The basement and volcanic activities of the Xisha Islands: Evidence from the kilometre‐scale drilling in the northwestern South China Sea

Zhang, Yu; Yu, Kefu; Qian, Handong; Fan, Tianlai; Yue, Yuanfu; Wang, Rui; Jiang, Wei; Xu, Shendong; Wang, Yinghui

doi:10.1002/gj.3416

Cited by 22 publications

(22 citation statements)

References 84 publications

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“…5-7). Our interpretation that significant volcanism occurred during the Neogene is also supported by radiometric dating of onshore and offshore volcanic rocks along the northern South China Sea (Tu et al, 1992;Zou et al, 1993;Hoang and Flower, 1998;Yan et al, 2006;Wang et al, 2012;Xu et al, 2012;Yan et al, 2014;Zhao et al, 2016;Zhang et al, 2020). Offshore, early Neogene volcanism is equally supported by Pliocene to early Miocene basalts drilled in the Taixinan Basin, Pearl River Mouth Basin, Zhongjiannan Basin, Xisha High and offshore Vietnam (Fig.…”

Section: Timing Of Magmatic-hydrothermal Activitysupporting

confidence: 72%

“…Exploration wells BY2, BY7-1, CK2 and 121-CM-1X, drilled in the study area, penetrated volcanic rocks adjacently to the study area (Shao et al, 2007;Fyhn et al, 2009;Zhao et al, 2016;Zhang et al, 2020). Based on a dominant seismic frequency of 35 Hz in the interval with igneous sills, and an assumed interval velocity of 5500 m/s (Jackson et al, 2012;Magee et al, 2013), we estimate that igneous sills thicker than 39 m are resolved in our seismic data.…”

Section: Methodsmentioning

confidence: 80%

“…6 and 8). Well CK2, which penetrated basement rocks, encountered Late Oligocene (∼35.5 Ma) to Early Miocene (∼19.6 Ma) pyroclastic basalts based on radiocarbon dates (Zhang et al, 2020). Surrounding the volcanoes, sub-parallel stacked strong amplitude anomalies are observed (Figs.…”

Section: Interpretation Of Magmatic Bodiesmentioning

confidence: 99%

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Widespread hydrothermal vents and associated volcanism record prolonged Cenozoic magmatism in the South China Sea

et al. 2021

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The continental margin of the northern South China Sea is considered to be a magma-poor rifted margin. This work uses new seismic, bathymetric, gravity, and magnetic data to reveal how extensively magmatic processes have reshaped the latter continental margin. Widespread hydrothermal vent complexes and magmatic edifices such as volcanoes, igneous sills, lava flows, and associated domes are confirmed in the broader area of the northern South China Sea. Newly identified hydrothermal vents have crater- and mound-shaped surface expressions, and occur chiefly above igneous sills and volcanic edifices. Detailed stratigraphic analyses of volcanoes and hydrothermal vents suggest that magmatic activity took place in discrete phases between the early Miocene and the Quaternary. Importantly, the occurrence of hydrothermal vents close to the present seafloor, when accompanied by shallow igneous sills, suggest that fluid seepage is still active, well after main phases of volcanism previously documented in the literature. After combining geophysical and geochemical data, this study postulates that the extensive post-rift magmatism in the northern South China Sea is linked to the effect of a mantle plume over a long time interval. We propose that prolonged magmatism resulted in contact metamorphism in carbon-rich sediments, producing large amounts of hydrothermal fluid along the northern South China Sea. Similar processes are expected in parts of magma-poor margins in association with CO2/CH4 and heat flow release into sea water and underlying strata.

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Section: Timing Of Magmatic-hydrothermal Activitysupporting

confidence: 72%

Section: Methodsmentioning

confidence: 80%

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Widespread hydrothermal vents and associated volcanism record prolonged Cenozoic magmatism in the South China Sea

et al. 2021

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“…3. Stratigraphic column of the northwestern South China Sea continental margin (modified after Fyhn et al, 2009a;Fyhn et al, 2013;Zhang et al, 2019) showing regional unconformities and lithostratigraphic units. Fyhn et al, 2013;Vu et al, 2017) (Fig.…”

Section: Geological Settingsmentioning

confidence: 99%

Distribution, Seismic Characteristics and Controlling Factors of Carbonate Platforms on the Northwestern Margin of the South China Sea

Li¹,

Wang²,

Yang³

et al. 2021

Acta Geologica Sinica (Eng)

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Carbonate platforms are recognised from seismic data all over the world, mainly developing in tropical and subtropical settings (Wu et al., 2014). Carbonate platforms are large tabular bodies of shallow-marine limestone and dolostone that can survive in the geological record for billions of years (Fralick and Riding, 2015). Their architecture is influenced by a combination of tectonics, eustasy, oceanography and climatic conditions, that cause complex variations in platform morphology (e.g, ramp, steep-sloped platform, or bypass escarpment) and internal facies distribution (

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“…The basaltic pyroclastic rocks have conformable contacts with underlying carbonate rocks. Zircon U-Pb ages suggest that the basaltic pyroclastic rocks were deposited as early as 35.5 ± 0.9 Ma [57]. The volcanic clastic rocks contain a small number of marine bioclastic fossils, sometimes with reef limestone breccia.…”

Section: Introductionmentioning

confidence: 99%

LA-ICP-MS Analysis of Clinopyroxenes in Basaltic Pyroclastic Rocks from the Xisha Islands, Northwestern South China Sea

Zhang

Qian

2018

Minerals

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Cenozoic volcanic rocks were recently discovered during full-coring kilometer-scale major scientific drilling in the Xisha Islands, northwestern South China Sea. A systematic mineralogical study of these samples was performed for this paper. The results show that the volcanic rock samples are basaltic pyroclastic. The major elements demonstrate that the clinopyroxenes are diopside and fassaite, which contain high Al 2 O 3 (5.33-11.2 wt. %), TiO 2 (2.13-4.78 wt. %) and wt. %). Clinopyroxenes have high REE abundances (104-215 ppm) and are strongly enriched in LREE (LREE/HREE = 3.56-5.14, La/Yb N = 2.61-5.1). Large-ion lithophile elements show depleted characteristics. Nb/Ta shows obvious fractionation features: Nb is lightly enriched, relative to primitive mantle, but Ta is heavily depleted, relative to primitive mantle. The parental magma of the basaltic pyroclastic rocks belongs to a silica-undersaturated alkaline series, characterized by a high temperature, low pressure, and low oxygen fugacity. The Al IV content increases with decreasing Si concentration. The Si-unsaturated state causes Si-Al isomorphic replacement during the formation of clinopyroxene. The electric charge imbalance caused by the replacement of Si by Al is mainly compensated by Fe 3+ . The clinopyroxene discrimination diagrams show that the parental magma formed in an intraplate tectonic setting environment.The mineral composition of igneous rocks depends on the chemical composition and crystallization environment of magma. Changes in mineral composition and structure are direct evidence of changes in the diagenetic environment and material composition. Therefore, the characteristics of mineral composition can be used to explore mineral petrogenesis and the magma evolution mechanism [18]. Clinopyroxene is one of the main rock-forming minerals of mafic-ultramafic rocks and plays a major role in the generation and subsequent differentiation of magma [16,[19][20][21][22][23][24]. Clinopyroxene composition mainly depends on primary magma characteristics, the crystallization environment, and the tectonic setting of magmatism [25][26][27][28][29][30][31][32]. Relative to other minerals in mafic-ultramafic rocks, clinopyroxene is considered to be the main carrier for most trace elements and holds a unique further record of magma history [33,34]. The mineral chemistry of relict clinopyroxene in igneous rocks can reflect the characteristics of the primary magma well and has been widely used to study the nature of the original magma and complicated processes that have affected the lithospheric mantle [21,[35][36][37][38][39][40][41][42]. Furthermore, clinopyroxenes in altered basalts are of interest, because they often survive in a relatively pristine form, after the matrix and other minerals have been converted to secondary minerals. The major-and minor-element geochemistry of clinopyroxene is varied and provides a filtered view of the composition of the magma from which the clinopyroxene crystallized, lending it the potential to provide insight into t...

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The basement and volcanic activities of the Xisha Islands: Evidence from the kilometre‐scale drilling in the northwestern South China Sea

Cited by 22 publications

References 84 publications

Widespread hydrothermal vents and associated volcanism record prolonged Cenozoic magmatism in the South China Sea

Widespread hydrothermal vents and associated volcanism record prolonged Cenozoic magmatism in the South China Sea

Distribution, Seismic Characteristics and Controlling Factors of Carbonate Platforms on the Northwestern Margin of the South China Sea

LA-ICP-MS Analysis of Clinopyroxenes in Basaltic Pyroclastic Rocks from the Xisha Islands, Northwestern South China Sea

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