Formation and evolution of Precambrian continental lithosphere in South China

2013 ◽  
Vol 23 (4) ◽  
pp. 1241-1260 ◽  
Author(s):  
Shao-Bing Zhang ◽  
Yong-Fei Zheng
Keyword(s):  
South China ◽  
Continental Lithosphere ◽  
Formation And Evolution

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

Magnetotelluric imaging of a fossil oceanic plate in northwestern Xinjiang, China

Geology ◽  
2020 ◽  
Vol 48 (4) ◽  
pp. 385-389 ◽  
Author(s):  
Y.X. Xu ◽  
B. Yang ◽  
A.Q. Zhang ◽  
S.C. Wu ◽  
L. Zhu ◽  
...  
Keyword(s):  
Subcontinental Lithospheric Mantle ◽  
Oceanic Plate ◽  
Continental Lithosphere ◽  
Magnetotelluric Data ◽  
Long Period ◽  
Continental Plate ◽  
Formation And Evolution ◽  
Magnetotelluric Imaging ◽  
Plate Subduction ◽  
Continental Accretion

Abstract Because an oceanic plate colliding with a continental plate will usually be subducted and recycled into the deep mantle, a fossil oceanic plate after the closure of an ancient ocean has rarely been imaged in the subcontinental lithospheric mantle. This has led to a long-standing debate about the fate of subducted ocean plates. The problem can be addressed by imaging the lithosphere in a continental accretion zone with past ocean subduction. We present a study using long-period magnetotelluric data that reveals a large shallow-mantle conductor in a Phanerozoic accretion area in northwestern Xinjiang, China. This conductor extends >300 km laterally at depths from 120 to 220 km and resembles a segment of a fossil oceanic plate. The reduced resistivity is ascribed to the volatile-bearing metasomatic minerals, based on its relatively fertile nature and low temperature. Our results demonstrate that an oceanic plate can be trapped in continental lithosphere, underscoring the significance of oceanic plate subduction to continental accretion, and shedding new light on our understanding of continental 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.

Syn-collisional magmatic record of Indian steep subduction by 50 Ma

2020 ◽  
Author(s):  
Yue Qi ◽  
Chris J. Hawkesworth ◽  
Qiang Wang ◽  
Derek A. Wyman ◽  
Zheng-Xiang Li ◽  
...  
Keyword(s):  
High Volume ◽  
Isotope Ratios ◽  
Eastern Himalaya ◽  
Continental Lithosphere ◽  
Southern Tibet ◽  
Geochemical Composition ◽  
Crustal Rocks ◽  
Continental Subduction ◽  
Magmatic Rocks ◽  
Formation And Evolution

Subduction of Indian continental lithosphere during the Asia-India collision played an important role in the formation and evolution of the Himalaya-Tibetan orogen. However, the geometry of early Indian continental subduction remains debated. Given that the Indian continent is characterized by enriched isotope ratios (87Sr/86Sr > 0.730, εNd(t) < −10), relative to those in subducted oceanic materials (87Sr/86Sr < 0.704, εNd(t) ≈ +8), changes in the composition of magmatic rocks with time, in particular their radiogenic isotope ratios, is used to constrain the timing and nature of continental subduction. This study reports the field relations, zircon U-Pb ages and geochemical composition of a syn-collisional batholith that crosscuts the central Indus-Yarlung Zangbu suture in the Saga area of southern Tibet. Zircon U/Pb ages for the batholith mainly range from 50 to 46 Ma. Samples from the Lopu Range batholith have enriched zircon Hf (εHf(t) = −0.4 to −8.6) and whole rock 87Sr/86Sri = 0.7094−0.7121 and εNd(t) = −7.3 to −9.8, suggesting that they were derived from a mixture of juvenile Gangdese and isotopically enriched Indian crustal materials. This result indicates that subduction of Indian crustal rocks occurred before 50 Ma in the central Himalaya. The geochemical composition and distribution of high volume ca. 51 Ma magmatism in the Gangdese belt, combined with thermal models of the subduction zone, suggests a steepening of the subducted Indian continental lithosphere occurred between the onset of India-Asia collision (59 Ma) and 46 Ma in the central-eastern Himalaya.

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