Stratigraphic and sedimentological data from New South Wales and Queensland, eastern Australia, indicate that the late Paleozoic ice age consisted of at least eight discrete glacial intervals (each 1–8 m.y. in duration) separated by nonglacial intervals of comparable duration. These events spanned an interval from the mid-Carboniferous (ca. 327 Ma) to the early Late Permian (ca. 260 Ma), and they illustrate a pattern of increasing climatic austerity and increasingly widespread glacial ice from initial onset until an acme in the Early Permian, followed by an opposite trend toward the final demise of glaciation in the Late Permian. Glacial facies are composed of diamictites, interbedded diamictites, conglomerates and sandstones, rhythmites, laminated mudrocks with dispersed outsize gravel, glendonites, clastic intrusions, faceted, striated, and bullet-shaped clasts, and rare, well-sorted siltstones interpreted as windblown loessites. Carboniferous glacial intervals are predominantly of continental origin and were deposited in an array of mainly glaciofluvial and glaciolacustrine environments. Permian glacial facies, by contrast, were formed mainly in glaciomarine environments. Cyclical vertical stacking patterns occur on a variety of scales, suggesting glacial-interglacial and longer-term fluctuations in climatic conditions.

Abstract Using replicate measurements of a homogeneous reference zircon, the discrimination of Pb + and UO + ions relative to U + observed in zircon analysis with the SHRIMP ion microprobe has been established as a power law relationship. This relationship minimizes uncertainty in comparative measurement of 206 Pb/ 238 U ages in zircons. Ages thus obtained have been compared with isotope dilution thermal ionisation mass spectrometric (1DTIMS) analysis of zircons in the Paterson Volcanics (Carboniferous, Australia) and 40 Ar/ 39 Ar dating of sanidines in the Z1 tonstein (Carboniferous, Germany). No bias can be detected between the three dating methods, confirming that SHRIMP zircon 206 Pb/ 238 U ages are accurate and comparable with other well-measured Phanerozoic ages. The age of the Westphalian B Stage of Europe is constrained by the Z1 tonstein; SHRIMP zircon analysis supports the 40 Ar/ 39 Ar age of 311 Ma and improves on its precision by a factor of two. The Paterson Volcanics mark both the Australian base of the Kiaman magnetic superchron and onset of the major, Late Palaeozoic period of Gondwana glaciation; SHRIMP and 1DTIMS zircon dating reassign these processes to the Namurian from the late Westphalian assignment used until now for global correlations.

Abstract Zircon U-Pb ages measured with the SHRIMP ion microprobe have been used to date volcanic horizons associated with Early Carboniferous sediments of the Southern New England Orogen in eastern Australia. These results calibrate the numerical ages of eastern Australian biozones, including the four Early Carboniferous brachiopod zones between the Schellwienella burlingtonensis and Rhipidomella fortimuscula Zones, which include cosmopolitan faunas and so also constrain ages for European and international substages of the Carboniferous System. Refinements to the Early Carboniferous timescale include the ages of the Devonian-Carboniferous boundary, the Tournaisian-Viséan boundary, and correlation with the Holkerian Stage of Britain. New biostratigraphic correlations and ages constrain the associations of the Granulatisporites frustulensis Microflora and Grandispora maculosa Assemblage and indicate that the Nothorhacopteris flora, previously thought to be confined to Late Carboniferous units, ranges down into the upper Viséan Series (V3a). The zircon ages delimit the durations of the major volcanic events within the Southern New England Orogen and the time significance of depositional hiatuses within the stratigraphic succession, and revise correlations and the associated Viséan palaeogeography of eastern Australia.