Continental crust melting induced by subduction initiation of the South Tianshan Ocean: Insight from the Latest Devonian granitic magmatism in the southern Yili Block, NW China

Bao, Zihe; Cai, Keda; Sun, Min; Xiao, Wenjiao; Wan, Bo; Wang, Yannan; Wang, Xiangsong; Xia, Xiaoping

doi:10.1016/j.jseaes.2017.04.026

Cited by 30 publications

(16 citation statements)

References 141 publications

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“…The northward subduction of the South Tianshan paleo-ocean underneath Yili central Tianshan may start at Early Silurian and last until Early Carboniferous, producing a series of continental arc along the southern margin of Yili-central Tianshan block [93][94][95]. There are a lot of mafic to felsic magmatic plutons and volcanic rocks related to continental arc from Early Silurian to Late Carboniferous (ranging from~450 Ma to~320 Ma) reported in the South Tianshan orogen ( [96][97][98] and references therein). There are also lots of syn-collisional and post-collisional magmatism (ranging from~320 Ma to~270 Ma) reported along this orogen ( [99,100] and references therein).…”

Section: Timing Of Episodic Fluid Actionmentioning

confidence: 99%

Episodic Fluid Action in Chinese Southwestern Tianshan HP/UHP Metamorphic Belt: Evidence from U–Pb Dating of Zircon in Vein and Host Eclogite

et al. 2019

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Fluid plays a key role in metamorphism and magmatism in subduction zones. Veins in high-pressure (HP) to ultrahigh-pressure (UHP) rocks are the products of fluid–rock interactions and can thus provide important constraints on fluid processes in subduction zones. In this study, we present an integrated study of zircon in situ U–Pb dating, trace element and mineral inclusion analysis for a complex vein and its host eclogite in the southwestern Tianshan UHP terrane, aiming to decipher the episodic fluid action during slab subduction and exhumation. Both zircon in eclogite and vein have euhedral, prismatic morphology similar to those crystallized from metamorphic fluid. Zircon in eclogite shows core–rim structures with distinct bounds and mineral inclusions. Zircon in the vein shows sector zoning or weak zoning, with bright rims around most zircon grains, which suggests recrystallization of the zircon crystals after their formation and multiple evolution of the vein. Eclogite zircon rims yield a weighted mean of 311 ± 3 Ma and cores yield a range from 413 ± 4 to 2326 ± 18 Ma, respectively. Vein zircon yields four groups of age (~355 Ma, ~337 Ma, ~315 Ma, and ~283 Ma), which date four episodes of fluid flow involving zircon growth. The first two groups of age may represent prograde epidote–amphibolite facies and amphibolite/blueschist facies metamorphism stage, respectively. The third group is similar to that of eclogite zircon rims, which is thought to date the eclogitic facie metamorphism (320–305 Ma), and the fourth group dates a later retrograde metamorphism after greenschist facies. The vein-forming fluid system was supposed to be an open system indicated by trace element of vein zircon and mineral assemblage of the vein. The coexistence of rutile, zircon, and garnet in prograde vein and the heavy rare earth elements (HREE) enrichment characteristic of vein zircon suggest that the vein-forming fluid are enriched in high field strength elements (HFSE) and HREE, and such fluid could be formed under low P–T conditions.

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Section: Timing Of Episodic Fluid Actionmentioning

confidence: 99%

Episodic Fluid Action in Chinese Southwestern Tianshan HP/UHP Metamorphic Belt: Evidence from U–Pb Dating of Zircon in Vein and Host Eclogite

et al. 2019

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“…The coeval A‐type magmatism, sanukitic high‐Mg andesite, and adakitic granitoids, which are distributed in the western Yili Block, are considered to have been generated under high‐temperature conditions (Thorkelson, ). Zircon saturation temperatures (T Zr ) of the studied I‐type syenitic granites range from 797°C to 825°C, which are pronouncedly higher than those of normal subduction of Latest Devonian–Early Carboniferous I‐type granitoids from Chinese western Tianshan (T Zr = 713–783°C, Figure ; Bao et al, ), demonstrating the occurrence of a thermal anomaly in the Early Carboniferous as well. Moreover, as discussed in Section , mafic rock–granitoid associations are commonly generated in extensional tectonic settings (Tang et al, ).…”

Section: Discussionmentioning

confidence: 82%

“…T Zr versus Zr diagram for the Atengtao syenitic granites. Data for the I‐ and A‐type granitoid of Yili Block are represented by ZSB (Bao et al, ) and ZYC (N.B. Li et al, ) in Figure b, respectively.…”

Section: Discussionmentioning

confidence: 99%

Early Carboniferous mafic dike–syenitic granite association in the Atengtao Mountain, Yili Block (NW China): Geochronology, petrogenesis, and tectonic significance

Wang

Yang

et al. 2019

Geological Journal

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The Carboniferous is an important period for understanding tectonic evolutionary history and subduction processes of Chinese western Tianshan orogen. Here, we present results of petrologic, geochemical, and in situ LA-ICP-MS zircon U-Pb and Hf isotope data from an Early Carboniferous mafic dike-syenitic granite association in Atengtao Mountain, Yili Block, aiming to constrain their ages and petrogenesis and tectonic significance. Zircon U-Pb dating results reveal that the mafic dikes and syenitic granites were coevally emplaced at ca. 345-349 Ma. Geochemically, the mafic dikes contain high MgO, Nb, TiO 2 , and Ta contents, low SiO 2 contents, and high Na 2 O/K 2 O ratios, showing Nb-enriched affinities. Additionally, they are enriched in LILEs, relatively depleted in HFSEs, and positive εHf (t) values (+1.2 to +8.7), likely representing melts derived from partial melting of a depleted mantle wedge metasomatized by subducted slab-derived fluids, with minor involvement of asthenospheric components. Compared with mafic dikes, the coeval syenitic granites display calc-alkaline I-type features and have high SiO 2 , Al 2 O 3 , and low MgO, Mg # (<40), Ni, and Cr contents, considered to have been derived from the reworking of the Precambrian basementwith an input of mantle-derived components. These mafic dike-syenitic granite associations likely formed in an arc-related setting rather than postcollision or mantle plume setting. In addition, pronouncedly higher zircon saturation temperature of the syenitic granites, compared with the coeval I-type granitoids from western Tianshan, imply the occurrence of a thermal anomaly in this period (ca. 345 Ma). With these studied results, together with previously published data, we argue that a slab breakoff model was likely responsible for the mafic dike-syenitic granite association, and related rocks, in the western Yili Block during Early Carboniferous.

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“…The special magmatic rocks that formed contemporaneously with the Early Carboniferous sanukitic HMAs, including the adakitic porphyry rocks (Y. J. Li, Gu, Pang, Luan, & Tong, ), Nb‐enriched basalts (NEB; G. Y. Li et al, ), alkaline olivine basalts + tholeiitic basalts association (Qian et al, ), A‐type granites (J. L. Li, Qian, et al, ), A‐type rhyolites, and bimodal volcanic suites (Y. J. Li et al, ; Z. P. Wang, Li, et al, ), were all emplaced in the western part of Yili Block (Figure b and Table S1). Additionally, most of calc‐alkaline volcanic rocks and I‐type granites are also distributed in the region (Bao et al, ; Cao et al, ; Ru et al, ; F. R. Zhang, Cheng, Yu, & Lou, ; Y. F. Zhu, Zhou, Song, Zhang, & Guo, ). Petrogenesis of these adakitic rocks and NEBs was suggested to be related to the subducting hot oceanic slab melting, and A‐type magmatic rocks distributed in this area are also regarded as products of high temperature (Thorkelson, ).…”

Section: Discussionmentioning

confidence: 99%

“…Numerous studies for these magmas on the geochronology, geochemistry, and isotopes have been conducted, to reconstruct the tectonic evolutionary history of the Palaeo‐Tianshan Ocean. However, for a long time, there is still no consensus on the geodynamic setting (rift, arc, post‐orogenic, and back‐arc extension) of these magmatic rocks during the Late Devonian to Carboniferous (An, Zhu, Wei, & Lai, ; Bao et al, ; Che, Liu, Liu, & Luo, ; Han et al, ; Y. J. Li, Hu, Zhou, & Tong, ; J. L. Li, Qian, et al, ; Qian, Gao, Xiong, Long, & Huang, ; Q. Wang, Wyman, et al, ; Windley et al, ; Xia et al, ; Y. F. Zhu, Guo, Song, Zhang, & Gu, ), which hampers our better understanding for the regional tectonic evolution. Recently, the local extension within the whole Yili Block was proposed during Late Devonian to Early Carboniferous (Y. J. Li et al, ; Z. P. Wang, Li, et al, ).…”

Section: Introductionmentioning

confidence: 99%

Petrogenesis and geochemical characteristics of Early Carboniferous sanukitic high‐Mg andesite from Atengtao Mountain, Yili Block: Implications for the tectonic setting during Late Palaeozoic in Chinese West Tianshan

Wang

Yang

et al. 2019

Geological Journal

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Tianshan contains voluminous Late Palaeozoic volcanic rocks. Here, we present geochronological, geochemical, and in situ Lu-Hf isotopic data from the Atengtao sanukitic high-Mg andesites (HMAs) of the western Yili Block. LA-ICP-MS zircon U-Pb analyses indicate that the Atengtao high-Mg andesites were generated in the Early Carboniferous (346 ± 2 Ma). All the studied rock samples are characterized by high MgO (3.30-5.45 wt.%), SiO 2 (53.25-60.10 wt.%), Cr (90.3-157 ppm), and Ni (31.0-46.7 ppm) contents, with geochemical characteristics analogous to those of sanukitoids of the Setouchi Volcanic Belt (SVB), SW Japan, and Bieluagaxi area, West Junggar. The Atengtao sanukitic HMAs are enriched in LILE and LREE but depleted in HFSE, similar to those of typical arc-related magmatic rocks. They are also characterized by high Nb (11.4-15.8 ppm) concentrations, high Th/La (0.3) and Th/Yb (2.6-4.0) ratios, and varying zircon εHf(t) values (−2.3 to +4.3). These features are suggested to result from the partial melting of a relatively enriched mantle wedge metasomatized by subducting oceanic slab-derived sediments. Considering the occurrence of sanukitic HMAs, combined with the contemporaneous special rock assemblages (such as slab-derived adakite, Nb-enrich basalt, A-type granite/rhyolite, and bimodal volcanic rocks) found in the western part of Yili Block, we propose that the generation of the Carboniferous sanukitic HMAs in Atengtao Mountain were most likely related to the slab break-off following the southern Tianshan Ocean slab northward subduction beneath the Yili-Central Tianshan Block. This mechanism not only produces intense magmatism with compositional diversity but also gives rise to a local extension in the western part of Yili Block. The slab break-off model may play an important role in the crustal growth of the CAOB in Phanerozoic time.

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Continental crust melting induced by subduction initiation of the South Tianshan Ocean: Insight from the Latest Devonian granitic magmatism in the southern Yili Block, NW China

Cited by 30 publications

References 141 publications

Episodic Fluid Action in Chinese Southwestern Tianshan HP/UHP Metamorphic Belt: Evidence from U–Pb Dating of Zircon in Vein and Host Eclogite

Episodic Fluid Action in Chinese Southwestern Tianshan HP/UHP Metamorphic Belt: Evidence from U–Pb Dating of Zircon in Vein and Host Eclogite

Early Carboniferous mafic dike–syenitic granite association in the Atengtao Mountain, Yili Block (NW China): Geochronology, petrogenesis, and tectonic significance

Petrogenesis and geochemical characteristics of Early Carboniferous sanukitic high‐Mg andesite from Atengtao Mountain, Yili Block: Implications for the tectonic setting during Late Palaeozoic in Chinese West Tianshan

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