Tectono-sedimentary signature of the second rift phase in multiphase rifts: A case study in the Lufeng Depression (38–33.9 Ma), Pearl River Mouth Basin, south China sea

• Published in: Marine and petroleum geology Vol. 114; p. 104218
• Main Authors: Ge, Jiawang, Zhu, Xiaomin, Zhao, Xiaoming, Liao, Jijia, Ma, Bingshan, Jones, Brian G.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-04-2020
• Subjects: Fault evolution; Lufeng depression; Multiphase rifts; Pearl river mouth basin; Second rift phase; Sediment dispersal pattern; Sediment dispersal pattern; Lufeng depression; Multiphase rifts; Fault evolution; Second rift phase; Pearl river mouth basin
• ISSN: 0264-8172; 1873-4073
• DOI: 10.1016/j.marpetgeo.2020.104218

Compared to first rift phase (RP1) or single rift basins, the relationship between fault behaviours and depositional architecture during the second rift phase (RP2) remains insufficiently understood in multiphase rifts. This study attempts to provide implications for tectono-sedimentary signatures during the RP2 in multiphase rift evolution, according to an integrated analysis of 3D seismic reflections, wire logs and cores from the Lufeng Depression in the Pearl River Mouth Basin, South China Sea. The four recognised third-order sequences, ESQ1-4, define a two-stage tectono-sedimentary evolution, including an early (ESQ1-2) and a late stage (ESQ3-4) of the RP2 (38–33.8 Ma) in the Lufeng Depression. Fan-deltaic, braided deltaic sandstone-prone and lacustrine mud-prone deposits are interpreted from the basin margin towards to the central areas. During the early stage of the RP2, two relatively steep dipping E-W striking faults in the northern area were very active, undergoing rapid reactivation with a high displacement, while other faults were less active, had low displacements with respect to the extension direction and possibly represent pre-existing fault geometries. Two tectono-depositional signatures are identified during the early stage of the RP2: 1) facilitation of newly captured axially-dominated deltaic systems in the rapidly reactivated fault propagated areas, as a more uniform distribution of connected and elongated depocentres establishes an axial-supply drainage catchment; 2) sustained previous drainages from the end of the RP1 showed an increase of dip-slope sourced systems in low-displacement faulted-controlled areas, i.e. these areas lack fault-controlled topographic re-organisation but show establishment of a hanging dip-slope. The late stage of the RP2 is characterised by a low-accommodation basin as faulting activities totally waned, and thus large-sized shallow-water deltaic systems and long-distance transported sandstones are promoted. This study highlights the distinctive stratigraphic architectures and associated sediment dispersal patterns induced by progressive fault activity during the RP2 cycle. Furthermore, the proposed depositional signatures may be used as a reference when studying less data-rich multiphase rifts elsewhere.
•Tectono-depositional patterns of the second rift phase (RP2) cycle are described in the Lufeng Depression.•Axially-dominated deltaic systems are facilitated in the rapidly reactivated fault areas in the early stage of the RP2.•An increase of dip-slope sourced systems is developed in low-displacement faulted areas in the early stage of the RP2.•Large-sized shallow-water deltaic systems are promoted during the late stage of the RP2.•A two-stage tectono-sedimentary motif of the RP2 in the multiphase rifts is proposed.