The stratigraphy of a Late Palaeozoic borehole section at Douglas River, eastern Tasmania: a synthesis of marine macro-invertebrate and palynological data

Abstract

A section 236.8 mi n thickness of Late Palaeozoic (Late Carboniferous-Permian) rocks of the Lower Parmeener Super-Group was encountered in a borehole at Douglas River, eastern Tasmania. Lithological, marine macro-invertebrate and palynological data are documented and collated. The section displays many similarities with sequences elsewhere in eastern and northeastern Tasmania, but is unusual in the development of rocks (including Tasmanites shale) as old as Early Tamarian. This occurrence may indicate a narrow, but significant east-west breaching of the land barrier which persisted throughout the Tamarian over most of eastern and northeastern Tasmania. Acritarch swarms coeval with Late Palaeozoic Borehole Section at Douglas River, Tasmania Triassic coal measures Siluro-Devonian Mathinna Beds Upper Marine Sequence (Three distinctive units as indicated) Lower Marine Sequence Lower Freshwater Sequence Sandy carbonaceous mudstone Pebbly quartz sandstone Black mudstone. richly fossiliferous (bryozoans. brachiopods) Coarse. cross-bedded, quartz sandstone Black mudstone with gritty. pebbly horizons; rare plant fragments; rare forams Bioclastic limestone and fossiliferous mudstone. siltstone and sandstone. with dropstones Dark grey mudstone. with forams. sparse dropstones. rare woody debris Bioturbated fine quartz sandstone, rare plant fragments Fine quartz sandstone, minor thin, carbonaceous mudstone Tasmanites shale Black mudstone with sporadic gritty horizons. dropstones Conglomerate _ Poorly-sorted glauconitic sandstone-Graphic log, Douglas River borehole.

Southern high-latitude terrestrial climate change during the Palaeocene–Eocene derived from a marine pollen record (ODP Site 1172, East Tasman Plateau)

“…This pattern is consistent with the fact that sporomorph-bearing sediments of Permian and Triassic age occur in several regions of Tasmania (e.g. Playford, 1965;Truswell, 1978;Calver et al, 1984). In contrast, reworked sporomorphs on the continental shelf off George V Land (Antarctica; Fig.…”

Carbon cycle perturbations and environmental change of the middle permian and Late Triassic Paleo-Antarctic circle

“…The Lower Parmeener Supergroup in Bicheno-5 consists primarily of the upper marine sequence, which includes calcarenite limestone (282.1–300 m), richly-fossiliferous siltstone (264.5–282.1 m), conglomerate followed by glauconitic sandstone occurring at 267.1–264.3 m, and siltstone-dominated deposit with some evidence of dropstones (217–264.3 m). Palynological data from the Upper Marine Sequence of Bicheno-5 and the nearby correlative Bicheno-10 core 80 (Fig. 2 ; Fig.…”

“…2 ; Fig. SI – S3 ), indicate a Cisuralian, specifically Kungurian to Guadalupian age (~ 283.3 to 259.55 Ma, Australian Palynostratographic Permian zone, APP 3 and 4 80 with updates adapted from 81 – 83 . These palynostratigraphic stages have in recent years also been correlated to high precision U–Pb geochronology across the Sydney Basin, further constraining and confirming the assignment of ages of these zones with the Geological Time Scale (cf.…”