Controls of faulting on synrift infill patterns in the Eocene PY4 Sag, Pearl River Mouth Basin, South China Sea

AbstractTectono-stratigraphic analysis of the Eocene PY4 Sag, Pearl River Mouth Basin, reveals that the evolution of normal faulting exerted an important control on the basin infill patterns. Seismic, well log and core data jointly indicate the Eocene Wenchang Formation can be subdivided into four third-order sequences that are related to early rift (WSQ1), rift climax (WSQ2–3) and late rift (WSQ4) stages. During the early rift stage, the PY4 Sag was defined by three, small-sized depocentres; it was related to low tectonic subsidence and likely overfilled by footwall-derived fan-delta deposits. The isolated depocentres coalesced and formed a larger and more uniform depocentre during the rift climax stage. Significantly increased tectonic subsidence during the rift climax WSQ2 sub-stage gave rise to prominent deep lake deposition including nearshore subaqueous fans, turbidite fan deposits and good source rocks. Two sediment infill patterns adjacent to boundary fault are developed during the rift climax WSQ...