Devonian arc-related granitoids in the Northwestern Chinese Tianshan, Central Asian Orogenic Belt: implications for the bending of the Kazakhstan Orocline

Sun, Minghui; Cai, Keda; Sun, Min; Wan, Bo; Wang, Xiangsong; Bao, Zihe

doi:10.1080/00206814.2020.1737975

Cited by 7 publications

(18 citation statements)

References 94 publications

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“…For instance, Jourdon et al (2017) proposed that the South Tianshan Ocean closed by southward subduction, because some structures had a northward polarity. However, because the Ili‐Central Tianshan arc had a very different composition and rheology from the Tarim Craton (Muhetaer et al, 2020; Sun, Cai, Sun, Wan, & Bao, 2020), the different provenance of the respective material challenges the above northward subduction polarity. The fact that the provenance and detrital zircon age patterns from the sediments in the South Tianshan accretionary complex rule out any input from the Tarim Craton (Sang et al, 2018) suggests that the South Tianshan accretionary complex was attached to the southern margin of the Ili‐Central Tianshan arc.…”

Section: Interpretations Discussion and Conclusionmentioning

confidence: 99%

“…Therefore, the above evidence implies that the South Tianshan Ocean was not a limited ocean, but rather that it was a wide, long-lived, major ocean that evolved from the Ordovician-Silurian (Hegner et al, 2020;Ma et al, 2007;Shen et al, 2017) to the Late Permian (Li et al, 2003) or even Early to Mid-Triassic (Sang et al, 2017;Sang et al, 2018). The early to Late Devonian conodonts in the ophiolitic mélange (Alekseev et al, 2007) (Muhetaer et al, 2020;Sun, Cai, Sun, Wan, & Bao, 2020), the different provenance of the respective material challenges the above northward subduction polarity. The fact that the provenance and detrital zircon age patterns from the sediments in the South Tianshan accretionary complex rule out any input from the Tarim Craton (Sang et al, 2018) suggests that the South Tianshan accretionary complex was attached to the southern margin of the Ili-Central Tianshan arc.…”

Section: Tectonic Significancementioning

confidence: 98%

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Radiolarian age and geochemistry of cherts from the Atbashi accretionary complex, Kyrgyz South Tianshan

et al. 2020

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, radiolarites, and radiolarian cherts are one of the most important components of accretionary complexes, and much used in the reconstruction of imbricated sections of ocean plate stratigraphy, and of the palaeogeographic and tectonic settings of ophiolitic mélanges. There has been little research on radiolarian cherts in the Kyrgyz South Tianshan, and the tectonic setting and temporal framework of the South Tianshan ocean are controversial. Here, we report well-preserved radiolarians in ribbon-bedded cherts in an ophiolitic mélange of the Atbashi accretionary complex (South Tianshan, Kyrgyzstan), which provide key evidence of ambient Palaeozoic oceanic conditions. The hydrofluoric acid technique was used to extract from the cherty rocks siliceous radiolarian, which yielded an age of late Early Carboniferous. Analyses of major, trace, and rareearth elements of four cherts indicate they are biogenic and deposited with little hydrothermal influence in a hemipelagic to continental margin environment. Our fossil ages and geochemical results of the radiolarian cherts from the Atbashi accretionary complex indicate that the South Tianshan ocean was still open in the Late Carboniferous, implying that it was a wide, long-lived, major ocean that closed by northward subduction.

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Section: Interpretations Discussion and Conclusionmentioning

confidence: 99%

Section: Tectonic Significancementioning

confidence: 98%

Radiolarian age and geochemistry of cherts from the Atbashi accretionary complex, Kyrgyz South Tianshan

et al. 2020

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“…The DVB, a Japanese-type volcanic arc, is mainly composed of Early to Middle Devonian plutonic and volcanic rocks [7,8] and the eastward extension of its southeastern part is still unclear. Additionally, the geodynamic mechanism for the formation of the Late Paleozoic arc magmatism is unclear, especially whether it has a continuous subduction of the Junggar-Balkhash Ocean with trench retreating [9] or not [10,11]. Bodies of Middle Ordovician to Carboniferous magmatites outcrop in the north margin of the YB, which was attributed to the southward subduction of the Junggar (or North Tianshan) oceanic crust beneath the YB [4,9,[11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, the geodynamic mechanism for the formation of the Late Paleozoic arc magmatism is unclear, especially whether it has a continuous subduction of the Junggar-Balkhash Ocean with trench retreating [9] or not [10,11]. Bodies of Middle Ordovician to Carboniferous magmatites outcrop in the north margin of the YB, which was attributed to the southward subduction of the Junggar (or North Tianshan) oceanic crust beneath the YB [4,9,[11][12][13][14][15][16]. The Middle to Late Ordovician [4,5,17,18] and the Middle to Late Devonian [11,13,19,20] arc-type magmatism were both reported in the northern margin of YB.…”

Section: Introductionmentioning

confidence: 99%

“…Bodies of Middle Ordovician to Carboniferous magmatites outcrop in the north margin of the YB, which was attributed to the southward subduction of the Junggar (or North Tianshan) oceanic crust beneath the YB [4,9,[11][12][13][14][15][16]. The Middle to Late Ordovician [4,5,17,18] and the Middle to Late Devonian [11,13,19,20] arc-type magmatism were both reported in the northern margin of YB. However, during the Caledonian and Hercynian orogenic periods, whether a magmatic gap occurred in the Late Silurian-Early Devonian or not is little known and their origin and tectonic implication are unclear in the northern margin of YB.…”

Section: Introductionmentioning

confidence: 99%

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Early Devonian Arc-Related Volcanic Rocks in the Haerdaban, North Margin of the Yili Block: Constraint on the Southward Subduction of the Junggar Ocean

et al. 2021

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The origin and tectonic implication of Early–Middle Devonian magmatism in the northern margin of YB (Yili Block) remain enigmatic and are important for understanding Late Paleozoic evolution of the Junggar Ocean and southern Kazakhstan Orocline. Here, we present the systematic study of whole-rock geochemical and Sr–Nd isotope features as well as U–Pb–Hf isotope characteristics of zircon crystals for newly identified Early Devonian volcanic rocks from the northern margin of YB. The volcanic rocks are composed of rhyolite, rhyolite porphyry, and rhyolitic tuff. Zircon U-Pb age dating indicates they were formed at ca. 407~418 Ma. They have high SiO2 (70.16–77.52 wt.%) and alkali (5.10–9.56 wt.%) contents, and high Zr + Nb + Ce + Y content (~456 ppm), indicative of A-type magma. Their relative depletion of Nb, Ta, and Ti, and enrichment of LILEs show arc affinity. Their low initial 87Sr/86Sr ratios (0.699708–0.709822) and negative εNd(t) values (−1.8 to −4.0) indicate a mainly continental magma source and their positive εHf(t)values (+6.13 to +14.81) are possibly due to the garnet effect. All these above reveal that volcanic rocks were generated by re-melting of lower crust under a high temperature condition, which was induced by long-lived heat accumulation with no or minimal basalt flux. Combined with active continental margin inference evidenced by contemporaneous sedimentary rocks, we attribute the generation of the volcanic rocks to a continental arc setting related to the southward subduction of Junggar oceanic crust. Thus, we infer the Early–Middle Devonian arc-related magmatic rocks in the northern margin of YB are eastward counterparts of the southern limb of the Devonian Volcanic Belt, which resulted from a relatively steady-state southward subduction.

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Genesis of the Lamasu large skarn Cu deposit, northern Xinjiang: Constraints from garnet U–Pb dating, micro‐textural and geochemical analyses

Wang,

Liu,

Lai

et al. 2023

Geological Journal

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The Lamasu deposit is the first large copper (Cu) deposit with ~0.6 Mt Cu reserve in the Chinese Western Tianshan Orogen (NW China). The Cu orebodies are mainly hosted in the exoskarn of the Proterozoic Kusongmuqieke Group. Now, the metallogenic mechanism of newly discovered skarn Cu orebodies (0.5 Mt Cu) remains poorly constrained. In this study, we conducted LA‐ICP‐MS U–Pb isotope dating, EPMA and LA‐ICP‐MS geochemical analyses on different generations of garnet from Lamasu to elucidate the magmatic hydrothermal evolution and its timing. Garnets from the Lamasu exoskarn can be divided into three types: reddish‐brown coarse‐grained Grt‐I, light brown fine‐grained Grt‐II and yellowish‐green heterogranular Grt‐III, with U–Pb age of 389.1 ± 2.0 Ma, 387.1 ± 1.8 Ma and 387.0 ± 2.3 Ma, respectively. These dates represent the oldest Cu mineralization age in the Chinese Western Tianshan, coeval with the Middle Devonian subduction of the North Tianshan oceanic plate. Grt‐I to Grt‐III particles are mainly andradite with minor grossularite, and they have different REE compositions. The Grt‐I has total REE contents (∑REE) of 101.47 to 262.87 ppm, with steeply right‐inclining REE distribution patterns (LREE/HREE of 3.81 to 68.50) and positive Eu anomaly. The Grt‐II core has ∑REE of 163.49–249.52 ppm, LREE/HREE of 2.00–4.71, and negative Eu anomaly. The Grt‐II rim has ∑REE of 46.34–99.99 ppm, with LREE/HREE of 18.06–177.23, and positive Eu anomaly. The ∑REE of Grt‐III range from 31.71 to 219.02 ppm, with flat REE distribution pattern and positive Eu anomaly, and the LREE/HREE ranges from 2.16 to 9.07. These garnets have similar trace element compositions, featured by LILE‐depletions (e.g., Rb, Ba and Sr) and HFSE enrichments (e.g., Th, U, Nb and Ce). Micro‐texture and geochemical composition of garnets indicate that the Lamasu magmatic hydrothermal system could have changed from an open to a closed environment, and from infiltration metasomatism to diffusive metasomatism, which formed Grt‐I, Grt‐II and Grt‐III successively. These garnets generally formed in a relatively oxidized fluid environment, which inhibited early sulphide precipitation and favoured for Cu enrichment during the ore fluid evolution.

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Devonian arc-related granitoids in the Northwestern Chinese Tianshan, Central Asian Orogenic Belt: implications for the bending of the Kazakhstan Orocline

Cited by 7 publications

References 94 publications

Radiolarian age and geochemistry of cherts from the Atbashi accretionary complex, Kyrgyz South Tianshan

Radiolarian age and geochemistry of cherts from the Atbashi accretionary complex, Kyrgyz South Tianshan

Early Devonian Arc-Related Volcanic Rocks in the Haerdaban, North Margin of the Yili Block: Constraint on the Southward Subduction of the Junggar Ocean

Genesis of the Lamasu large skarn Cu deposit, northern Xinjiang: Constraints from garnet U–Pb dating, micro‐textural and geochemical analyses

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