First report of coupled Early Permian paleomagnetic and geochronologic data from the Dunhuang block (NW China), and implications for the tectonic evolution of the Paleo-Asian ocean

Xu, Wei; Sun, Zhilei; Shi, G.R.; Lu, Jincai; Yu, Lushan; Niu, Yazhuo; Zhao, Yue; Han, Xiqiu; Wang, Baowen; Song, Bo; Cao, Yongluo

doi:10.1016/j.gr.2018.10.012

Cited by 18 publications

(7 citation statements)

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“…Xu, Sun, Shi, et al. (2019) proposed that the Paleo‐Asian Ocean was still open in the Early Permian based on the geochronology and paleomagnetism of Early Permian tuffs in the Shibanshan Arc. The youngest known basalts from an ophiolite in the Hongliuhe mélange have whole‐rock 40 Ar/ 39 Ar isochronal ages as 277 ± 11, 278 ± 17, and 305 ± 14 Ma (Chen et al., 2016; Pan et al., 2008); these basalts have OIB and E‐MORB geochemical signatures (Pan et al., 2008; Z. H. Zhao et al., 2006).…”

Section: Discussionmentioning

confidence: 99%

“…The oblique drift of the Tarim plate during the middle Paleozoic induced collision of the eastern segment of the Tarim plate with the Tianshan arc in the Late Devonian, so creating an irregular (promontory and gulf) active continental margin in the southeast of the Tianshan (Chen et al., 1999). During the northward movement of the Beishan tectonic unit in the Late Paleozoic, the Xingxingxia shear zone accommodated the irregular subduction boundary between the Tianshan tectonic unit and Beishan tectonic unit as a transition fault zone (Li, 2006; Tian et al., 2017; Xiao, Mao, et al., 2010; Xu, Sun, Shi, et al., 2019). …”

Section: Introductionmentioning

confidence: 99%

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The Dashui Subduction Complex in the Eastern Tianshan‐Beishan Orogen (NW China): Long‐Lasting Subduction‐Accretion Terminated by Unique Mid‐Triassic Strike‐Slip Juxtaposition of Arcs in the Southern Altaids

et al. 2022

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Comprehensive studies of the tectonic nature and the formation age of the Dashui complex in the Eastern Tianshan‐Beishan Orogen may address and help to better understand the complicated accretionary tectonics of the southern Altaids. Based on our detailed geological mapping, structural analysis, and understanding of new geochemistry and detrital zircon U‐Pb dating of critical samples, the Dashui complex can be subdivided into one mélange (Central Zone) and two units of forearc basin and slope basin (Northern and Southern Zones). The Northern Zone is composed of debris flows and turbidites. The Central Zone has a “block‐in‐matrix” structure, and the blocks of basalts have E‐MORB or N‐MORB geochemical signatures. The Southern Zone is characterized by debris flows. Therefore, we name these rocks Dashui subduction complex. Detrital zircons from the three zones show a major single age peak at ca. 460–420 Ma and a minor age peak at ca. 280–260 Ma, and the maximum depositional ages from north to south are: 264, 244 and 246 Ma, respectively, indicate that the Dashui subduction complex developed independently within an overall intra‐oceanic arc until ca. 244 Ma, and there must have been a large‐scale tectonic separation between the Central Tianshan Arc to the north and the Shuangyingshan Arc to the south. The structural geometry and kinematics of the Dashui complex and adjacent areas indicate that this complex likely experienced syn‐subduction thrusting and strike‐slip deformation. In particular, the late Xingxingxia strike‐slip faulting finally juxtaposed the Central Tianshan, Mazongshan, and Shuangyingshan arcs.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Dashui Subduction Complex in the Eastern Tianshan‐Beishan Orogen (NW China): Long‐Lasting Subduction‐Accretion Terminated by Unique Mid‐Triassic Strike‐Slip Juxtaposition of Arcs in the Southern Altaids

et al. 2022

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“…335-315 Ma postcollisional potassic granites (Zhao et al, 2017). Recently, however, based on the latest paleogeographic study, Xu et al (2019) suggested that the Paleo-Asian Ocean between the Tarim craton and the Dunhuang terrane was still open in the Early Permian .…”

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%

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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“…The Dunhuang region has long been regarded as the Precambrian basement of the Tarim Craton (TC) or the North China Craton (NCC). However, recent studies have demonstrated that the Dunhuang region is part of the CAOB and shares a similar geological history with the Beishan orogeny (Zhao et al 2016(Zhao et al , 2019Feng et al 2018;Zhu et al 2019;Xu et al 2019). In the southern CAOB, the Beishan belt underwent a complex tectonic evolution and crustal growth during the Palaeozoic Era, and the widespread late early Palaeozoic granitic rocks in the southern Beishan orogeny constrain the timing of the collisional orogenic event (Zhang et al 2011;Li et al 2012;He et al 2014;Zhao et al 2017).…”

Section: Introductionmentioning

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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First report of coupled Early Permian paleomagnetic and geochronologic data from the Dunhuang block (NW China), and implications for the tectonic evolution of the Paleo-Asian ocean

Cited by 18 publications

References 97 publications

The Dashui Subduction Complex in the Eastern Tianshan‐Beishan Orogen (NW China): Long‐Lasting Subduction‐Accretion Terminated by Unique Mid‐Triassic Strike‐Slip Juxtaposition of Arcs in the Southern Altaids

The Dashui Subduction Complex in the Eastern Tianshan‐Beishan Orogen (NW China): Long‐Lasting Subduction‐Accretion Terminated by Unique Mid‐Triassic Strike‐Slip Juxtaposition of Arcs in the Southern Altaids

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

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