NEAR-FIELD STRATIGRAPHIC RECORD OF THE LATE PALEOZOIC GONDWANAN ICE AGE FROM EASTERN AUSTRALIA PROVIDES A FRAMEWORK FOR EXAMINING FAR-FIELD STABLE ISOTOPE RECORDS

We have carried out a comprehensive re-evaluation of the Carboniferous-Permian stratigraphic record in eastern Australia in an effort to better constrain the character and duration of the late Paleozoic Gondwanan ice age (LPGIA). This work shows that the LPGIA comprises eight short-lived (3–5 m.y.) pulses of glaciation separated by distinctly warmer, perhaps ice-free, intervals of comparable length. The duration and temporal distribution of glacial periods indicate an abrupt transition from greenhouse to icehouse conditions during the latest Mississippian, with individual glacial episodes becoming progressively longer and more intense during Pennsylvanian to Early Permian time. This trend reversed during the Middle Permian as climate ameliorated and conditions shifted toward a protracted greenhouse climate state. The eastern Australian stratigraphic record provides an ideal context in which to examine and interpret temporal trends in stable isotope compositions of marine carbonates derived from paleoequatorial settings in North America, Europe, and the Russian Platform. Previous workers have demonstrated the presence of synchronous, and thus globally significant, excursions in the δ¹³C and δ¹⁸O values of marine carbonate. Interpretations of these shifts in far-field proxy records have shaped our perceptions of the LPGIA. Examination of these isotopic trends in the context of the near-field stratigraphic record reveals both commonalities and departures between high and low latitude data sets, which will refine our understanding of what is arguably the most significant icehouse interval of the Phanerozoic.