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The final closing time of the west Lamulun River-Changchun-Yanji plate suture zone: Evidence from the Dayushan granitic pluton, Jilin Province
... VAG-volcanic-arc granite; Syn-CLOG-syn-collision granite; WPG-within plate granite; ORG-oceanridge granite. Data are from the literature [26,28,29,35,38,41,64,65,68,[70][71][72][78][79][80]124,125]. ...
... Based on Devonian stable continental margin sedimentary formation in Northeastern China, Xu et al. [12,31] argue that the closure time of PAO is Middle-Late Devonian. Based on the presence of syn-collisional granites (Faku Baijiagou pluton (248 Ma), Jilin Dayushan pluton (248 Ma), Yanbian Liushugou pluton (245 Ma), Helong Yongxin pluton (238 Ma)) along the SXCYS, many researchers propose that the eastern Paleo-Asian Ocean closed in Early-Middle Triassic [26,35,72,80]. Based on molasse sedimentary formation (Central Jilin Dajianggang Formation), some researchers maintain that the final closure of the eastern PAO took place before the Late Triassic [131][132][133]. ...
... The age of these granites gradually decreases from west to east. In particular, the Faku Baijiagou pluton (248 Ma), Jilin Dayushan pluton (248 Ma), Yanbian Liushugou pluton (245 Ma), and Helong Yongxin pluton (238 Ma) are prime examples of such granites [26,35,72,79]. (5) As shown in Figure 14c, the Early Permian and Middle Permian-Late Permian felsic rocks are located in the volcanic arc granite field, whereas the Late Permian-Middle Triassic felsic rocks (including Chaijialing dacite samples QC04) are mainly situated in the volcanic arc and syn-collisional granite field. ...
The Central Asian Orogenic Belt (CAOB) is the world’s largest accretionary orogenic belt, and its formation is related to the closure of the Paleo-Asian Ocean (PAO). However, the closure time and style of the PAO remain controversial. To address these issues, this paper presents zircon U-Pb dating, whole-rock geochemistry and zircon Lu-Hf isotope analyses of the volcanic rocks in the Faku-Kaiyuan area on the northern margin of the North China Craton. The results show that the Bachagou andesites formed in the Early Permian (287 ± 2 Ma), while the Chaijialing andesites and dacites formed in the Late Permian (253.3 ± 3.7 Ma) and Middle Triassic (244.3 ± 1.3 Ma), respectively. The Bachagou andesites and Chaijialing andesites are enriched in LILEs and LREEs and depleted in HFSEs and HREEs, indicating that they formed in the active continental margins. The Chaijialing dacites show similar geochemical signatures to adakite and formed in a syn-collisional setting. Geochemistry and isotopic analysis indicates that the Bachagou andesites were derived from a partial melting of the mantle wedge that was metasomatized by subduction fluids. The Chaijialing andesites were generated from a metasomatized mantle by slab-derived and sediment fluids. The Chaijialing dacites formed by a partial melting of thickened lower crust. Combined with previous research results, we can conclude that the Eastern PAO closed by a scissor-like movement from west to east during the Late Permian–Middle Triassic.
... The CAOB (Figure 1a) is one of the largest and most complex orogens in the world [36][37][38][39]. The eastern segment of the CAOB (accepted as the Xing'an-Mongolia Orogenic Belt, XMOB) is composed of a series of microblocks and orogens consisting of Phanerozoic island arc and accretionary/collisional complex, and it experienced the reformation of the Paleo-Asian Ocean, the Mongo-Okhotsk Ocean, and the Paleo-Pacific Ocean regimes during the Paleozoic to Mesozoic [13,[15][16][17]19,[38][39][40][41][42]. Microblocks mainly consist of, from northwest to southeast, the Erguna, Xing'an, Songnen-Zhangguangcai Range, Jiamusi, and Khanka massifs ( Figure 1b). ...
... Volcanic rocks with an age of 256 to 253 Ma in the Daheishan horst imply that they may be related to the volcanic arcs formed by the subduction of the Paleo-Asian oceanic plate [95]. Rb-Sr mineral isochron data indicate that the metamorphism age of the Hulan Group, intruded by the syn-collisional Dayushan pluton (248 Ma) [15], occurred at~250 Ma, reflecting that the final oceanic closure took place in the Late Permian to early Triassic [43]. In the last decade, substantial data have supported the hypothesis that the Solonker-Xar Moron-Changchun-Yanji Suture (SXCYS) marks where the Paleo-Asian Ocean finally closed. ...
... In the last decade, substantial data have supported the hypothesis that the Solonker-Xar Moron-Changchun-Yanji Suture (SXCYS) marks where the Paleo-Asian Ocean finally closed. A double-sided subduction model along the SXCYS has been established thanks to the following evidence: (1) the Late Permian-Middle Triassic high-Mg diorite or andesite are distributed along the SXCYS in both the southern combined NE China Blocks [26,98] and the northern NCC [93,99]; (2) igneous rock with arc affinities exists on both sides of the SXCYS [14,15,17,18,[28][29][30][33][34][35]69,94,95,100]; (3) accretionary complexes related to subduction have been discovered in both the southern combined NE China Blocks and the northern NCC [25,93,99]. Liu et al. [19] gave a detailed discussion about the position of the eastern SXCYS and concluded that Changchun-Jilin-Dunhua-Yanji was the eastern extension of the SXCYS, as supported by paleontology, paleogeography, sediments and granitoid studies ( [19] and references therein). ...
This study presents new data from zircon U–Pb dating and Hf isotope analysis, as well as whole-rock major- and trace-element compositions of the Hongtaiping high-Mg diorite in the Wangqing area of Yanbian, NE China. Laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) zircon U–Pb dating gives an eruption age of ca. 267 Ma for the high-Mg diorite. These samples have MgO contents of 13.30% to 16.58% and high transition metal element concentrations, classified as sanukite. Their rare earth element (REE) contents range from 45.2 to 68.4 ppm and are characterized by slightly positive Eu anomalies (Eu/Eu* = 1.08–1.17). They show enrichment in light REEs (LREEs) and depletion in heavy REEs (HREEs), with LREE/HREE ratios = 6.54–6.97 and (La/Yb)N values = 7.24–8.08. The Hongtaiping high-Mg diorite is enriched in Rb, U, K, and Sr, but depleted in Th, Nb, and Ta. High MgO contents, Mg# values, and transition metal element concentrations imply that the magma experienced insignificant crystallization fractionation and crustal contamination. Relatively homogenous positive Hf isotopic values indicate that the original magma was generated by the partial melting of a depleted mantle wedge that was metasomatized by subducting slab fluids. The magma was generated by the moderate degree partial melting (20%–30%) of a garnet lherzolite source. Combined with previous studies, this shows that the high-Mg diorite was formed by the northward subduction of the Paleo-Asian oceanic plate during the Middle Permian.
... The Early-Middle Triassic adakitic rocks form a nearly E-W-trending magmatic belt within the northern margin of the northeastern NCC (Figure 2(a)), distributed in Kaiyuan-Huadian, Yanji-Helong, and Hunchun area ( Figure 3). From east to west, the belt comprises tonalite (245 ± 4 and 249 ± 6 Ma) and granodiorite (237 ± 5 Ma) in southern Hunchun area (Yang et al. 2017a(Yang et al. , 2017b; the Yongxin monzogranite (237 ± 2 and 236 ± 1 Ma), the Fudongzhen biotite granite (249 ± 1 Ma), the Nantian granodiorite (235 ± 1 and 243 ± 2 Ma), and Liushugou monzogranite (245 ± 1 Ma) in Helong area (Wang et al. 2015;Tang et al. 2019;Guan et al. 2020); the Dayushan monzogranite (248 ± 4 Ma) in Hulan town, Panshi area (Sun et al. 2004); the Yishan monzogranite (247 ± 1 Ma) in Liaoyuan; the Jianping monzogranite (249 ± 1 Ma) in Kaiyuan area (Cao et al. 2013); and the Jianshanzi monzogranite (251 ± 1 Ma) and Daganhe monzogranite (242 ± 1 Ma) in Qingyuan area . ...
... The rocks in the eastern segment are mainly adakitic (Tang et al. 2018), and these adakitic rocks are distributed in a nearly E-W trending belt along the SXCYS in southeastern Jilin Province (Figure 2). The Jianshanzi (251 Ma (Sun et al. 2004;Cao et al. 2013;Wang et al. 2015;Liu et al. 2019;Tang et al. 2019;Guan et al. 2020). The Dayushan and Yongxin plutons are typical syn-collisional granites (Sun et al. 2004;Guan et al. 2016). ...
... The Jianshanzi (251 Ma (Sun et al. 2004;Cao et al. 2013;Wang et al. 2015;Liu et al. 2019;Tang et al. 2019;Guan et al. 2020). The Dayushan and Yongxin plutons are typical syn-collisional granites (Sun et al. 2004;Guan et al. 2016). The increase in Sr/Y and La N /Yb N values of the Early-Middle Triassic granites along the SXCYS records the evolution of crustal thickening . ...
Chronological and geochemical studies of adakites and adakitic rocks are important in understanding the tectonic evolution and geodynamic processes. We present new zircon U–Pb ages, Hf isotope, and geochemical analyses of adakitic rocks exposed in the Baishan area, southeastern Jilin Province, China. These new ages, together with existing age data, indicate that adakitic magmatism in southeastern Jilin Province can be subdivided into four stages: Early–Middle Triassic (251–235 Ma), Late Triassic (221–219 Ma), late Early–early Late Jurassic (176–156 Ma), and Early Cretaceous (ca. 130 Ma). Early–Middle Triassic adakitic rocks occur in a nearly E–W-trending belt within the northern margin of the northeastern North China Craton, indicating a compressional tectonic setting caused by the scissor-like closure of the Paleo-Asian Ocean from west to east. Late Triassic adakitic rocks occur in the Tonghua area and formed in an extensional setting caused by delamination after subduction and collision between the Yangtze Craton and NCC. Late Early–early Late Jurassic adakitic rocks occur in the Baishan and Kaiyuan areas and originated from partial melting of thickened lower crust in a compressional setting related to subduction of the Paleo-Pacific Plate. Early Cretaceous adakitic rocks occur in the Baishan area and were derived from partial melting of thickened lower crust above the subduction zone and delaminated lower crust, indicating that the subducting Paleo-Pacific Plate retreated to the eastern part of southern Jilin Province during the Early Cretaceous (ca. 130 Ma) and that the tectonic setting of the northeastern part of the NCC changed from compression to extension, starting in the east and progressing westward. In summary, the northeastern part of the NCC has been affected by a series of tectonic events during the Mesozoic, such as the closure of the Paleo-Asian Ocean, the collision between the NCC and YC, and the subduction of the Paleo-Pacific Plate.
... 1a) and reflects a complex tectonic evolution closely connected to the closure of the Paleo-Asian Ocean (PAO) (Khain et al. 2002;Windley et al. 2007;Xiao et al. 2015;Zhang et al. 2019;Wu et al. 2007;Pei et al. 2016). Northeastern China (NE China), also called the Xing'an-Mongolian Orogenic Belt (XMOB; Sun et al. 2004;Xu et al. 2014), is located in the eastern segment of the CAOB and has witnessed the amalgamation of NE China massifs during Paleozoic and early Mesozoic, which from west to east are Erguna, Xing'an, Songnen and Jiamusi-Khanka massifs or terranes, all of which are separated by major faults or suture belts (Wu et al. 2007(Wu et al. , 2011Zhou et al. 2011aZhou et al. , b, 2015Cao et al. 2012Cao et al. , 2013Santosh & Somerville, 2013;Sun et al. 2013;Xu et al. 2014;Mi et al. 2017;Li, 2006;Tang et al. 2013;Fig. 1a). ...
... Most studies agree that the final suturing occurred during the Permian-Triassic (Cao et al. 2013;Du et al. 2019Du et al. , 2021Guan et al. 2022;Han et al. 2019Han et al. , 2020Han et al. , 2021Li, 2006;Li & Zhao, 2007;Liu J et al. 2017Liu J et al. , 2020Shi et al. 2020;Song et al. 2018;Sun et al. 2022;Wang et al. 2015a, b;Wu et al. 2007;Yuan et al. 2016), while some propose it occurred before the Permian (Zhang et al. 2008;Shi et al. 2010), or even before the Late Devonian (Xu & Chen, 1997;Zhao et al. 2013;Xu et al. 2015;Zhu & Ren, 2017), or between the Late Devonian and Early Carboniferous (Tang, 1989;Hong et al. 1995). Others suggest that closure spanned from the Permian to Triassic, encompassing late Early Permian (Yu et al. 2022;Feng et al. 2010;Liu et al. 2010), Middle to Late Permian (Sengör et al. 1993;Chen et al. 2000Chen et al. , 2009Jian et al. 2010;Lin et al. 2013), Late Permian (Li, 2006;Wu et al. 2011), Late Permian to Early Triassic (Sengör et al. 1993;Li, 1998Li, , 2006Xiao et al. 2003;Sun et al. 2004;Zhang et al. 2004;Wu et al. 2007Wu et al. , 2011Xu et al. 2009;Peng et al. 2012;Cao et al. 2013;Eizenhöfer et al. 2014;Li et al. 2014;Wilde, 2015;Han et al. 2015;Guo et al. 2016;Wu & Li, 2022), Late Permian to Middle Triassic (Jia et al. 2004;Wang F et al. 2015;Xiao et al. 2015;Guan et al. 2023) and Middle-Late Triassic (Peng et al. 2012;. This controversy largely arises from insufficient time constraints and sedimentological data for the transition from subduction to collision in the eastern segment of CAOB . ...
The Central Asian Orogenic Belt is the world’s largest accretionary orogenic belt, associated with the closure of the Paleo-Asian Ocean (PAO). However, the final closure timing of the eastern PAO remains contentious. The Permian-Triassic sedimentary sequences in the Wangqing area along the Changchun-Yanji suture zone offer important clues into this final closure. New data on petrology, whole-rock geochemistry, zircon U-Pb geochronology and zircon Hf isotopes of sedimentary rocks from the Miaoling Formation and Kedao Group in Wangqing area provide new insights into the final closure of the eastern end of the PAO. The maximum deposition ages of the Miaoling Formation and Kedao Group have been constrained to the Late Permian (ca. 253 Ma) and early Middle Triassic (ca. 243 Ma), respectively. These sedimentary rocks exhibit similar geochemical characteristics, showing low textural and compositional maturities, implying short sediment transport, with all detrital zircons suggesting their origins from felsic igneous rocks. The εHf(t) values of the Miaoling Formation range from −6.09 to 12.43 and from −2.20 to 7.59 for the Kedao Group, implying these rocks originated from NE China. Considering our new data along with previously published data, we propose that a reduced remnant ocean remained along the Changchun-Yanji suture zone in the early Middle Triassic (ca. 243 Ma), suggesting the final closure of the eastern PAO likely occurred between the latest Middle Triassic and early Late Triassic.
... The Solonker-Xar Moron-Changchun-Yanji Suture (SXCYS) is an accretionary belt preserving the records of active tectonic and magmatic activities. It separates the NCC to the south from several blocks or accretionary terranes to the north (i.e., Songliao Accretionary Terrane and Jiamusi block) and extends over 1,500 km ( Fig. 2b) (Sun et al., 2004;Wu et al., 2011;Cao et al., 2013). In the southern part of NE China, an EW-trending Early Palaeozoic accretionary arc belt exists between the SXCYS and the NCC, known as the Bainaimiao arc belt (Wu et al., 2011). ...
... The samples exhibit an obvious positive correlation between the contents of P 2 O 5 and SiO 2 , and higher Al 2 O 3 / (CaO + Na 2 O + K 2 O) (A/CNK) ratios (av. = 1.22), suggesting that the granitic rocks are inconsistent with the characteristics of typical S-type granite (Sun et al., 2004;Guan et al., 2016). The zirconium saturation temperatures (T Zr ) of the Baerhushan granodiorite ranges from 846 ℃ to 892℃ (av. ...
... The exact location and timing of suturing between the Siberia and North China Blocks have been a subject of debate. Most scholars consider the Solonker-Xar Moron-Changchun-Yanji line as the suture zone [14][15][16][17][18], while others argue for the He'genshan-Heihe fault zone [19][20][21][22]. There are also differing views on the final closure time of the Paleo-Asian Ocean, ranging from the Middle Devonian [20,23,24] to the Late Devonian to Early Carboniferous [25][26][27], with most scholars leaning towards the Middle-Late Permian to Early-Middle Triassic [11,15,[28][29][30][31][32]. ...
The Permian to Triassic period represents a pivotal phase in the evolution of the Paleo-Asian Ocean, marked by significant tectonic transitions from subduction, collision, and post-orogenic extension. The timing of closure of the Paleo-Asian Ocean in northeastern China has always been controversial. In this contribution, the petrology, zircon U-Pb geochronology and geochemistry are conducted on granite found in well HFD1, Songliao Basin, eastern part of Central Asian orogenic belt. Zircon U-Pb dating indicates that granite crystallized at 258.9 ± 2.2 Ma, as the product of magmatism occurred in the early Late Permian. The rocks have high SiO2, Al2O3, Na2O content, negative Eu anomaly, light enrichment of rare-earth elements, depletion of heavy rare-earth elements, high Sr (448.29–533.11 ppm, average 499.68 ppm), low Yb (0.49–0.59 ppm, average 0.54 ppm), Y (4.23–5.19 ppm, average 4.49 ppm), and high Sr/Y ratios (98–125, average 112) and can be classified as O-type adakite. This is the first discovery of late Paleozoic adakite in the Songliao Basin and the neighboring areas. The geochemistry of adakite indicates derivation by partial melting of MORB-type subducted oceanic crust, indicating that the subduction of the Paleo-Asian Oceanic lithosphere lasted until at least 258.9 Ma.
... The location and timing of the formation of the PAO suture are disputed. Most studies have regarded the Xar Moron-Changchun-Yanji line as the suture zone between the Siberian and North China plates [8,[18][19][20][21][22][23]. However, others have considered that the amalgamation zone of the two plates is located along the Hegenshan-Heihe fault zone [24][25][26][27]. ...
The tectonic evolution of the Paleo-Asian Ocean (PAO) has been well studied, including its gradual narrowing and closure by subduction. However, aspects of the tectonic evolution of the oceanic domain remain unclear, including the exact timing and nature of the closure. The Central Asian Orogenic Belt (CAOB) was formed by the closure of the PAO and, therefore, contains information about the tectonic evolution of the oceanic domain. Here, we report a study of the petrology, geochronology, and geochemistry of the Taohaiyingzi section of the Permian Linxi Formation in Alukhorqin Banner (Northeast China) in the central part of the CAOB. A newly discovered andesitic tuff from the lower part of the Linxi Formation yields a weighted mean 206Pb/238U age of 262.2 ± 1.1 Ma (n = 87), indicating that the lower part of the Linxi Formation of the Taohaiyingzi section was deposited during the late Guadalupian. Provenance weathering indicators show that the sedimentary rocks of the Linxi Formation are of low maturity. Element geochemical characteristics indicate that the Linxi Formation clastic rocks were derived from eroded magmatic rocks that formed in a continental arc setting and were deposited close to the arc in a continental arc basin environment. The active margin setting was generated by the subduction of the paleo-Asian oceanic plate beneath the Xilinhot–Songliao block. The inferred palaeosalinity of the sedimentary environment changed gradually from brackish to fresh water, suggesting the end of oceanic plate subduction during the late Guadalupian, and the closure of the PAO during or after the Lopingian.
... The Late Triassic and Early Jurassic Yuejinshan Complex basalts are consistent with the basic lithology and age of the Raohe Complex, as well as the plagioclase amphibolite and biotite plagiogneiss in the Heilongjiang Complex (Guo, 2016;Zeng, 2017;Wang et al., 2019). The trace element and isotopic compositions of the Raohe Complex (Tian, 2007;Zhou et al., 2014;Han and Zhou, 2020) indicate that the MORB- (Sun et al., 2004;Zhang and Mizutani, 2004;Liu et al., 2010;Cao et al., 2013;Wang et al., 2015;Wang et al., 2016;Li et al., 2020a;Yang et al., 2022); and (b) Plot of age versus frequency for the magmatic rocks in Northeast Asia in the Paleo-Pacific to Pacific tectonic domain from the Late Triassic to the Late Cretaceous (Wu et al., 2011;Wilde, 2015). type alkaline basalts were formed by the subduction of the Paleo-Pacific Plate in a back-arc extension environment, and the OIB-type basalts were formed by the accretion and collage of the seamounts and islands carried by the Paleo-Pacific Plate (Zhou et al., 2014;Xu et al., 2022). ...
... The Central Asian Orogenic Belt is considered to have a complex tectonic history (Jahn et al., 2000a, b;Windley et al., 2007, Schulman and Paterson, 2011, Liu et al., 2016Chen et al., Original Article Mongolian Geoscientist 2017). Terminal closure of the Paleo-Asian Ocean resulted in a collision between North China and Siberia (Sun et al., 2004;Guan et al., 2018). The Tarvagatai Block is located in the northern part of Central Mongolia and is a distribution of multiple stages of magmatism. ...
The Tarvagatai Block is located in the northern part of Central Mongolia, which is a widespread occurrence and occupies roughly 60% of the whole exposure along the Khangai fault and the Tarvagatai uplift. Granitic magmatism was emplacement during the Middle Paleozoic, which is predominantly composed of granite-granodiorite and gabbro-diorite and rarely gabbro. This article represents petrographical, geochemical, and U-Pb zircon age data from the Telmen Complex of the Tarvagatai Block, Central Mongolia. The U-Pb dating of zircon yields a Late Silurian emplacement age (419±3 Ma) for the Telmen Complex. Geochemically, the Telmen Complex is an I-type intrusion of metaluminous nature with a SiO2 content ranging from 53.06 to 72.25 wt.% and mainly of medium to high K calc-alkaline series. Telmen Complex granites show enrichments in light rare earth elements, depletion in heavy rare earth elements, with a ratio of 4.053, (La/Yb)N =9.15, and weak positive or normal Eu anomalies. A spider diagram indicates that these rocks are enriched in Ba, K, Pb, and Sr and depleted in Nb, Ta, and Ti. The Early Paleozoic Telmen Complex granitics have trace element features, for example, Nb-Ta depletions, which indicate that these rock units were emplaced in a convergent-margin setting and typical of the lower continental crust. In addition, the geochemical data show that the volcanic arc tectonic setting and, moreover, the continental arc array setting display on the Nb/Yb versus TiO2/Yb diagrams. Therefore, we suggest that they were probably positioned in an active continental setting and in a Silurian ~419 Ma.
... The Xilamulun suture zone began to close in the late Permian to Early-Middle Triassic and began to provide provenance for the Linxi Formation in the Linxi area, as evidenced by the Permian pillow lava in the ophiolite (~260 Ma, Miao et al., 2007); the Permian Radiolaria in the semi-deep-sea or deep-sea siliceous rocks of the ophiolite belt in Linxi County (Wang and Fan, 1997); the syn-collision granite in Dayushan, Jilin Province (248 Ma, Sun et al., 2004); and the Early Mesozoic detrital zircon composition in the Linxi Formation sandstones in eastern Inner Mongolia (238 Ma, Han et al., 2015;249~233 Ma, Wang et al., 2021). ...
Located on the Songnen block of the Northeast Asia block group, the Songliao Basin is sandwiched by three major plates in Siberia, North China, and the Pacific Ocean. The recognition of the basin's properties and the dynamic processes of formation, evolution, and late reformation of the Late Paleozoic–Early Mesozoic Basin (LP-EMB), which has suffered from intense multi-stage, and various types of late reformation, are always controversial. On the basis of previous research on the regional tectonic geological background, combined with petrochemical and chronological data from core samples and seismic data, the attributes, evolution process, and late reformation of the LP-EMB and its dynamic environments have been deeply analyzed. Since the Late Paleozoic, it has successively experienced the development of Late Hercynian to Early–Middle Indosinian rifts and subsequent multi-stage superimposed transformation stages, which can be divided into the near-north-trending thrust reformation in the Late Indosinian, the near-west-trending thrust reformation in the Early Yanshanian, the differential extensional reformation in the early Late Yanshanian, the strike-slip shearing and deep burial reformation in the middle Late Yanshanian, and the strike-slip compression fold transformation in the late Late Yanshanian to the early Himalayan. The formation of the LP-EMB was mainly controlled by back-arc extension caused by the subduction and retreat of the paleo-Pacific Plate and partly by the closure of the Paleo-Asian Ocean between the North China Plate and the Northeast Asia micro-block group. The later reformation stages were closely related to the collision extrusion, strike-slip activity, and deep mantle activity caused by either the relative convergence movement between Songnen and other micro-blocks in the Northeast China micro-block group or by the remote collision effect of the Northeast China micro-block group and the surrounding plates. The inner fault zone (body), which was formed by multi-phase fault cutting, and the top weathering and denudation unconformity surface, are potential sites of hydrocarbon accumulation, from which natural gas has been transported along the fault and fracture belt into the weathering crust and the inner fracture zone in the Upper Paleozoic–Lower Mesozoic (UP-LM). This study significantly expands our knowledge of the tectonic evolution and gas exploration of the Songliao Basin.
... Jilin Province is one of the main Mo-producing areas in northeast China, and there are many medium-large porphyry Mo deposits, such as Daheishan, Fu'anbao and Sifangdianzi, which are mainly distributed in central-eastern Jilin Province. In recent years, with the continuous in-depth research of many geologists, fruitful results have been achieved in regional strata, structures, magmatic rocks, minerals and metallogenetic regularities (Shao & Tang, 1995;Sun et al., 2004;Wu, Jahn, et al., 2000;. The ...
The recently discovered Yizuoying Mo deposit is located in central‐eastern Jilin Province, NE China. The molybdenum (Mo) mineralization, mainly hosted in granite porphyry, is considered to be granite‐related. Zircon U–Pb dating of the granite porphyry yielded concordant ages of 160.81 ± 0.62 Ma, which is consistent with the weighted mean U–Pb age of 160.53 ± 0.65 Ma, indicating that the emplacement of granitic plutons occurred in the Late Jurassic. The granite porphyry samples are peraluminous, high‐K calc‐alkaline and show an A‐type geochemical signature with high Na2O+K2O and Zr+Nb+Ce+Y content, K2O/MgO, Fe2O3T/(Fe2O3T+MgO), REEs (rare earth elements) and 10000 Ga/Al ratios. Based on the trace element content of zircons, they have high Th, U, Zr, Hf and Pb abundance and obvious La and Eu anomalies, and their distribution pattern is similar to that of A‐type granites. The zircon εHf(t) values range from 4.5 to 10.5 with Neoproterozoic TDM2 ages (536–922 Ma) for Hf isotopes, and they have relatively high values of εNd(t) (3.14 to 3.49; TDM2 = 665–693 Ma) and initial 87Sr/86Sr (0.723260–0.734669). Detailed elemental and isotopic data suggest that the Yizuoying granite porphyry belongs to the A2‐ subtype and was formed by partial melting of a crustal source with a Neoproterozoic overall residence age. Integrating new data on the oxygen fugacity of zircons and published data on the tectonic evolution, we suggest that the granite porphyry and associated Mo mineralization in the Yizuoying deposit formed in an extensional environment at ~160 Ma, related to the subduction of the Paleo‐Pacific plate. The evolution of granitic magma in this period contributed to Mo mineralization.
... As discussed by previous studies, the Paleo-Asia Ocean began to subduct during the Early Silurian along the Xar Moron fault (Sengör and Natal'in, 1996;Xiao et al., 2003;Sun et al., 2004;Zhang et al., 2008Zhang et al., , 2009b, and finally closed in the Late Permian-Early Triassic (Zorin et al. 2001;Chen et al, 2007), causing the first-stage deep delamination and initial destruction of the NCC, as well as associated post-collisional magmatism occurring from ca. 250 Ma Zhao et al., 2010;Li et al., 2019a;Zeng et al., 2021). The Mo mineralization and related magmatism in the Dasuji area were suggested to occur during this period (ca. ...
The Quanzigou porphyry molybdenum deposit is located in Fengzhen County, Inner Mongolia, China, belonging to the northern margin of the North China Craton. A Yanshanian granitic complex, namely the Hongniangshan complex, is exposed in the deposit, mainly composed of medium–coarse-grained granite, porphyritic granite, and quartz porphyry. The Mo orebodies occur mainly in the porphyritic granite as ore-bearing quartz veins or veinlets. Previous study on molybdenite Re–Os and zircon U–Pb dating suggests that the Hongniangshan complex emplaced during 173–160 Ma and that the Quanzigou Mo deposit formed at ca. 160 Ma. Geochemical analyses in this study show that all these Middle–Late Jurassic granites are peraluminous, high-K calc-alkaline granite, featured by enrichment in Rb, Th, U, Hf, and Zr and depletion of Ba, P, and Ti, with high K2O/Na2O ratios. Nearly all the samples from the medium–coarse-grained granite and the porphyritic granite show weakly negative Eu anomalies, whereas the negative Eu anomalies of the quartz porphyry are moderate or strong. The Hongniangshan complex has low zircon εHf(t) values (−14.4 to − 6.7), old single-stage and two-stage model ages (1099–1471 Ma and 1637–2124 Ma, respectively), and low K-feldspar Pb isotopic compositions (²⁰⁶Pb/²⁰⁴Pb = 17.019–17.590, ²⁰⁷Pb/²⁰⁴Pb = 15.365–15.489, ²⁰⁸Pb/²⁰⁴Pb = 37.002–37.670), with K-feldspar δ¹⁸O values of 8.0–10.4‰, suggesting that the granitic complex was predominantly originated from a Paleoproterozoic lower crust source. Geochemical characteristics, combined with results from previous studies, show that the Quanzigou Mo mineralization was closely related to the quartz porphyry. The Middle Jurassic medium–coarse-grained granite was likely formed in the back-arc extension environment triggered by the subduction of the Mongol–Okhotsk Ocean and the Paleo-Pacific plate, and the formation of the Late Jurassic porphyritic granite and the quartz porphyry was controlled by both the post-collisional process of the Mongol–Okhotsk orogenic belt and the coeval subduction of the Paleo-Pacific plate.
... The newly assemblaged terrane experienced secondary tectonic deformation along the weaker early Paleozoic suture zone in the Late Permian and Early Triassic (260-240 Ma), and stretched to form a new limited ocean basin, the Mudanjiang Ocean (Dong et al. 2017Liu et al. 2017;Xu et al. 2012). The Paleo-Asian Ocean closure time is controversial, including the Middle-Late Permian (Li 2006;Wu 2007) the Late Permian-Middle Triassic (Wang et al. 2015) or the Middle-Late Triassic (You et al. 2004), but the main controversy is based on the collision-type granites in the Xing'an-Mongolian Orogenic belt and the North China Plate suture zone. Due to the different locations of the granites, the cognition conclusions are different, and the Paleo-Asian Ocean has an obvious scissor closure from west to east (Xu et al. 2019), the east is obviously later than the west, and the north is later than the south, indicating that the Paleo-Asian Ocean plate gradually subducted and disappeared from west to east, and all of them subducted northward. ...
Late Paleozoic tectonic evolution of northeastern China is complicated by the interaction of the Central Asian Orogenic belt development and the initiation of subduction from the Pacific Ocean plate along the eastern margin of Asia. In this study, we elucidate this problem by collecting new geochemical and geochronological data from late Paleozoic bimodal igneous rocks from the eastern margin of the Jiamusi block. By LA–ICP–MS zircon U–Pb dating, the 206Pb/238U age of the granitoid sample is 313–279 Ma, and the diabase 206Pb/238U age is 298–276 Ma. Rock geochemical studies show that diabase and granitoid have obvious chemical differentiation characteristics, indicating that they are the products of non-homologous magmatic evolution. Zircon Lu–Hf isotopes indicate that diabase magma originates from the metasomatism of the mantle wedge by subducting oceanic crust melts, granitoid magma mainly comes from the lower crust and the new crust. Our results together with a synthesis of existing data show that bimodal magmatism occurred in the study area from the Late Carboniferous to Early Permian when the Jiamusi block was an active continental margin and in a stretching background. Our synthesis of the existing data places our new data into a regional tectonic framework, and our proposed tectonic model provides the following new insights: (1) the northward expansion of the Paleo-Tethys Ocean from the Late Carboniferous to the Early Triassic led to the overall northward drift of the Paleo-Asian Ocean and the Xing’an-Mongolian Orogenic belt, which marks the easternmost segment of the Central Asian Orogenic belt, (2) the Paleo-Asian Ocean continued Late Permian–Early Triassic subduction caused back extension that rifted the Jiamusi and Songnen blocks apart and formed the Mudanjiang Ocean.
... The presence of the Xilingol Complex, terrestrial Linxi Formation deposition (Li et al., 2014b), collisional-related granites (Chen et al., 2009), and Wudaoshimen ophiolite (Wang et al., 2014) support this interpretation. Moreover, existing geological evidence suggests that melting of the thickened lower crust occurred because of amalgamation of the NE China blocks and NCC during the subduction of the PAO, which induced the formation of granitic parental magmas for W mineralization in this area, including the Middle Permian-Early Triassic syn-collisional granitoids in the eastern Jilin Province (Cao et al., 2013), Late Permian I-type granitoids along the SXCF (Sun et al., 2004), Triassic mafic volcanics and lacustrine molasses in the SGB (Zhang et al., 2008a), granodiorites in the Baiyinnuoer area (SGB; 245 Ma) , Middle Triassic tonalities in the central Great Xing'an Range (GXR) (234-240 Ma) (Jiang et al., 2011), Early-Middle Triassic syn-collisional S-type granitoids in Linxi (SGB) and the Horqin right wing middle banner (the central GXR) (Li et al., 2007;Zhang et al., 2015), and synchronous adakitic plutons in the Yanbian fold belt (251-240 Ma) (Ma et al., 2017). Furthermore, the final closure stage of the PAO is marked by an extensional setting represented by the occurrence of Late Triassic bimodal volcanics (217-202 Ma) , A-type granitic (Gou et al., 2013), and rhyolitic rocks (Xu et al., 2013b;Guo et al., 2015) in the Lesser Xing'an-Zhangguangcai Range. ...
NE China, located at the eastern Central Asian Orogenic Belt, experienced extensive magmatism during the Mesozoic and hosts multistage granitic plutons and accompanying W mineralization. However, due to the limited number of studies on Triassic W deposits and spatially related granitoids, the petrogenesis of these granitoids and their relation to W mineralization remain enigmatic. The Tantoushan quartz-wolframite vein-type deposit is located on the southern margin of NE China. Tungsten mineralization occurs mainly in the veins and veinlets within monzogranites. A lower intercept ²⁰⁶Pb/²³⁸U age of 234.3 ± 6.2 Ma (1σ, MSWD = 0.41) was obtained for wolframite, which is identical within uncertainties to the zircon weighted mean ²⁰⁶Pb/²³⁸U age of 233.1 ± 1.8 Ma (1σ, MSWD = 0.41) from the W-bearing monzogranites. The monzogranites have the petrological, mineralogical, and geochemical characteristics of highly fractionated I-type granitoids. The rocks are enriched in Rb, Th, U, K, and Pb, and depleted in Ba, Sr, P, and Ti. They have higher W concentrations and Rb/Sr ratios, and lower Nb/Ta, Zr/Hf, and K/Rb ratios than the contemporary W-barren granitoids in NE China. These geochemical characteristics and negative zircon εHf(t) values (−17.7 to −8.6), as well as old two-stage model ages (TDM2 = 1807–2378 Ma), suggest that the monzogranites were derived as a product of the partial melting of the Paleoproterozoic lower crust and subsequently underwent extreme fractional crystallization. Geochronological and geochemical evidence collectively suggest that the W mineralization in the Tantoushan deposit is genetically related to the W-bearing monzogranites, and extreme fractional crystallization was essential for W enrichment in the granitic magma. In contrast, Triassic W-barren granitoids did not induce W mineralization, probably because of their low fractionated signatures. We preliminarily demonstrate that an isovalent substitution mechanism of 4A(Fe, Mn)²⁺ + 8BW⁶⁺ + B□ ↔ 3AM³⁺ + AN⁴⁺ + 7B(Nb, Ta)⁵⁺ + 2BN⁴⁺ played a critical role in the formation of hydrothermal wolframite in the Tantoushan deposit, and the trace elements compositions of wolframite were controlled by both the crystallochemical parameters and composition of the initial hydrothermal fluids. In the context of the regional geology, we propose that the Tantoushan monzogranites and corresponding W mineralization were formed in a post-collision extensional setting controlled by the closure of the Paleo-Asian Ocean during the Late Triassic. In combination with previous studies, we suggest that NE China may have enormous potential for Triassic W mineralization and the Triassic highly fractionated granitoids distributed on both sides of the Solonker-Xar Moron-Changchun Fault represent potential targets for future exploration of additional W resources.
... The two wings of the syncline extended to the NW and SE, formed some small-scale anticlines and thrust nappes under the influence of later tectonic activities [38]. The available geochronological data divided the widespread magmatic rocks in the study area into the following main periods: (1) Hercynian (362-250 Ma) intrusive rocks mainly consist of syenogranite, granodiorite, and monzogranite, as well as a small amount of maficultramafic rocks as batholiths [39]; (2) Indosinian intrusive rocks (250-235 Ma) commonly have the characteristics of adakite, suggesting that they are related to the final closure of the paleo Asian Ocean [40][41][42]; (3) and Yanshanian intrusive rocks are mostly A/I-type granites, including diorite, tonalite, granodiorite, granite, etc. [20,43], which were spatially and temporally associated with the Mo mineralization in the region [1,2]. In addition, there are various dikes such as diorite porphyrite and granite porphyry intruded in the late Yanshanian period. ...
The Toudaochuan gold deposit is a recently discovered lode gold deposit in Central Jilin Province. Gold ore bodies are dominantly controlled by NE-trending fault. The major hydrothermal period can be further divided into the quartz–pyrite stage (stage I), quartz–gold–polymetallic sulfides stage (stage II, major gold mineralization stage), and quartz–carbonate stage (stage III). Primary fluid inclusions (FIs) identified in quartz at different hydrothermal stages include liquid-rich aqueous FIs (L-type), CO2 FIs (C-type, including CO2-bearing C1-type FIs and CO2-rich C2-type FIs), and minor vapor-rich aqueous FIs (V-type). Microthermometry studies on different fluid inclusions indicate that the original ore-forming fluids belonged to the CO2–H2O–NaCl system characterized by a moderate–low temperature and low salinity in stages I and II, and they finally evolved into a H2O–NaCl system characterized by low temperature and low salinity in stage III. Fluid immiscibility is considered to be the key ore-forming mechanism. The initial ore-forming fluid was originated from magmatic water and was mixed with meteoric water in the later stage. The S and Pb isotope data suggest that the ore metal materials were derived from the mixed source of mantle and crust. Based on all the above data, therefore, it can be proposed that the Toudaochuan gold deposit is a mesothermal magmatic–hydrothermal gold deposit.
... However, the delineation of the microplates in the northeastern region is still controversial. Previous studies hold that the Ergun Massif and the Hinggan Massif merge along the Tayuan-Xijiatu Fault, and the Late Paleozoic Ergun-Hinggan Massif and the Jiamusi-Songnen Massif amalgamate along the Hegen Mountain-Nenjiang River-Heihe River area [1][2][3][4][5][6][7][8][9]. The volcanic rocks in the Da Hinggan Mountains have been considered as Mesozoic medium-acidic volcanic rocks [10][11][12][13][14][15]. ...
The Da Hinggan Mountains are an important area in the tectonic evolution of the Central Asian Orogenic Belt (CAOB), and there are disputes over the closure time of the Paleo-Asian Ocean and the amalgamation spatiotemporal relationship between the Ergun-Hinggan Massif and the Songnun Massif. The geochronology and geochemistry of the Late Cambrian-Late Silurian volcanic rock assemblages in the ARong Qi area at the eastern margin of the Da Hinggan Mountains are studied in this paper. The results suggest that the U-Pb zircon ages of the Late Cambrian, Late Ordovician and Late Silurian volcanic rock assemblages are 507.5 ± 1.0 Ma, 456.2 ± 1.0 Ma, 446.1 ± 0.95 Ma and 423.3 ± 1.4 Ma, respectively. The Late Cambrian-Late Silurian volcanic rocks are quasi-aluminous-peraluminous, belonging to calc-alkaline-shoshonite series, which is rich in HREE but has insignificant europium anomalies. There are abundant large ion lithophile elements (LILE) in the rock, and remarkable Nb, Ta and Ti negative anomalies. The previous data and the current study indicate that a continental margin arc tectonic setting existed in the ARong Qi-Zalantun region during the Early Paleozoic, which is inferred to be the product of the subduction-accretion-amalgamation of the plates along the eastern margin of the Ergun Massif during the Early Paleozoic.
Subduction of the Paleo-Pacific oceanic lithosphere has dominated the tectonic evolution of northeastern Eurasia since the Mesozoic. We document the time of subduction initiation based on the age, character, and paleogeographic record of the Jilin-Yanji Suture that separates the Jiamusi-Khanka Block (of Northeast China) from the northeastern North China Craton. The suture contains a series of accretionary complexes that provide abundant information for elucidating the evolution of the oceanic plates. Zircon U-Pb and Lu-Hf isotope, as well as zircon trace element data, from nine sedimentary rock samples from the Kaishantun Accretionary Complex in the easternmost segment of the Jilin-Yanji Suture document a volcanic arc setting in the end-Permian to Middle Triassic (255−244 Ma) involving the addition of juvenile crust. Based on our new data and previous studies, we propose that southwestern-directed subduction of the Jilin-Heilongjiang Ocean dominated the evolution of regional tectonics between 260 Ma and 230 Ma, which resulted in the formation of arc-related volcano-sedimentary rocks and the generation of accretionary complexes within the Jilin-Yanji Suture. The Paleo-Pacific Ocean started to subduct beneath northeastern Eurasia at ca. 235 Ma, which accelerated the closure of the Jilin-Heilongjiang Ocean and provided the major driving force for the final amalgamation of the northeastern North China Craton and the Jiamusi-Khanka Block.
The petrogenesis and geodynamic setting of the Mesozoic magmatic rocks in the Erguna Block, NE China remains controversial, especially the relationship between magmatism and the subduction history of the Mongol–Okhotsk oceanic plate. Here we present data for the Early Jurassic–Early Cretaceous adakite-like magmatic rocks from Chaoman Farm in the northeastern part of the Erguna Block. Zircon U-Pb dating reveals that the syenogranites crystallized at around 190–180 Ma, while the monzonites, quartz diorite porphyries, and quartz monzonite porphyries were emplaced at around 147–143 Ma. The syenogranites, monzonites, quartz diorite porphyries, and quartz monzonite porphyries are adakite-like rocks. The syenogranites and quartz monzonite porphyries were produced by the partial melting of a thickened ancient mafic lower continental crust and a thickened juvenile lower crust, respectively. Meanwhile, the monzonites and quartz diorite porphyries were formed as a result of partial melting of the oceanic crust. In conclusion, the occurrence of these Early Jurassic magmatic rocks was closely linked to the process of southward subduction of the Mongol–Okhotsk oceanic plate. On the contrary, the Late Jurassic to early Early Cretaceous magmatism (147–143 Ma) occurred in an extensional environment, and was probably triggered by upwelling of the asthenosphere.
The initial timing and history of subduction of the Paleo-Pacific Plate beneath Eurasia are controversial. The crustal thickness variations at a convergent margin typically reflect the convergent process between the two plates. This study used a recently proposed machine-learning model to estimate the crustal thickness variations along the northeast Asian continental margin during the Mesozoic. The northeast Asian continental margin, particularly the eastern North China Craton, had its thickest crust during the Early Triassic and underwent crustal thinning during the Middle−Late Triassic. The former reflects the subduction and collision between the South China Block and North China Craton, and the latter occurred in a post-orogenic extensional setting. From the Early to Middle Jurassic, sustained crustal thickening occurred along the northeast Asian continental margin, which coincided with initial subduction of the Paleo-Pacific Plate beneath Eurasia. From the Early to Late Cretaceous, the northeast Asian continental margin generally underwent crustal thinning, but crustal thickening events occurred at 130 Ma, 110 Ma, and 90 Ma, which is consistent with rollback of the subducted Paleo-Pacific Plate beneath Eurasia. The relationship between crustal thickness and mineralization suggests that thicker crust favored the formation of porphyry-type Cu-Mo deposits, whereas thinner crust in an extensional setting favored the formation of epithermal Au deposits related to magmatism.
Since the Paleozoic, the tectonic evolution of northeastern Eurasia has been dominated by the Paleo-Asian Ocean and the Paleo-Pacific Ocean tectonic domains. However, the spatiotemporal framework and the timing of tectonic transition between these two oceanic domains remain enigmatic. To address this issue, we report petrological, geochronological, and geochemical data for eight sandstone samples deposited along the convergent margin between the Northeast China terranes and the North China craton in central Jilin Province, China. The results show that these sandstones are immature graywackes with a maximum depositional age of Early Triassic (248 ± 1 Ma), and their sediments were largely derived from coeval magmatic rocks in a juvenile continental arc. According to our new results and previous studies, we identified a sedimentary basin (most likely an intra-arc or forearc basin) intimately associated with one or more continental arcs along the northeastern edge of the North China craton, and we suggest that the southwestward subduction of the Jilin-Heilongjiang Ocean in the early Mesozoic accounts for this continental arc setting. There is a distinct temporal gap between the closure of the Paleo-Asian Ocean (ca. 260 Ma) and the onset of Paleo-Pacific plate subduction (234−220 Ma), which is essentially coeval with the southwestward subduction of the Jilin-Heilongjiang Ocean between 256 Ma and 239 Ma, meaning the latter is a key link that marks the transition between these two tectonic domains.
The central Inner Mongolia, located at the intersection of the northern margin of the North China Craton (NCC) and the Central Asian Orogenic Belt, is crucial for deciphering the Late Palaeozoic tectonic evolution associated with the subduction and closure of the Palaeo‐Asian Ocean (PAO). Our study focused on petrology, detrital zircon LA–ICP–MS U–Pb geochronology and whole‐rock geochemistry for the Late Carboniferous to Permian sandstones within the Shuanmazhuang, Dahongshan, Naobaogou, and Laowopu formations in Siziwang Banner, central Inner Mongolia. This comprehensive analysis shed light on the dynamic interplay between the NCC and the South Mongolia Block. Detrital zircon U–Pb ages in investigated samples mainly cluster between 250 and 2650 Ma, with significant peaks at 2.4–2.5 Ga, 1.8–2.0 Ga, 400–430 Ma, and 250–320 Ma, respectively. The geochemistry data are characterized by SiO 2 contents (56.29–77.95 wt. %), Na 2 O / K 2 O ratios (0.45–1.58) and SiO 2 /Al 2 O 3 ratios between 4.33 and 7.44. Moreover, they exhibit the slight enrichment in large ion lithophile elements (Rb and Ba) and the depletion in high field strength elements (Nb, Ta, Th, and U). These facts indicate that the sedimentary detritus predominantly originates from felsic sources, probably deriving from the Late Carboniferous–Permian continental island arc‐related intermediate‐acid igneous rocks, the Late Ordovician‐Silurian magmatic rocks in the Bainaimiao arc and the basements of the NCC. Furthermore, our present results also suggest that during the Early–Middle Permian, accelerating oceanic crust subduction triggered significant magmatic events in Siziwang Banner, leading to rapid uplift and the erosion of arc magmatic rocks, as well as the abundant corresponding sediments. Subsequently, the gradual convergence and eventual collision between the NCC and the Southern Mongolian Block took place at the end of the Permian, representing final closure of the PAO.
The Paleo-Asian Ocean (PAO) had multiple collage systems and closed along multiple sutures. The final timing of the closure of the PAO was closely related to the formation of Pangea. The final timing of closure of the eastern PAO is controversial and may have been from the Middle Permian to the Middle Triassic. This paper presents new zircon U–Pb ages and Hf isotope data for sedimentary and volcanic rocks layer in the Linxi Formation in the Xingmeng Orogenic Belt (XMOB). We also obtained geochemical data for the volcanic rocks layer to constrain the timing and mechanisms of the PAO closure. Detrital zircon U–Pb dating yielded the youngest ages peak of ca. 263 and 260 Ma for two sandstone samples. Combined with the crystallization age of the volcanic rocks layer (254.2 ± 1.3 Ma), this indicates the Linxi Formation was deposited during the Late Permian. Age spectra and Hf isotopic compositions of the detrital zircons from the Linxi Formation suggest that detrital zircons with ages of <1500 Ma were derived from the XMOB, whereas those with ages of 2100–1600 Ma were derived from both the XMOB and the North China Craton (NCC). The detrital zircons with ages of >2400 Ma were derived from the NCC. Geochemical features of the volcanic rocks layer are consistent with eruption in a compressional tectonic setting and derivation by partial melting of the lower crust. Based on our data and the Late Permian history of magmatism and sedimentation, the Linxi Formation was likely deposited in a tectonic setting that transitioned from convergence to collision. Finally, we suggest the PAO closed in a ‘scissor-like’ fashion in the eastern CAOB during the Late Permian, in a setting of tectonic compression.
The Songjianghe gold deposit is located in the southeastern part of the Jiapigou–Haigou metallogenic belt, north of the North China Craton. The distribution of the ore body is governed by ductile shear zones and fractures oriented in the SN direction. The gold ore body consists of lenticular gold-bearing quartz veins. Mineralization can be divided into five stages: the quartz-oxidation stage (I), the pyrite-magnetite-quartz stage (II), the quartz-polymetallic sulfide stage (III), the telluride stage (IV), and the carbonate stage (V), with the main mineralization stages being III and IV. On the basis of lithological characteristics, three types of fluid inclusions were identified in the vein mineral assemblage: NaCl-H2O (W-type), CO2-H2O (C-type), and a minor amount of pure CO2 (pc-type). W-type and C-type inclusions coexist randomly around natural gold minerals in the same quartz grain, indicating that the mineralizing fluid is heterogeneous. The mineralizing fluids had a medium temperature and low to medium salinity based on micro temperature measurements of various inclusions. During the main mineralization phase, H-O isotope tests indicate that the mineralizing fluids are mantle-driven and mixed with atmospheric precipitation during mineralization. δ34S data indicate that the mineralizing material originated from the mantle. The aforementioned characteristics suggest that Songjianghe is an orogenic gold deposit based on its dynamical background, with fluid immiscibility and sulfidation being the primary mechanisms of gold precipitation and enrichment.
The crystallization age of the Sunjiafen Formation volcanic rocks is 253.9 ± 1.1 Ma. Geochemical data show that these volcanic rocks belong to the shoshonitic and metaluminous series and have high Sr and low Y contents (461–582 and 5.60–6.74 ppm, respectively), MgO = 1.32–2.65 wt%, and Na2O/K2O = 0.81–1.40. In MgO−SiO2, Cr−SiO2, Sr/Y−Y and (La/Yb)N−YbN diagrams, data for the samples plot in the adakite and “adakite related to thickened lower crust” fields. As such, we suggest that the Sunjiafen Formation C−type adakitic andesites formed in a compressional tectonic setting. The youngest age (youngest peak age) of two sandstone samples from the Linxi Formation are 251 Ma (257 Ma) and 237 Ma (254 Ma). Detrital zircons with ages of >1500 Ma have εHf(t) values of −5.87 to +6.31. A comparison of the age spectra and εHf(t) values of the detrital zircons in the Linxi Formation with those of igneous zircons from the Central Asian Orogenic Belt and North China Craton indicates the formation was derived from both the belt and the craton. We identified “Jura–type Folds” that formed in peripheral foreland basin in the Linxi Formation, and along with plant fossil fragments (Paracalamites frigidus). These and previously published results indicate the Paleo–Asian Ocean closed along the Xar Moron–Changchun Suture zone during the Late Permian. The study area was in a continuous compressional setting during the Late Permian and formed a peripheral foreland basin that was related to continent–continent collision.
The sandstone-hosted uranium deposits in the SW Songliao Basin differ from typical sandstone-hosted uranium deposits in terms of the geological features of the ore-deposits, including the geometry of the orebodies, mineral assemblage and petrography. Detailed drill core and microscopic observations, scanning electron microscopy (SEM), electron microprobe analysis (EMPA), heavy mineral concentrates, and fluid inclusion studies of the Upper Cretaceous Yaojia Formation, i. e., the uranium-bearing layer, were integrated to investigate the roles of hydrothermal fluids in the formation of these uranium deposits. We found that the kaolinite alteration is developed in the mineralized zones, but it is less common in the peripheral areas. The fluid inclusions are hydrothermal fluids with a medium-low temperature (67 to 179 °C) and a high salinity (5.9 wt.% to 20.1 wt.%). According to the analyses, three kinds of hydrothermal fluids, i.e., the acid fluid, the groundwater heated by the mafic magma, and the alkaline fluid rich in Ca2+ and CO32−, were identified. The fluids might have low U content, but they have participated in the formation of the uranium deposits successively. Kaolinite formed by the acid-hydrothermal fluid absorbed large amounts of uranium. Subsequently, the thermal energy from the hydrothermal fluids changed the intrastratal redox environment and increased the solubility of the uranium minerals in the fluid. The alkaline-hydrothermal fluid rich in Ca2+ and CO32− facilitated the formation of stable Ca-U(VI)-CO3 complex, which led to the enrichment of soluble uranium in solution, and final precipitation as pitchblende, brannerite and Ti-bearing uranium minerals in the uranium ores.
The Xar Moron River fault zone, located in the eastern segment of the Central Asian Orogenic Belt (CAOB), represents the intensely debated final collision zone of the Siberian Craton (SC) and North China Craton (NCC). To determine the tectonic evolution of the eastern segment of the CAOB, we undertook petrography and zircon U-Pb dating of the Huanggangliang and Linxi formations in the Wufendi and Xingfuzhilu areas along the Xar Moron River. Petrographic analysis of Permian sandstones revealed a close relationship between the sedimentary and orogenic sources suggesting short transport distances. A sample from the Huanggangliang Formation yielded detrital zircon U-Pb ages ranging from 2653 Ma to 265 Ma, with three age populations: at 2653 to 2443 Ma, 1935 to 1764 Ma, and 482 to 265 Ma, whereas samples from the Linxi Formation yielded detrital zircon U-Pb ages ranging from 3363 Ma to 257 Ma, with four age populations: at 2705 to 2403 Ma, 2011 to 1203 Ma, 571 to 375 Ma, and 356 to 257 Ma. The age spectrum differences of sandstones on both banks indicate that the Xar Moron River fault zone is the final collision zone of the eastern segment of the CAOB. The sandstone of Huanggangliang Formation yielded a weighted mean age of 265.7 ± 1.5 Ma, suggesting that the main deposition of the Huanggangliang Formation was during the Middle Permian. In addition, a comparison of the youngest age in the sedimentary rocks with U-Pb ages obtained for pyroclastic rock implies that the Linxi Formation formed in the late Permian. The results of our study support the view that the final closure of the eastern segment of Paleo-Asian Ocean (PAO) occurred during late Permian to earliest Triassic times.
The Bajiazi gold deposit, located in the northeast of the North China Craton, is a typical representative of the Jiapigou ore cluster in northeast China. The deposit is hosted within the Neoarchean–Paleoproterozoic supracrustal rocks (greenstone belts) and metamorphosed plutonic rocks. The orebodies occur along NE-trending ductile–brittle faults as auriferous quartz veins. The mineral assemblages reveal three stages of mineralization: quartz–pyrite (early), quartz–polymetallic sulfide (main), and quartz–carbonate (late). Three types of primary fluid inclusions (FIs), namely A-type (aqueous), C-type (aqueous–carbonic), and PC-type (pure carbonic) FIs, have been distinguished in different stages of quartz. The early- and main-stage quartz grains contain C-, A-, and a few PC-type FIs, while the late-stage quartz grains contain only A-type FIs. The early-, main-, and late-stage FIs homogenized at temperatures of 288–397 °C, 183–281 °C, and 120–190 °C, corresponding to salinities of 8.8–19.5, 3.9–18.8, and 3.2–11.3 wt% NaCl eqv., respectively. The ore fluid system evolved from H2O–NaCl–CO2 to H2O–NaCl during ore formation. The gold precipitation resulted from fluid immiscibility during the main mineralization stage. The HO isotope data reveal that the ore fluids originally came from magmatic water, and mixed with meteoric water during ore formation. The δ³⁴S values (−0.2 ‰ to 8.3 ‰) of ore-related sulfides suggest that the sulfur in the ores was originally magmatic-sourced, and mixed with the sulfur in wall rocks during fluid migration. The Pb isotope ratios (²⁰⁶Pb/²⁰⁴Pb = 15.890–16.794, ²⁰⁷Pb/²⁰⁴Pb = 15.188–15.530, and ²⁰⁸Pb/²⁰⁴Pb = 36.589–37.710) of ore-related sulfides indicate the metals in the ores originated primarily from the lower crust, with a minor mantle contribution, and most likely came from a deep magmatic system. The Late Triassic gold mineralization has a clear genetic link to a quartz syenite porphyry. Based on the geological, FI, and isotopic constraints, the Bajiazi deposit is classified as a mesothermal lode gold deposit, which formed in an extensional setting after the closure of the Paleo-Asian Ocean.
The ductile Kaiyuan–Jiapigou Shear Zone (KJSZ) is located within the eastern part of the northern margin of the North China Craton (NCC). The foliation within the shear zone generally dips at 55° towards N20° and contains a lineation that plunges at 40° towards N30°. Field and thin section observations and quartz c-axis fabrics of the KJSZ indicate that this zone records top-to-the-SSW shearing associated with a NNE–SSW regional compression event. Muscovite, biotite, and hornblende ⁴⁰Ar/³⁹Ar step-heating ages constrain the timing of shearing and the tectonothermal history of the KJSZ. Quartz c-axis fabrics and mineral deformation features indicate the deformation within the KJSZ occurred at temperatures of 400°C–450°C, which are lower than the Ar–Ar closure temperature of hornblende but higher than the closure temperatures of muscovite and biotite. Samples from the KJSZ yield ⁴⁰Ar/³⁹Ar step-heating ages from 164.6 ± 0.5 to 165.2 ± 0.6 Ma for hornblende samples and from 161.4 ± 0.4 to 163.1 ± 0.4 Ma for mica samples. Combining these ages with the temperature of deformation within the KJSZ indicates that this shear zone most likely formed between 165.2 ± 0.6 and 161.4 ± 0.4 Ma. Linking these new data with the tectonics and geochronology of the eastern part of the northern margin of the NCC suggests that the deformation within this region was most likely controlled by a nearly N–S compressional event associated with the far field effect of the Mongol–Okhotsk Ocean closure during the Middle–Late Jurassic.
The Central Asian Orogenic Belt (CAOB) was generated through multiple collisional and accretionary events in the Paleo-Asian Ocean, a major global ocean that existed from the late Neoproterozoic into the late Paleozoic. Nevertheless, the question of when the Paleo-Asian Ocean finally closed has notoriously been enigmatic, especially due to the absence of large-scale investigations. The South Tianshan-Solonker Suture, is the largest and southernmost suture within the CAOB, and records the ultimate collision between the Tarim-North China cratons with the Siberia craton, and is commonly interpreted as marking the eventual closure of the Paleo-Asian Ocean. In this paper, we synthesize and evaluate relevant Chinese papers on the area, which are not readily available to an international audience, and extend this across the full length of the suture zone. Based on this review, we can divide the suture zone into four distinct segments, which are, from west to east: the South Tianshan Belt, the Beishan Belt, the Solonker Belt and the Yanji Belt. This enables us to provide a more systematic understanding of the nature and development of the South Tianshan-Solonker suture.
Geochronological data from Paleozoic cover rocks and high-pressure metamorphic rocks show that during the late Carboniferous, the western section of the Paleo-Asian Ocean closed when the Tarim Craton moved northward to collide with the Kazakhstan-Yili Block, thus marking the initial development of the South Tianshan Belt. The Beishan Belt to the east formed when the Dunhuang-Alxa blocks were transported northward to collide with the Tuva-Mongolia Block, with the youngest zircon UPb data from ophiolites indicating that closure of the local Beishan Ocean was in the early-middle Permian, although its final closure may not have been until the early late Permian along the northern margin of the Alxa Block, thus making it slightly younger than the South Tianshan Belt. Further to the east, the available petrographic, geochronological and paleontological data from the Solonker Belt indicate that this belt was formed in the middle-late Permian, during which time bi-directional subduction occurred and the North China and Siberia cratons were amalgamated during an ‘Appalachian-type’ orogeny. Furthermore, we observe that a transition in polarity from northward to bi-directional subduction occurred along the boundary between the Beishan and Solonker belts, which may be related to the East Gobi Transform Fault. In contrast, under the influence of the westward subduction of the Paleo-Pacific Ocean, the Jiamusi-Khanka Block moved southwestward along the Yilan-Yitong Fault in the middle-late Triassic (230–220 Ma) to amalgamate with the North China Craton.
The formation of the South Tianshan-Solonker Suture can be characterized by four distinct west-to-east accretion/collision events that lasted from the late Carboniferous to the late Permian. The South Tianshan Belt, the Beishan Belt and the Solonker Belt therefore demarcate, respectively, the amalgamation between the Tarim Craton and the Kazakhstan-Yili Block, the Dunhuang-Alxa Block and the Tuva-Mongolia Block, and the North China Craton with the Siberia Craton, representing the final closure of the Paleo-Asian Ocean. During the middle-late Triassic, the Yanji Belt in the far east was influenced by the Paleo-Pacific tectonic domain as a result of amalgamation between the Jiamusi-Khanka Block and the North China Craton.
The Jilin–Yanji Suture is situated at the convergent margin between the North China Craton and Jiamusi-Khanka Massif, playing as a key hinge to link up the tectonic transition from the Paleo-Asian Ocean to the Paleo-Pacific Ocean. However, many parameters of this suture, e.g. the timing of its emplacement, tectonic setting and precise location remain controversial. For addressing these issues, we focused on the high-Mg andesites within the Seluohe Group which is a typical subduction-related volcanic association along the Jilin–Yanji Suture. Seven chlorite schist and six andesite samples were collected for petrological, geochemical and geochronological analyses. The geochemical results indicate the protoliths of chlorite schists and the andesite samples are high-Mg andesites, and their magma source was produced by the metasomatized mantle wedge by subducted slab-derived fluids in a continental island arc setting. Eight high-Mg andesites give the crystallization ages of 249 ± 3 Ma–246 ± 4 Ma, with a weighted mean age of 247 ± 1 Ma (MSWD = 0.27) yielded by 69 youngest zircons, indicative of an Early Triassic age. Based on our new results and the field investigation, we propose that the Seluohe Group is a set of Early Triassic volcanic-sedimentary association with continental island arc affinity related to the south-westward subduction of the Heilongjiang Ocean, rather than a Mesoproterozoic sequence or Late Permian accretionary complex as previously considered. Integrated with previous studies on the regional tectonic evolution, we suggest the Jilin-Yanji Suture belongs to the southern extension of the Jilin-Heilongjiang high-pressure metamorphic belt, which records the final collision between the Jiamusi-Khanka Massif and North China Craton during the Triassic caused by the subduction of the Paleo-Pacific Ocean, and the Late Permian-Late Triassic is a key period of tectonic transition from the Paleo-Asian Ocean to the Paleo-Pacific Ocean in the eastern edge of Eurasia.
The Langshan Group is an important constituent of the Precambrian metamorphic rocks in the Langshan area. The accurate determination of its metamorphic age is of great scientific significance for the further study of the Precambrian geological evolution in the region. Disputes remain regarding the metamorphism and deformation overprinting of the Langshan Group. This paper presents a detailed study comprising a field geological investigation, petrological observations, and zircon U-Pb aging of garnet-bearing mica quartz schists in the BangBang District. The result of detrital zircon U-Pb dating from the metamorphosed volcanic sedimentary rock series and geological investigation of the garnet-bearing mica quartz schists suggest the strata formed in the Neoproterozoic. The results from cathodoluminescence (CL) image analysis and U-Pb dating of zircons indicate a large number of metamorphic zircons exist in the garnet-bearing mica quartz schists. The metamorphic overgrowth rims of zircon from two samples were analyzed by LA-ICP-MS. The 206Pb/238U weighted average age of ca. 244 Ma of the zircon metamorphism rims represents the timing of Indosinian greenschist-amphibolite facies metamorphism in the Langshan area, which may be in response to the collision-type orogeny of the North China and Siberian plates in the Late Paleozoic. Acid-intermediate magmatic intrusive activities occurred in the Langshan area, and metamorphic events developed at the same time or at a later stage during the closure of the Paleo-Asian Ocean.
The volcanic rock system of the Miaoling Formation contains the main ore-bearing rocks of two volcanogenic massive sulfide (VMS)-type deposits in the Yanbian area of NE China. Investigation of the VRSMF is needed to better understand the formation of these VMS-type deposits and the tectonic evolution of the Yanbian area. To determine the petrogenesis, material sources, and formation age of the VRSMF, and elucidate its late Paleozoic tectonic evolution and metallogenic significance, this paper presents new petrological, geochronological, geochemical, whole-rock Sr–Nd and in situ zircon Hf isotopic data for the VRSMF. The VRSMF is composed of marine carbonate, intermediate–felsic volcanic rocks (andesite–trachyandesite–dacite) and pyroclastic rocks. Laser-ablation–inductively coupled plasma–mass spectrometry zircon U–Pb dating gives an eruption age of ca. 265 Ma for the pyroclastic rocks in the VRSMF. These rocks are classified as low- to medium-K calc-alkaline series. They are characterized by enrichments in large-ion lithophile elements (e.g., K, Rb, and Ba) and light rare earth elements, and depletions in high field-strength elements (e.g., Nb, Ta, and Ti) and heavy rare earth elements, showing affinity to igneous rocks formed in arc-related tectonic settings. These features, together with homogeneous zircon εHf(t) values of 10.9–15.7 and depleted Sr–Nd isotopic compositions [εNd(t) values of 2.4–5.0], suggest that the parental magma was derived from the partial melting of depleted mantle that had been metasomatized by subduction-related fluids. These results, along with findings of regional geological investigations, suggest that the formation of the VRSMF was related to subduction of the Paleo-Asian oceanic plate during the middle Permian. The VMS-type mineralization in the Hongtaiping and Dongfengnanshan deposits is interpreted to have formed in a bimodal–felsic setting in a back-arc extensional tectonic environment.
The Weizigou gold deposit is located in the western Jiamusi Massif, Northeast China. Gold mineralization is hosted in the amphibolite, which intruded the granitic gneiss. Although the deposit shows similarities to iron-oxide–copper–gold deposits, the detailed ore-forming process remains uncertain. To determine the formation age, petrogenesis, and tectonic setting of the granitic gneiss and amphibolite, LA–ICP–MS zircon, titanite, and monazite UPb dating, whole-rock major- and trace-element analyses, and LA–ICP–MS in situ zircon Hf isotope analyses were conducted on samples from these rocks. The granitic gneiss yielded two age populations of 951–882 Ma, and ca. 500 Ma, with a monazite UPb concordia age of 501.5 ± 5.1 Ma. The amphibolite yielded a crystallization age of 292 Ma, consistent with the results for magmatic titanite UPb dating, and a metamorphic age of 272–258 Ma. The granitic gneiss contains typical aluminum-rich minerals, such as garnet and muscovite, mean SiO2 = 73.31 wt%, and molar ratio Al2O3/(CaO + K2O + Na2O) values of 1.02–1.07, indicating an S-type granite protolith. The amphibolite belongs to the tholeiitic basalt series and has low SiO2 and high MnO contents. These results, together with εHf(t) values and two-stage model ages ranging from −9.5 to 2.3 and − 0.3 to 5.7, and from 2010 to 1659 Ma and from 1331 to 947 Ma, respectively, allow us to infer that the parental magmas of the granitic gneiss and amphibolite were derived from the partial melting of Paleoproterozoic lower crust and the partial melting of metasomatized depleted mantle, respectively. The granitic gneiss is characterized by positive Th and Hf anomalies, and negative Nb, Ta, Sr and Ti anomalies, whereas the amphibolite is enriched in K, Rb, and depleted in Ba, Nb, Ti, and Zr. These geochemical features suggest that the S-type granite was formed in an active continental margin during the Neoproterozoic and underwent granulite-facies metamorphism during the early Paleozoic. The protolith of the amphibolite was gabbro that formed in an extensional setting (e.g., a backarc basin) associated with westward subduction of the Paleo-Pacific oceanic plate beneath the eastern Jiamusi Massif during the early Permian. The gold mineralization can most likely be attributed to contact metasomatic metamorphism of gabbro during the middle–late Permian.
Late Palaeozoic igneous rock associations in response to subduction, accretion, and final closure of the eastern Palaeo-Asian Ocean play a significant role in understanding the geodynamic evolution of the southeastern Central Asian Orogenic Belt. Previous studies have identified a Permian arc magmatic belt associated with the southward-dipping subduction of the eastern Palaeo-Asian Ocean along the Solonker–Changchun suture zone. The genetic mechanism and associated geodynamic settings are of great importance in deciphering the evolution of the eastern Palaeo-Asian Ocean. This paper presents zircon U–Pb–Hf isotope and whole-rock geochemical analyses for a suite of magmatic rocks including the early Permian diorite porphyrites ( ca . 281.0 Ma), andesites ( ca . 276 Ma) and rhyolites ( ca . 275 Ma) in the Kulun region. The diorite porphyrites and andesites have high SiO 2 and total alkali contents, and low MgO contents and Mg no. values, with enrichments in large ion lithophile elements and depletions in high-field-strength elements. These geochemical characteristics, together with low-Sr and high-Yb contents, a weak concave-upward shape of middle rare earth elements and negative Eu anomalies, suggest that these intermediate igneous rocks were generated by partial melting of amphibolitic lower crust at a crustal depth of 30–40 km. The rhyolites have heterogeneous isotopic compositions, with ϵ Hf ( t ) values and T DM2 ages of –20.8 to +0.5 and 3578∼1494 Ma, implying that they were likely derived from partial melting of a mixed source dominated by recycled ancient crust with minor juvenile crustal materials. The rhyolites show potassic affinity with relatively high K 2 O and very low Na 2 O, which was attributed to liquid immiscibility of felsic magma and subsequent limited fractional crystallization of plagioclase. The regional igneous associations, metamorphic events, and coeval sedimentary rocks along the Solonker–Changchun suture zone indicate that the early Permian igneous rocks were formed in an active continental arc environment in response to southward subduction of the eastern Palaeo-Asian Ocean.
Subduction erosion is widely thought to play a significant role in crustal recycling at modern convergent plate margins. However, identifying subduction erosion in fossil accretionary margins is difficult due to multiple episodes of tectonic superimposition and an absence of direct geophysical evidence. By assessing provenance and metamorphic records in this study, we are the first to document the record of subduction erosion in Late Triassic to Middle Jurassic meta-sedimentary rocks from the Luobei Heilongjiang Complex, NE China. Most detrital zircons from four meta-sedimentary samples have typical core-rim textures. Approximately 90% of the detrital zircon cores yielded Phanerozoic ages with εHf(t) values of +12.8 to −17.6. Geochronological and isotopic comparisons indicate that the meta-sedimentary rocks have a provenance in the eastern Songnen Block and were deposited in a forearc basin. The youngest ages of detrital zircon cores span from 229 to 176 Ma, while the metamorphic ages obtained from detrital zircon rims range from 209 to 185 Ma. Combined with the 186−165 Ma phengite 40Ar-39Ar ages of the meta-sedimentary rocks, this suggests that their protoliths were deposited during the Late Triassic−Middle Jurassic. Mineral inclusions define peak blueschist-facies metamorphism at pressure-temperature conditions of 0.9−1.0 GPa and 359−365 °C; this indicates that forearc sediment from the overriding plate was abraded into the subduction channel and underwent high-pressure metamorphism. Metamorphic ages (209−165 Ma) obtained from phengite and detrital zircon rims suggest that a period of subduction erosion occurred during slab subduction. These results reveal rapid progression from early forearc sedimentation (229−165 Ma) to subduction erosion (209−165 Ma) during westward subduction of the Mudanjiang Ocean.
The Changchun–Yanji suture zone (CYSZ) in NE China is considered as the suture between the North China Craton (NCC) and Central Asian Orogenic Belt (CAOB). The geochronology, geochemistry and Sr‐Nd‐Hf isotopes of Early–Middle Triassic adakitic plutions from the CYSZ, are presented in this paper to discuss their petrogenesis and tectonic setting, as well as to constrain the timing and style of the Paleo‐Asian Ocean's final closure. In Early Triassic, the Dayushan pluton (ca. 250 Ma) from western CYSZ has negative εNd(t) values, bidirectional provenances (NCC and CAOB) of εHf(t), which are formed in a collision tectonic setting. In contrast, in eastern CYSZ, the early Triassic samples in Liangshan (ca. 242 Ma) were high Mg# values, positive εNd(t), single provenances (CAOB) of εHf(t) resulting from a subduction setting. In the Middle Triassic, the A‐type granites in western CYSZ are found in previous studies representing a post‐collisional extensional environment, whereas syn‐collisional Lianyanfeng granites (ca. 237 Ma) in eastern CYSZ with low ISr and large scale εNd(t) and εHf(t) values from bidirectional provenances (NCC and CAOB), represent a collisional setting. The Paleo‐Asian Ocean's occurred in a scissor‐like fashion along the CYSZ during the Triassic period.
This study reports petrography, geochemistry, geochronology, and Lu–Hf isotopic analyses of Xiaofangshen, Lingshansibei, and Shidonggou plutons, which are located in the northern Liaoning Province, eastern segment of the northern margin of the North China Craton. In this study, we discuss their formation ages, petrogenesis, and tectonic environment. Petrographic characteristics suggest that these plutons are composed mainly of granitic rocks and are widely altered by later deformation. Zircon U–Pb dating results suggest formation ages of 248.2 ± 1.4 Ma, 245.1 ± 1.5 Ma, and 230.6 ± 2.5 Ma for the Xiaofangshen, Lingshansibei, and Shidonggou plutons, respectively. The geochemical characteristics indicate that both the Xiaofangshen and Lingshansibei plutons are metaluminous, high‐K calc‐alkaline‐shoshonitic granites that formed in a crustal thickening environment; the Shidonggou pluton is peraluminous, calc‐alkaline I‐type granite that formed in a post‐orogenic environment. All granitic plutons in the study area are enriched in large‐ion lithophile elements and light rare earth elements (REEs) and depleted in high‐field‐strength elements and heavy REEs. Combined with geochemical characteristics of the plutons and previous studies on the region, we conclude that the eastern part of the Palaeo‐Asian Ocean closed in the Late Permian to Early Triassic. The orogeny of the eastern segment of the northern margin of the North China Craton continued until the early Late Triassic. The evolution of the study area can be divided into three stages during the Triassic. First, the region entered the stage of Palaeo‐Asian Ocean extinction and oceanic plate detachment. Second, a transition stage from post‐collisional orogeny to extensional collapse took place. Third, the environment changed from collisional orogenic to post‐orogenic tectonic.
The tectonic setting of Jurassic magmatism in the Northeast China (NE China) is unclear. Here, we present new petrological, whole-rock geochemical, zircon U-Pb geochronological, and zircon Lu-Hf isotope data for Jurassic granitoids of the Wulong region, Liaodong Peninsula, NE China. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) zircon U-Pb data indicate that these granitoids were emplaced at 165–156 Ma. The biotite monzogranite, two-mica monzogranite, monzogranite, granodiorite, biotite granodiorite, and syenogranite are strongly peraluminous (A/CNK=1.09–1.29), contain peraluminous minerals such as muscovite, have high normative corundum abundances (1.26 wt.%–3.28 wt.%), and have high K2O/Na2O ratios (0.76–1.48), all of which indicate an S-type granite affinity. However, the biotite granodiorite and syenogranite have high Sr (391 ppm–570 ppm) and low Y (3.06 ppm–5.94 ppm) contents, with high Sr/Y (65.8–185.9) ratios, and the two-mica monzogranite, monzogranite, and granodiorite have relatively high Sr (138 ppm–379 ppm) and low Y (3.38 ppm–8.71 ppm) contents, with high Sr/Y ratios (19.1–77.9). All of the analyzed samples have negative zircon εHf(t) values (−41.4 to −20.6) with old two-stage Hf model ages (TDM2(Hf)=2.50–3.76 Ga). Therefore, we infer that the biotite monzogranite is the typical feature of S-type granite that was derived by partial melting of metagraywacke. The monzogranite, two-mica monzogranite, granodiorite, biotite granodiorite, and syenogranite exhibit geochemical characteristics of S-type granite with K-rich adakitic features, and were possibly derived by mixing of melts from clastic crustal materials and adakitic magmas. There are voluminous Jurassic igneous rocks in the NE China. By combining our study with the previous researches, this paper infers that the Jurassic magmatism within the Erguna-Xing’an Massif was related to the southward subduction and closure of the Mongol-Okhotsk Ocean; the Early Jurassic magmatism to the east of the Songliao Basin and in the northern North China Craton (NCC) was related to the subduction of the Pacific Plate; however, the Middle-Late Jurassic igneous rocks to the west of the Songliao Basin were related to the closure of the Mongol-Okhotsk Ocean and, in the northern NCC, were related to closure of the Mongol-Okhotsk Ocean with an influence from flat-slab subduction of the Pacific Plate.
The Late Paleozoic–Mesozoic tectonic evolution in the northeastern (NE) Asian continental margin has been a controversial issue. Accretionary complexes (ACs) and sedimentary formations, as the direct material records of the reconstruction of plate subduction history and surface response, respectively, are the categorically ideal indicators to explore tectonic evolution of the NE Asian continental margin. This study reviews recent geological and geophysical advances about the crustal structures beneath the massifs and ACs such as the Yuejinshan and Raohe ACs and conducts a detailed dissection on lithology, degree of metamorphism and deformation, deep crustal structure, and formation time of these fossil ACs. These results, together with the coeval sedimentary formations and igneous rock associations, provide new insights for Late Paleozoic-Mesozoic tectonic evolution of NE Asian continental margin, i.e., the NE Asian continental margin experienced the evolution of two tectonic regimes during the Late Paleozoic–Mesozoic: 1) the stage of the Paleo-Asian Ocean tectonic regime, including a passive continental margin in the early stage of the Late Paleozoic, an active continental margin in the early Permian, and tectonic transition in the Triassic. A paleo-ocean occurred between the Jiamusi Massif and an unnamed massif during the Late Devonian–late Permian; and 2) the stage of the Paleo-Pacific tectonic regime, including the subduction onset of the Paleo-Pacific Plate beneath Eurasia in the Early Jurassic, the accretion and emplacement of the Jurassic ACs during the Late Jurassic–early Early Cretaceous, and the continuous westward subduction during the Late Mesozoic. The Yuejinshan AC was the product of the Paleo-Asian Ocean tectonic regime and formed during the Late Devonian–early Permian. Its final emplacement occurred in the late Permian. The Raohe AC was the product of the Paleo-Pacific tectonic regime and experienced the following stages: 1) the formation of seamounts and deposition of the terrigenous clastic sediments in the Middle–Late Jurassic; 2) the seamount–Eurasia collision in the Late Jurassic; 3) the northward migration of the embryo of the Raohe AC during the Late Jurassic–early Early Cretaceous (160–140 Ma); 4) the deposition of the early Early Cretaceous sediments; and 5) the final emplacement of the Raohe AC in the late Early Cretaceous (140–130 Ma).
Palaeozoic ophiolites are rare in the south-eastern Central Asian Orogenic Belt (CAOB) and are genetically significant for understanding the formation, evolution, and closure processes of the Palaeo-Asian Ocean (PAO). The Faku ophiolite is located in north Liaoning, NE China, and is dominated by the south-eastern CAOB within the Songliao Basin. It consists of several discontinuous tectonic blocks made up of serpentinised ultramafic rocks, gabbros, basalts, high-Mg andesites, marine and continental sedimentary formations, which are intruded by younger granites. We characterize the geochronology and geochemistry of the ophiolite. The ophiolite and granitic rocks have restricted εNd(t) (+2.60 to +6.08) and εNd(t) (+0.42 to +1.66). Zircons from the ophiolite and granite yielded weighted mean ²⁰⁶Pb/²³⁸U ages of 369–249 Ma and ca. 248.2 Ma, respectively, that we interpret as their crystallization (eruption) times. The ophiolitic rocks have a resemblance to enriched mid-ocean ridge basalts and within-plate basalts in terms of geochemistry, thereby representing a back-arc-type tectonic setting. The granite geochemically belongs to I-type, and formed in a syn-collisional orogenic environment. The sandstones from marine sediments are enriched with light rare earth elements and have low contents of SiO2 and MgO, and a positive zircon ɛHf(t) value indicating the affinities similar to those of ophiolitic rocks. The provenance of molasse is from the Baijiagou granites suggesting that the post-collisional orogeny and uplift occurred after the Early Triassic. We speculate that a juvenile intra-continental back-arc oceanic basin, which represents the southern affiliated branch of the PAO, might have formed by the continuous extension in southern CAOB since the late Devonian, and ultimately closed in the Early Triassic.
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