Astronomical forcing of sedimentary cycles of Late Eocene Liushagang Formation in the Bail

Astronomical forcing of sedimentary cycles of Late Eocene Liushagang Formation in the Bailian Sag, Fushan Depression, Beibuwan Basin, South China

Sea

曹海洋;金思丁;孙鸣;王华

【期刊名称】《中南大学学报（英文版）》 【年(卷),期】2016(023)006

【摘要】Sediments in the Liushagang Formation of Late Eocene form a group of key hydrocarbon play fairways in the Beibuwan Basin, South China Sea. As an important reservoir-forming combination, the Liushagang Formation consists of deltaic siliciclastic and show clear sedimentary cyclicity. According to paleontology research and stratigraphic correlation, the boundary between Liushagang Formation (Els) and Weizhou Formation (Ewz) is regarded as the Eocene-Oligocene boundary. The oxygen isotope dating for well cores from the top of the first Member of Liushagang Formation (Els1) and the bottom of the third Member of Weizhou Formation (Ewz3) give an isochron age of 35.2 Ma. Here, we use GR logging data as a paleoenvironmental proxy to conduct a detailed cyclostratigraphic study of the Els1 in the Bailian Sag, Fushan Depression. Power spectra, evolutionary fast Fourier transformation and wavelet analysis all reveal significant sedimentary cycles in Els1. The ratios of cycle wavelengths in these stratigraphic units