1248 / 2024-09-20 20:00:27

Quantifying climate conditions for the formation of bauxites and kaolinites

deep-time climate evolution, bauxites, kaolinites, temperature, precipitation

Session 42 - Deep-time ocean and climate changes: insights from models and proxies

Bauxites and kaolinites, products of intense chemical weathering, are commonly considered qualitative indicators of warm and humid environmental conditions in paleoclimate studies. Despite their recognized significance, a comprehensive quantitative analysis of the relationship between the formation of bauxites and kaolinites in the geological past and climatic factors remains lacking. Here, we integrate geological records with climate simulations to establish the quantitative relationships between bauxite and kaolinite occurrences and temperature-precipitation patterns during the Phanerozoic. During the late Paleozoic, bauxites and kaolinites were concentrated in the equatorial region, and they shifted to the subtropics of ~ 30 °N for much of the Mesozoic and Cenozoic. Our findings reveal that bauxites formed with an annual mean temperature (AMT) of 26.8 °C and annual mean precipitation (AMP) of 1743 mm y^-1 before 250 Ma, shifting to an AMT of 24.3 °C and AMP of 982 mm y^-1 after 250 Ma. Kaolinites formed with a medium AMT of 25.1 °C and AMP of 1427 mm y^-1 in the Paleozoic, followed by a shift to a medium AMT of 20.5 °C and AMP of 1121 mm y^-1 in the Mesozoic and Cenozoic. The variations in latitudes, temperatures and precipitation of bauxites and kaolinites are attributed to land distribution and climate states. It’s notable that net precipitation associated with bauxites and kaolinites remained stable across time. These quantitative insights enhance our understanding of the weathering processes of the metallogenesis of bauxites and kaolinites.