Journal of Earth Science  2018, Vol. 29 Issue (5): 1081-1101   PDF    
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Early Paleozoic Granulite-Facies Metamorphism and Magmatism in the Northern Wulan Terrane of the Quanji Massif: Implications for the Evolution of the Proto-Tethys Ocean in Northwestern China
Qinyan Wang1,2, Yanjun Dong2,3, Yuanming Pan4, Fanxi Liao2, Xiaowei Guo2    
1. School of Earth Sciences, Zhejiang University, Hangzhou 310027, China;
2. School of Earth Sciences, State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China;
3. Hubei Earthquake Administration, Wuhan 430071, China;
4. Department of Geological Sciences, University of Saskatchewan, Saskatoon S7N 5E2, Canada
ABSTRACT: The nature and evolution of the Proto-Tethys Ocean originated from the breakup of the supercontinent Rodinia remain controversial. Early Paleozoic magmatism and metamorphism can provide important constraints on the closure of the Proto-Tethys Ocean. This paper reports on a set of geological, petrographical, geochronological, mineralogical and geochemical data for Early Paleozoic granite, gabbro, granulite and granitic leucosome in the northern Wulan terrane of the Quanji Massif. Zircon LA-ICP-MS U-Pb dating reveals two episodes of magmatism, with the emplacement of a granitic pluton at 476.7±2.8 Ma and a gabbroic dike at 423±2 Ma. Whole-rock geochemistry suggests an arc affinity for the magma of the granitic pluton but a post-collisional extension setting for the gabbroic dike. Zircon LA-ICP-MS U-Pb dating also shows that the peak granulite-facies metamorphism and anatexis occurred at~475 Ma, coeval with the formation of the granitic pluton in the Quanji Massif as well as the early lawsonite-bearing eclogites in the North Qaidam high-pressure and ultrahigh-pressure (HP-UHP) metamorphic belt to the south. The granulite-facies metamorphism with peak P-T conditions at 718-729℃ and 0.46-0.53 GPa is characterized by an anticlockwise P-T path. Our data provide compelling evidence for Early Paleozoic paired metamorphic belts with HP-UHP metamorphism in the North Qaidam to the south and low P/T metamorphism in the Quanji Massif as a continental arc to the north, hence suggesting a northward subduction polarity for the Proto-Tethys oceanic plate. The intrusion of the post-collisional gabbroic dike supports for the closure of the Proto-Tethys Ocean in northwestern China before 423 Ma.
KEY WORDS: arc magmatism    low P/T granulite-facies metamorphism    paired metamorphic belts    Proto-Tethys Ocean    northern Wulan terrane    NW China    

0 INTRODUCTION

The Proto-Tethys Ocean originated from the breakup of the supercontinent Rodinia is an east-west trending oceanic basin, which existed from Neoproterozoic to the end of the Early Paleozoic (Li et al., 2017, 2016a, b, c, d; Zhang et al., 2017, 2015). The Paleo-Qilian Ocean (Li et al., 2017) in northwestern China is considered as a branch of the Proto-Tethys Ocean during the Early Paleozoic. Many microcontinents (such as Alxa, Qilian, Quanji and Qaidam) and continents (i.e., Tarim, North China and Yangtze) were located in and near the Paleo-Qilian Ocean, generating a complex archipelagic ocean (Li S Z et al., 2017; Song et al., 2017, 2015, 2014, 2013, 2006; Zhang et al., 2017, 2015; Pan et al., 2012, 1997; Chen et al., 2009; Lu et al., 2009, 2008, 2006; Li Z X et al., 2008; Gao et al., 2005). The Qilian-Qaidam area recorded complex Early Paleozoic subduction-collision processes (Li et al., 2017, 2016a, b, c, d; Zhang et al., 2017, 2015; Xia et al., 2016). In particular, the North Qaidam tectonic belt (NQTB), bounded by the Qilian Block in the north and the Qaidam Block in the south (Fig. 1), is characterized by the occurrences of abundant high-pressure to ultrahigh-pressure (HP-UHP) metamorphic rocks as well as ophiolites and subduction-accretionary complexes, thus resulting in long-standing questions about Early Paleozoic orogenesis types (accretion or collision), subduction polarity, and the time-span and closure of the Paleo-Qilian Ocean and more broadly the Proto-Tethys Ocean in northwestern China.

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Figure 1. (a) Geological map of the Quanji Massif and the North Qaidam HP-UHP metamorphic belt (modified after Chen et al., 2013a; Wang et al., 2009). Also, the study area (shown in Fig. 2) in the northern Wulan terrane is outlined. Inserts (b) showing the tectonic location of (a), and (c) simplified geological units in the North Qaidam tectonic belt (NQTB).

The North Qaidam tectonic belt (NQTB) (Fig. 1b), in particular, has been the focus of enormous studies over the past 30 years for its tectonic evolution (Song et al., 2018, 2017, 2014, 2013, 2006, 2005, 2003; Li et al., 2017; Zhang et al., 2017, 2015; Yu et al., 2015, 2014, 2011; Chen et al., 2013a, b, 2009; Wu et al., 2011, 2009, 2005; Lu et al., 2008, 2006; Yang and Powell, 2008; Yang et al., 2005, 2003; Lu, 2002; Yang and Deng, 1994; BGMQ, 1991). It consists of three tectonic units: the Quanji Massif (QM) to the north, the Tanjianshan volcanic zone in the middle (suture zone), and the North Qaidam HP-UHP metamorphic belt to the south (Figs. 1a and 1c). The latter two units are collectively referred to as the North Qaidam (NQD). Early Paleozoic magmatic and metamorphic events related to the closure of the Proto-Tethys Ocean have been reported to occur in the NQD, but poorly documented in the dominantly Proterozoic QM (He et al., 2018; Ma et al., 2018a, b; Li X C et al., 2018, 2015; Wang L et al., 2016; Wang Q Y et al., 2015). This contribution reports on new results of zircon U-Pb ages and petrological/geochemical data of Early Paleozoic granulites and associated granites and gabbroic dikes in the northern Wulan terrane of the QM (Fig. 1). These results are used to better constrain the low P/T metamorphism and contemporaneous magmatism in the QM, especially their relationships to the HP-UHP metamorphism in the NQD, thus providing evidence for Early Paleozoic paired metamorphic belts and subduction polarity as well as constraints on the closure of the Proto-Tethys Ocean in northwestern China.

1 GEOLOGICAL SETTING AND SAMPLE FEATURES 1.1 The North Qaidam

The North Qaidam (NQD) is composed of three subunits in lithology: a medium pressure (MP) metamorphic belt, a HP-UHP metamorphic belt and the Tanjianshan volcanic zone (e.g., Zhang et al., 2015 and references therein). The NQD HP-UHP metamorphic belt is characterized by abundant HP-UHP metamorphic rocks such as garnet peridotites and eclogites, which formed at 500–420 Ma with pressures up to 2.8 GPa (Song et al., 2018, 2017, 2014, 2006, 2005; Zhang et al., 2017, 2015, 2010; Yang et al., 2005, 1998; Yang and Deng, 1994). Zhang et al. (2017) and Song et al.(2014, 2006) suggested an earlier oceanic subduction at 460–440 Ma and a later continental subduction stage at 440–420 Ma. The MP metamorphic belt in the northern margin of the Qaidam Block (Zhang et al., 2017, 2007, 2005; Yu et al., 2015, 2014, 2011, 2010) is characterized by typical Barrovian zones of kyanite and sillimanite as well as syn-collisional Iand S-type granitoids at 450–420 Ma (Zhang et al., 2017, 2015, 2009, 2008; Wu C L et al., 2011, 2009, 2006, 2004a, b; Meng and Zhang, 2008; Meng et al., 2005; Wang et al., 2005, 2001). The Tanjianshan volcanic zone (Peng et al., 2016; Sun et al., 2015; Zhang J X et al., 2015; Gao et al., 2011; Shi et al., 2006, 2004; Zhang G B et al., 2005; Wang et al., 2003; Yuan et al., 2002; Lai et al., 1996a, b) spreads on the northern side of the NQD and adjacent to the southern margin of the QM (Fig. 1c). It is mainly composed of ultramafic rocks, gabbros, and intermediate-basic volcaniclastic rocks, with minor ophiolitic complexes and islandarc volcanic rocks, and diachronous formation during 540–500 Ma (Gao et al., 2011; Shi et al., 2006, 2004; Wang et al., 2003; Lu, 2002; Yang et al., 1998; BGMQ, 1991). The Tanjianshan volcanic zone at 540–500 Ma has been suggested to have formed from volcanic island-arc magmatism related to oceanic subduction (Song et al., 2018, 2014; Zhang J X et al., 2017, 2014) before Middle Ordovician and the disappearance of the South Qilian Ocean between the Qaidam Block and the Quanji Massif by collision orogeny.

1.2 The Quanji Massif

The Quanji Massif is a nearly NW-SE-trending (locally E-Wtrending) long and narrow small remnant continental fragment sandwiched between the South Qilian orogenic belt and the North Qaidam. The QM is characterized by component of double-layer structure: Early Paleoproterozoic granitoid gneisses and mediumto high-grade metamorphic rocks constitute its basement (He et al., 2018; Liao et al., 2018a, b, 2014, 2012; Gong et al., 2014, 2012; Zhang L et al., 2014, 2011; Chen N S et al., 2013a, b, 2012, 2009, 2008, 2007; Wang et al., 2009, 2008; Lu et al., 2008, 2006; Wan et al., 2006, 2001), and Mesoproterozoic–Phanerozoic sedimentary rocks form the cover (Ma et al., 2018a, b; Wang et al., 2016; Zhang et al., 2012; Lu et al., 2008, 2006; Zhao et al., 2000). Previous researches focused on the Proterozoic rocks and interested in the role that the QM played in the assembly and breakup of the supercontinents Columbia and Rodinia (He et al., 2018; Wang L et al., 2016; Chen et al., 2013a, b, 2012, 2009, 2008; Wang Q Y et al., 2009, 2008; Lu et al., 2008, 2006; Wan et al., 2006). However, Paleozoic assemblages formed from magmatism and metamorphism are also known to occur in the QM but have not been investigated in detail. For example, an island-arc magmatic zone with ages from 514 to 440 Ma occurs on the southern margin of the QM and mainly consists of Ordovician diorite and granite intrusions (Xia et al., 2016; Zhu et al., 2014; Wu C L et al., 2011, 2009, 2006, 2004a, b; Xu et al., 2006). In particular, island-arc granitoids emplaced at 475–460 Ma formed significantly after magmatism in the Tanjianshan volcanic zone but were broadly coeval with the earlier oceanic subduction in the NQD HP-UHP metamorphic belt. It has been proposed that the QM was located within the South Qilian Ocean during the Early Paleozoic, closer to the Qilian Block than to the Qaidam Block. The QM and Qaidam Block were finally welted in subduction-collision by the Tanjianshan volcanic zone. Both the UHP eclogites and the MP granulites associated with the Ordovician granitoids in the NQD at the Luliangshan and Xitieshan areas record two distinct groups of ages (470–445 and 438–420 Ma) (Song et al., 2018; Zhang J X et al., 2017, 2015; Zhang G B et al., 2005). However, it remains unclear whether the MP granulites in the NQD recorded regional Barrovian metamorphism or multiple episodes of oceanic crust subduction and how the QM involved in the evolution of the Proto-Tethys Ocean.

1.3 Geology of the Northern Wulan Terrane

This study was carried out in the northern Wulan terrane on the northern side of the Quanji Massif (Fig. 2). This terrane consists of three litho-tectonic units: an Early Mesoproterozoic unit in the middle, a Late Mesoproterozoic to Early Neoproterozoic unit on the northeastern and southwestern sides of the Early Mesoproterozoic unit, and an Early Paleozoic unit on the most northeastern margin in fault-contact with the Late Mesoproterozoic to Early Neoproterozoic unit (Wang, 2016; Wang et al., 2016).

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Figure 2. Detailed geological map showing the northern Wulan terrane in the Quanji Massif and the sample locations (modified after Wang et al., 2016).

The Early Mesoproterozoic unit consists of dominantly Al-rich pelitic gneisses and schists, intruded by ~1.5 Ga trondhjemite, ~1.1 Ga mega-porphyritic granodiorite and ~1.0 Ga monzogranite. This unit experienced amphibolite-facies metamorphism, locally up to granulite-facies conditions with pervasively developed anatectic leucosomes at ~1.1 Ga and intensively reworked at ~0.47 Ga (Wang, 2018). The deposition of this unit has been constrained to occur between ~1.67 and 1.5 Ga by the youngest ages of detrital zircon and the ~1.5 Ga trondhjemitic intrusions. The Late Mesoproterozoic to Early Neoproterozoic unit is composed of two subunits with depositional ages of ~1.1 and ~0.94–0.90 Ga (Wang, 2016; Yu et al., 1994), respectively. The unit, which consists mainly of meta-sandstones, metavolcanic rocks, amphibolites and calc-silicate rocks, is characterized by the development of large volumes of thick-layered marbles, 860–810 Ma garnet-bearing granites (Ma et al., 2018a, b), and amphibolite-facies metamorphism.

The northern Wulan terrane was collided to and welted with on the northern margin of the QM at the Early Neoproterozoic (Wang, 2018). The Early Paleozoic unit in the northern Wulan terrane includes a series of gneissic granitoids, pelitic gneiss and amphibole-biotite gneiss, with minor mafic granulite lenses in granitic and pelitic gneisses (Da et al., 2017; Li et al., 2017, 2015; Wang et al., 2015; Dong, 2014; Guo et al., 2009). The Early Paleozoic metamorphic rocks recorded lowto medium-pressure granulite-facies metamorphism (Li et al., 2015; Wang et al., 2015). Early Paleozoic to Mesozoic igneous rocks also have been identified in the northern Wulan terrane, such as granitoids (Wu et al., 2016; Sun et al., 2015; Wang et al., 2015) and gabbros (Cheng et al., 2015; Guo et al., 2009). However, relationships between Early Paleozoic magmatism and granulite-facies metamorphism in the QM remain unclear.

1.4 Petrography of Magmatic and Metamorphic Rocks in the Northern Wulan Terrane

Six representative samples investigated in this study were collected from a granitic pluton (11WL-18), a gabbroic dike (11WL-23), granulites (11WL-1, 11WL-2 and 11WL-20) and a granitic leucosome (11WL-19) from the southern part of the Late Mesoproterozoic to Early Neoproterozoic unit in the northern Wulan terrane. Specifically, sample 11WL-18 is a monzogranite (Fig. 2), which occurs as small apophyses intruding the Late Mesoproterozoic to Early Neoproterozoic metamorphic strata (Figs. 3a3b). The granitic pluton contains variable sized xenoliths of granulites and marbles. The monzogranite of a gneissic texture (Fig. 3b) contains mainly of K-feldspar (Kfs), quartz (Qtz), and plagioclase (Pl), with minor biotite (Bt) and accessory minerals of titanite (Ttn), allanite (Aln), magnetite (Mag), rutile (Rt) and zircon (Zrn) (Fig. 4a). The Kfs crystals are mostly subhedral plates of ~3 cm in length, while Qtz grains are commonly anhedral.

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Figure 3. Photographs showing the field occurrences of granitoids and associated granulites in the northern Wulan terrane. (a) The granitic pluton intruded into the Late Mesoproterozoic to Early Neoproterozoic unit and granulites as xenoliths in the granitic pluton; (b) banded granitic leucosome associated with the granite; (c) pelitic granulite; (d) felsic granulite; and (e) a gabbroic dike in the northern Wulan terrane.
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Figure 4. Photomicrographs showing microtextural relationships of minerals in the samples from the northern Wulan terrene. (a) Monzogranite (11WL-18); (b) gabbro (11WL-23); (c) felsic granulite (11WL-1); (d) felsic granulite (11WL-2); (e) pelitic granulite (11WL-20); and (f) granitic leucosome (11WL-19).

Sample 11WL-23 was collected from a gabbroic dike of 3–5 m wide (Fig. 3e). The gabbro has a gabbro-diabasic texture (Fig. 4b), and is composed mainly of plagioclase and clinopyroxene (Cpx), with minor amounts of orthopyroxene (Opx), hornblende (Hb) and Bt, and accessory Mag, ilmenite (Ilm) and Zrn. Both Cpx and Opx usually have exsolution lamellae of Ilm, while Hb occurs as a narrow retrograde rim around Cpx (Fig. 4b). Some fined grained Opx are enclosed by large lath-shaped Pl crystals, forming the typical ophitic texture.

Two felsic granulites (samples 11WL-1 and 11WL-2) occur as xenoliths in the granitic pluton (Figs. 3a, 3d). Sample 11WL-1 shows a porphyroblastic texture (Fig. 4c) and consists of dominantly Pl, garnet (Grt), Bt, Opx and Qtz, minor Cpx and Kfs, and accessory Mag, Ilm and Zrn. The Grt porphyroblasts (GrtI) are commonly 0.5–2 mm in diameter and have abundant inclusions of Qtz (Qtz0), Bt (Bt0), chlorite (Chl0) and Pl (Pl0) in the core (GrtI-c) and an inclusion-free rim (GrtI-r). These porphyroblasts often have embayed edges, suggesting that resorption occurred along the margins. The matrix consists of finegrained Grt (GrtII), Pl, Opx, Bt, Kfs and Qtz. GrtII is 0.01–0.2 mm in diameter and commonly occurs close to the edges of large Opx grains (OpxI). Most plates of Bt define the main gneissosity and appear to be part of the peak metamorphic generation (BtI). Fine-grained aggregates of Cpx, Qtz, PlII and BtII locally occur as replacement after OpxI. Therefore, sample 11WL-1 has three generations of mineral assemblages: with n1 of Pl0+Qtz0+Bt0+Chl0 occurring as inclusions in the cores of Grt porphyroblasts (GrtI-c); n2 of OpxI+PlI+Kfs±GrtI-r±BtI±Qtz; and n3 of GrtII+Qtz+Cpx+PlII±BtII.

Another felsic granulite (sample 11WL-2) shows similar characteristics as 11WL-1 (Fig. 4d) and consists dominantly of Grt, Pl and Opx, minor Cpx, Bt, actinolite (Act), Chl and epidote (Ep), and accessory Mag, Ilm and Zrn. Sample 11WL-2 also has two prograde mineral assemblages (c1 of OpxI+PlI+ GrtI±Qtz and c2 of GrtII+Qtz+Cpx±OpxII±PlII), and one retrograde metamorphic assemblage (c3 of Act+Chl+Ep). In particular, Cpx occurs as corona around OpxI and is partially replaced by fine-grained aggregates of Act+Chl+Ep (Fig. 4d).

The pelitic granulite (sample 11WL-20) with a strong NW-SE gneissosity displays a porphyroblastic texture (Fig. 4e), and consists of dominantly Grt, sillimanite (Sil), Bt, Kfs and Pl, with minor cordierite (Cord), Opx, Chl, Qtz and muscovite (Mus), and accessory Mag, Ilm and Zrn. Garnet occurs in two generations with GrtI as porphyroblasts (5–8 mm) and GrtII in the matrix (< 0.5–1.0 mm). The GrtI porphyroblasts commonly contain abundant inclusions Qtz0, Chl0, Bt0 and Pl0 in the core (GrtI-c) and a narrow inclusion-free rim (GrtI-r). The edges of GrtI porphyroblasts commonly show embayment, indicative of resorption. GrtII occurs locally with fine-grained Cord and Kfs (and less commonly Opx) close to prismatic Sil (SilI) (Fig. 4e). K-feldspar (KfsI), CordI and PlI are locally replaced by late SilII, PlII and BtII. Therefore, the pelitic granulite is interpreted to contain three distinct generations of mineral assemblages: m1: GrtI-c+Chl0+ Qtz0±Mus0±Bt0±Pl0, m2: GrtI-r+SilI+KfsI+CordI+BtI±PlI±Qtz, and m3: GrtII±SilII±PlII+BtII+Qtz.

The granitic leucosome (sample 11WL-19) occurs as an irregular dike of 10–50 cm wide (Fig. 3f), crosscutting the main gneissosity in the granitic pluton. The granitic leucosome has a massive to pegmatitic texture (Fig. 4f) and consists mainly of microperthite, Qtz and albite with minor Mus and Bt, as well as trace Zrn.

2 ANALYTICAL METHODS 2.1 Whole-Rock Geochemical Analysis

All six representative samples were used for whole-rock geochemical analysis at the State Key Laboratory of Geological Processes and Mineral Resources (GPMR), China University of Geosciences (Wuhan). All details about the sample preparation, analytical methods and uncertainties of whole-rock geochemical analyses are similar to those described in Wang et al. (2014) and Liu et al.(2008a, b). The analytical data are listed in Table 1.

Table 1 Whole-rock bulk (wt.%) and trace elements and REE (ppm) compositions of samples from the northern Wulan terrane
2.2 Zircon U-Pb Dating

The procedures for the separation and preparation of zircon grains used for laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis are similar to those described in Wang et al. (2014). Zircon cathodoluminescence (CL) images were taken on an LEO1450VP SEM at the Institute of Geology and Geophysics, Chinese Academy of Science in Beijing. In situ zircon U-Pb dating and trace element analyses were made by LA-ICP-MS at GPMR, China University of Geosciences (Wuhan). The diameter of individual spots for LA-ICP-MS analysis is 32 µm with a laser pulse rate of 6 Hz at 40 mJ/cm2 energy density. The analytical procedure and operating conditions for the laser ablation system and the ICP-MS instrument as well as data reduction are similar to those described in Wang et al. (2014), which followed methods developed by Liu et al.(2010a, b, 2008a), Hu et al.(2008a, b) and Ludwig (2003). The analytical data of zircon U-Pb dating are given in Tables S2 and 2.

Table 2 Summary of zircon data in samples from the northern Wulan terrane of the Quanji Massif
2.3 Electron Microprobe Analysis

Chemical compositions of minerals such as garnet, orthopyroxene, plagioclase and biotite in the granulites have been determined using a JEOL JXA-8230 electron probe microanalyzer (EPMA) at the Materials Research and Testing Center, Wuhan University of Technology. Analytical conditions included an accelerating voltage of 15 kV, a beam current of 20 nA, and beam sizes of ≤5 µm in diameter. Natural minerals and synthetic oxides were used as standards for the analyses of major and minor elements, and data reduction used the ZAF correction procedures. Chemical formulas included Fe3+ were calculated using the method of Droop (1987). Compositional data of representative minerals in the granulites are given in Table 3, and additional EMPA data of minerals in the granulites are available in Tables S1-1–S1-5 as supplementary information.

Table 3 Compositions (wt.%) of selected minerals in granulites from the northern Wulan terrane of the Quanji Massif
3 RESULTS 3.1 Whole-Rock Analytical Results

The two granitic samples (11WL-18 and 11WL-19) show variations in K2O (3.46 wt.%–5.45 wt.%), Na2O (2.27 wt.%–2.90 wt.%), and TiO2 (0.05 wt.%–1.38 wt.%). They are high-K calc-alkaline rocks (Le Maitre et al., 1989), featured by high values of 1.6 to 2.3 (Rittmann, 1962) and the A/CNK values of 0.81 to 1.09 (Table 1). The variation in total rare earth element (∑REE) is large (105 ppm–317 ppm) (Table 1). The chondrite-normalized REE patterns show significant negative Eu anomalies with EuN/EuN* from 0.46 to 0.87 (Table 1, Fig. 5a), and are characterized by strong fractionation between LREE and HREE ((La/Yb)N=14.3–28.8). Strong enrichments in large ion lithophile elements (LILE) over high field strength elements (HFSE) are also evident (Fig. 5b). These geochemical data suggest that monzogranite and granitic leucosome probably formed from melting of crustal sources as well. These rocks are similar to those from Andean-type arcs or continental margin arcs (Stern, 2002; MacDonald et al., 2000).

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Figure 5. Whole-rock geochemical data for six representative samples from the northern Wulan terrane. (a) Chondrite-normalized REE patterns and (b) MORBnormalized trace element spider diagrams. Chondrite and MORB normalization values are from Sun and McDonough (1989) and Pearce (1983), respectively.

The felsic granulites (11WL-1 and 11WL-2) are characterized by high abundances of Si, Fe, Mg and K but low Al and Na contents. The pelitic granulite (11WL-20) has high SiO2 (63.3 wt.%), relatively high K2O (3.64 wt.%) and Al2O3 (17.3 wt.%) but low Na2O (1.1 wt.%), and is similar in composition to khondalites occurred widely in the Quanji Massif (Wan et al., 2006). All three granulite samples have relatively high K2O (2.91 wt.%–3.64 wt.%) (Table 1), the elemental contents and ratios (e.g., Na2O/K2O < 1, MgO/Fe < 0.7, Al2O3/TiO2 < 30) combined with the discrimination of MgO/CaO vs. P2O5/TiO2 are all indicative of para-metamorphic origins. Moreover, these granulites have high LILE concentrations (Table 1, Fig. 5b), high Cr/Ni values, but low ∑REE (112 ppm to 254 ppm) and (La/Yb)N ratios (4.8 to 7.6), and negative Eu anomalies (EuN/EuN*=0.53–0.90) (Table 1, Fig. 5a). Their REE contents and ratios are comparable with those of post-Archean sedimentary rocks around the world (McLennan, 1989).

The gabbro (11WL-23) has low SiO2 (48.9 wt.%), high CaO (7.19 wt.%) and high loss on ignition (LOI: 3.15 wt.%) values. This rock is also enriched in LREE (Fig. 5a) and most of the LILE, such as Rb, Sr and Ba, but anomalously depleted in Nb-Ta-Ti (Fig. 5b), indicative of island arc magmatism (e.g., Kelemen et al., 1993).

3.2 Zircon U-Pb Geochronological Data 3.2.1 Monzogranite (11WL-18)

Zircon grains from sample 11WL-18 are mostly euhedral prismatic in shape, with a combination of the {100}+{110} prisms and the {111} dipyramid. Grain sizes vary from 40–200 µm in length, with the length-to-width ratios mainly from 1.5 : 1 to 5 : 1. These zircon grains are highly luminescent in CL and have well-developed oscillatory zoning (Fig. 6a), typically crystallized from magmas (Corfu et al., 2003; Belousova et al., 2002; Rubatto, 2002). All 30 analyses from 27 zircon grains are characterized by high Th/U values from 0.40 to 1.31 (Table S2). Excluding two analyses from the rims, all remaining concordant analyses give a weighted mean 206Pb/238U age of 476.7±2.8 Ma (MSWD=0.42, N=28) (Fig. 7a). The two analyses on the rims (spots 12 and 13) give a weighted mean 206Pb/238U age of 443±9 Ma (Fig. 7a). On the basis of the morphological and luminescent features and high Th/U values, the ~477 Ma is interpreted to represent the crystallization age of the monzogranite (Table 2). The ~443 age obtained from zircon rims probably records a late metamorphic/deformation event (Table 2).

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Figure 6. Zircon CL images from the six samples investigated in this study showing the zircon morphology, analytical spots and corresponding U-Pb ages.
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Figure 7. Zircon U-Pb concordia diagrams showing the ages from the six samples investigated in this study. (a) Monzogranite (11WL-18); (b) gabbro (11WL-23); (c) felsic granulite (11WL-1); (d) felsic granulite (11WL-2); (e) pelitic granulite (11WL-20); and (f) granitic leucosome (11WL-19).
3.2.2 Gabbro (11WL-23)

Zircon grains from the gabbro dike are mostly subhedral to anhedral prismatic in shape. They are 80–200 µm long, with length-width ratios from 2 : 1 to 3 : 1. Most crystals display dark gray luminescence with distinct oscillatory zoning (Fig. 6b), indicative of magmatic origin (Corfu et al., 2003; Belousova et al., 2002; Rubatto, 2002). Thirty spot analyses on 30 zircon grains yielded highly concordant data with a weighted mean 206Pb/238U age of 423±2 Ma (MSWD=0.03, N=30) (Fig. 7b). These zircon grains have Th/U values from 0.47 to 1.51 (Table S2), further supporting a magmatic origin (Belousova et al., 2002).

3.2.3 Felsic granulite (11WL-1)

Zircon grains from sample 11WL-1 are mostly subhedral to anhedral and exhibit apparent core-rim textures (Fig. 6c). The crystal sizes range from 30 to 120 µm in length, and the length-to-width ratios are mainly 1.5 : 1~2.5 : 1. These zircon grains can be divided into two types. The first type is characterized by a core of bright CL (e.g., spots 9, 16, 17 and 20 in Fig. 6c) and a narrow rim of dark luminescence. The second type has small cores of high CL and wide rims of dark luminescence (e.g., spots 2–3, 4–5, 27–28, and 29–30 in Fig. 6c). Thirty analyses on 25 zircon grains from sample 11WL-23 are listed in Table S2. Three analyses from the bright CL cores plot on a concordant line (i.e., spots 2, 20, and 21), yielding a weighted mean age of 1 752±50 Ma (Fig. 7c). However, twenty analyses from the bright cores are discordant and plot roughly along three discordant lines (Fig. 7c) with the upper intercept ages of 2 431±51 (MSWD=0.88, N=5), 2 047±85 (MSWD=0.84, N=8) and 1 130± 46 Ma (MSWD=2.1, N=7). One analysis from a bright core (i.e., spot 14) exhibits apparent Pb loss. The remaining six analyses from the dark wide rims of the second type are all concordant and give a weighted mean 206Pb/238U age of 472±4.8 Ma (MSWD=0.062, N=6). The dark rims show weak or no zoning (Fig. 6c) and have low Th/U values from 0.01 to 0.04 (Table S2), indicative of metamorphic overgrowth. Therefore, the age of ~472 Ma is interpreted to represent the timing of the granulitefacies metamorphism (Table 2).

3.2.4 Felsic granulite (11WL-2)

Zircon grains from sample 11WL-2 have morphological features similar to their counterparts from sample 11WL-1. They are 40–150 µm in length, with the length-to-width ratios from 1 : 1 to 2.5 : 1. The zircon grains have bright CL cores with occasionally oscillatory zoning and narrow rims of dark CL (Fig. 6d). Thirty analyses on the cores of 27 zircon grains are given in Table S2. The data define two discordant lines, with upper intercept ages of 1 909±30 (MSWD=0.45, N=17) and 1 721±73 Ma (MSWD=0.23, N=12) (Fig. 7d), excluding one point (04) for apparent Pb loss. These two ages from zircon cores are interpreted to represent the crystallization ages of detrital zircon (Table 2). This interpretation is supported by the high Th/U values (Table S2), which are indicative of magmatic origin. Unfortunately, the dark rims of zircon are too narrow for LA-ICP-MS analysis. It is interesting to note that the detrital grains of zircon with an upper intercept age of ~1 909 Ma also define a lower intercept age of 474±32 Ma (Fig. 7d), which is identical to the age of the granulite-facies metamorphism obtained from sample 11WL-1 (Fig. 7c, Table 2).

3.2.5 Pelitic granulite (11WL-20)

Zircon grains from sample 11WL-20 can be divided into three types on the basis of morphology. Type 1 is characterized by subto euhedral prismatic shapes and is 50–120 µm in length, with the length-to-width ratios from 1.5 : 1 to 3 : 1. The CL images reveal a core-mantle-rim texture, with highly luminescent cores of probably detrital origin (i.e., spot 28 in Fig. 6e), dark mantles and grey rims. Type 2 is mostly subhedral prismatic in shape and is 40–80 µm in length, with the length-to-width ratios from 1.5 : 1 to 2 : 1. Grains of Type 2 are characterized by dark CL cores and grey rims (i.e., spots 6 and 20 in Fig. 6e), which are interpreted to represent inherited remnants and metamorphic overgrowth, respectively. Type 3 without a core-rim texture is generally dark in CL and often exhibits a weak oscillatory zonation (i.e., spots 12 and 15 in Fig. 6e). A few grains of Type 3 with dark CL do not have any apparent oscillatory zonation.

Of the forty analyses on 40 zircon grains (Table S2), six analyses on the cores of types 1 and 2 define one discordant line with an upper intercept age of 2 698±87 Ma (MSWD=1.3, N=6) (Fig. 7e), whereas another spot on the concordant line gives an age of 2 309±87 Ma (Table 2). The remaining 33 analyses roughly along the discordant line yield 206Pb/238U ages between ~402 and 499 Ma, with the exception of two analyses (i.e., spots 9 at 513 Ma and 38 at 574 Ma). These discordant 206Pb/238U ages from zircon with low Th/U values (0.01–0.09) were interpreted to represent metamorphic ages and can be further divided into three populations with the mean ages at 496±6 Ma (MSWD=1.9, N=10) with Th/U values (0.01–0.12), 474±3.7 Ma (MSWD=0.04, N=10) with Th/U values (0.01–0.19), and 446±3.5 Ma (MSWD=0.64, N=10) with Th/U values (0.01–0.06), excluding spot 11 (Tables S2 and 2). Interestingly, the second population at ~474 Ma is comparable to those (~472 and ~474 Ma) obtained from metamorphic zircon in the felsic granulites (Table 2).

3.2.6 Granitic leucosome (11WL-19)

Zircon grains from sample 11WL-19 are mostly subhedral prismatic in shape. The crystal sizes range from 50 to 200 µm in length, and the length-to-width ratios are mainly 1 : 1~3 : 1. They are characterized by low luminescence and no apparent oscillatory zonation (Figs. 6f, spots 10 and 16). However, a few grains have a distinct core-rim texture with bright CL cores and dark rims (Fig. 6f, spots 12–13). Thirty analyses on 27 zircon grains (Table S2) define a concordant line with a weighted mean 206Pb/238U age of 474.8±2.3 Ma (MSWD=0.04, N=28) (Fig. 7f), excluding one spot 13 for its apparent Pb loss and another spot 16 that has a concordant age of 443±6 Ma. This ~475 Ma age from zircon grains with Th/U values from 0.02 to 0.24 (Table S2) is interpreted to record anatexis, whereas the ~443 Ma age probably represents a late metamorphic/deformation event (Table 2).

3.3 Mineral Compositions, Metamorphic P-T Conditions and P-T Paths 3.3.1 Mineral compositions 3.3.1.1 Garnet

Garnets in the pelitic granulite (11WL-20) are richer in the almandine component but poorer in the pyrope component than those in the felsic granulites (11WL-1 and 11WL-2) (Fig. 8a; Table 3 and Tables S1-1–S1-5). The texturally different generations of garnet in all three granulite samples are also distinct in chemical composition (Fig. 8b; Table 3). For example, GrtI and GrtII in sample 11WL-1 have compositions of Alm0.61Prp0.29 Grs0.07Sps0.04 and Alm0.64Prp0.26Grs0.07Sps0.04, respectively, whereas GrtI and GrtII in sample 11WL-2 are Alm0.54–0.58 Prp0.29–0.33Grs0.07–0.13Sps0.04 and Alm0.58–0.59Prp0.29–0.30Grs0.07 Sps0.04–0.05, respectively (Table S1-1). In sample 11WL-20, GrtI-c has a composition of Alm0.78Prp0.14Sps0.04Grs0.03, distinct from GrtI-r at Alm0.73Prp0.21Sps0.03Grs0.03 (Fig. 8b). Fine-grained GrtII in sample 11WL-20 is homogeneous in individual grains but exhibits small compositional variations from grain to grain, with an average composition of Alm0.75Prp0.19Sps0.03Grs0.03 (Table S1-1).

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Figure 8. (Alm+Sps)-Grs-Prp triangular plots showing (a) compositional differences of garnet between the felsic granulites (11WL-1 and 11WL-2) and the pelitic granulite (11WL-20), and (b) compositional differences among texturally distinct varieties of garnet in the pelitic granulite (11WL-20).
3.3.1.2 Orthopyroxene

Orthopyroxene in the felsic granulites (11WL-1 and 11WL-2) is compositionally homogeneous in individual grains and is dominated by the enstatite-ferrosilite series, in the range of En0.59–0.64Fs0.35–0.41 (Table S1-2). Orthopyroxene in sample 11WL-1 at En0.59–0.60Fs0.39–0.41 is slightly richer in Fe than that in sample 11WL-2 at En0.59–0.64Fs0.35–0.41 (Table S1-2). Minor compositional differences between OpxI and OpxII in sample 11WL-2 are also notable (Table 3).

3.3.1.3 Plagioclase

Two or three generations of plagioclase can be distinguished on the basis of their occurrences in the cores or rims of garnet porphyroblasts and in the matrix (Figs. 4c, 4d4e). The compositions of plagioclase differ significantly between the felsic granulites (An0.81–0.85Ab0.13–0.19) and the pelitic granulite (An0.28–0.31Ab0.69–0.71) (Tables 3 and S1-3).

3.3.1.4 Biotite

The three generations of biotite in the pelitic granulite differ significantly in the TiO2 and XMg contents (Tables 3 and S1-4). Also, the XMg values of 0.61–0.71 for biotite in the felsic granulites are notably higher than those (0.43–0.57) of its counterpart in the pelitic granulite (Table S1-4).

3.3.1.5 Other minerals

Representative compositions of K-felspar, muscovite, cordierite, and sillimanite in the granulites are given in Table S1-5.

3.3.2 Metamorphic P-T conditions and P-T paths

The P-T conditions for the three stages of regional metamorphism have been estimated using conventional geothermobarometry. Specifically, the GB-GASP geothermobarometry (Wu et al., 2006; Holdaway, 2001, 2000) and the GB-GBPQ geothermobarometry (Wu C M et al., 2004; Holdaway, 2001, 2000) have been used for the mineral assemblages in the pelitic granulite. The Grt-Opx (or Grt-Cpx) geothermometer (Taylor, 1998; Brey and Köhler, 1990) and the Grt-Opx-Pl-Qtz geobarometer (Nimis and Taylor, 2000; Perkins and Chipera, 1985; Harley, 1984) were used for mineral assemblages in the felsic granulites. These calculations show that the granulite-facies metamorphism recorded peak P-T conditions of 729 C and 0.46 GPa from the pelitic granulite, and 718 C and 0.53 GPa from the felsic granulites (i.e., points m2 and n2 in Fig. 9; Table 4). The early stage of the prograde metamorphism constrained from the pelitic granulite occurred at 598 C and 0.28 GPa (Table 4).

Table 4 Metamorphic mineral assemblages and P-T conditions in granulites from the northern Wulan terrane

The mineral assemblages m3, n3 and c3 (Figs. 4e, 4c4d) suggest a late episode of near-isobaric cooling after the peak granulite-facies metamorphism. Mineral assemblages of m3 and n3 yielded the post-peak conditions of 583–669 C and 0.43–0.44 GPa (Table 4; Fig. 9). For example, the replacements of biotite and sillimanite (SilI) by garnet (GrtII) and cordierite, and then Kfelspar and cordierite by sillimanite (SilII) and biotite (BtII), (Sil+ Bt+Qtz=Grt+Cord+Kfs+H2O and Kfs+Cord=Sil+Bt) are observed in the pelitic granulite (Fig. 4e). These characteristic reactions are indicative of nearly isobaric heating followed by isobaric cooling, which is commonly attributable to uplifting or collapse after crustal thickening and excess heating. The anticlockwise P-T path (Fig. 9) in the pelitic granulite is characterized by the metamorphic reactions of Bt+Pl+Qtz±Chl→GrtI-c (m1) and Mus+Qtz→SilI+Kfs (m2), via Sil+Bt→Cord+Kfs and Kfs+Cord→SilII+Phl, to GrtII+ SilII+Phl+PlII±BtII±Qtz (m3) (Table 4).

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Figure 9. Metamorphic evolution in the pelitic granulite (from m1 to m2 and m3) and the felsic granulites (from n2 to n3), showing the anticlockwise P-T paths (after Winter, 2014).

Similarly, the mineral assemblages in the felsic granulites suggest the following reactions: (1) Bt0+Pl0=GrtI-c, (2) BtI+Qtz= OpxI+Kfs, and (3) GrtI-r+Qtz±Cpx=OpxI+PlI. Reaction (2) is characteristic of granulite-facies metamorphism, and reaction (3) is variable depending on the occurrence of orthopyroxene or garnet (Figs. 4c4d). The anticlockwise P-T path in the felsic granulite is constrained by the metamorphic reactions of Bt+Qtz→Opx+Kfs (n2) and Opx+Pl→Grt+Qtz±Cpx (n3) (Fig. 9). The replacement of orthopyroxene and garnet by retrograde minerals such as actinolite, chlorite and epidote further supports an anticlockwise P-T path involving decompressional cooling (Table 4).

4 DISCUSSION 4.1 Timing of Early Paleozoic Magmatism and Regional Metamorphism

The whole-rock Sm-Nd isochron age of ~3 450 Ma for the granulites reported by Wang et al. (2000) is difficult to explain, because the oldest U-Pb age of detrital zircon in the same rocks is only ~2.70 Ga (Table 2). The five populations of U-Pb ages (~2.70, 2.43–2.31, 2.05–1.91, ~1.73, and ~1.13 Ga; Table 2) from detrital zircon suggest that the protoliths of the granulites have complex Precambrian sources. However, the detrital zircon age of ~1.13 Ga is similar to that of magmatic zircon from granitoids (Wang, 2016) and constrains the maximum deposition age for the protoliths of the granulites (Wang et al., 2016).

Our U-Pb dating of magmatic, metamorphic and inherited or detrital zircon from monzogranite, gabbro, granulites and granitic leucosome (Tables S2 and 2) yielded at least two pulses of magmatism at ∼477 and ∼423 Ma, as well as three episodes of regional metamorphism at ∼496, ~474, and ∼443 Ma. The crystallization age of 476.7±2.8 Ma from magmatic zircon in the monzogranite constrains the peak timing of island arc magmatism. The younger age at 443±9 Ma from zircon in the monzogranite is attributable to late metamorphic/deformation overprint, although a ∼443 Ma magmatism has also been reported to occur in the Yutuan Mountain (Wu et al., 2008). The zircon U-Pb age of 423 Ma from the gabbroic dike recorded an episode of mafic magmatism.

Zircon grains of metamorphic origin from the granulites yielded U-Pb ages of 496±6, 474±3.7, 472±4.8, and 446±3.5 Ma (Table 2). The ~496 Ma age from the pelitic granulite is interpreted to represent the earliest episode of Paleozoic metamorphism in the northern Wulan terrane. The ages of 474±3.7 and 472±4.8 Ma, together with the lower intercept age of 474±32 Ma from detrital zircon in the felsic granulite, all constrain the peak granulite-facies metamorphism to have occurred at ~475 Ma. These U-Pb ages for the peak granulite-facies metamorphism are also within analytical uncertainties to that (474.8±2.3 Ma) from the granitic leucosome, confirming that anataxis accompanied the peak metamorphism. Interestingly, the younger age of 443±6 Ma from a zircon rim with dark CL in the granitic leucosome is similar to those in the monzogranite (443±9 Ma) and the pelitic granulite (446±4 Ma) (Table 2), apparently representing a late episode of metamorphism/deformation in the northern Wulan terrane.

4.2 Early Paleozoic Paired Metamorphic Belts in the NQTB

Previous studies recognized two stages of subductioncollision in the North Qaidam HP-UHP metamorphic belt, with an earlier oceanic subduction at ~470 Ma and a late continental collision at ~440 Ma (Zhang et al., 2017; Song et al., 2014, 2013, 2006; Xiong et al., 2012, 2011). For example, Song et al. (2018) documented early HP lawsonite-bearing eclogites formed from "cold" subduction at 470–445 Ma and late "hot" and "dry" UHP kyanite eclogites related to continental subduction/collision at 438–420 Ma. Several studies showed that the exhumation and retrograde metamorphism in the North Qaidam HP-UHP metamorphic belt involved isothermal decompression along a clockwise P-T path (Song et al., 2018, 2014; Zhang et al., 2017). In contrast, the low-P/T metamorphism in the northern Wulan terrane is characterized by an anticlockwise P-T path involving nearly isobaric cooling during retrograde metamorphism.

Cold subduction of an oceanic lithosphere beneath a continental plate usually causes arc magmatism and low P/T metamorphism on the continental arc margin or island arc region, such as in the Andean Range and Japanese Islands. One characteristic feature at such convergent margins is the occurrences of paired metamorphic belts with a high P/T metamorphic belt on the ocean side and a low to medium P/T metamorphic belt on the continental side (Brown, 2010; Miyashiro, 1973). The present study shows that the peak granulite-facies metamorphism and associated anatexis at ~475 Ma were contemporaneous with the island arc magmatism in the northern Wulan terrane. Moreover, the low P/T granulite-facies metamorphism, anataxis and island arc magmatism in the northern Wulan terrane are broadly coeval with the early HP metamorphism in the North Qaidam HP-UHP metamorphic belt, providing compelling evidence for Early Paleozoic paired metamorphic belts (Fig. 10). In particular, the anticlockwise P-T path observed in the northern Wulan terrane is characteristic of low P/T metamorphism associated with subduction-induced arc magmatism in continental arcs such as the Quanji Massif. This clearly suggests that the northern Wulan terrane of the Quanji Massif was on the side of the overriding plate and participated in the subsequent continentcontinent collision process in the Early Paleozoic.

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Figure 10. Schematic N-S cross-sections of the North Qaidam tectonic belt illustrating the closure of the South Qilian Ocean (i.e., the Proto-Tethys Ocean) and Early Paleozoic tectonic evolution.
4.3 Implications for the Closure of the Proto-Tethys Ocean

Early Paleozoic has long been proposed to be a key time in the final amalgamation of various components to form the Gondwana supercontinent and the initiation of subduction for the closure of the Proto-Tethys Ocean along the peri-Gondwana margin (Li et al., 2017; Cawood and Buchan, 2007; Meert, 2003). Several studies have suggested an Early Paleozoic Andean-type orogeny along the peri-Gondwana Proto-Tethys margin (Li et al., 2017; Zhang J X et al., 2014; Cawood et al., 2007).

Our new data from granulites and granitoids in the northern Wulan terrane, including recognition of Early Paleozoic paired metamorphic belts in the North Qaidam tectonic belt, provide further support for the Andean-type orogeny between ~540 and 440 Ma (see also Li et al., 2017), responsible for the closure of the South Qilian Ocean, which was part of the larger ProtoTethys Ocean (Fig. 10). We envision that the 540–500 Ma Tanjianshan volcanic zone represented an early volcanic island arc formed from the northward subduction of the Proto-Tethys oceanic plate. Continuing subduction and HP metamorphism in the lower plate between 500 and 440 Ma (Song et al., 2018) gave rise to further island-arc magmatism in the Quanji Massif as a continental arc, which in turn was responsible for low P/T granulite-facies metamorphism and associated anataxis in the upper plate (Fig. 10). Therefore, the Proto-Tethys Ocean in northwestern China was most likely completely closed by ~440 Ma (Fig. 10), when the continent-continent collision became dominant in the North Qaidam tectonic belt. The closure of the Proto-Tethys Ocean at this time is further supported by the intrusion of the post-collisional gabbroic dike at ~423 Ma.

5 CONCLUSIONS

The low P/T pelitic and felsic granulites in the northern Wulan terrane are characterized by an anticlockwise P-T path and have metamorphic ages of 500–440 Ma. A granitic pluton of dominantly monzogranite intruded at 476.7±2.8 Ma and is characteristic of island arc magmatism with high potassium calc-alkaline metaluminous compositions. Magmatic zircon from a granitic leucosome yielded a crystallization age of 474.8±2.3 Ma. The contemporaneous low P/T granulite-facies metamorphism, anatexis and island-arc magmatism in the northern Wulan terrane of the Quanji Massif were coeval with the early lawsonite-bearing eclogites in the North Qaidam HP-UHP metamorphic belt to the south, providing evidence for Early Paleozoic paired metamorphic belts with a northward subduction of the Proto-Tethys oceanic plate and the closure of the Proto-Tethys Ocean in northwestern China.

ACKNOWLEDGMENTS

This paper is dedicated to the celebration of Prof. Zhendong Youʼs 90th birthday. In particular, Qinyan Wang and Yuanming Pan both benefited directly from Prof. Youʼs metamorphic petrology courses. We also thank three journal reviewers as well as Profs. Neng-Song Chen, Qunke Xia, Yixian Xu and Xianhua Li for constructive reviews and helpful suggestions. This research supported by the National Natural Science Foundation of China (Nos. 41072044, 41130315 and 41530319). The final publication is available at Springer via https://doi.org/10.1007/s12583-018-0881-6.

Electronic Supplementary Materials: Supplementary materials (Tables S1 and S2) are available in the online version of this article at https://doi.org/10.1007/s12583-018-0881-6.


REFERENCES CITED
Belousova, E., Griffin, W., O'Reilly, S. Y., et al., 2002. Igneous Zircon:Trace Element Composition as an Indicator of Source Rock Type. Contributions to Mineralogy and Petrology, 143(5): 602-622. DOI:10.1007/s00410-002-0364-7
Brey, G. P., Köhler, T., 1990. Geothermobarometry in Four-Phase Lherzolites Ⅱ. New Thermobarometers, and Practical Assessment of Existing Thermobarometers. Journal of Petrology, 31(6): 1353-1378. DOI:10.1093/petrology/31.6.1353
Brown, M., 2010. Paired Metamorphic Belts Revisited. Gondwana Research, 18(1): 46-59. DOI:10.1016/j.gr.2009.11.004
Bureau of Geology and Mineral Resources Qinghai Province, 1991. Regional Geology of Qinghai Province. Geological Publishing House, Beijing. 315-318.
Cawood, P. A., Buchan, C., 2007. Linking Accretionary Orogenesis with Supercontinent Assembly. Earth-Science Reviews, 82(3/4): 217-256. DOI:10.1016/j.earscirev.2007.03.003
Cawood, P. A., Johnson, M. R. W., Nemchin, A. A., 2007. Early Palaeozoic Orogenesis along the Indian Margin of Gondwana:Tectonic Response to Gondwana Assembly. Earth and Planetary Science Letters, 255(1/2): 70-84. DOI:10.1016/j.epsl.2006.12.006
Chen, D. L., Sun, Y., Liu, L., 2007. The Metamorphic Ages of the Country Rocks of the Yukahe Eclogites in the Northern Margin of Qaidam Basin and Its Geological Significance. Earth Science Frontiers, 14(1): 108-116. DOI:10.1016/s1872-5791(07)60005-0
Chen, N.-S., Gong, S. L., Xia, X. P., et al., 2013a. Zircon Hf Isotope of Yingfeng Rapakivi Granites from the Quanji Massif and~2. 7 Ga Crustal Growth. Journal of Earth Science, 24(1): 29-41. DOI:10.1007/s12583-013-0309-2
Chen, N.-S., Liao, F. X., Wang, L., et al., 2013b. Late Paleoproterozoic Multiple Metamorphic Events in the Quanji Massif:Links with Tarim and North China Cratons and Implications for Assembly of the Columbia Supercontinent. Precambrian Research, 228: 102-116. DOI:10.1016/j.precamres.2013.01.013
Chen, N.-S., Zhang, L., Sun, M., et al., 2012. U-Pb and Hf Isotopic Compositions of Detrital Zircons from the Paragneisses of the Quanji Massif, NW China:Implications for Its Early Tectonic Evolutionary History. Journal of Asian Earth Sciences, 54. DOI:10.1016/j.jseaes.2012.04.006
Chen, N.-S., Gong, S. L., Sun, M., et al., 2009. Precambrian Evolution of the Quanji Block, Northeastern Margin of Tibet:Insights from Zircon U-Pb and Lu-Hf Isotope Compositions. Journal of Asian Earth Sciences, 35(3/4): 367-376. DOI:10.1016/j.jseaes.2008.10.004
Chen, N.-S., Sun, M., Wang, Q. Y., et al., 2008. U-Pb Dating of Zircon from the Central Zone of the East Kunlun Orogen and Its Implications for Tectonic Evolution. Science in China Series D:Earth Sciences, 51(7): 929-938. DOI:10.1007/s11430-008-0072-x
Chen, N.-S., Wang, X. Y., Zhang, H. F., et al., 2007. Geochemistry and Nd-Sr-Pb Isotopic Compositions of Granitoids from Qaidam and Oulongbuluke Micro-Blocks, NW China:Constraints on Basement Nature and Tectonic Affinity. Earth Science-Journal of China University of Geosciences, 32(1): 7-21.
Cheng, T. T., Niu, M. L., Wu, Q., et al., 2015. Petrogenesis of the Chahannuo Gabbro on the Northern Margin of Qaidam Basin:Constraint from Geochemistry, Zircon U-Pb Dating and Lu-Hf Isotopes. Chinese Journal of Geology, 50: 741-755.
Corfu, F., Hanchar, J. M., Hoskin, P. W., et al., 2003. Atlas of Zircon Textures. Reviews in Mineralogy and Geochemistry, 53: 469-500. DOI:10.2113/0530469
Da, L. C., Niu, M. L., Li, X. C., et al., 2017. Tectonic Deformation Characteristics of the L Tectonites in Erlangdong Area at the Northern Margin of Qaidam Basin and Its Geological Significance. Chinese Journal of Geology, 52: 1038-1057.
Dong, Y. J., 2014. The Formation of Granulites and Its Tectonic Implications in Northern Wulan of the Quanji Massif: [Dissertation]. China University of Geosciences, Wuhan (in Chinese with English Abstract)
Droop, G. T. R., 1987. A General Equation for Estimating Fe3+ Concentrations in Ferromagnesian Silicates and Oxides from Microprobe Analyses, Using Stoichiometric Criteria. Mineralogical Magazine, 51(361): 431-435. DOI:10.1180/minmag.1987.051.361.10
Gao, C. L., Huang, Z. G., Ye, D. L., et al., 2005. Three Paleo-Oceans in the Early Paleozoic and Their Control to Basins in China. Petroleum Geology and Experiment, 27(5): 439-448.
Gao, X. F., Xiao, P. X., Jia, Q. Z., 2011. Redetermination of the Tanjianshan Group:Geochronological and Geochemical Evidence of Basalts from the Margin of the Qaidam Basin. Acta Geologica Sinica, 85(9): 1452-1463.
Gong, S. L., Chen, N.-S., Geng, H. Y., et al., 2014. Zircon Hf Isotopes and Geochemistry of the Early Paleoproterozoic High-Sr Low-Y Quartz-Diorite in the Quanji Massif, NW China:Crustal Growth and Tectonic Implications. Journal of Earth Science, 25(1): 74-86. DOI:10.1007/s12583-014-0401-2
Gong, S. L., Chen, N.-S., Wang, Q. Y., et al., 2012. Early Paleoproterozoic Magmatism in the Quanji Massif, Northeastern Margin of the Qinghai-Tibet Plateau and Its Tectonic Significance:LA-ICPMS U-Pb Zircon Geochronology and Geochemistry. Gondwana Research, 21(1): 152-166. DOI:10.1016/j.gr.2011.07.011
Guo, A. L., Zhang, G. W., Qiang, J., et al., 2009. Indosinian Zongwulong Belt on the Northeastern Margin of the Qinghai-Tibet Plateau. Acta Petrologica Sinica, 25: 1-12.
Hao, G. J., Lu, S. N., Li, H. K., et al., 2001. Determimation and Significance of Eclogite on Shaliuhe, in the North Margin of the Qaidam Basin. Geological Survey and Research, 24(3): 154-162.
Harley, S. L., 1984. The Solubility of Alumina in Orthopyroxene Coexisting with Garnet in FeO-MgO-Al2O3-SiO2 and CaO-FeO-MgO-Al2O3-SiO2. Journal of Petrology, 25(3): 665-696. DOI:10.1093/petrology/25.3.665
He, C., Gong, S. L., Wang, L., et al., 2018. Protracted Post-Collisional Magmatism during Plate Subduction Shutdown in Early Paleoproterozoic:Insights from Post-Collisional Granitoid Suite in NW China. Gondwana Research, 55: 92-111. DOI:10.1016/j.gr.2017.11.009
Holdaway, M. J., 2000. Application of New Experimental and Garnet Margules Data to the Garnet-Biotite Geothermometer. American Mineralogist, 85(7/8): 881-892. DOI:10.2138/am-2000-0701
Holdaway, M. J., 2001. Recalibration of the GASP Geobarometer in Light of Recent Garnet and Plagioclase Activity Models and Versions of the Garnet-Biotite Geothermometer. American Mineralogist, 86(10): 1117-1129. DOI:10.2138/am-2001-1001
Hu, Z. C., Gao, S., Liu, Y. S., et al., 2008a. Signal Enhancement in Laser Ablation ICP-MS by Addition of Nitrogen in the Central Channel Gas. Journal of Analytical Atomic Spectrometry, 23(8): 1093-1101. DOI:10.1039/b804760j
Hu, Z. C., Liu, Y. S., Gao, S., et al., 2008b. A Local Aerosol Extraction Strategy for the Determination of the Aerosol Composition in Laser Ablation Inductively Coupled Plasma Mass Spectrometry. Journal of Analytical Atomic Spectrometry, 23(9): 1192-1203. DOI:10.1039/b803934h
Kelemen, P. B., Shimizu, N., Dunn, T., 1993. Relative Depletion of Niobium in Some Arc Magmas and the Continental Crust:Partitioning of K, Nb, La and Ce during Melt/Rock Reaction in the Upper Mantle. Earth and Planetary Science Letters, 120(3/4): 111-134. DOI:10.1016/0012-821x(93)90234-z
Lai, S. C., Deng, J. F., Zhao, H. L., 1996a. Paleozoic Ophiolites and Its Tectonic Significance on North Margin of Qiadam Basin. Geoscience, 10(1): 18-28.
Lai, S. C., Deng, J. F., Zhao, H. L., 1996b. Volcanism and Tectonic Setting during Ordovician Period on North Margin of Qaidam. Journal of Xi'an College of Geology, 18(3): 8-14.
Le Maitre, R. W., Bateman, P., Dudek, A., et al., 1989. A Classification of Igneous Rocks and a Glossary of Terms.
Li, Z. X., Bogdanova, S. V., Collins, A. S., et al., 2008. Assembly, Configuration, and Break-up History of Rodinia:A Synthesis. Precambrian Research, 160(1/2): 179-210.
Li, S. Z., Yang, Z., Zhao, S. J., et al., 2016a. Global Early Paleozoic Orogens (Ⅰ):Collision-Type Orogeny. Journal of Jilin University (Earth Science Edition), 46(4): 945-967.
Li, S. Z., Yang, Z., Zhao, S. J., et al., 2016b. Global Early Paleozoic Orogens (Ⅱ):Subduction-Accretionary-Type Orogeny. Journal of Jilin University (Earth Science Edition), 46(4): 968-1004.
Li, S. Z., Li, X. Y., Zhao, S. J., et al., 2016c. Global Early Paleozoic Orogens (Ⅲ):Intracontinental Orogen in South China. Journal of Jilin University (Earth Science Edition), 46(4): 1005-1025.
Li, S. Z., Yang, Z., Zhao, S. J., et al., 2016d. Global Early Paleozoic Orogens (Ⅳ):Plate Reconstruction and Supercontinent Carolina. Journal of Jilin University (Earth Science Edition), 46(4): 1026-1041.
Li, S. Z., Zhao, S. J., Liu, X., et al., 2017. Closure of the Proto-Tethys Ocean and Early Paleozoic Amalgamation of Microcontinental Blocks in East Asia. Earth-Science Reviews. DOI:10.1016/j.earscirev.2017.01.011
Li, X. C., Niu, M. L., Yan, Z., et al., 2015. LP/HT Metamorphic Rocks in Wulan County, Qinghai Province:An Early Paleozoic Paired Metamorphic Belt on the Northern Qaidam Basin. Chinese Science Bulletin, 60: 3501-3513.
Li, X. C., Niu, M. L., Yakymchuk, C., et al., 2018. Anatexis of Former Arc Magmatic Rocks during Oceanic Subduction:A Case Study from the North Wulan Gneiss Complex. Gondwana Research, 61: 128-149. DOI:10.1016/j.gr.2018.04.016
Liao, F. X., Wang, Q. Y., Chen, N.-S., et al., 2018a. Geochemistry and Geochronology of the~0. 82 Ga High-Mg Gabbroic Dykes from the Quanji Massif, Southeast Tarim Block, NW China:Implications for the Rodinia Supercontinent Assembly. Journal of Asian Earth Sciences, 157: 3-21. DOI:10.1016/j.jseaes.2017.06.021
Liao, F. X., Chen, N.-S., Santosh, M., et al., 2018b. Paleoproterozoic Nb-Enriched Meta-Gabbros in the Quanji Massif, NW China:Implications for Assembly of the Columbia Supercontinent. Geoscience Frontiers, 9(2): 577-590. DOI:10.1016/j.gsf.2017.05.007
Liao, F. X., Zhang, L., Chen, N.-S., et al., 2014. Geochronology and Geochemistry of Meta-Mafic Dykes in the Quanji Massif, NW China:Paleoproterozoic Evolution of the Tarim Craton and Implications for the Assembly of the Columbia Supercontinent. Precambrian Research, 249: 33-56. DOI:10.1016/j.precamres.2014.04.015
Liao, F. X., Gong, S. L., Dong, Y. J., et al., 2012. LA-ICP-MS Zircon U-Pb Age of Meta-Basic Plutons in Eastern Quanji Massif:Evidence for Mesoproterozoic Continental Break-up. Geological Bulletin of China, 31(8): 1279-1286.
Liu, Y. S., Hu, Z. C., Gao, S., et al., 2008a. In situ Analysis of Major and Trace Elements of Anhydrous Minerals by LA-ICP-MS without Applying an Internal Standard. Chemical Geology, 257(1/2): 34-43. DOI:10.1016/j.chemgeo.2008.08.004
Liu, Y. S., Zong, K. Q., Kelemen, P. B., et al., 2008b. Geochemistry and Magmatic History of Eclogites and Ultramafic Rocks from the Chinese Continental Scientific Drill Hole:Subduction and Ultrahigh-Pressure Metamorphism of Lower Crustal Cumulates. Chemical Geology, 247(1/2): 133-153. DOI:10.1016/j.chemgeo.2007.10.016
Liu, Y. S., Gao, S., Hu, Z. C., et al., 2010a. Continental and Oceanic Crust Recycling-Induced Melt-Peridotite Interactions in the Trans-North China Orogen:U-Pb Dating, Hf Isotopes and Trace Elements in Zircons from Mantle Xenoliths. Journal of Petrology, 51(1/2): 537-571. DOI:10.1093/petrology/egp082
Liu, Y. S., Hu, Z. C., Zong, K. Q., et al., 2010b. Reappraisement and Refinement of Zircon U-Pb Isotope and Trace Element Analyses by LA-ICP-MS. Chinese Science Bulletin, 55(15): 1535-1546. DOI:10.1007/s11434-010-3052-4
Lu, S. N., Li, H. K., Zhang, C. L., et al., 2008. Geological and Geochronological Evidence for the Precambrian Evolution of the Tarim Craton and Surrounding Continental Fragments. Precambrian Research, 160(1/2): 94-107. DOI:10.1016/j.precamres.2007.04.025
Lu, S. N., Yu, H. F., Li, H. K., et al., 2009. Precambrian Geology in the Central China Orogen (Western Part).
Lu, S. N., Yu, H. F., Li, H. K., et al., 2006. Research on Precambrian Major Problems in Chinese.
Lu, S. N., 2002. Preliminary Study of Precambrian Geology in the North Tibet-Qinghai Plateau.
Ludwig, K. R., 2003. Userʼs Manual for ISOPLOT/Ex 3.00: A Geochronological Toolkit for Microsoft Excel. Berkeley Geochronology Center, Berkeley: 1-71.
Ma, J. J., Wang, H., He, C., et al., 2018a. Neoproterozoic Post-Collision Magmatism in South Qilian Orogen, China: Evidenced by Geochronology and Geochemistry. Journal of Earth Sciences and Environment, 40(2): 133-154.
Ma, J. J., Wang, H., He, C., et al., 2018b. Zircon U-Pb Age Evidence of Jinningan Kekesha Granite in North-Wulan Terrane, Western Qinghai. Geological Bulletin of China, in Press.
MacDonald, R., Hawkesworth, C. J., Heath, E., 2000. The Lesser Antilles Volcanic Chain: A Study in Arc Magmatism. Earth-Science Reviews, 49(1/2/3/4): 1-76. DOI:10.1016/s0012-8252(99)00069-0
Mattinson, C. G., Wooden, J. L., Liou, J. G., et al., 2006. Age and Duration of Eclogite-Facies Metamorphism, North Qaidam HP/UHP Terrane, Western China. American Journal of Science, 306: 683-711. DOI:10.2475/09.2006.01
McLennan, S. M., 1989. Rare Earth Elements in Sedimentary Rocks: Influence of Provenance and Sedimentary Processes. Mineralogical Society of America, 21: 683-724.
Meert, J. G., 2003. A Synopsis of Events Related to the Assembly of Eastern Gondwana. Tectonophysics, 362(1/2/3/4): 1-40. DOI:10.1016/s0040-1951(02)00629-7
Meng, F. C., Zhang, J. X., 2008. Contemporaneous of Early Palaeozoic Granite and High Temperature Metamorphism, North Qaidam Mountains, Western China. Acta Petrologica Sinica, 24: 1585-1594.
Meng, F. C., Zhang, J. X., Yang, J. S., 2005. Tectono-Thermal Event of Post-HP/UHP Metamorphism in Xitieshan Area of the North Qaidam Mountains, Western China: Isotopic and Geochemical Evidence of Granite and Gneiss. Acta Petrologica Sinica, 21: 45-56.
Miyashiro, A., 1973. Metamorphism and Metamorphic Belts. Geo. Allen and Unwin Ltd., London.
Nimis, P., Taylor, W. R., 2000. Single Clinopyroxene Thermobarometry for Garnet Peridotites. Part Ⅰ. Calibration and Testing of a Cr-in-Cpx Barometer and an Enstatite-in-Cpx Thermometer. Contributions to Mineralogy and Petrology, 139(5): 541-554. DOI:10.1007/s004100000156
Pan, G. T., Chen, Z. L., Li, X. Z., et al., 1997. The Geological Tectonic Formation and Evolution of the Eastern Tethys. Geological Publishing House, Beijing. 65-128.
Pan, G. T., Wang, L. Q., Li, R. S., et al., 2012. Tectonic Model of Archipelagic Arc-Basin: The Key to the Continental Geology. Sedimentary Geology and Tethyan Geology, 32(3): 1-20.
Pearce, J. A., 1983. The Role of Sub-Continental Lithosphere in Magmagenesis at Destructive Plate Margins. In: Hawkesworth, C. J., Norry, M. J., eds., Continental Basalts and Mantle Xenoliths. Shiva, Nantwith. 230-249
Peng, Y., Ma, Y. S., Liu, C. L., et al., 2016. Geological Characteristics and Tectonic Significance of the Indosinian Granodiorites from the Zongwulong Tectonic Belt in North Qaidam. Earth Science Frontiers, 23(2): 206-221.
Perkins, D. Ⅲ, Chipera, S. J., 1985. Garnet-Orthopyroxene-Plagioclase-Quartz Barometry: Refinement and Application to the English River Subprovince and the Minnesota River Valley. Contributions to Mineralogy and Petrology, 89(1): 69-80. DOI:10.1007/bf01177592
Rittmann, A., 1962. Volcanoes and Their Activity. John Wiley & Sons Inc., New York. 1-305.
Rubatto, D., 2002. Zircon Trace Element Geochemistry: Partitioning with Garnet and the Link between U-Pb Ages and Metamorphism. Chemical Geology, 184(1/2): 123-138. DOI:10.1016/s0009-2541(01)00355-2
Shi, R. D., Yang, J. S., Wu, C. L., et al., 2006. Island Arc Volcanic Rocks in the North Qaidam UHP Belt, Northern Tibet Plateau: Evidence for Ocean-Continent Subduction Preceding Continent-Continent Subduction. Journal of Asian Earth Sciences, 28(2/3): 151-159. DOI:10.1016/j.jseaes.2005.09.019
Shi, R. D., Yang, J. S., Wu, C. L., et al., 2004. Island Arc Volcanic Rocks in the North Qaidam UHP Metamorphic Belt. Acta Geologica Sinica, 78(1): 52-64.
Song, S. G., Niu, Y. L., Su, L., et al., 2014. Continental Orogenesis from Ocean Subduction, Continent Collision/Subduction, to Orogen Collapse, and Orogen Recycling: The Example of the North Qaidam UHPM Belt, NW China. Earth-Science Reviews, 129: 59-84. DOI:10.1016/j.earscirev.2013.11.010
Song, S. G., Niu, Y. L., Su, L., et al., 2013. Tectonics of the North Qilian Orogen, NW China. Gondwana Research, 23(4): 1378-1401. DOI:10.1016/j.gr.2012.02.004
Song, S. G., Niu, Y. L., Zhang, G. B., et al., 2018. Two Epochs of Eclogite Metamorphism Link 'Cold' Oceanic Subduction and 'Hot' Continental Subduction, the North Qaidam UHP Belt, NW China. Geological Society, London, Special Publications, 474. DOI:10.1144/sp474.2
Song, S. G., Wang, M. J., Wang, C., et al., 2015. Magmatism during Continental Collision, Subduction, Exhumation and Mountain Collapse in Collisional Orogenic Belts and Continental Net Growth: A Perspective. Science China Earth Sciences, 58(8): 1284-1304. DOI:10.1007/s11430-015-5102-x
Song, S. G., Yang, J. S., Xu, Z. Q., et al., 2003. Metamorphic Evolution of the Coesite-Bearing Ultrahigh-Pressure Terrane in the North Qaidam, Northern Tibet, NW China. Journal of Metamorphic Geology, 21(6): 631-644. DOI:10.1046/j.1525-1314.2003.00469.x
Song, S. G., Yang, L. M., Zhang, Y. Q., et al., 2017. Qi-Qin Accretionary Belt in Central China Orogen: Accretion by Trench Jam of Oceanic Plateau and Formation of Intra-Oceanic Arc in the Early Paleozoic Qin-Qi-Kun Ocean. Science Bulletin, 62(15): 1035-1038. DOI:10.1016/j.scib.2017.07.009
Song, S. G., Zhang, L. F., Niu, Y. L., et al., 2006. Evolution from Oceanic Subduction to Continental Collision: A Case Study from the Northern Tibetan Plateau Based on Geochemical and Geochronological Data. Journal of Petrology, 47(3): 435-455. DOI:10.1093/petrology/egi080
Song, S. G., Zhang, L. F., Niu, Y. L., et al., 2005. Geochronology of Diamond-Bearing Zircons from Garnet Peridotite in the North Qaidam UHPM Belt, Northern Tibetan Plateau: A Record of Complex Histories from Oceanic Lithosphere Subduction to Continental Collision. Earth and Planetary Science Letters, 234(1/2): 99-118. DOI:10.1016/j.epsl.2005.02.036
Stern, R. J., 2002. Subduction Zones. Reviews of Geophysics, 40(4): 1-40. DOI:10.1029/2001rg000108
Sun, J. P., Chen, S. Y., Peng, Y., et al., 2015. Research on Northern Qaidam Tectonic Attributes during Devonian. Journal of China University of Petroleum (Edition of Natural Science), 39(2): 23-30.
Sun, S. S., McDonough, W. F., 1989. Chemical and Isotopic Systematics of Oceanic Basalts: Implications for Mantle Composition and Processes. Geological Society, London, Special Publications, 42(1): 313-345. DOI:10.1144/gsl.sp.1989.042.01.19
Taylor, W. R., 1998. An Experimental Test of Some Geothermometer and Geobarometer Formulations for Upper Mantle Peridotites with Application to the Thermobarometry of Fertile Lherzolite and Garnet Websterite. Neues Jahrbuchfür Mineralogie—Abhandlungen, 172: 381-408.
Wan, Y. S., Xu, Z. Q., Yang, J. S., et al., 2001. Ages and Compositions of the Precambrian High-Grade Basement of the Qilian Terrane and Its Adjacent Areas. Acta Geologica Sinica, 75: 375-384.
Wan, Y. S., Zhang, J. X., Yang, J. S., et al., 2006. Geochemistry of High-Grade Metamorphic Rocks of the North Qaidam Mountains and Their Geological Significance. Journal of Asian Earth Sciences, 28(2/3): 174-184. DOI:10.1016/j.jseaes.2005.09.018
Wang, H., 2016. The Grenville Granitic Magmatismin North-Wulan Terrane, Qinghai Province: Evidence from Geochronology and Geochemistry: [Dissertation]. China University of Geosciences, Wuhan (in Chinese with English abstract)
Wang, H. C., Lu, S. N., Mo, X. X., et al., 2005. An Early Paleozoic Collisional Orogeny on the Northern Margin of the Qaidam Basin, Northwestern China. Geological Bulletin of China, 24(7): 603-612.
Wang, H. C., Lu, S. N., Yuan, G. B., et al., 2003. Tectonic Setting and Age of the "Tanjianshan Group" on the Northern Margin of the Qaidam Basin. Geological Bulletin of China, 22(7): 487-493.
Wang, H. C., Yuan, G. B., Xin, H. T., et al., 2001. Occurrence of the Eclogite and Its Genesis in the Luliangshan Area, the Northern Margin of the Qaidam Basin. Geology in China, 28(7): 22-27, 8.
Wang, L., Wang, H., He, C., et al., 2016. Mesoproterozoic Continental Breakup in NW China: Evidence from Gray Gneisses from the North Wulan Terrane. Precambrian Research, 281: 521-536. DOI:10.1016/j.precamres.2016.06.016
Wang, L., 2018. Petrogenesis of Metamorphosed MesoproterozoicNeoproterozoic Rocks in the North Wulan Terrane, Southern Qilian Orogen and Its Tectonic Implications: [Dissertation]. China University of Geosciences, Wuhan (in Chinese with English Abstract)
Wang, Q. Y., Chen, N.-S., Li, X. Y., et al., 2008. LA-ICPMS Zircon U-Pb Geochronological Constraints on the Tectonothermal Evolution of the Early Paleoproterozoic Dakendaban Group in the Quanji Block, NW China. Science Bulletin, 53(18): 2849-2858. DOI:10.1007/s11434-008-0265-x
Wang, Q. Y., Dong, Y. J., Guo, X. W., et al., 2015. Early Paleozoic Granulite-Facies Metamorphism and Magmatism in Northern Wulan of the Quanji Massif, Northwestern China, and Their Tectonic Implications. International Association for Gondwana Research Conference Series, 21: 126-127.
Wang, Q. Y., Pan, Y. M., Chen, N.-S., et al., 2009. Proterozoic Polymetamorphism in the Quanji Block, Northwestern China: Evidence from Microtextures, Garnet Compositions and Monazite CHIME Ages. Journal of Asian Earth Sciences, 34(5): 686-698. DOI:10.1016/j.jseaes.2008.10.008
Wang, Q. Y., Zheng, J. P., Pan, Y. M., et al., 2014. Archean Crustal Evolution in the Southeastern North China Craton: New Data from the Huoqiu Complex. Precambrian Research, 255: 294-315. DOI:10.1016/j.precamres.2014.10.005
Wang, Y. Z., Liang, C. Y., Wang, G. X., 2000. Discovery of Granulite in the North Margin of Qaidam Basin and Its Geological Characteristics. Qinghai Geology, 9(1): 33-38.
Winter, J. D., 2014. Principles of Igneous and Metamorphic Petrology, Pearson New International Edition (Second Edition). Pearson Prentice Hall, New York. 1-745.
Wu, C. L., Gao, Y. H., Frost, B. R., et al., 2011. An Early Palaeozoic DoubleSubduction Model for the North Qilian Oceanic Plate: Evidence from Zircon SHRIMP Dating of Granites. International Geology Review, 53(2): 157-181. DOI:10.1080/00206810902965346
Wu, C. L., Gao, Y. H., Wu, S. P., et al., 2007. Zircon SHRIMP U-Pb Dating of Granites from the Da Qiadam Area in the North Marign of Qaidam Basin, NW China. Acta Petrologica Sinica, 23(8): 1861-1875.
Wu, C. L., Gao, Y. H., Wu, S. P., et al., 2008. Geochemistry and Zircon SHRIMP U-Pb Dating of Granitoids from the West Segment of the North Qaidam. Science China Series D: Earth Sciences, 38(8): 930-949.
Wu, C. L., Lei, M., Wu, D., et al., 2016. Zircon SHRIMP Dating and Genesis of Granites in Wulan Area of Northern Qaidam. Acta Geoscientica Sinica, 37(4): 493-516.
Wu, C. L., Wooden, J. L., Robinson, P. T., et al., 2009. Geochemistry and Zircon SHRIMP U-Pb Dating of Granitoids from the West Segment of the North Qaidam. Science in China Series D: Earth Sciences, 52(11): 1771-1790. DOI:10.1007/s11430-009-0147-3
Wu, C. L., Wooden, J. L., Yang, J. S., et al., 2006. Granitic Magmatism in the North Qaidam Early Paleozoic Ultrahigh-Pressure Metamorphic Belt, Northwest China. International Geology Review, 48(3): 223-240. DOI:10.2747/0020-6814.48.3.223
Wu, C. L., Yang, J. S., Xu, Z. Q., et al., 2004a. Granitic Magmatism on the Early Paleozoic UHP Belt of Northern Qaidam, NW China. Acta Geologica Sinica, 78(5): 658-674.
Wu, C. L., Yang, J. S., Yang, H. Y., 2004b. Two Types of Ⅰ-Type Granite Dating and Geological Significance from North Qilian, NW China. Acta Petrologica Sinica, 20(3): 425-432.
Wu, C. L., Yang, J. S., Yao, S. Z., et al., 2005. Characteristics of the Granitoid Complex and Its Zircon SHRIMP Dating at the South Margin of the Bashikaogong Basin, North Altun, NW China. Acta Petrologica Sinica, 21: 846-858.
Wu, C. M., Zhang, J., Ren, L. D., 2004. Empirical Garnet-Muscovite-PlagioclaseQuartz Geobarometry in Mediumto High-Grade Metapelites. Lithos, 78(4): 319-332. DOI:10.1016/j.lithos.2004.06.008
Xia, L. Q., Li, X. M., Yu, J. Y., et al., 2016. Mid-Late Neoproterozoic to Early Paleozoic Volcanism and Tectonic Evolution of the Qilian Mountain. Geology in China, 43(4): 1087-1138.
Xiong, Q., Zheng, J. P., Griffin, W. L., et al., 2012. Decoupling of U-Pb and Lu-Hf Isotopes and Trace Elements in Zircon from the UHP North Qaidam Orogen, NE Tibet (China): Tracing the Deep Subduction of Continental Blocks. Lithos, 155: 125-145. DOI:10.1016/j.lithos.2012.08.022
Xiong, Q., Zheng, J. P., Griffin, W. L., et al., 2011. Zircons in the Shenglikou Ultrahigh-Pressure Garnet Peridotite Massif and Its Country Rocks from the North Qaidam Terrane (Western China): MesoNeoproterozoic Crust-Mantle Coupling and Early Paleozoic Convergent Plate-Margin Processes. Precambrian Research, 187(1/2): 33-57. DOI:10.1016/j.precamres.2011.02.003
Xu, Z. Q., Yang, J. S., Wu, C. L., et al., 2006. Timing and Mechanism of Formation and Exhumation of the Northern Qaidam Ultrahigh-Pressure Metamorphic Belt. Journal of Asian Earth Sciences, 28(2/3): 160-173. DOI:10.1016/j.jseaes.2005.09.016
Yang, J. J., Powell, R., 2008. Ultrahigh-Pressure Garnet Peridotites from the Devolatilization of Sea-Floor Hydrated Ultramafic Rocks. Journal of Metamorphic Geology, 26(6): 695-716. DOI:10.1111/j.1525-1314.2008.00780.x
Yang, J. S., Liu, F. L., Wu, C., et al., 2005. Two Ultrahigh-Pressure Metamorphic Events Recognized in the Central Orogenic Belt of China: Evidence from the U-Pb Dating of Coesite-Bearing Zircons. International Geology Review, 47(4): 327-343. DOI:10.2747/0020-6814.47.4.327
Yang, J. S., Liu, F. L., Wu, C. L., et al., 2003. Two Ultra-High Pressure Metamorphic Events Recognized in the Central Orogenic Belt of China: Evidence from the U-Pb Dating of Coesite-Bearing Zircons. Acta Geologica Sinica, 77: 463-477.
Yang, J. S., Xu, Z. Q., Li, H. B., et al., 1998. Discovery of Eclogite at Northern Margin of Qaidam Basin, NW China. Chinese Science Bulletin, 43(20): 1755-1760. DOI:10.1007/BF02883981
Yang, J. J., Deng, J. F., 1994. Garnet Peridotite and Eclogites in the Northern Qaidam Mountains, Tibetan Plateau: A First Record on UHP Metamorphism and Tectonics. Ⅱ.P Task Group Ⅲ-6, Stanford. A-20
Yu, F. C., Wei, G. F., Sun, J. D., 1994. Metallogenic Modal for the Syntectonic Gold Deposits in Black Series—A Case Study of the Tanjianshan Deposit. Northwest University Press, Xi'an. 1-130.
Yu, S. Y., Zhang, J. X., Li, J. P., et al., 2010. Zircon U-Pb Geochronology of High-Pressure Granulite and Its Tectonic Implications in the Dulan Area, North Qaidam Mountains, Western China. Acta Petrologica et Mineralogica, 29: 139-150.
Yu, S. Y., Zhang, J. X., Mattinson, C. G., et al., 2014. Paleozoic HP Granulite-Facies Metamorphism and Anatexis in the Dulan Area of the North Qaidam UHP Terrane, Western China: Constraints from Petrology, Zircon U-Pb and Amphibole Ar-Ar Geochronology. Lithos, 198/199: 58-76. DOI:10.1016/j.lithos.2014.03.016
Yu, S. Y., Zhang, J. X., Real, P. G. D., 2011. Petrology and P-T Path of High-Pressure Granulite from the Dulan Area, North Qaidam Mountains, Northwestern China. Journal of Asian Earth Sciences, 42(4): 641-660. DOI:10.1016/j.jseaes.2010.11.009
Yu, S. Y., Zhang, J. X., Sun, D. Y., et al., 2015. Petrology, Geochemistry, Zircon U-Pb Dating and Lu-Hf Isotope of Granitic Leucosomes within Felsic Gneiss from the North Qaidam UHP Terrane: Constraints on the Timing and Nature of Partial Melting. Lithos, 218/219: 1-21. DOI:10.1016/j.lithos.2015.01.008
Yuan, G. B., Wang, H. C., Li, H. M., et al., 2002. Zircon U-Pb Age of the Gabbros in Luliangshan Area on the Northern Margin of Qaidam Basin and Its Geological Implication. Progress in Precambrian Research, 25(1): 37-40.
Zhang, G. B., Song, S. G., Zhang, L. F., et al., 2005. Ophiolite-Type Mantle Peridotite from Shaliuhe, North Qaidam UHPM Belt, NW China and Its Tectonic Implications. Acta Petrologica Sinica, 21(4): 1049-1058.
Zhang, L., Ba, J., Chen, N.-S., et al., 2012. U-Pb Age Spectra and Trace Elements of Detrital Zircon from Quanji Group: Implications for Thermal Events and Early Evolution in the Basement. Earth Science—Journal of China University of Geosciences, 37(Suppl): 28-42.
Zhang, L., Liao, F. X., Ba, J., et al., 2011. Mineral Evolution and Zircon Geochronology of Mafic Enclave in Granitic Gneiss of the Quanji Block and Implications for Paleoproterozoic Regional Metamorphism. Earth Science Frontiers, 18(2): 79-84.
Zhang, L., Wang, Q. Y., Chen, N.-S., et al., 2014. Geochemistry and Detrital Zircon U-Pb and Hf Isotopes of the Paragneiss Suite from the Quanji Massif, SE Tarim Craton: Implications for Paleoproterozoic Tectonics in NW China. Journal of Asian Earth Sciences, 95: 33-50. DOI:10.1016/j.jseaes.2014.05.014
Zhang, J. X., Mattinson, C. G., Meng, F. C., et al., 2008. Polyphase Tectonothermal History Recorded in Granulitized Gneisses from the North Qaidam HP/UHP Metamorphic Terrane, Western China: Evidence from Zircon U-Pb Geochronology. Geological Society of America Bulletin, 120(5/6): 732-749. DOI:10.1130/b26093.1
Zhang, J. X., Mattinson, C. G., Meng, F. C., et al., 2005. An Early Palaeozoic HP/HT Granulite-Garnet Peridotite Association in the South Altyn Tagh, NW China: P-T History and U-Pb Geochronology. Journal of Metamorphic Geology, 23(7): 491-510. DOI:10.1111/j.1525-1314.2005.00585.x
Zhang, J. X., Mattinson, C. G., Yu, S. Y., et al., 2010. U-Pb Zircon Geochronology of Coesite-Bearing Eclogites from the Southern Dulan Area of the North Qaidam UHP Terrane, Northwestern China: Spatially and Temporally Extensive UHP Metamorphism during Continental Subduction. Journal of Metamorphic Geology, 28(9): 955-978. DOI:10.1111/j.1525-1314.2010.00901.x
Zhang, J. X., Mattinson, C. G., Yu, S. Y., et al., 2014. Combined Rutile-Zircon Thermometry and U-Pb Geochronology: New Constraints on Early Paleozoic HP/UHT Granulite in the South Altyn Tagh, North Tibet, China. Lithos, 200/201: 241-257. DOI:10.1016/j.lithos.2014.05.006
Zhang, J. X., Meng, F. C., Yu, S. Y., et al., 2007. Metamorphic History Recorded in High Pressure Mafic Granulites in Luliangshan, North Qaidam Mountains: Evidence from Petrology. Earth Science Frontiers, 14(1): 85-97.
Zhang, J. X., Yu, S. Y., Li, Y. S., et al., 2015. Subduction, Accretion and Closure of Proto-Tethyan Ocean: Early Paleozoic Accretion/Collision Orogeny in the Altun-Qilian-North Qaidam Orogenic System. Acta Petrologica Sinica, 31(12): 3531-3554.
Zhang, J. X., Yu, S. Y., Mattinson, C. G., 2017. Early Paleozoic Polyphase Metamorphism in Northern Tibet, China. Gondwana Research, 41: 267-289. DOI:10.1016/j.gr.2015.11.009
Zhang, J. X., Yu, S. Y., Meng, F. C., et al., 2009. Paired High-Pressure Granulite and Eclogite in Collision Orogens and Their Geodynamic Implications. Acta Petrologica Sinica, 25(9): 2050-2066.
Zhang, J. X., Yang, J. S., Xu, Z. Q., et al., 2000. Peak and Retrograde age of Eclogites at the Northern Margin of Qaidam Basin, Northwestern China: Evidence from U-Pb and Ar-Ar Dates. Geochimica, 29(3): 217-222.
Zhao, F. Q., Lu, S. N., Li, H. K., 2000. The Geochemical Characteristics of the Meso-Neoproterozoic Granite Belt in the Dakendaban Complex Rocks of the Qaidam Block. In: Abstracts of the Second Cross Strait: Qilian Mountains and Its Adjacent Areas, Beijing. 95-97 (in Chinese)
Zhu, X. H., Chen, D. L., Liu, L., et al., 2014. Geochronology, Geochemistry and Significance of the Early Paleozoic Back-Arc Type Ophiolite in Lüliangshan Area, North Qaidam. Acta Petrologica Sinica, 30(3): 822-834.