Thin-skinned thrust-fault tectonics offshore south-west Vietnam

Abstract

In the c. 40 000 km² large Phu Quoc basin south-west of Vietnam reflection seismic data suggest a thin-skinned thrust-fault complex concealed by Neogene marine sediments (Fig. 1; Fyhn et al. 2010). The deformed sedimentary succession in the complex is of Early Cretaceous age, which is documented by biostratigraphical studies of outcrops and a 500 m deep well on the Phu Quoc island. A model for the thrust-fault deformation suggests that piggy-back basins were formed during displacement along the thrust faults. The translation was 3–8 km from east to west. The model is based on detailed structural analyses of 36 seismic sections that cover the Phu Quoc basin (Fig. 1). The main structural elements in the complex are flats and ramps with hanging-wall anticlines developed above the ramps. The crests of the hanging-wall anticlines occur as remnants of partially eroded structural highs. This paper describes the thin-skinned thrust-fault structures that form the basis for the interpretation of the concealed fold-belt complex in the Phu Quoc basin.