Depositional setting analysis using seismic sedimentology: Example from the Paleogene Lishagang sequence in the Fushan depression, South China Sea

Source rock evaluation within a sequence stratigraphic framework of the Palaeogene Liushagang Formation in the Fushan Depression, South China Sea

“…During the deposition of SQls3, the lake level was relatively high (Figure 3). The sediments were transported to the deep lacustrine areas by the channel systems (Y. Li et al, 2017) (Figure 1c), and finally deposited as the braided river deltas, turbidite fans, and semi‐deep lake facies in the western region of the Fushan Depression. The SQls2 was deposited during the highest lake level period of the Liushagang Formation (Figure 3), resulting in widespread distribution of dark mudstones.…”

“…The SQls1 period with the lowest lake level (Figure 3). There are three provenance systems of the sediments: southern slope belt provenance system, western Lingao uplift provenance system, and north‐eastern Maniao Fault provenance system, respectively (Y. Li et al, 2017) (Figure 1c). Braided river delta facies developed in the southern slope, fan delta facies deposited in the west and north‐east of Huangtong Sag, and semi‐deep lake facies distributed in the north of Huangtong Sag.…”

“…The mudstone to stratum thickness ratio is an effective material to evaluate the areal distribution of mudstone (Lai, Li, Liu, Mao, Liu, et al, 2020). Y. Li et al (2017) analysed the depositional setting of the Liushagang Formation, using three‐dimensional seismic data. In this study, we first recognized the sedimentary facies of different sequences on the basis of previous studies and wells‐correlation geological profiles.…”

“…(c) The sketch map of the western region of Fushan Depression and wells location. Sediment source directions of the Liushagang depositional period are from Y. Li, Lin, Wang, & Luo, 2017…”

“…During the depositional period of the Els, braided river delta systems were widely distributed in the southern slope, and fan delta systems were developed in the Chaoyang step‐fault zone (Figure 3) (Y. Li et al, 2017; Liu et al, 2014, 2015, 2020). The central Huangtong Sag frosted turbidite fans and lacustrine facies with dark grey source rocks (Y. Li et al, 2017; Liu et al, 2014, 2015, 2020).…”