Abstract:

       Basalt weathering acts as a major atmospheric CO2 sink. Climate conditions have important effect on basalt weathering
and CO2 consumption rate. In this study, typical weathering profiles of Cenozoic basalts from different climatic zones in eastern China were selected to conduct clay mineral analysis and major elements measurement. Results show that as climate changes from dry-cold in the north to humid-hot in the south in the studied region, the assemblages of clay minerals in the profiles transfer as follows: smectite+ illite+ kaolinite → smectite+ kaolinite → kaolinite+ gibbsite. Chemical composition of the weathered samples exhibits correspondent changes. Ca, K, Na and Si in the soils are relatively enriched due to dust input compared to the concentrations of overlying parent basaltic rocks in Inner Mongolia under dry-cold climate. Ca, K and Na begin to be leached in the soils in Shandong and Si is leached in Jiangsu and Anhui under temperate climate. Si is leached heavily while the alkalineelements are almost lost in soils due to intensive weathering in Hainan under humid-hot climate. According to relative percentagechange of elements and normalization using average composition of dust in northern China, CO2 consumption rate from basalt weathering in eastern China can be estimated about 5.37~181.00 t/km2·yr, which is within the similar range provided by Dessert et al.’s (2003).

Key words: basalts；weathering；clay mineral；CO2 consumption rate