Sedimentary facies and evolution of aeolianites on Shidao Island, Xisha Islands

The aeolianite deposits on Shidao Island of the Xisha Islands, the South China Sea, contain five stages of aeolian biocalcarenites and four paleosols. The aeolian biocalcarenites consist of two sedimentary facies: dune and interdune deposits. In the dunes, large-scale festoon cross-bedding, humped cross-bedding and high-angle foreset bedding are well developed, and in the interdunes, large-scale flat-bedding and low-angle wedge shaped cross-bedding are well developed. The sedimentary structures and lamella features indicate that the aeolian deposits are driven mainly by the northeast monsoon. The aeolian biocalcarenite and paleosols may reflect the arid and humid climates of the East Asian monsoon, respectively. By comparison with the stalagmite oxygen isotope climosequence of Hulu Cave, Nanjing, we inferred that the aeolianite formed in the last glacial stage, and the paleosols were formed during relatively long-term warm events.