CONTRIBUTION OF LATE PERMIAN PALEOGEOGRAPHY IN MAINTAINING A TEMPERATE CLIMATE IN GONDWANA

NUMERICAL simulations based on general circulation and energy-balance models consistently indicate that. the high latitudes of Gondwana experienced seasonal extremes in climate during the Late Permian period1-3. But palaeogeographic maps based on the distribution of climate-sensitive rocks4, palynological and palaeobotanical data5,6 and dicynodont fossil records7 all imply a temperate climate. The reason for this discrepancy has not been clear. Recently, it has emerged from studies of Upper Permian fluviolacustrine deposits throughout southern Africa that the geography was dominated by a series of giant lakes, perhaps interconnected within major fluvial frameworks8. Here I review these data and their implications for a temperate climate. I suggest that the discrepancy between the climate modelling results which indicate seasonal temperature extremes, and the increasing body of geological information documenting a temperate climate, may be explained by the fact that the palaeogeography used in the models does not take into account the existence of these lakes and rivers, which would have had a major influence on the regional climate. The results demonstrate the importance of incorporating accurate palaeogeographies into numerical modelling studies when attempting to reconstruct past climates.