Extension Discrepancy of the Hyper‐Thinned Continental Crust in the Baiyun Rift, Northern Margin of the South China Sea

Zhao, Yanghui; Ding, Weiwei; Ren, Jianye; Li, Jiabiao; Tong, Dianjun; Zhang, Jiangyang

doi:10.1029/2020tc006547

Cited by 17 publications

(28 citation statements)

References 123 publications

(256 reference statements)

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“…A number of large-scale rifted basins have shared Mesozoic basements along the northern margin of the SCS, including Qiongdongnan, Pearl River Mouth and Taixinan basins (Figure 1b,c) (Dong et al, 2009;Yang et al, 2015). The Pearl River Mouth Basin underwent rifting during the Late Cretaceous-Early Oligocene, followed by a transition period during the Late Oligocene-Early Miocene and a thermal subsidence period since the Middle Miocene (Figure 2) (Sun et al, 2014;Zhao et al, 2021). From the Oligocene onwards, this basin has experienced F I G U R E 2 General tectonic-sedimentary columns for the Baiyun Sag, including the Paleogene-Quaternary stratigraphic sequences and three key tectonic events (Modified from Xie et al, 2017;Zhang et al, 2017) the Nanhai, Baiyun and Dongsha events, corresponding to the T7 (33.9 Ma), T6 (23.0 Ma), and T3 (11.6 Ma) geological interfaces, respectively (Figure 2) (Chen et al, 2020;Sun et al, 2014;Xie et al, 2017).…”

Section: Geological Settingmentioning

confidence: 99%

“…SCS is the largest marginal sea in the Western Pacific, which can be divided into the Northwest, Southwest and Central‐Eastern sub‐basins (Figure 1a). The formation and NE–SW spreading of the SCS basin have been pivotal tectonic events in Southeast Asia during the Cenozoic (Deng et al, 2019; Zhao et al, 2021). Among the mainstream models for explaining the opening of this ocean basin (Holloway, 1982; Northrup et al, 1995; Storey, 1995; Tapponnier, 1982), slab pulls from the subduction of the proto‐SCS (Hall, 2017; Holloway, 1982; Taylor & Hayes, 1980, 1983) is widely accepted.…”

Section: Geological Settingmentioning

confidence: 99%

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How do fault systems and seafloor bathymetry influence the structure and distribution characteristics of gas chimneys?

et al. 2023

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Gas chimneys are key pathways for geofluid vertical migration; therefore, deciphering their formation and evolution is crucial for hydrocarbon exploration and geohazard risk assessment. However, the influences of ambient conditions (e.g. bathymetry, tectonics, sediment supply flux) on gas chimney development have not been thoroughly investigated. Using high‐resolution 3D seismic data, we have identified 59 gas chimneys beneath the Shenhu Slope (a gas hydrate test production area on the northern South China Sea margin), 35 of which intersect faults. Above fault interfaces, internal seismic structures are dominated by chaotic discontinuous reflections. Internal structures below interfaces display more continuous reflections, which are also apparent in gas chimneys, not intersecting faults. A higher degree of chaotic or discontinuous seismic reflections may indicate more fragmented networks. This may occur due to increased fluid flow along faults and concomitant fluid overpressure. The present‐day undulating seafloor comprises the inter‐canyon (IT) region, intra‐canyon (IN) region and flat slope (FD) region downstream of canyons. Gas chimneys beneath IT and IN regions exhibit elongated elliptical shapes in the plane, with the long axis azimuth (sub‐) parallel to the main strike of canyons. Chimneys beneath the IT region have larger heights than those beneath the IN and FD regions. Thicker sediment in the IT region corresponds to a higher overburden pressure, which may induce stronger overpressure in the subsurface reservoir region. This overpressure may promote chimneys gathering in the IT region. Canyons' main directions are likely to limit hydraulic fracturing due to maximum gradient boundaries between overlying sediment stress fields. This study provides insights into gas chimney distribution, morphology and structure evolution in relation to bathymetry and fault conditions. It contributes to an improved understanding of how geofluids migrate in marginal ocean basins.

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Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

How do fault systems and seafloor bathymetry influence the structure and distribution characteristics of gas chimneys?

et al. 2023

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“…The extensional tectonics of the Cenozoic are evidenced by the development of half-grabens with styles including serial, parallel and en echelon. Some half-grabens merge into lowangle detachment systems, forming a decollement system in the continent-ocean transition zone (Ding et al, 2013(Ding et al, , 2020Zhao et al, 2021). Data from recent International Ocean Discovery Program (IODP) boreholes suggest that seafloor spreading started during the Early Oligocene in the East Subbasin (ca.…”

Section: Tectonic Settingmentioning

confidence: 99%

Unravelling rift propagation from Cenozoic subsidence patterns: Examples from the Dangerous Grounds, South China Sea

et al. 2023

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How seafloor spreading in marginal basins controls subsidence patterns in continental margins under rift propagation settings remains poorly understood. Herein, based on detailed geological interpretation and backstripping of 37 high‐resolution multichannel seismic reflection sections, we calculate the Cenozoic tectonic subsidence across the Dangerous Grounds (DG), South China Sea, in order to study interactions between seafloor spreading and the propagation of rift basins. Our results show that rapid subsidence occurred in the eastern Dangerous Grounds (EDG) from the Palaeocene to early Oligocene, then migrated westwards to the middle Dangerous Grounds (MDG) during the early Oligocene to early Miocene, and finally reached the western Dangerous Grounds (WDG) during the early to middle Miocene. We interpret this western migration of intensive subsidence as the response of the inherited pre‐Cenozoic heterogeneous lithospheric structure of South China. Thermal re‐equilibration of the lithosphere then dominated the rapid post‐spreading subsidence throughout the whole DG from the middle Miocene. An anomalous subsidence deficit occurred in the EDG during the early Oligocene to early Miocene, and in the MDG during the early to middle Miocene; this phenomenon might be related to small‐scale mantle convection associated with the propagation of seafloor spreading from east to southwest.

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“…The partial subduction of the SCS along the Manila trench represents the last phase of a near-complete Wilson cycle, following continental rifting, breakup, and seafloor spreading. Based on deep-tow magnetic anomalies, multi-channel seismic data, the results of microfossils from IODP Expeditions and 39 Ar/ 40 Ar data, the SCS has undergone multiphase rifting events since the Late Cretaceous to Paleogene (Sun et al, 2009;Franke et al, 2014;Li et al, 2015;Sibuet et al, 2016;Ding et al, 2020;Zhang et al, 2020;Zhao et al, 2021), leading to the opening of the SCS basin at ~32-33 Ma, and stopped spreading at ~15 Ma in the east subbasin and ~16 Ma in the southwest subbasin, followed by eastward subduction under the Philippine Sea Plate (PSP) along the Manila trench (Li C. F. et al, 2013(Li C. F. et al, , 2015Chen et al, 2017Chen et al, , 2021Jian et al, 2018;Sun et al, 2018;Deng et al, 2020;Hung et al, 2020). Large amounts of magmatism persisted for nearly 10 Ma after the cessation of seafloor spreading and generated the Zhenbei-Huangyan seamount chain (Sibuet et al, 2016;Hung et al, 2020).…”

Section: Geological Backgroundmentioning

confidence: 99%

Bathymetric Highs Control the Along-Strike Variations of the Manila Trench: 2D Numerical Modeling

Chen

Cheng

et al. 2022

Front. Earth Sci.

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The Manila Trench is located at the eastern boundary of the South China Sea (SCS). It develops through the subduction of the SCS beneath the Philippine Sea Plate (PSP) since the early Neogene, driven by the northwestern plate motion of the PSP. The northern segment of the Manila trench at around 18° N—21.5°N is characterized by an obvious eastward convex in the trench shape and abrupt changes of slab dip angle, whereas the southern segment of the Manila trench at around 15°N—18°N is featured by an almost straight NS-trending trench line and smooth subducting slab morphology. However, the cause for the along-strike variations along the Manila trench remains poorly understood. In this study, we use 2-D thermo-mechanical modeling to investigate how bathymetric highs embedded in the subducting slab affect the topography of overriding plate and the morphology of subducting plate. Three major factors of bathymetric highs are systematically examined: 1) the crustal properties, 2) the width, and 3) the thickness. Geodynamic results suggest that the most important factor controlling abrupt changes in dipping angle is the crustal properties of bathymetric highs. Also, reduction of crustal thickness and increasing the width of continental bathymetric highs favor the abrupt change of dipping angle, whereas thicker (≥25 km) bathymetric highs are more likely to be blocked in the subduction zone before slab break-off. According to our numerical modeling results, we suggest that dramatic changes in the dip angle in the northern Manila trench and the convex shape were caused by subduction of a large thin continental terrane, whereas the smooth morphology of subducting slab in the southern segment and straight trench were associated with normal oceanic subduction with small seamounts.

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Extension Discrepancy of the Hyper‐Thinned Continental Crust in the Baiyun Rift, Northern Margin of the South China Sea

Cited by 17 publications

References 123 publications

How do fault systems and seafloor bathymetry influence the structure and distribution characteristics of gas chimneys?

How do fault systems and seafloor bathymetry influence the structure and distribution characteristics of gas chimneys?

Unravelling rift propagation from Cenozoic subsidence patterns: Examples from the Dangerous Grounds, South China Sea

Bathymetric Highs Control the Along-Strike Variations of the Manila Trench: 2D Numerical Modeling

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