Geochronology, geochemistry, and Sr-Nd isotopes of Early Carboniferous magmatism in southern West Junggar, northwestern China: Implications for Junggar oceanic plate subduction

2021 ◽  
Author(s):  
Pengde Liu ◽  
Xijun Liu ◽  
Wenjiao Xiao ◽  
Zhiguo Zhang ◽  
Yujia Song ◽  
...  
Keyword(s):  
Early Carboniferous ◽  
Northwestern China ◽  
Oceanic Plate ◽  
Nd Isotopes ◽  
West Junggar ◽  
Plate Subduction

Early Carboniferous Paleo-Asian oceanic plate subduction: Implications from geochronology and geochemistry of early Carboniferous magmatism in southern West Junggar, NW China 

2021 ◽  
Author(s):  
Pengde Liu ◽  
Xijun Liu ◽  
Zhiguo Zhang ◽  
Yujia Song ◽  
Yao Xiao ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Partial Melting ◽  
Early Carboniferous ◽  
Orogenic Belt ◽  
Island Arc ◽  
Spinel Lherzolite ◽  
Oceanic Plate ◽  
Island Arcs ◽  
West Junggar

<p>    The subduction and closure of the Paleo-Asia Ocean generated the Central Asian Orogenic Belt (CAOB), which extends from the Urals in the west through Kazakhstan, northwestern China, Mongolia, and northeastern China to the Russian Far East. It is generally accepted that the CAOB comprises a complicated and varied collage of terranes, including island arcs, ophiolites, accretionary prisms, seamounts, and microcontinents. The CAOB is the world’s largest accretionary orogen and is also considered a type area for studying Phanerozoic continental growth. The accretionary processes of the orogen might have resulted from either the progressive duplication of a single and long-lived island-arc system or the collision of several island arcs and micro-continents, similar to the complex archipelago systems in the modern southwestern Pacific. West Junggar is located in a key area of the CAOB, has been a focus of studies of the tectonic evolution and crustal growth of the orogenic belt. West Junggar has been considered by some geologists as a paleo-Asian intra-oceanic subduction system, whereas others have variously argued that West Junggar was formed by single subduction, arc–arc collision, or ridge subduction, or by post-collisional processes after the early Carboniferous. An understanding of the Carboniferous tec-tonic setting is critical for determining the evolution of West Junggar. A series of early Carboniferous volcanic and intrusive rocks occur in the southern West Junggar. Our new zircon U–Pb geochronological data reveal that diorite intruded at 334.1 ± 1.1 Ma, and that basaltic andesite was erupted at 334.3 ± 3.7 Ma. These intrusive and volcanic rocks are calc-alkaline, display moderate MgO (1.62–4.18 wt.%) contents and Mg# values (40–59), low Cr (14.5–47.2 ppm) and Ni (7.5–34.6 ppm) contents, and are characterized by enrichment in light rare-earth elements and large-ion lithophile elements and depletion in heavy rare-earth elements and high-field-strength elements, meaning that they belong to typical subduction-zone island-arc magma. The rocks show low initial <sup>87</sup>Sr/<sup>86</sup>Sr ratios (0.703649 to 0.705008), positive Ɛ<sub>Nd(t) </sub>values (+4.8 to +6.2, mean +5.4), and young T<sub>DM</sub> Nd model ages ranging from 1016 to 616 Ma, indicating a magmatic origin from depleted mantle involving partial melting of 10%–25% garnet and spinel lherzolite. Combining our results with those of previous studies, we suggest that these rocks formed as a result of northwestward subduction of the Paleo-Asian Junggar oceanic plate, which caused partial melting of sub-arc mantle. We conclude that intra-oceanic arc magmatism was extensive in southern Paleo-Asian Ocean during the early Carboniferous.</p><p>This study was financially supported by the National Natural Science Foundation of China (41772059) and the CAS “Light of West China” Program (2018-XBYJRC-003).</p>

Geology and geochemistry of pillow basalt in the Huilvshan region (west Junggar, China): implications for magma source and tectonic setting

2018 ◽  
Vol 55 (12) ◽  
pp. 1339-1353
Author(s):  
Huichao Zhang ◽  
Yongfeng Zhu
Keyword(s):  
Tectonic Setting ◽  
Weighted Average ◽  
Early Carboniferous ◽  
Tectonic Activity ◽  
Chromian Spinel ◽  
Magma Source ◽  
Spinel Lherzolite ◽  
Pillow Basalt ◽  
Depleted Mantle ◽  
West Junggar

Geological characteristics and geochemical analyses are reported for the early Carboniferous pillow basalt in the Huilvshan region (west Junggar, Northwest China), with the aim to indicate its petrogenesis, magma source characteristics, and tectonic implication. This pillow basalt consists of clinopyroxene and plagioclase with trace amounts of magnetite, apatite, and chromian spinel. It is tholeiitic in composition with low concentrations of Na2O + K2O (1.52–4.74 wt.%). Similar to the N-MORB, the samples of this pillow basalt have nearly flat chondrite-normalized REE patterns ((La/Yb)N = 0.87–1.47) with insignificant Eu anomalies (Eu/Eu* = 0.84–1.18), and show no obvious enrichments of LILEs and insignificant depletions in HFSEs. Petrology and geochemical characteristics suggest that this pillow basalt is the product of MORB-like magma derived from a depleted mantle corresponding to ≤4% partial melting of spinel lherzolite. SIMS analysis of the zircons separated from tuff interlayered with basalt gives a weighted average U–Pb age of 328 ± 3 Ma (MSWD = 1.4), which represents the magma eruption time in the Huilvshan region. From these observations, in combination with the previous work, we conclude that an extensional tectonic regime dominated the tectonic activity of west Junggar during early Carboniferous.

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.

Early Carboniferous intra-oceanic arc and back-arc basin system in the West Junggar, NW China

2013 ◽  
Vol 55 (16) ◽  
pp. 1991-2007 ◽  
Author(s):  
Ping Shen ◽  
Hongdi Pan ◽  
Wenjiao Xiao ◽  
Xian-hua Li ◽  
Huawu Dai ◽  
...  
Keyword(s):  
Early Carboniferous ◽  
The West ◽  
Nw China ◽  
West Junggar ◽  
Back Arc ◽  
Basin System

Geochemistry and tectonic implications of the Early Carboniferous Keketuobie intrusion in the West Junggar foldbelt, NW China

2018 ◽  
Vol 159 ◽  
pp. 142-154
Author(s):  
Yu-Feng Deng ◽  
Feng Yuan ◽  
Taofa Zhou ◽  
Pete Hollings ◽  
Dayu Zhang
Keyword(s):  
Early Carboniferous ◽  
The West ◽  
Nw China ◽  
Tectonic Implications ◽  
West Junggar

Early Carboniferous volcanic rocks of West Junggar in the western Central Asian Orogenic Belt: implications for a supra-subduction system

2014 ◽  
Vol 56 (7) ◽  
pp. 823-844 ◽  
Author(s):  
Gaoxue Yang ◽  
Yongjun Li ◽  
Inna Safonova ◽  
Shanxin Yi ◽  
Lili Tong ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Early Carboniferous ◽  
Orogenic Belt ◽  
Central Asian Orogenic Belt ◽  
Central Asian ◽  
West Junggar ◽  
Subduction System

Petrogenesis and tectonic implications of early Carboniferous alkaline volcanic rocks in Karamay region of West Junggar, Northwest China

2016 ◽  
Vol 58 (10) ◽  
pp. 1278-1293 ◽  
Author(s):  
Gaoxue Yang ◽  
Yongjun Li ◽  
Lili Tong ◽  
Ganyu Li ◽  
Le Wu ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Early Carboniferous ◽  
Northwest China ◽  
Tectonic Implications ◽  
West Junggar

Oceanic plate subduction history in the western Pacific Ocean: Constraint from late Mesozoic evolution of the Tan-Lu Fault Zone

2018 ◽  
Vol 61 (4) ◽  
pp. 386-405 ◽  
Author(s):  
Guang Zhu ◽  
Cheng Liu ◽  
Chengchuan Gu ◽  
Shuai Zhang ◽  
Yunjian Li ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Fault Zone ◽  
Western Pacific ◽  
Western Pacific Ocean ◽  
Oceanic Plate ◽  
Late Mesozoic ◽  
The Western Pacific ◽  
Plate Subduction

Phanerozoic accretionary history of Japan and the western Pacific margin

2018 ◽  
Vol 158 (1) ◽  
pp. 13-29 ◽  
Author(s):  
Koji Wakita ◽  
Takanori Nakagawa ◽  
Masahiro Sakata ◽  
Natsuki Tanaka ◽  
Nozomu Oyama
Keyword(s):  
North China ◽  
Japan Sea ◽  
Detrital Zircons ◽  
Oceanic Plate ◽  
The South ◽  
The North ◽  
Before And After ◽  
History Of ◽  
Japanese Islands ◽  
Plate Subduction

AbstractIt is generally accepted that oceanic plate subduction has occurred along the eastern margin of Asia since about 500 Ma ago. Therefore, the Japanese Islands have a >500 Ma history of oceanic plate subduction in their geological records. In this paper, the accretionary history of the Japanese Islands is divided into six main stages based on the mode and nature of tectonic events and the temporal gaps in the development of accretionary processes. In the first stage, oceanic plate subduction and accretion started along the margin of Gondwana. After detachment of the North and South China blocks in Devonian time, accretionary complexes developed along island arcs offshore of the South and North China blocks. After the formation of back arc basins such as the Japan Sea, accretionary processes occurred only along the limited convergent margin, e.g. Nankai Trough. Detrital zircons of sandstones revealed the accretionary history of Japan. An evaluation of a comprehensive dataset on detrital zircon populations shows that the observed temporal gaps in the development of the Japanese accretionary complexes were closely related to the intensity of igneous activity in their provenance regions. Age distributions of detrital zircons in the accretionary complexes of Japan change before and after the Middle Triassic period, when the collision of the South and North China blocks occurred.

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