Abstract：The southern South China Sea(SCS)is widely developed with large-scale deltas,down-cutting channels and deep-water turbidite fans. These geological structures are enriched with oil and gas resources and have a good potential for exploration. The Rajang Group sediments in the central Borneo formed a very thick deep-water turbiditic sequence which was deposited between the Late Cretaceous and early-middle Eocene. The fan system was deposited in an interval of at least 30 Ma and became one of the world’s largest ancient submarine fans. Due to the lack of systematic source-to-sink analysis,the provenance evolution and sedimentary infilling processes of the Rajang Group sediments remains ambiguous,which strongly affect the petroleum resources assessment. In this study,we conducted petrography,heavy mineral analyses and detrital zircon U-Pb dating,to generate a comprehensive interpretation of sediment provenance evolution in the southern South China Sea during the Eocene. We find that during the late Mesozoic to early-middle Eocene,the Rajang group was mainly controlled by the local uplift area of magmatic rocks in the northern South China Sea and Indo-China Peninsula;Since the late Eocene,the Sarawak Orogeny induced intense uplift and deformation of the Rajang Group,resulting in the Rajang Group exposed in the central Borneo and extended into the oil-bearing Sarawak Basin now. There was no good reservoir in the Rajang Group,because the strata were dominated by mud with very thin sandstone deposited. However,there may be good shallow water reservoirs in the Beikang-Nanweixi basins on the north side of Zengmu basin,and these will be the potential target of hydrocarbon exploration.
Li Li-Ni,Zhao Zhi-Gang,Cui Yu-Chi et al. “Source-to-sink” analysis of turbidite deposits in the Upper Cretaceous-Eocene Rajang Group in southern South China Sea[J]. JOPC, 2022, 24(1): 61-72.
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