U-Pb zircon dating constraints on formation time of Qilian high-grade metamorphic rock and its tectonic implications

Xu, Wenchao; Zhang, Hongfei; Liu, Xiaoming

doi:10.1007/s11434-007-0082-7

Cited by 83 publications

(55 citation statements)

References 21 publications

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“…In the tectonic aspect, it has been thought that the Qilian Block was rifted from the North China Craton before the Caledonian orogenic activities and subsequently again amalgamated with the North China Craton [5][6][7][8] . However, recent geochemical and geochronological data from the Qilian Block prefer a Yangtze Craton affinity [9][10][11][12] . Regarding the formation age, the Qilian Block has long been considered to have a Paleoproterozoic Zhongtiao cycle crystalline basement based on the ages of the overlying strata, few radiometric dating, and regional lithological correlations [13][14][15][16][17][18] .…”

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confidence: 99%

SHRIMP U-Pb geochronology of the zircons from the Precambrian basement of the Qilian Block and its geological significances

Tung¹,

Yang²,

Yang³

et al. 2007

CHINESE SCI BULL

153

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Origin and tectonic evolution of the Qilian Precambrian basement on NW China were investigated using zircon U-Pb ages with collaborating stratigraphic and paleontological evidence. Zircon grains were separated from two schists, two granitic gneisses and one mylonized gneiss and dated with SHRIMP. Seventy percent of sixty-one detrital zircon ages from two schists ranges from 0.88 Ga to 3.09 Ga, mostly within 1.0 Ga to 1.8 Ga with a peak at 1.6 Ga to 1.8 Ga, and twenty percent varies from 2.0 Ga to 2.5 Ga. A few falls in the Archean and Neoproterozoic periods. The two granitic gneisses were dated 930±8 Ma and 918±14 Ma, whereas the mylonized granitic gneiss was dated 790±12 Ma. These ages represent two periods of magmatisms, which can be correlated with the early and late stages of magmatisms associated with the Jinningian movement on the Yangtze Blocks.The results from this and previous studies indicate that the ages of the Precambrian detrital zircons from the Qilian Block are widely distributed in the Proterozoic era, distinct from the North China Block which was stable in the Neo-Mesoproterozoic era. By contrast, the age histograms of the detrital zircons from the Qilian Block is similar to those from Precambrian basement of the Yangtze Craton. Therefore, it is suggested that the Qilian Block had a strong affinity toward the Yangtze Craton and might belong to the supercontinent Gondwana in the Neoproterozoic time. This inference is supported by Nd model age (T DM ), stratigraphic, and paleontological evidence. It is further considered that the Qilian Block was rifted from the supercontinent Gondwana during late Sinian to form an isolated continent in the Proto-Tethyan Ocean, moving towards the Alaxa Block in the North China Craton. The part of Proto-Tethyan Ocean between the Qilian and Alaxa Blocks should correspond to the so-called Paleo-Qilian Ocean. Following the closure of the Paleo-Qilian Ocean in the early Paleozoic, the Qilian Block collided with the Alaxa Block to form the North Qilian Orogenic Belt. Based on this tectonic explanation, the North Qilian ophiolites should represent parts of lithosphere from the Proto-Tethyan Ocean. Lithological and geochronological evidence also indicates that the Qilian Block underwent continental reactivation possibly induced by the deep northward subduction of the North Qaidam Block in early Paleozoic time.

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confidence: 99%

SHRIMP U-Pb geochronology of the zircons from the Precambrian basement of the Qilian Block and its geological significances

Tung¹,

Yang²,

Yang³

et al. 2007

CHINESE SCI BULL

153

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“…In e and f, ARC p island-arc basalt; CFB p continental flood basalt; LIP p large igneous province; MORB p mid-ocean ridge basalt; OIB p ocean-island basalt; SSZ p suprasubduction zone. (BGMRQP 1991;Xia et al 1995Xia et al , 2003Zhang et al 1997;Mao et al 1999Mao et al , 2000Wang et al 2005a;Chen 2007;Yu et al 2010), 1.1-0.8 Ga (2) for the Central Qilian Block (Guo et al 2000;Wan et al 2000Wan et al , 2001Gehrels et al 2003b;Tung et al 2007a;Wang et al 2007;Xu et al 2007;Yong et al 2008a;Xue et al 2009), and 2.1-1.7 and 2.6-2.4 Ga (3 and 4, respectively) for the North China Craton (Krö ner et al 1988;Wan et al 2003;Darby and Gehrels 2006;Tung et al 2007b;Li et al 2008). Taylor and McLennan (1985).…”

Section: Discussionmentioning

confidence: 99%

“…The late Paleoproterozoic to Neoproterozoic detritalzircon grains in the analyzed samples were probably derived from the Central Qilian Block, where Mesoproterozoic-Neoproterozoic granitic intrusions and metamorphosed sedimentary rocks with late Paleoproterozoic to Neoproterozoic detrital zircons constitute the major part of the basement ( fig. 9e, 9f; Guo et al 2000;Wan et al 2001;Gehrels et al 2003aGehrels et al , 2003bTung et al 2007a;Wang et al 2007;Xu et al 2007;Yong et al 2008a;Xue et al 2009). Cambrian-Ordovician zircon grains, in addition to Precambrian detritus, occur in the Lujiaogou Formation of the Sunan area in the Sunan Subprovince ) and in the Late Ordovician sediments of Xiehao area in the Jingyuan Subprovince (Xu et al 2010; fig.…”

Section: Discussionmentioning

confidence: 99%

“…Potential ophiolitic source rocks within the North Qilian Belt are represented by the Jiugequan, Dachadaban, and Yushigou-Dongcaohe ophiolites, which were emplaced during the Cambrian to Early-Middle Ordovician within/between the back (Xu et al 2010); e, Central Qilian Block granitic intrusions (Guo et al 2000;Wan et al 2000Wan et al , 2001Gehrels et al 2003b;Tung et al 2007a;Wang et al 2007;Xu et al 2007;Yong et al 2008a;Xue et al 2009); f, metasedimentary basement of the Central Qilian Block (Gehrels et al 2003a;Tung et al 2007a;Xu et al 2007); g, detrital zircons from the basement of the North China Craton (Krö ner et al 1988;Wan et al 2003;Darby and Gehrels 2006;Tung et al 2007b;Li et al 2008 (Xia et al 2003) and the high-Crcontent rocks of the Dachadaban ophiolite (Chen et al 1995;Zhang et al 1998b). The average value of Shuiquan samples, representing the continent provenances ), was calculated with Dachadaban ophioliteprovenance average value to generate two-end-member mixing lines, accounting for the high Cr/Th and Cr/V ratios of some samples from the Lujiaogou Formation.…”

Section: Discussionmentioning

confidence: 99%

“…These basement rocks have a Yangtze (Gondwana) affinity based on geochronology, geochemistry, and paleontology (Zhang et al 1998aGuo et al 2000;Wan et al 2000Wan et al , 2006Gehrels et al 2003a;Tung et al 2007a;Xu et al 2006Xu et al , 2007Yong et al 2008a). The Neoproterozoic basement assemblage within the belt underwent early Paleozoic orogeny (BGMRQP 1991;Fan and Lei 2007;He et al 2007;Chen et al 2008;Yong et al 2008b;Tseng et al 2009).…”

Section: Introductionmentioning

confidence: 99%

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From Subduction to Collision in the Northern Tibetan Plateau: Evidence from the Early Silurian Clastic Rocks, Northwestern China

Yang

Cawood³

et al. 2012

The Journal of Geology

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. The University of Chicago Press A B S T R A C TThe Qilian Orogen records early Paleozoic collisional suturing of the Qaidam Block and the Central Qilian Block to the North China Craton. The composition and U-Pb age of detrital zircons and the composition of Cr-spinels from the Early Silurian Lujiaogou and Angzanggou formations in the northern part of orogen indicate derivation from evolving oceanic and continental source terranes. Heavy-mineral chemistry indicates the incorporation of suprasubduction zone-type ophiolitic detritus in addition to continent-derived material. Integrating these chemical and age data with regional data on the duration of subduction-related magmatic activity, syn-and postcollisional granitic rocks, and high-pressure metamorphic rocks constrains the transformation from oceanic subduction to continental collision to 450-440 Ma. The collision resulted in a flood of detritus into the northern part of the orogen from the Central Qilian Block, which masked input from the intervening magmatic arc, implying rapid exposure of the block.

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Early Paleozoic arc magmatism and metamorphism in the northern Qilian Block, western China: Petrological and geochronological constraints

Peng

Zhang

et al. 2017

Geological Journal

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The Datong–Menyuan Complex, located in the northern margin of the Qilian Block, is composed dominantly of high‐grade metamorphic rocks covered by a Paleozoic–Mesozoic sedimentary sequence. In this study, we present petrographic observation, conventional thermobarometry and P–T pseudosection modelling, whole‐rock major and trace geochemistry, zircons U–Pb dating and Hf isotopic data together, to reveal the relationship between the magmatism and metamorphism along the northern margin of the Qilian Block. The anticlockwise P–T paths of gneiss and amphibolites are obtained using the garnet isopleths thermobaromety combined with phase equilibria modelling. The P–T pseudosection also shows that the gneiss and amphibolite underwent similar retrograde metamorphism with slightly different peak metamorphic conditions at ~720 °C and ~6.4 kbar for the former and ~700 °C and ~7.1 kbar for the latter. This indicates the Datong–Menyuan Complex recorded an amphibolite–granulite‐facies metamorphism. The zircon U–Pb analyses of 3 intrusive rocks including granitic dike, diorite, and granite are dated at ca. 499.8 ± 4.3, 495.9 ± 3.3, and 505.5 ± 3.2 Ma, and 3 representative metamorphic rocks underwent contemporaneous metamorphism at ca. 498.9 ± 4.1, 504.4 ± 3.9, and 499.3 ± 2.9 Ma. Zircon Hf isotopic analyses show that 505‐Ma zircons from the granitoid have positive εHf(t) values ranging from +8.5 to +12.8, indicating a depleted mantle source. Based on the penecontemporaneous magmatic and metamorphic event, we suggest that the southward subduction of the north Qilian Ocean triggered the activity of mantle‐derived magma and coeval metamorphic event. A subsequent compression is attributed to crustal thickening, indicating counter clockwise P–T paths. Combining these data with previous studies, it suggests paired metamorphic belts: the penecontemporaneous high‐temperature metamorphic belt related to an arc along the northern Qilian Block and high‐pressure/low‐temperature metamorphic belt existed in the north Qilian suture.

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U-Pb zircon dating constraints on formation time of Qilian high-grade metamorphic rock and its tectonic implications

Cited by 83 publications

References 21 publications

SHRIMP U-Pb geochronology of the zircons from the Precambrian basement of the Qilian Block and its geological significances

SHRIMP U-Pb geochronology of the zircons from the Precambrian basement of the Qilian Block and its geological significances

From Subduction to Collision in the Northern Tibetan Plateau: Evidence from the Early Silurian Clastic Rocks, Northwestern China

Early Paleozoic arc magmatism and metamorphism in the northern Qilian Block, western China: Petrological and geochronological constraints

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