Prediction of modern bauxite occurrence: implications for climate reconstruction

The formation of bauxite and laterite strongly depends on prevailing climate. We use modern climate and bauxite distribution data to investigate quantitatively the role of climate in bauxite formation and to develop a method for testing general circulation models (GCMs). We find that a very satisfactory prediction for “potential” bauxite formation can be achieved using two different sets of criteria. The first requires the mean annual temperature to be greater than 22°C, with annual mean precipitation greater than 1200 mm, and 6 or fewer months when the rainfall is less than 60 mm. The alternative model requires precipitation greater than evaporation for at least 6 months per year, and monthly mean temperatures greater than 23°C for at least 8 months. These proxy models are also used with simulations of the present day using a general circulation model. The results show that the climate models are robust, suggesting that bauxitization can be used to evaluate quantitatively such climate models for ancient times. We also show that, based on climate model predictions, the regions favourable for bauxitization have remained stable through the Holocene but, with the exception of the Malay peninsula, bauxite formation would have ceased at the last glacial maximum.