PREDICTION OF MODERN BAUXITE OCCURRENCE - IMPLICATIONS FOR CLIMATE RECONSTRUCTION

The formation of bauxite and laterite strongly depends on prevailing c limate. We use modern climate and bauxite distribution data to investi gate quantitatively the role of climate in bauxite formation and to de velop a method for testing general circulation models (GCMs). We find that a very satisfactory prediction for ''potential'' bauxite formatio n can be achieved using two different sets of criteria. The first requ ires the mean annual temperature to be greater than 22 degrees 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 degrees C for at least 8 months. These proxy models are also used with simulations of the pre sent day using a general circulation model. The results show that the climate models are robust, suggesting that bauxitization can be used t o evaluate quantitatively such climate models for ancient times. We al so show that. based on climate model predictions, the regions favourab le for bauxitization have remained stable through the Holocene but, wi th the exception of the Malay peninsula, bauxite formation would have ceased at the last glacial maximum. (C) 1997 Elsevier Science B.V.