Abstract: The Nanpanjiang Basin, located at the junction of the South China and Indochina blocks, is regarded as the foreland basin of Indosinian orogen. Due to the MesozoicCenozoic tectonic superimposition, the structural style of the basin is complex as superposed folds are common. Accordingly, the Badu domelike complex anticline in the middle of the Nanpanjiang Basin was chosen as the study object. Combining surface deformation analysis with deeper seismic profile interpretation and zircon geochronology of diabase, we reconstructed the structural styles and deformation sequences. The Badu complex anticline, which has a Devonian core and limbs of Permian and Triassic, is an arcshaped fold with northward axis. At the deep level, the structure is dominated by a NEdirecting duplex; at the middle and shallow level, there are Ndirected imbricates with faultrelated folds. The magmatic zircon from diabase yielded a youngest age population of 62 Ma, indicating a possible contemporaneous uplifting. Integrating structural styles at different levels, the deformation sequence of the region was divided into three deformations, D1, D2 and D3. D1, the duplex, was caused by Indosinian subduction; D2, the imbricate, was a result of Indosinian compression; and D3, represented by normal faults and diabase dykes, was a result of the Late Yanshanian extension. The formation and evolution of the Badu complex anticline is a typical example of the superimposition of the Nanpanjiang foreland Basin, which shows that the foreland basin of Indosinian underwent subduction, compression, tectonic transition from compression to extension during the Yanshanian, and finally uplifting in the Cenozoic era.

Key words: Nanpanjiang Basin, complex anticline, deformation sequence, seismic profile, diabase, zircon U-Pb age