Clay mineral evolution and formation of intermediate phases during pedogenesis on picrite basalt bedrock under temperate conditions (Yunnan, southwestern China)

•Weathering of picrite basalt produced smectite and mixed-layers.•Mixed-layers K/S, I/S, and I/S/K formed during weathering and pedogenesis of basalt.•Smectite kaolinization occurred in the initial stage of weathering.•Illitic and kaolinitic minerals formed throughout the lifetime of the soil.