Palynostratigraphic analysis of probable tertiary samples from central Australia, LP009 LP0031 RN18585 TT001

Abstract

This report discusses the chronostratigraphic implications of spore-pollen recovered from (1) two uranium exploration coreholes drilled by Toro Pty Ltd. near the southwest margin of Lake Mackay on the WA/NT border, (2) a hydrogeological corehole drilled by the Northern Territory Geological Survey in the Kintore Palaeovalley about 250 km west of Alice Springs, and (3) two diamond coreholes drilled by CRA Ltd. in the Ti Tree Basin about 100 km north of Alice Springs. All samples were processed and submitted for palynostratigraphic dating.

The data confirm that Nothofagidites spp. were present in northwest Australia during the Late Cretaceous but this morphogenus is absent in Late Cretaceous and Early Eocene sequences in Central Australia. Nothofagidites emarcidus-heterus and related species such as N. falcatus are frequent to dominant in Middle-Late Eocene and Oligo-Miocene sequences in the Alice Springs District but are rare or absent in Pliocene sediments near Broken Hill. The parent plants [Nothofagus (Brassospora) spp.] became extinct across Australia during the Plio-Pleistocene transition (Gelasian) but survive in montane rainforest in New Guinea and New Caledonia. Malvacipollis regattaensis typically is restricted to Pliocene deposits in southeastern Australia but it is possible that a species of the mallow family (Malvaceae) still growing in central Australia produces this pollen type. Modern plant distribution data follow Jessop (1981).