THE EFFECT OF CO2 PARTIAL-PRESSURE IN THE GENESIS OF CENOZOIC BAUXITES

The bauxitization of Al-Si rocks may be a one-stage process (replaceme nt of initial rocks by bauxite without intermediate weathering product s) or a multistage one (one or more clayis weathering products are dep osited before bauxite). The former and latter alternative of bauxitiza tion in the weathering crust are controlled by acidic-alkaline conditi ons that, in turn, depend on the type of soil + plant cover. Petrochem ical features of the matrix and P-CO2, depending on the mass exchange between soil + plant cover and atmosphere are the main the factors of the bauxitization process. The critical value of P-CO2, which is the h ighest one allowing bauxitization of the Al-Si rocks, is calculated. C omparison of the above data with P-CO2 value in the recent tropical zo ne suggests that bauxitization of any rocks (except kaolins) in the Ce nozoic epoch cannot occur everywhere. The process is more common in sa vannas than in damp tropic forests.