Cenozoic sedimentary evolution of deepwater sags in the Pearl River Mouth Basin, northern South China Sea

Xie, Hui; Zhou, Di; Pang, Xiong; Li, Yuanping; Wu, Xiangjie; Qiu, Ning; Li, Pengchun; Chen, Guanghao

doi:10.1007/s11001-013-9183-7

Cited by 55 publications

(25 citation statements)

References 28 publications

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“…Clift et al (2015) proposed that the mid and lower crustal flow was initiated due to a climatically triggered sharp increase in sediment flux on to the continental margin starting around 20 Ma, which they associated with an intensification of the East Asian summer monsoon around that time. Whatever the reason for the increase, independent three-dimensional mapping of the continental margin stratigraphy now confirms that accumulation in the Baiyun Sag did increase sharply around this time (Xie et al 2013). This is a time when there is little evidence for extensional faulting.…”

Section: Baiyun Sag Basinmentioning

confidence: 76%

Coupled onshore erosion and offshore sediment loading as causes of lower crust flow on the margins of South China Sea

Clift

2015

Geosci. Lett.

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Hot, thick continental crust is susceptible to ductile flow within the middle and lower crust where quartz controls mechanical behavior. Reconstruction of subsidence in several sedimentary basins around the South China Sea, most notably the Baiyun Sag, suggests that accelerated phases of basement subsidence are associated with phases of fast erosion onshore and deposition of thick sediments offshore. Working together these two processes induce pressure gradients that drive flow of the ductile crust from offshore towards the continental interior after the end of active extension, partly reversing the flow that occurs during continental breakup. This has the effect of thinning the continental crust under super-deep basins along these continental margins after active extension has finished. This is a newly recognized form of climate-tectonic coupling, similar to that recognized in orogenic belts, especially the Himalaya. Climatically modulated surface processes, especially involving the monsoon in Southeast Asia, affects the crustal structure offshore passive margins, resulting in these "load-flow basins". This further suggests that reorganization of continental drainage systems may also have a role in governing margin structure. If some crustal thinning occurs after the end of active extension this has implications for the thermal history of hydrocarbon-bearing basins throughout the area where application of classical models results in over predictions of heatflow based on observed accommodation space.

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Section: Baiyun Sag Basinmentioning

confidence: 76%

Coupled onshore erosion and offshore sediment loading as causes of lower crust flow on the margins of South China Sea

Clift

2015

Geosci. Lett.

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“…In the Baiyun Sag and the Liwan Sag of the Pearl River Mouth Basin, the Eocene deposits are characterized by lacustrine facies, with maximum sedimentation rate reaching up to 600 m/myr [ Xie et al ., ]. The youngest zircon U‐Pb ages for the three samples from borehole L21 constrain a stratigraphic age of the Late Eocene (33–40 Ma).…”

Section: Discussionmentioning

confidence: 96%

“…Moreover, the well‐rounded zircon shapes in sample X28‐2 suggest a long transport path from a fluvial provenance. The terrigenous supply from the northern landmass (South China) could have even contributed to the rapid deltaic deposition in the Baiyun Sag, as revealed by a large set of southward prograding sediment bodies in earlier seismic studies [ Pang et al ., ; Xie et al ., ]. This explanation, however, appears to be inapplicable to sample L13‐3, in which the typical zircon grains without abrasion features may imply a nearby provenance instead.…”

Section: Discussionmentioning

confidence: 99%

Detrital zircon provenance of the Paleogene syn‐rift sediments in the northern South China Sea

Shao

Cao

Pang

et al. 2016

Geochem Geophys Geosyst

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The early rift sedimentation history of the South China Sea is still not well understood due to restricted borehole coverage of the Paleogene strata and lack of reliable stratigraphic dating. We use detrital zircon U‐Pb geochronology to explore the source‐to‐sink characteristics of syn‐rift sequences in the northern South China Sea. The results reveal significant intrabasinal provenances in addition to the well‐perceived terrigenous supply from the north. The Dongsha Uplift is considered to account for the dominance of the Early Cretaceous zircons in the Eocene samples. The Lower Oligocene sediments in the Qiongdongnan Basin could have been sourced from Hainan Island and local uplifts, but their distinction cannot be confirmed by the U‐Pb age spectra. Contemporary sediments in the northern Pearl River Mouth Basin were most likely transported from southeastern South China with well‐rounded zircon grains showing U‐Pb age similarity to those from the northeastern tributaries of the Pearl River. By contrast, intrabasinal sources from the west and east are suggested to have contributed the infill of the southern part of the Pearl River Mouth Basin based on generally euhedral zircon shapes. These sedimentary source patterns appear to change very little in the Oligocene northern South China Sea. However, the newly detected Neoproterozoic zircons in the Upper Oligocene sediments from borehole L21 tend to indicate a southern source. The episodic and diachronic nature of rifting and erosion processes in the early South China Sea is the cause of complex patterns in the Paleogene provenance history.

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“…Correspondingly, the Moho depth increases from 25 km beneath the Zhu I Depression to approximately 27 km beneath the Dongsha Rise then decreases to 24 km. The final RayInvr model predicted a uniformly thick (1-3 km) sediment layer in the Zhu I Depression, with a velocity varying from 1.8 km/s near the top to 2.5 km/s at the base, which is completely composed of a Cenozoic sedimentary sequence [Xie et al, 2013]. In contrast, the Dongsha Rise sediment thins slightly in the northwestern part but presents high velocities (3.0-4.0 km/s) at the base.…”

Section: Continental Shelfmentioning

confidence: 99%

Deep seismic structure of the northeastern South China Sea: Origin of a high‐velocity layer in the lower crust

et al. 2017

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We present a 2‐D seismic tomographic image of the crustal structure along the OBS2012 profile, which delineates the Moho morphology and magmatic features of the northeastern South China Sea margin. The image was created by forward modeling (RayInvr) and traveltime tomographic inversion (Tomo2D). Overall, the continental crust thins seaward from ~27 km to ~21 km within the continental shelf across the Zhu I Depression and Dongsha Rise, with slight local thickening beneath the Dongsha Rise accompanying the increase in the Moho depth. The Dongsha Rise is also characterized by ~4–7 km thick high‐velocity layer (HVL) (~7.0–7.6 km/s) in the lower crust and exhibits a relatively high velocity (~5.5–6.4 km/s) in the upper crust with a velocity gradient lower than those of the Zhu I Depression and Tainan Basin. Across the continental slope and continent‐ocean transition (COT), which contain the Tainan Basin, the crust sharply thins from 20 km to 10 km seaward and a ~2–3 km thick HVL is imaged in the lower crust. We observed that volcanoes are located only within the COT, but none exist in the continental shelf; the Dongsha Rise exhibits a high magnetic anomaly zone and different geochemical characteristics from the COT. Based on those observations, we conclude that the HVL underlying the COT is probably extension related resulting from the decompression melting in the Cenozoic, whereas the HVL beneath the Dongsha Rise is probably arc related and associated with the subduction of the paleo‐Pacific plate. These findings are inconsistent with those of some previous studies.

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Cenozoic sedimentary evolution of deepwater sags in the Pearl River Mouth Basin, northern South China Sea

Cited by 55 publications

References 28 publications

Coupled onshore erosion and offshore sediment loading as causes of lower crust flow on the margins of South China Sea

Coupled onshore erosion and offshore sediment loading as causes of lower crust flow on the margins of South China Sea

Detrital zircon provenance of the Paleogene syn‐rift sediments in the northern South China Sea

Deep seismic structure of the northeastern South China Sea: Origin of a high‐velocity layer in the lower crust

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