher than in samples that underwent standard acid processing, while spores and pollen grains occur in lower abundances. A slightly higher species count was gained from samples with acid-free treatment but biostratigraphical index taxa were present in both sets of samples and, in general, the assemblages appeared to be quantitatively comparable. To improve the efficacy for future application, in particular more accurate statistical analyses with higher counts, absolute abundance calculations using a Lycopodium spike and refinement of the acid-free technique using hydrogen peroxide treatments, multiple density separation steps or sonication during sieving are suggested to remove phytoclasts. Further work is required to determine if the higher abundances of phytoplankton are influenced by the processing technique or if they better reflect a true proportion within a given sample.