scholarly journals Formation and Evolution of a Magmatic System in a Rifting Continental Margin: Neoproterozoic Arc- and MORB-like Dike Swarms in South China

2018 ◽  
Vol 59 (9) ◽  
pp. 1811-1844 ◽  
Author(s):  
Jun-Hong Zhao ◽  
Paul D Asimow
Keyword(s):  
Continental Margin ◽  
South China ◽  
Magmatic System ◽  
Formation And Evolution ◽  
Dike Swarms

Nature and origin of the volcanic ash beds near the Permian–Triassic boundary in South China: new data and their geological implications

2019 ◽  
Vol 157 (4) ◽  
pp. 677-689 ◽  
Author(s):  
Binsong Zheng ◽  
Chuanlong Mou ◽  
Renjie Zhou ◽  
Xiuping Wang ◽  
Zhaohui Xiao ◽  
...  
Keyword(s):  
Trace Element ◽  
Continental Margin ◽  
South China ◽  
Volcanic Ash ◽  
Active Continental Margin ◽  
Main Body ◽  
Early Triassic ◽  
Late Permian ◽  
Triassic Boundary ◽  
Permian Triassic Boundary

AbstractPermian–Triassic boundary (PTB) volcanic ash beds are widely distributed in South China and were proposed to have a connection with the PTB mass extinction and the assemblage of Pangea. However, their source and tectonic affinity have been highly debated. We present zircon U–Pb ages, trace-element and Hf isotopic data on three new-found PTB volcanic ash beds in the western Hubei area, South China. Laser ablation inductively coupled plasma mass spectrometry U–Pb dating of zircons yields ages of 252.2 ± 3.6 Ma, 251.6 ± 4.9 Ma and 250.4 ± 2.4 Ma for these three volcanic ash beds. Zircons of age c. 240–270 Ma zircons have negative εHf(t) values (–18.17 to –3.91) and Mesoproterozoic–Palaeoproterozoic two-stage Hf model ages (THf2) (1.33–2.23 Ga). Integrated with other PTB ash beds in South China, zircon trace-element signatures and Hf isotopes indicate that they were likely sourced from intermediate to felsic volcanic centres along the Simao–Indochina convergent continental margin. The Qinling convergent continental margin might be another possible source but needs further investigation. Our data support the model that strong convergent margin volcanism took place around South China during late Permian – Early Triassic time, especially in the Simao–Indochina active continental margin and possibly the Qinling active continental margin. These volcanisms overlap temporally with the PTB biocrisis triggered by the Siberian Large Igneous Province. In addition, our data argue that the South China Craton and the Simao–Indochina block had not been amalgamated with the main body of Pangea by late Permian – Early Triassic time.

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

2021 ◽  
Author(s):  
Fang Zhao ◽  
Christian Berndt ◽  
Tiago M. Alves ◽  
Shaohong Xia ◽  
Lin Li ◽  
...  
Keyword(s):  
South China Sea ◽  
Continental Margin ◽  
South China ◽  
Hydrothermal Vents ◽  
Northern South China Sea ◽  
Contact Metamorphism ◽  
Magnetic Data ◽  
Geochemical Data ◽  
Time Interval ◽  
China Sea

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.

Cenozoic tectonic subsidence in the southern continental margin, South China Sea

2016 ◽  
Vol 11 (2) ◽  
pp. 427-441 ◽  
Author(s):  
Penggao Fang ◽  
Weiwei Ding ◽  
Yinxia Fang ◽  
Zhongxian Zhao ◽  
Zhibing Feng
Keyword(s):  
South China Sea ◽  
Continental Margin ◽  
South China ◽  
Tectonic Subsidence ◽  
China Sea

The formation and evolution of the paleo-Pearl River and its influence on the source of the northern South China sea

2019 ◽  
Vol 106 ◽  
pp. 171-189
Author(s):  
Ming Ma ◽  
Guojun Chen ◽  
Chengfu Lyu ◽  
Gongcheng Zhang ◽  
Chao Li ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Northern South China Sea ◽  
Pearl River ◽  
China Sea ◽  
Formation And Evolution

Petrogenesis of Silurian ultramafic–mafic plutons in southern Jiangxi: implications for the Wuyi–Yunkai orogen, South China

2020 ◽  
pp. 1-16
Author(s):  
Jie Yang ◽  
Wei Liu ◽  
Zuozhen Han ◽  
Zuoxun Zeng ◽  
Le Wan ◽  
...  
Keyword(s):  
South China ◽  
Lithospheric Mantle ◽  
First Episode ◽  
Jiangxi Province ◽  
South China Block ◽  
The South ◽  
Mafic Rocks ◽  
Formation And Evolution ◽  
Early Palaeozoic ◽  
T Values

Abstract The South China Block is one of the largest continental blocks located on the East Asian continent. The early Palaeozoic Wuyi–Yunkai orogen of the South China Block (known as the Caledonian orogen in Europe) is a major orogenic belt in East Asia and represents the first episode of extensive crustal reworking since Neoproterozoic time. Although this orogen is key to deciphering the formation and evolution of the South China Block, details about the orogen remain poorly defined. The Songshutang and Wushitou ultramafic–mafic units in southern Jiangxi Province, South China, have 206Pb–238U ages of c. 437 Ma, suggesting a Silurian formation age. All the Songshutang and Wushitou ultramafic–mafic rocks show relatively flat chondrite-normalized rare earth element patterns, depletions in Nb, Ta, Zr, Hf and Ti, and low ϵNd(t) values from −9.12 to −5.49 with negative zircon ϵHf(t) values from −10.84 to −2.58, resembling a typical arc magma affinity. Geochemical and isotopic data indicate that the newly identified ultramafic–mafic rocks, along with the reported Silurian mafic rocks in South China, possibly originated from the similar partial melting of an ancient subducted slab, fluid/sediment and metasomatized lithospheric mantle with varying degrees of fractional crystallization. In conjunction with other records of magmatism and metamorphism in South China, a late-orogenic extensional event led to the melting of the sub-continental lithospheric mantle in Silurian time and generated ultramafic–mafic rocks with a limited distribution along the Wuyi–Yunkai orogen and widespread late-orogenic granitic plutons in the South China Block.

scholarly journals South China Sea documents the transition from wide continental rift to continental break up

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Hongdan Deng ◽  
Jianye Ren ◽  
Xiong Pang ◽  
Patrice F. Rey ◽  
Ken R. McClay ◽  
...  
Keyword(s):  
South China Sea ◽  
Continental Margin ◽  
South China ◽  
North American ◽  
Continental Rift ◽  
Continental Breakup ◽  
North American Cordillera ◽  
China Sea ◽  
The North ◽  
Continental Rifts

Abstract During extension, the continental lithosphere thins and breaks up, forming either wide or narrow rifts depending on the thermo-mechanical state of the extending lithosphere. Wide continental rifts, which can reach 1,000 km across, have been extensively studied in the North American Cordillera and in the Aegean domain. Yet, the evolutionary process from wide continental rift to continental breakup remains enigmatic due to the lack of seismically resolvable data on the distal passive margin and an absence of onshore natural exposures. Here, we show that Eocene extension across the northern margin of the South China Sea records the transition between a wide continental rift and highly extended (<15 km) continental margin. On the basis of high-resolution seismic data, we document the presence of dome structures, a corrugated and grooved detachment fault, and subdetachment deformation involving crustal-scale nappe folds and magmatic intrusions, which are coeval with supradetachment basins. The thermal and mechanical weakening of this broad continental domain allowed for the formation of metamorphic core complexes, boudinage of the upper crust and exhumation of middle/lower crust through detachment faulting. The structural architecture of the northern South China Sea continental margin is strikingly similar to the broad continental rifts in the North American Cordillera and in the Aegean domain, and reflects the transition from wide rift to continental breakup.

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