The Zhaheba ophiolite complex in Eastern Junggar (NW China): Long lived supra-subduction zone ocean crust formation and its implications for the tectonic evolution in southern Altaids

Luo, Jun; Xiao, Wenjiao; Wakabayashi, John; Han, Chunming; Zhang, Jien; Wan, Bo; Ao, Songjian; Zhang, Zhiyong; Tian, Zhonghua; Song, Dongfang; Chen, Yichao

doi:10.1016/j.gr.2015.04.004

Cited by 46 publications

(29 citation statements)

References 70 publications

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“…The 206 Pb/ 238 U ages range from 415 to 500 Ma (Figure 8b). The youngest zircon U-Pb age is 415 ± 8 Ma, which is consistent with the age of the rhyolite (Du & Chen, 2017;Luo et al, 2017;Yang et al, 2018).…”

Section: Other Rock Associationssupporting

confidence: 79%

“…The andesite from northwest of the Hebukesaier ophiolite mélange has a concordant age of 326 ± 2 Ma (Chen et al, 2017b), which represents the time of major activity of the Saur Arc. The turbidite (16-EM-150) from the eastern part of the Saur area has detrital zircon ages ranging from 333 to 402 Ma with the predominant zircon peak of 350-360 Ma, consistent with the period of major magmatic activity of the Saur Arc (Chen et al, 2017b;Han et al, 2006;Luo et al, 2017;Yin et al, 2015;Yuan et al, 2007). These detrital zircon ages are different from those dating the magmatic activity of the Chingiz Arc, which was active from late Silurian to early Devonian times (Chen et al, 2010;Shen et al, 2012;Yin et al, 2017), and the 410-430 Ma peak is absent in the sediments in the Saur area.…”

Section: The Boundary Between the Chingiz And Saur Arcsmentioning

confidence: 86%

“…In the southern segment of the mélange, the serpentinite is widely distributed, heavily weathered and foliated ( Figure 2a). The serpentinite ( Figure 3c) contains relics of harzburgite and pyroxenite in which olivines are thoroughly altered, but primary mineral textures are preserved ( Figure 4a; Luo et al, 2017). Blocks of coarse-grained gabbro ( Figure 3c) consist of clinopyroxene (45-50%), plagioclase (50-55%), and minor amphibole; the pyroxenes and plagioclases are medium to coarse-grained (2 and 3 mm) and euhedral to subhedral ( Figure 4b).…”

Section: Exotic Blocks In the Hebukesaier Ophiolitic Mélangementioning

confidence: 99%

“…However, the subduction polarities and process of amalgamation of the two island arcs (Abrajevitch et al, 2007) remain enigmatic and controversial. For example, , Luo et al (2017), , and Shen et al (2012) proposed that the Chingiz and Saur arcs were generated by southward subduction of the Irtysh Ocean, and the evolution of the two arcs was continuous. Alternatively, Chen et al (2017b) proposed that the Chingiz Arc was generated by southward subduction, but that the Saur Arc was formed by northward subduction.…”

Section: Introductionmentioning

confidence: 99%

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Late Paleozoic Chingiz and Saur Arc Amalgamation in West Junggar (NW China): Implications for Accretionary Tectonics in the Southern Altaids

et al. 2020

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The Saur‐Chingiz Belt (SCB) in northern West Junggar is regarded as the amalgamation zone of the Saur and Chingiz arcs. It contains diagnostic rocks of accretionary origin, providing critical information about the evolution of the southern Paleo‐Asian Ocean. We recognize various lithologies in the SCB, including an ophiolitic mélange, turbidites, conglomerates, rhyolites, breccias, and diorites, and investigate the structures of the Hebukesaier ophiolitic mélange. Kinematic analysis indicates top‐to‐the‐N thrusting. A coarse‐grained gabbro (ca. 490 Ma) and a fine‐grained gabbro (ca. 318 Ma) have normal mid‐ocean ridge basalt (N‐MORB)‐type geochemical signatures, and three groups of pillow basalts exhibit N‐MORB, enriched mid‐ocean ridge basalt (E‐MORB), and ocean island basalts (OIB) fingerprints, respectively. Detrital zircons in tuffs, conglomerates, and turbidites associated with the Hebukesaier mélange display predominant ages of 410–440 Ma, which are consistent with the age of the Chingiz Arc. This suggests that the mafic rocks (ophiolitic components) in the Hebukesaier mélange were generated at a mid‐ocean ridge and were later accreted to the Chingiz Arc, which formed above a southward‐dipping subduction zone that consumed the Paleo‐Asian Ocean. The predominant zircon age peaks of turbidites from the Saur area, north of the Hebukesaier mélange, range from 326 to 360 Ma, which areconsistent with a provenance from the Saur Arc. The distinctive detrital zircons of the Chingiz and Saur arcs indicate that the northern boundary of the Hebukesaier mélange is the tectonic boundary between the Chingiz and Saur arcs. We suggest that Paleo‐Asian Ocean closed before Late Triassic as indicated by a diorite vein (ca. 218 Ma) that intruded the Hebukesaier mélange.

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Section: Other Rock Associationssupporting

confidence: 79%

Section: The Boundary Between the Chingiz And Saur Arcsmentioning

confidence: 86%

Section: Exotic Blocks In the Hebukesaier Ophiolitic Mélangementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Late Paleozoic Chingiz and Saur Arc Amalgamation in West Junggar (NW China): Implications for Accretionary Tectonics in the Southern Altaids

et al. 2020

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“…It contains remnants of the Paleozoic intraoceanic magmatic arcs (viz., the Dulate arc and the Yemaquan arc), accretionary complexes, and ophiolitic mélanges. The Zhaheba ophiolite complex, which extends to the south of the NW‐trending Armantai‐Ulungur Fault, separates the Dulate arc to the north from the Yemaquan arc to the south (Long et al, 2012; Luo et al, 2017; Xiao et al, 2004; Zhang et al, 2008). The Zhaheba ophiolites are considered to represent the site of an important suture between the two arcs based on the presence of UHP assemblages exhumation dated as Early Permian (Niu et al, 2007; Xiao et al, 2009) leading Xiao et al (2004) to interpret the Dulate and Yemaquan arcs as two distinct terranes.…”

Section: Geological Background Of the Chinese Altai And The East Junggarmentioning

confidence: 99%

Revision of the Chinese Altai‐East Junggar Terrane Accretion Model Based on Geophysical and Geological Constraints

et al. 2020

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Potential field data analysis, geology, and geochemistry are used to revise the terrane accretion model of the Chinese Altai and East Junggar. Major gradients of potential field data demarcate significant crustal structures and their continuity in depth. These data demonstrate that the distribution of geophysical anomalies does not match with terranes boundaries defined previously. Instead, heterogeneously developed NE/SW-trending gravity and NW-SE magnetic anomalies in both units correlate with Devonian and Permian tectonometamorphic zones, respectively. Geophysical data also indicate a dense lower crust of the East Junggar confirmed by previous igneous petrology studies and seismic experiment. The northern tip of this dense crust coincides with the main gravity gradient beneath the Chinese Altai and a prominent magnetic high located above a NW/SE-trending zone of Permian granulites. This zone forms a boundary between north-and south-dipping gravity and magnetic anomalies that are interpreted as reflecting quasi-symmetrical extrusion of the Chinese Altai crust. In contrast, all geophysical data show the absence of a prominent deep-seated discontinuity which can be correlated with the Erqis Zone. These data are compared with corresponding data sets from southern Mongolia allowing the proposition of a new geodynamic model for the studied area. This model involves (1) accretionary stage characterized by Late Devonian joint evolution of the East Junggar and Chinese Altai characterized by N-S trending orogenic fabrics and (2) Early Permian oroclinal bending associated with underthrusting of the dense Junggar basement beneath the Chinese Altai and the development of NW-SE trending deformation zones in both units.

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Petrogenesis of an Early Permian bimodal intermediate‐felsic suite in the East Junggar in Central Asian Orogenic Belt and tectonic implications

Zhang

Santosh

et al. 2020

Geological Journal

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The bimodal intermediate‐felsic suites are rare, and their petrogenesis remains unsolved. Here, we report a bimodal intermediate‐felsic magmatic suite from East Junggar (NW China) composed of rhyolites, basaltic andesites, and andesites. The basaltic andesites and andesites are porphyritic with phenocrysts predominantly of plagioclase. The rhyolites are porphyritic with phenocrysts of alkali‐feldspar, quartz, and minor plagioclase. LA–ICP–MS zircon U–Pb dating yielded an age of 284 ± 2 Ma for rhyolites. The basaltic andesites and andesites show SiO2 ranging from 54.67 to 58.26 wt%, and exhibit moderate TiO2 (1.45–1.77 wt%), and K2O (1.59–2.07 wt%) with low MgO (1.51–2.25 wt%). They display enrichment in HFSE and LILE together with negative Th, Nb, Ta, Ti anomalies, and exhibit low 87Sr/86Sr(t) ratios (0.7040–0.7046), high positive εNd(t) values (+5.82 to +6.16) and young TDM ages (<0.6 Ga). The rhyolites exhibit highSiO2(>75 wt%), negative Nb, Ta anomalies and significant depletion in Ba, Eu, Sr, Ti, and P. They also show high εNd(t) values (+5.51 to +7.08) and young TDM ages (<0.6 Ga), which are close to those of the intermediate rocks. Except for elements dominantly controlled by fractional crystallization, the other trace elements of the bimodal suite display similar patterns. Based on these characteristics, the MELTS simulation further suggests that the felsic rocks were possibly evolved from the intermediate magmas through fractional crystallization of feldspar, clinopyroxene, iron‐titanium oxide, and apatite. In contrast, the magmas parental to basaltic andesites were derived from the remelting of basaltic rocks underplated beneath the lower crust. The petrogenesis of this bimodal suite also provides new insights into Permian crustal reworking in the East Junggar, and suggest that the Junggar Ocean was closed prior to the Early Permian.

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The Zhaheba ophiolite complex in Eastern Junggar (NW China): Long lived supra-subduction zone ocean crust formation and its implications for the tectonic evolution in southern Altaids

Cited by 46 publications

References 70 publications

Late Paleozoic Chingiz and Saur Arc Amalgamation in West Junggar (NW China): Implications for Accretionary Tectonics in the Southern Altaids

Late Paleozoic Chingiz and Saur Arc Amalgamation in West Junggar (NW China): Implications for Accretionary Tectonics in the Southern Altaids

Revision of the Chinese Altai‐East Junggar Terrane Accretion Model Based on Geophysical and Geological Constraints

Petrogenesis of an Early Permian bimodal intermediate‐felsic suite in the East Junggar in Central Asian Orogenic Belt and tectonic implications

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