Paleozoic subduction of the southern Dunhuang Orogenic Belt, northwest China: metamorphism and geochronology of the Shuixiakou area

Wang, Hao; Zhang, Qian W.L.; Chen, Hong‐Xu; Liu, Jiahui; Zhang, Hui C.G.; Pham, Van Tho; Peng, Tao; Wu, Chun‐Ming

doi:10.1080/09853111.2018.1427407

Cited by 30 publications

(18 citation statements)

References 76 publications

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“…1B). The latest studies have confirmed that the Dunhuang terrane is constituted by the Precambrian Dunhuang Complex (Zhang et al, 2013;Zong et al, 2013;Zhao et al, 2013Zhao et al, , 2015aZhao et al, , 2015bZhao et al, , 2017Wang et al, 2013b;Zhao and Sun, 2018) and a Paleozoic magmatic-metamorphic complex (Zong et al, 2012;He et al, 2014;Zhao et al, 2015cZhao et al, , 2016Zhao et al, , 2017Wang et al, 2016aWang et al, , 2016bWang et al, , 2016cWang et al, , 2017aWang et al, , 2017bWang et al, , 2017dWang et al, , 2018. It is now considered to be a mobile belt that underwent intensive reworking during a Paleozoic orogeny (Zhao et al, 2016;Wang et al, 2016aWang et al, , 2017aWang et al, , 2017bShi et al, 2018).…”

Section: Geological Backgroundmentioning

confidence: 98%

“…440-360 Ma arc-related granitoids (Wang et al, 2016b(Wang et al, , 2016cZhao et al, 2017), (garnet-bearing) amphibolite/highpressure mafic granulite with a metamorphic age of ca. 440-350 Ma (Zong et al, 2012;He et al, 2014;Zhao et al, 2016;Wang et al, 2016aWang et al, , 2017aWang et al, , 2017bWang et al, , 2017dWang et al, , 2018, and ca. 335-315 Ma postcollisional potassic granites (Zhao et al, 2017).…”

Section: Geological Backgroundmentioning

confidence: 99%

“…The Dunhuang terrane witnessed a complicated geological history during the Mesoarchean-Paleoproterozoic and Paleozoic Eras, as indicated by the Precambrian Dunhuang Complex and Paleozoic granitoid-metamafic rocks, respectively. Recent studies have mostly focused on Archean crustal evolution Zong et al, 2013;Zhao et al, 2013Zhao et al, , 2015aZhao et al, , 2015b, as well as Paleozoic tectonic evolution (Zong et al, 2012;He et al, 2014;Zhao et al, 2016;Wang et al, 2016aWang et al, , 2016bWang et al, , 2016cWang et al, , 2017aWang et al, , 2017bWang et al, , 2017dWang et al, , 2018Shi et al, 2018;Xu et al, 2019). However, the geodynamic mechanism and tectonic setting of the latest Paleoproterozoic magmatism have rarely been discussed, and both the A-type granites formed at ca.…”

Section: Introductionmentioning

confidence: 99%

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Latest Paleoproterozoic (ca. 1.8–1.6 Ga) extensional tectonic setting in the Dunhuang terrane, NW China: Evidence from geochronological and geochemical investigations on A-type granite and metamafic rock

Zhao

Zhang

et al. 2019

Lithosphere

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Latest Paleoproterozoic (ca. 1.8–1.6 Ga) magmatic rocks outcrop in the Dunhuang terrane, represented by A-type granites and mafic (basaltic) rocks that have metamorphosed into amphibolites. The A-type granites, emplaced at ca. 1.79–1.77 Ga, are geochemically characterized by high Na2O + K2O, Fe2O3T, Zr, Nb, and Ce contents, as well as high Fe2O3T/(Fe2O3T + MgO) and Ga/Al ratios. Furthermore, they have Nb/Ta, Y/Nb, Rb/Nb, and Sc/Nb ratios of 12.10–15.56, 1.45–1.79, 3.52–6.51, and 0.11–0.19, respectively, showing affinity to A2-type granite. The A-type granites have negative εNd(t) values (−5.4 to −4.8) with Neoarchean depleted mantle (TDM2) ages (2591–2494 Ma), corresponding to coupling between εHf(t) values (−4.85 to -0.92) and TDM2 ages (2817–2556 Ma) of zircons. Therefore, the A-type granite pluton was mostly generated by partial melting of Neoarchean tonalitic to granodioritic basement rocks of the Dunhuang Complex in a postcollisional tectonic setting following a late Paleoproterozoic continent-continent collisional event. The metamafic rocks have a protolith age of 1605 ± 45 Ma and metamorphic age of 317 ± 20 Ma, indicating a Paleozoic tectonic event. The metamafic rock samples are geochemically characterized by relatively high alkali (Na2O + K2O = 4.39–4.81 wt%) contents and low Nb/Y (0.63–0.66) ratios, and they show steep rare earth element (REE) patterns with light REE enrichment and insignificant Eu anomalies and Nb-Ta, Zr-Hf, and Ti anomalies, resembling subalkaline oceanic-island basalt affinity. They have positive εNd(t) values (+0.8 to +1.8) close to the chondrite evolutionary line and variable εHf(t) values (-1.09 to +9.06) of zircons. Hence, the protolith of the metamafic rocks may have been produced by magma mixing processes between a depleted mantle source and a metasomatized lithospheric mantle source during the initial rifting stage in an extensional setting, completing the formation of the Precambrian Dunhuang Complex. Considering the ca. 1.85–1.80 Ga regional metamorphism in the Dunhuang terrane, the latest Paleoproterozoic (ca. 1.8–1.6 Ga) A2-type granitic magmatism and mafic magmatism documented the postorogenic to initial rifting processes following the global-scale late Paleoproterozoic collisional event, which is comparable with ca. 1.80–1.67 Ga postcollisional and ca. 1.60–1.53 Ga anorogenic magmatism in the North China craton, but different from that of the Tarim craton.

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Section: Geological Backgroundmentioning

confidence: 98%

Section: Geological Backgroundmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Latest Paleoproterozoic (ca. 1.8–1.6 Ga) extensional tectonic setting in the Dunhuang terrane, NW China: Evidence from geochronological and geochemical investigations on A-type granite and metamafic rock

Zhao

Zhang

et al. 2019

Lithosphere

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“…1a). The Dunhuang region, as a Palaeozoic orogenic belt and part of the CAOB, represents a vital component of the southernmost CAOB within the Tianshan-Beishan-Mongolia-Xing'anling orogen (Yue et al 2001;Xiao et al 2010;Zhao et al 2016;Wang et al 2018;Zhu et al 2019). Meanwhile, the Beishan orogenic belt located to the north side of the Dunhuang region is also a part of the southernmost CAOB.…”

Section: Geological Background and Samplingmentioning

confidence: 99%

Duobagou Permian–Triassic granites from the Dunhuang orogenic belt, NW China: implications for the tectonic evolution of the southernmost Central Asian Orogenic Belt

Wang

Zhang

et al. 2020

Geol. Mag.

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The Duobagou Permian–Triassic granites of the Dunhuang orogenic belt are of great importance in understanding the tectonic evolution of the southernmost Central Asian Orogenic Belt. LA-ICP-MS U–Pb zircon ages indicate that Permian–Triassic granitic intrusions from the Duobagou area formed at 276–274 Ma and 246 ± 1 Ma. These granites have high SiO2, Na2O and K2O, but low Al2O3, CaO and MgO contents and belong mainly to the high-K calc-alkaline I-type granite series. Based on whole-rock geochemistry and Sr–Nd and zircon Hf isotopes, the Duobagou Permian–Triassic granites were dominantly derived from the partial melting of lower continental crust formed during late Palaeoproterozoic to Mesoproterozoic times in a post-collisional extensional setting. Permian granites with zircon ϵHf(t) values of −5.4 to +3.1 and Hf model ages of TDM2 = 1.14–1.70 Ga indicate the involvement of a mantle component in their petrogenesis. Triassic granites with higher zircon ϵHf(t) values (+0.5 to +3.8) and TDM2 = 1.08–1.31 Ga suggest more juvenile sources caused by a greater contribution of mantle-derived melts, indicating a significant crustal growth. Regional extension from lithospheric delamination and heating from asthenospheric upwelling were proposed to have triggered the partial melting of lower crust, resulting in the generation of the Permian–Triassic magmatism. This may have been the mechanism for the significant crustal growth during Permian and Triassic times in the southernmost Central Asian Orogenic Belt.

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“…In the southern Dunhuang Block, many eclogite, granulite, and amphibolite are exposing in the Hongliuxia complex. They record the Silurian–Devonian “clockwise” metamorphism P–T–t paths (Wang et al, 2017; Wang et al, 2018; Wang, Chen, et al, 2017). They are mainly exposed as tectonic blocks within the metasedimentary rocks (metamorphosed trench turbidites), exhibiting the “block‐in‐matrix” fabric (Shi et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Origins of the meta‐mafic rocks in the southern Dunhuang Block (NW China): Implication for tectonic framework of the southernmost Central Asian Orogenic Belt

Shi

Hou

et al. 2021

Geological Journal

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The Central Asian Orogenic Belt (CAOB) is one of the largest accretionary orogenic collages in the world with prominent juvenile crust addition, where the southernmost margin of the CAOB located is one hot topic in the international studies. The Dunhuang Block located to the south of the Beishan Orogen is a key position for outlining the tectonic framework of the south margin of the CAOB. However, at present, the tectonic attribution of the Dunhuang Block is still controversial. In this paper, we focus on the origins and protoliths of the meta‐mafic rocks from the Hongliuxia complex in the southern Dunhuang Block for determining the tectonic attribution of the Dunhuang Block. In the field, the meta‐mafic rocks are mainly exposed as tectonic blocks within the metasedimentary rocks displaying the “block‐in‐matrix” fabrics or as tectonic slices juxtaposed by faults. Geochemically, the meta‐mafic rocks could be divided into three groups based on the rare earth elements (REE) and trace elements: the group 1 samples are depleted in the LREE relative to HREE and show flat HREE patterns, similar to the mid‐oceanic ridge basalt; the group 2 samples show flat REE patterns without obvious differentiation between the LREE and HREE, like the oceanic plateau basalt; the group 3 samples are enriched in LREE relative to LREE, and have negative Nb, Ta, and Ti anomalies, similar to the island arc basalt. Conclusively, the protoliths of the meta‐mafic rocks dominantly belong to the oceanic plate components. They were metamorphosed during Early Silurian to Middle Devonian in different depths of the subduction zone documented in previous studies. So, we suggest the Hongliuxia complex is an exhumed Palaeozoic subduction–accretion complex (SAC) formed during the oceanic plate subduction. This result confirms the Palaeozoic subduction event occurred in the Dunhuang region and indicates that the Dunhuang Block is a Palaeozoic Orogen rather than a part of Precambrian continent block. Considering the regional geology context, we speculate the Dunhuang Orogen belongs to the southernmost margin of the CAOB.

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Paleozoic subduction of the southern Dunhuang Orogenic Belt, northwest China: metamorphism and geochronology of the Shuixiakou area

Cited by 30 publications

References 76 publications

Latest Paleoproterozoic (ca. 1.8–1.6 Ga) extensional tectonic setting in the Dunhuang terrane, NW China: Evidence from geochronological and geochemical investigations on A-type granite and metamafic rock

Latest Paleoproterozoic (ca. 1.8–1.6 Ga) extensional tectonic setting in the Dunhuang terrane, NW China: Evidence from geochronological and geochemical investigations on A-type granite and metamafic rock

Duobagou Permian–Triassic granites from the Dunhuang orogenic belt, NW China: implications for the tectonic evolution of the southernmost Central Asian Orogenic Belt

Origins of the meta‐mafic rocks in the southern Dunhuang Block (NW China): Implication for tectonic framework of the southernmost Central Asian Orogenic Belt

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