STRATIGRAPHIC RECORD OF LATE PALEOZOIC GONDWANAN ICE AGE IN NEW SOUTH WALES, AUSTRALIA: A REVIEW AND REVISION OF THE CARBONIFEROUS SYSTEM

The late Paleozoic Gondwanan Ice Age was one of the most significant events of the Paleozoic, yet its major defining characteristics remain elusive. The timing, duration, and nature of ice dynamics have yet to be constrained in eastern Australia. One difficulty in interpreting the record stems from the lack of studies that apply modern sedimentological and geochemical techniques in the diagnosis of ancient glacial deposits. Additionally, time scale discrepancies in current published literature set the stage for possible misunderstanding and further misinterpretation. This paper reviews the published literature describing Carboniferous glacial deposits in New South Wales, southeastern Australia, and places existing stratigraphic and sedimentologic data into a common geochronological framework in order to establish a firm and clear foundation from which future work may spring. According to literature to date, at least two and perhaps three discrete glacial episodes separated by non-glacial intervals are known from: 1) the Spion Kop Conglomerate at Tareela Creek, 30 km southwest of Barraba, and the Yagon Silstone, located in the Gloucester-Myall Lake area, 2) the Johnsons Creek Conglomerate, 4.5 km southeast of Wards River in the Stroud-Glouchester Region, and 3) the Rocky Creek Conglomerate at Rocky Creek, 39 km southwest of Bingara, and the Rosedale member of the Currabubula Formation . In addition, intervals of the Seaham Formation, 30 km northwest of Newcastle, may record glacial episodes contemporaneous with or overlapping in age with those identified in the aforementioned formations. The age of these formations have been well constrained using U-Pb dates from zircons in volcanic deposits, brachiopod biozones, and palynostratigraphy. Preliminary data suggest that Carboniferous glaciation in Eastern Australia was restricted to discrete intervals within the Namurian, Westphalian, and, possibly, Stephanian. Recent literature suggests that late Paleozoic glaciation was expressed in several discrete events of short duration with limited aerial extent, rather than one long, continuous event consisting of a large continental ice sheet, as traditionally believed.