Figure - available from: Marine Geophysical Research
This content is subject to copyright. Terms and conditions apply.
a Line drawings of 2D seismic line L5 from west of the Dangerous Grounds. The rift structure is larger in the outer proximal zone and is modified by the late volcanic event. b The syn-rift sequences are sealed by the REU of T50. c Seismic section of the ODP Site 1143. The approximately 500 m drill is of Upper Miocene to recent. REU rift end unconformity; see Fig. 1 for location Modified from Shipboard Scientific Party (2000)
Source publication
The South China Sea (SCS) has a long record of rifting before and after subsequent seafloor spreading, affecting the wide continent of the Dangerous Grounds, and its scissor-shape opening manner results in the rifting structures that vary along this margin. Some 2000 km of regional multichannel seismic data combined with borehole and dredge data ar...
Citations
... During the Paleogene, there was a period of rifting that occurred, resulting in the creation of half-grabens and horsts trending in an NE-SW direction. The sedimentary fill of the half-grabens consists of continental to shallow marine deposits (Franke et al. 2011;Steuer et al. 2014;Peng et al. 2019). ...
Seismic interpretation is a critical aspect of hydrocarbon exploration, where geoscientists often struggle to accurately recognize patterns and anomalies in large datasets. Machine learning techniques offer a promising solution by allowing for the quick and accurate analysis of multiple and large-size seismic volumes. This study leverages seismic facies analysis, seismic attribute analysis, and supervised machine learning to identify and characterize turbidite deposits in the Dangerous Grounds region, an underexplored area recently revealed by high-resolution broadband seismic data. Through seismic stratigraphy, two distinct phases of turbidite deposition were identified: a lower unit showing higher amplitude and signs of faulting effect, and an upper, present-day unit characterized by lower amplitude and continuous reflectors. The attribute expression of these turbidites shows strong amplitude response, high relative acoustic impedance, and high gray-level co-occurrence matrix entropy emphasizing their distinctiveness from surrounding facies, with variations in reflector continuity and spectral decomposition providing further insight into their depositional processes and sediment characteristics. By applying nine machine learning classifiers with twenty seismic attributes as input, this study achieved over 99% accuracy in distinguishing turbidite facies from background, with the neural network, random forest, K-nearest neighbors, decision tree, and support vector machine exhibiting optimal performance. The study contributes significantly to the regional understanding of turbidite deposits through detailed machine learning-aided seismic characterization. It underscores the value of integrating domain knowledge with machine learning techniques in enhancing subsurface interpretations, offering a comprehensive methodology for seismic facies analysis in similarly complex and underexplored regions.
... Submarine volcanoes have been found in scattered multi-channel seismic (MCS) data in the southern margin of the SCS Franke et al., 2014;Chang et al., 2017a;Peng et al., 2019;Luo et al., 2021), and volcanic rocks were obtained by partial petrological sampling, as well (Kudrass et al., 1986;Zhou et al., 2005;Yan et al., 2008). Previous studies have discussed the genetic relationship between volcanism and high-velocity bodies (HVBs) in the lower crust or hyperextended continental crust in the southern margin on the basis of the MCS profile, and gravity and magnetic data (Chang et al., 2017a). ...
Submarine volcanism is widely developed in the South China Sea (SCS). However, the characteristics, distribution, and genesis of submarine volcanoes in the southern margin of the SCS remain obscure. In this study, we analyzed the characteristics of submarine volcanoes and identified a total of 43 submarine volcanoes in the southern margin of the SCS, based on a newly acquired 310-km seismic reflection profile, along with previous 45 multi-channel seismic (MCS) profiles, petrological results from volcanic rocks sampled by dredging and drilling, nearby ocean bottom seismometer (OBS) wide-angle seismic profiles, and gravity and magnetic data. The study ascertains that most of these volcanoes are located in fault-block belts and graben-horst zones with strong crustal stretching and thinning. These volcanoes exhibit positive high-amplitude external seismic reflections, weak and chaotic internal seismic reflections, and are accompanied by local deformation of the surrounding sedimentary strata. Meanwhile, they have higher positive gravity anomalies and higher magnetic anomalies than the background strata. The petrological dating results show that volcanic ages are primarily in the Pliocene-Pleistocene, with geochemical characteristics indicating dominance of oceanic island basalt (OIB) -type alkali-basalts. Extensional faults have obviously spatial correspondence with post-spreading volcanism, suggesting these faults may provide conduits for submarine volcanism. The high-velocity bodies (HVBs) in the lower crust and magma underplating exist in the southern SCS, which could provide a clue of genesis for submarine volcanism. The inference is that the intensity of post-spreading volcanism in the southern margin might be affected by stretching faults, crustal thinning and magma underplating.
... Clift et al. [44] Reflection evidence for a Dangerous Grounds miniplate Ding et al. [46] Seismic stratigraphy and tectonic structure Steuer et al. [4] Oligo-Miocene carbonates in Reed Bank and Palawan region Franke et al. [2] Rifting evolution of the SCS Chang et al. [5] Seismic sequence stratigraphy of carbonate platform-Taiping Island Peng et al. [22] Rift to drift in the Dangerous Grounds area ...
... A recent investigation by Peng et al., [22] recommended that in the Dangerous Grounds, Reed Bank, and adjoining areas during the early rifting phase, the main structures composed are large half grabens restrained by listric faults and separations, grabens linked with high angle normal faults and in the hyper-extended continental crust, significant existence of rotated fault blocks. Some places within the syn-rift sediment, Middle Eocene intrusive (Fig. 1C) and in the post-rift section, Early Miocene intrusive have been observed by Banerjee and Salim [23] . ...
During past decades, worldwide deep-water hydrocarbon exploration has attained interest with significant commercial discoveries. The upside exploration possibilities of worldwide deep-water basins are not explored to their full potential, and it has been expected that near future, many new discoveries will come. Globally, deep-water petroleum settings of different basins are highly variable. Effective exploration exertions in the frontier region will hang on to the application of knowledge gathered from an improved understanding of the well-explored basins with known petroleum systems. In Southeast Asia, a proven petroleum system exists in the Sabah basin and has a substantial financial influence on this region. Present-day hydrocarbon discovery in the deep-water region, NW Sabah Trough encouraged an inclusive inquiry of the adjacent territory, e.g., the hydrocarbon prospectivity in the Dangerous Grounds region, where the exploration activities are in the initial phase. Earlier, the analysis was principally intensive on infrequent 2D seismic data and gravity-magnetic data investigation. An organised way of the seismic attribute analysis and well log interpretation of the carbonate platform of Late Oligocene-Middle Miocene age has not been conferred thus far in the published literature. In this research work, newly obtained 3D seismic data with high-resolution and well information have been used to evaluate the carbonate platform. Seismic sections reflect the faults related to syn-rift tectonic activity that was also prominent in the post-rift section. The variance extraction map reveals the structural trend in the platform region and also the growth of the reef on top of the carbonate platform. RMS amplitude extraction map reflects the delivery of carbonate platform with higher amplitude value; sweetness extraction map reveals the fault-related lateral discontinuities. Significant evidence of facies changes, carbonate to clay/shale has been observed. Density vs gamma-ray and density vs neutron porosity cross plot reflect the presence of limestone, sand, shaly sand/siltstone, and carbonaceous shale. Vp vs Vs cross plot reflects a linear trend. Vp/Vs vs P-impedance cross plot depicts the reservoir rock carbonates that are water-bearing. Mu-rho vs density cross plot discriminates the lithologies as carbonate, shaly sand/siltstone, shale. During the Middle Miocene end, the high influx of siliciclastic sediments has been observed, resulting in the demise and burial of carbonate.
... However, details on how this propagation occurred and how it is (Fig. 1a), and location of study area (Fig. 1b). The seismic lines 1 and 6 are from ; 2, 4 and 5 from Song et al. (2019); 3 from Pichot et al. (2014);7, 8, 9 and 10 from Franke et al. (2013); 12, 13 and 14 from Peng et al. (2019). The location of the OCT is adapted from Song et al. (2019). ...
... In line B, only WB can be defined since rifting failed and continental breakup did not occur. We use the same criteria to define WB and BB on the published lines Franke et al., 2014;Peng et al., 2019;Yao et al., 2019); (for location see Figs. 1 and 7a). This allowed us to define the distribution of WB and BB within the propagator (Fig. 7a) and to map three domains (box shaped, wedging and proto-oceanic). ...
... Lines A and B cross at the southern margin and consequently image the same structures and tracts. The aim of this chapter is to link T1, T2 and T3 that belong to the local syn-rift mega-sequence with the regional stratigraphic framework previously discussed in Ding et al. (2014, Peng et al. (2019)and Yao et al. (2019). Peng et al. (2019) introduced a stratigraphic subdivision and applied it to line B. In their interpretation, the central sag (between km 100 and 140, see Fig. 9 in Peng et al. (2019)) was subdivided into 3 packages: T100 to T50, T50 to T40 and T40 to seafloor. ...
In this study, we explore the tectono-sedimentary and magma evolution of final rifting and continental breakup along the SW conjugate margins of the South China Sea (SCS). Based on new seismic observations, we define and map three rift domains, referred to as “box-shaped”, “wedging” and “proto-oceanic”. Each of these domains is characterized by: (1) the shape and thickness of the crust; (2) the specific architecture of the syn-rift mega-sequence that includes three system tracts each one including syn- and post-rift packages; and (3) different deformation styles.
Results
are synthetized in two Wheeler diagrams that provide a complete description of the tectono-magmatic and stratigraphic evolution of final rifting and breakup within two neighboring segments of the SW-SCS. We conclude that: 1) localization of deformation occurs simultaneous and perpendicular to the migration of magma-emplacement in front of a propagating spreading system, 2) the arrival of magma controls continental breakup, and 3) the final rifting stage and breakup are diachronous. The relationships between extension, sedimentation and magmatic processes observed in the SW-SCS differ significantly from the classical models derived from the N-Atlantic or the Alpine Tethys. Main differences include the way the crust is thinning/necking, the sharp transition to breakup and the style of magma emplacement linked to crustal breakup.
... Although competing theory (Kingston et al., 1983;Levell, 1987;Madon et al., 1999a;Milsom et al., 1997;Clift et al., 2008 and references therein) exists related to rifting and seafloor spreading of SCS, the tectonic and structural evolution of the study area and adjacent regions is relatively well understood from the various studies. Previous works on the rifting, tectonic evolution of Dangerous Grounds and seafloor spreading of SCS mainly focused on understanding the mechanism of the rift in the SCS (Kudrass et al., 1986;Milsom et al., 1997;Madon et al., 1999aMadon et al., , 2015Clift et al., 2008;Franke et al., 2014;Peng et al., 2019), major extension phases (Ding et al., 2013) in the Dangerous Grounds and surrounding areas. Tectonostratigraphic units and sequence boundaries in and around the current study area were also identified in previous studies (Ding et al., 2013;Chang et al., 2017;Peng et al., 2019) and development of widespread carbonate platform across the Dangerous Grounds has also been suggested. ...
... Previous works on the rifting, tectonic evolution of Dangerous Grounds and seafloor spreading of SCS mainly focused on understanding the mechanism of the rift in the SCS (Kudrass et al., 1986;Milsom et al., 1997;Madon et al., 1999aMadon et al., , 2015Clift et al., 2008;Franke et al., 2014;Peng et al., 2019), major extension phases (Ding et al., 2013) in the Dangerous Grounds and surrounding areas. Tectonostratigraphic units and sequence boundaries in and around the current study area were also identified in previous studies (Ding et al., 2013;Chang et al., 2017;Peng et al., 2019) and development of widespread carbonate platform across the Dangerous Grounds has also been suggested. Depositional environment interpretations work based on seismic, and dredge sample data (Hutchison and Vijayan, 2010;Steuer et al., 2014;Chang et al., 2017) were mainly limited to reef growth and carbonate platforms observed in and around Dangerous Grounds. ...
... In the Dangerous Grounds, Reed Bank, and adjacent areas during the initial rifting phase, major structures formed are grabens associated with high angle normal faults; large half-grabens formed controlled by listric faults and detachments; and presence of rotated fault blocks in the hyper-extended continental crust (Peng et al., 2019). The Sabah Basin, including the Dangerous Grounds, witnessed the deposition of thick clastic sedimentary succession as a result of uplift during Miocene and rapid erosion of the Sabah land massif under favourable climatic conditions, which resulted in the northwest progradation of deltas under regressive condition (Jong et al., 2014). ...
The onshore and shallow marine conventional hydrocarbon resources around the world are mostly at the maturation phase and hence, exploration activity globally, showing increasing interest into progressively deeper water hydrocarbon prospects such as South China Sea basins. However, a comprehensive understanding of basin tectonics, depositional history, and petroleum systems of the basin is required to deduce the exploration prospectivity of these deeper reservoirs. The Sabah Basin is a prolific hydrocarbon province in southeast Asia and has a significant economic impact on this part. Recent discoveries in the deep-water hydrocarbon prospects in the NW Sabah Trough prompted a comprehensive investigation of the surrounding area, e.g., Dangerous Grounds for hydrocarbon prospectivity. Previous studies in the Dangerous Grounds mainly focused on the sparse 2D seismic and gravity-magnetic data analysis. A systematic review of stratigraphic evolution has not been presented thus far in the published literature. In this paper, recently acquired high-resolution 3D seismic data with the core and cuttings and conventional well log data from the adjacent areas have been combined to characterize the stratigraphic evolution of the Dangerous Grounds in the NW Sabah platform. Seven horizons interpreted from the 7570 sq. km 3D seismic data, calibrated with the global sea level and geological time scale, to establish the stratigraphic evolution in the study area. Based on distinct structural and seismic characteristics, and calibrated with the adjacent regions well data, two mega-sequences, namely, lower syn-rift and upper post-rift mega-sequences, have been identified and evaluated. The Paleocene to Early Oligocene syn-rift sequence consists of clastic sedimentary fill in grabens and half-grabens is overlain by Late Oligocene to recent post-rift sedimentary successions represented by siliciclastic and carbonates deposits. Major depositional units within these two mega-sequences, including carbonate, channel, mass transport deposits, and turbidites, have been identified and evaluated. During Late Oligocene to Middle Miocene, the area has witnessed the deposition of carbonate platforms and reefs on top of pre-existing structural highs. Late Oligocene to Middle Miocene channel-levee complexes with convex upward sand filling features is prominent in the seismic data. Mass Transport Deposits and turbidites have also been observed above the Middle Miocene Unconformity with distinct seismic characteristics. The pelagic and hemipelagic nature of the sedimentary succession deposited from Pliocene to recent in a passive margin condition have also been interpreted from their unique seismic features. Paleocene-Early Oligocene syn-rift siliciclastic hydrocarbon play, Late Oligocene-Middle Miocene carbonate play, and Late Miocene turbidite play within the study area have been interpreted.
... The northeastern margin has been well studied, based on multichannel reflection seismic (MCS) data (Gao et al., 2015;Lüdmann and Wong, 1999;Li et al., 2008a,b;McIntosh et al., 2014), wide-angle reflection/refraction experiments Wang et al., 2006;Xia et al., 2018;Yan et al., 2001;Zhao et al., 2010), potential field data (Barckhausen and Roeser, 2004;Briais et al., 1993;Hsu et al., 2004) and international scientific drilling campaigns (Li et al., 2015;Jian et al., 2018;Sun et al., 2018;Wang et al., 2000). By contrast, much of the southeastern margin, despite of its geological and hydrocarbon significance, remains underexplored (Franke et al., 2011;Kudrass et al., 1986;Liu et al., 2014;Peng et al., 2019;Sales et al., 1997;Steuer et al., 2013;Williams, 1997). This paper focuses on the NW Palawan and Liyue Bank. ...
Late Cenozoic continental rifting and breakup separated the southern margin of the South China Sea (SCS) from the northern margin. It remains unknown whether the high-density/velocity zones (HVZs) in the lower crust extend southwards from the northeastern margin of the SCS to the conjugate southern margin. We integrated two newly acquired and processed multichannel seismic reflection profiles with gravity and magnetic data across the Liyue (Reed) Bank and north Palawan basin to clarify the characteristics of crustal structure and their relationship to post-rift magmatism. Our results show an asymmetric distribution of the HVZs in the conjugate margins. The lower crust anomalous reflections are isolated and mostly restricted in the areas of the ocean-continent transition (OCT) and the distal sag. In gravity modeling, the crustal thickness decreases from ~20 km in the proximal sag to a minimum of ~6 km in the distal sag, and these anomalous reflections spatially correspond to high-density zones no more than 4 km in thickness. The magmatic features are presented by igneous intrusions at the top of the basement that deform post-rift strata in the Early Miocene. These HVZs, above which the crustal stretching factor is 3.3-5.8, support that an anomalously hot asthenospheric mantle persisted during lithospheric thinning, resulting in magmatic underplating and density drop in the uppermost mantle during early breakup.
... Biostratigraphic analysis of dredged samples (Kudrass et al., 1986) confirmed that the oldest rocks present in the Dangerous Grounds area are Late Triassic to the Jurassic age. A recent study by Peng et al. (2019) proposed that the rift-drift transition in the Dangerous Grounds results in the creation of grabens during the initial phases of rifting with high angle normal faults, followed by half grabens controlled by listric faults, detachments and finally rotated fault blocks in the hyper-extended continental crust. ...
The Sabah Basin is a prolific hydrocarbon province in Southeast Asia and has a significant economic impact on this part. Recent discoveries in the deep-water hydrocarbon prospects in the northwest Sabah Trough prompted a comprehensive investigation of the surrounding area, e.g., Dangerous Grounds for hydrocarbon prospectivity. Previous studies in the Dangerous Grounds mainly focused on the sparse 2D seismic and gravity-magnetic data analysis. A systematic review of detailed depositional history has not been presented so far in the published literature. To achieve this, recently acquired high-resolution 3D seismic data and well information has been used for seismic attribute analysis to establish the structural features and depositional pattern from the Paleocene to recent age. Two major sedimentary sequences have been evaluated from the seismic data, which include syn-rift and post-rift sequence. The pre-rift sequence considered to be acoustic basement is overlain by syn-rift sequence, deposited during the Paleocene to Early Oligocene age. Spectral decomposition analysis demarcates paleo-lows /depocenters, consist of siliciclastic sedimentary fills in grabens and half grabens with the syn-sedimentary deformation. Geobody interpretation helps to understand the different phases of syn-sedimentary faulting with the presence of antithetic faults in the grabens. Late Oligocene to Middle Miocene carbonate platform and reefs has been observed on top of the pre-existing structural highs. Sweetness attributes enable to appraise the reef structure to demarcate lithofacies boundaries. Variance and amplitude extraction maps reveal the development of reefs on top of the carbonate platform. Amplitude extraction map reflects the Late Oligocene to Middle Miocene channel-levee complex with the convex upward unconsolidated sand filling pattern. Sweetness map helps to delineate the meandering channel boundary, channel geomorphology with ox-bow lake, point bar, and west to east channel shifting. Carbonate and clastic dominated areas have been differentiated in the southwest part. Slides and debris flow Mass Transport Deposits, Late Miocene turbidites have been observed above the Middle Miocene Unconformity and evaluated based on their distinct seismic characteristics. During the Pliocene to recent, the basin has witnessed the deposition of thick pelagic-hemipelagic sediments in the outer-neritic to the bathyal environment in the passive margin condition.
... Along the southern margin, rifting in the southwestern section lasted longer than in the east, creating more intensive extension (Hayes and Nissen, 2005). Similar to the fault development in the Liyue Basin (Fig. 6), high-angle normal faults are common in the southern margin, accompanied by widespread grabens and half-grabens that are filled with wedge-shaped syn-rift sequences (Hutchison and Vijayan, 2010;Peng et al., 2018;Tong et al., 2019). Deeply rooted detachment faults were also found in places, soling out within the middle crust (Ding et al., 2013). ...
... Table 2 lists dredge samples of igneous rocks from the southern margin of the SCS (Kudrass et al., 1986;Yan et al., 2010). The sample locations are shown in Fig. 2. In addition, magmatic activity was identified in boreholes (Areshev et al., 1992;Holloway, 1982;Pupilli, 1973) and seismic profiles (Chang et al., 2017;Li et al., 2013;Peng et al., 2018). ...
... The mean crustal thickness in Dangerous Ground is 15 to 20 km based on deep seismic, refraction and gravity inversion (Ding et al., 2013;Pichot et al., 2014;Wei et al., 2015;Peng et al., 2018;Gozzard et al., 2018). The area thus remained remote from the main zones of extreme stretching/necking that lead to oceanic spreading in the South China Sea basins. ...
... In Figure 10, step 2, at variance with many studies in the area (e.g. Ding et al., 2013;Song & Li, 2015;Peng et al. 2018), we do not interpret the sedimentary unit just above the acoustic basement (Tg) in basins A/B as the main syn-rift, as already suggested by Wang et al. (2016). ...
... Two recent studies (Wang et al. 2016;Peng et al., 2018) have interpreted seismic profiles acquired close to ours. In Wang et al. (2016), sedimentary units below the erosive surface found within basins A and B (dashed red on Figure 5) are all interpreted as being Mesozoic. ...
We investigate the crustal structure of the Dangerous Ground (South China Sea) through processing and interpretation of coincident wide‐angle reflection and refraction seismic data. Continental crust of Dangerous Ground has been moderately thinned, down to 15 km, so that most of the structures accompanying the early opening of the South China Sea from Cretaceous to Miocene have been preserved. Subbasement reflectors as well as refraction velocities image an interpreted dismantled Mesozoic metamorphic unit in the southernmost section of our study area. A rollover structure indicates that the reflective base of the unit was used as a décollement where low‐angle normal faults root and blocks rafted. The metamorphic unit is discontinued in a nearby basin located immediately to the north, where the refraction velocity model shows thinning of the crust from 20 to 15 km, with the presence of a 5‐km‐high mantle dome. In this deeper basin, mass transport deposits are found lying on a strong amplitude basement reflector interpreted as the footwall of an ~15 km offset crustal detachment surface that we link down to the mantle dome. We infer that the detachment reactivated an inherited low‐angle contact most probably related to the Yanshanian belt. In map view, the reactivated structure forms a half‐graben basin oriented NNE‐SSW oblique to the generally accepted direction of extension. This orientation follows the general trend of a granitic belt that spanned the South China margin prior to extension, related to the subduction of the Paleo‐Pacific.
... More specifically, the depressions in the northern Pearl River Mouth Basin were characterized by the massive fluvial facies, because of the birth of small-scale Palaeo-Pearl River confirmed by seismic data and detrital provenance analysis Pang et al., 2009;, whereas the southern part of the Pearl River Mouth Basin and farther south to the continental-oceanic boundary mainly deposited the deltaic-lacustrine-littoral-neritic facies, where sediments were supplied from multiple provenance areas and potential influences from local uplifts are readily observable (C. Liu, Clift, et al., 2017;Shao et al., 2016; Bank (Peng, Shen, Mei, Zhao, & Xie, 2018;Steuer et al., 2014;Tong et al., 2019). To the western part of Dangerous Grounds, the Late Eocene-Early Oligocene Wan'an Basin was characterized by large-scale deltaic sequences, while the Nanweixi Basin featured the continental and transitional facies. ...
