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... For the tectonic and sedimentary environment in the eastern Junngar Basin, a series of studies have been carried out, but there are still many controversies. For example, there are two opinions on whether orogeny continued after the closure of the Kelameili ocean: One viewpoint is believed that the Kelameili ocean was closed at the early Early Carboniferous [3] . Instead of immediate orogeny, a residual basin was formed between the two continental blocks, and the Nanmingshui Formation developed in the late Early Carboniferous, covering above the ophiolite unconformably [89] . ...
... The Junggar Basin is located in the southern part of the Central Asian Orogenic Belt, and at the junction of the Kazakhstan, Siberian, and the Tarim plates (Fig. 1a). Kelameili range is located in the northeast margin of Junggar Basin (Fig. 1b), and is a Northwest trending linear orogenic belt [3] . It is about 220 km long and 20 to 50 km wide (Fig. 1c). ...
... It is about 220 km long and 20 to 50 km wide (Fig. 1c). Kelameili fault zone is the most important fault zone developed inside ZHANG Lei et al. / Petroleum Exploration and Development, 2020, 47(1): [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] 32 the orogenic belt [3] . Some researchers believe that this fault zone is a suture zone between the Kazakhstan and Siberian ancient plates, while some other researchers believe that the fault zone is a northward subduction zone of the ancient Siberian continental margin, rather than a suture zone between the two ancient plates [1,3,22] . ...
Based on comprehensive analysis of typical outcrops, latest deep wells drilled and high resolution seismic profiles in the study area, we examined the geologic structure of the Kelameili range, and analyzed the structural relationship between the Kelameili range and the Dajing depression, and discussed the tectonic-sedimentary framework in different periods of Carboniferous by using axial surface analysis and balanced section techniques. Understandings in three aspects are achieved: (1) The study area experienced five stages of compressional tectonic movements, the Early Carboniferous, the Late Carboniferous, the Middle-Late Permian, Late Cretaceous and Paleogene, and three stages of extensional tectonic movements, the middle-late Early Carboniferous, the middle-late Late Carboniferous and Early Permian. At the end of the Early Permian and the Mid-Late Cretaceous, the tectonic wedges moved southward respectively. (2) The Kelameili range and Dajing depression had the first basin-range coupling during the early Early Carboniferous, basin-range decoupling in the following middle-late Early Carboniferous to the Early Permian, then basin-range strong recoupling in the Middle Permian, and the basin-range coupling had been inherited in the subsequent Indosinian, Yanshanian and Himalayan movements. (3) During the early Early Carboniferous, the study area was a foreland basin where the Dishuiquan Formation source rock developed; in mid-late Early Carboniferous, a series of NW- and NWW-trending half-garben fault basins developed, where the Songkaersu Formation volcanic reservoir formed. In late Early Carboniferous, the study area entered into depression basin stage after rifting, and the Shuangjingzi Formation source rock developed; in the mid-late Late Carboniferous, Batamayineishan fault basin emerged, and the Upper-Carboniferous volcanic reservoir was formed, affected by the tectonic compression during late Carboniferous and Mid-Permian, the Batamayineishan Formation suffered extensive erosion, and only partially remains in the piedmont depression zone. Key words: Kelameili range, Dajing depression, basin-range coupling, Carboniferous tectonic-sedimentary framework, eastern Junggar Basin
... W. Xu et al., 2013b;Zhang et al., 2013). However, the Paleozoic tectonic evolution of the East Junggar terrane remains controversial and, in particular, the question about when the Kalamaili Ocean was formed and closed remains hotly debated (e.g., Cai et al., 2018b;Fang et al., 2015;Han and Zhao, 2018;Huang et al., 2012;Li, 1991;Li et al., 1990Li et al., , 2015Liu et al., 2017;Shu and Wang, 2003;Su et al., 2012;Wang et al., 2009;Xiao et al., 2009;Zhang et al., 2013). ...
... The occurrence of Tuvaella fauna on both the southern and northern sides of the Kalamaili ophiolite belt (KOB) and the evidence of Early Devonian microfossils in cherts in the ophiolite led Li, 1995;Li et al., 1990 to propose that the Kalamaili Ocean opened in the Early Devonian, which evolved from the Late Silurian epicontinental sea on the Siberian plate. According to one interpretation, this ocean probably closed before Early Carboniferous, a conclusion supported by: (a) a depositional age of 345-343 Ma for the sedimentary successions that unconformably overlie the Kalamaili ophiolite (Huang et al., 2012;Zhang et al., 2013); (b) the radiometric age of 348 Ma for the syn-collisional quartz diorites that intruded the ophiolite ; and (c) the 343 Ma date on the granitic ultramylonite that crosscuts the ophiolite belt (Wu et al., 2012). ...
... The terrane consists, from the north to the south, of the Dulate-Baytag arc, the Armantai ophiolite belt, the Yemaquan arc, the KOB, and the Jiangjunmiao accretionary complex (Fig. 1b). To the north, the Dulate-Baytag arc consists mainly of Devonian-Carboniferous volcanic and sedimentary rocks (Li et al., 1990;Zhang et al., 2009). The Armantai ophiolite belt was emplaced against Devonian-Carboniferous arc-type volcanic-sedimentary rocks (Xiao et al., 2009) and has an age between 503 Ma and 420 Ma (Jian et al., 2005;Liu et al., 2016;Luo et al., 2017;Xiao et al., 2009;Zeng et al., 2015). ...
The Kalamaili orogenic belt in northwestern China preserves a record of the magmatic and tectonic evolution of the Paleo-Asian Ocean and is thus an important region for reconstructing the Paleozoic evolution of the East Junggar terrane and the Central Asian Orogenic Belt. This study presents detailed field investigations, new SHRIMP U-Pb ages, whole-rock geochemistry, and in situ zircon Hf isotopic data for the early Paleozoic igneous rocks exposed in the Kalamaili orogenic belt. These igneous rocks are predominantly felsic plutons and mafic–intermediate volcanic rocks but include minor mafic–intermediate dikes. The igneous rocks have zircon U-Pb ages ranging from 463 Ma to 433 Ma and unconformably overlain by Late Silurian and Early Devonian sedimentary rocks. These early Paleozoic igneous rocks exhibit signatures similar to those of arc-related magmatic rocks such as enrichment in large-ion lithophile elements and depletion of high field strength elements. They have high positive εHf(t) values of +10.7 to +19.0, suggesting a juvenile source and considerable continental growth in the East Junggar terrane during the early Paleozoic. The geochemical signatures of the mafic–intermediate rocks suggest that they originated from the partial melting of mantle wedge material that had been metasomatized by slab-derived fluids; the felsic plutons were derived from the partial melting of juvenile crust. This early Paleozoic arc magmatic event, together with other evidence, indicates that the Kalamaili Ocean formed in the early Paleozoic, was subducted during Middle Ordovician–Early Silurian, and closed before Middle Silurian. Stratigraphic correlations reveal that the East Junggar terrane might not have experienced full extension to form a broad ocean during the late Paleozoic.
... It marked the docking of the Kazakhstan-Junggar plates into the accretionary system of the Siberia plate (Ma et al., 1997; Charvet et al., 2001; Buslov et al., 2002;). However, the time of the fi nal amalgamation is still controversial: It has been considered to be before early Carboniferous (J.Y. Li et al., 1990), to postdate early Carboniferous (Z.C. X.F. ...
... The Kalamaili orogenic belt marked the fi nal amalgamation of East Junggar, and also marked the suture between the Kazakhstan–Junggar plates and the accretionary system of the Siberia plate in East Junggar (Ma et al., 1997; Charvet et al., 2001; Buslov et al., 2002;). North of the Kalamaili suture zone, the Yemaquan arc consists of Devonian to Carboniferous volcanic and volcanosedimentary rocks (Li et al., 1990 ), and Upper Paleozoic composite granitoid batholiths, the largest of which is the Laoyaquan–Huangyangshan Batholith (G.X.). Early Devonian–Late Silurian intrusive rocks have been reported by Y.P. (muscovite granite, 413 ± 8 Ma) and Guo et al. (2009) (granodiorite, 416– 430 Ma) in the eastern part of the Yemaquan arc (Fig. 1B). ...
... LA-ICP-MS U-Pb ages of detrital zircons can be used to discriminate among different source regions (e.g., LaMaskin et al., 2011; CentenoGarcía et al., 2011). The age distributions of detrital zircons from the Tamugang and Songkarsu Formations are different from that of the unconformably underlying Devonian Kalamaili Formation (J.Y. Li et al., 1990; Y.P. Li et al., 2007) (Fig. 7). The Tamugang (52%), with some smaller peaks in the range of 460–500 Ma (12%), 510–540 Ma (11%), and Proterozoic (25%) (Fig. 7). ...
The age of the Kalamaili orogenic belt, marking the fi nal amalgamation in East Junggar, North Xinjiang, is signifi cant for the reconstruction of Paleozoic evolution of the southern Central Asian orogenic belt. The Tamugang and Songkarsu Formations of terrestrial molasse in the southeastern part of the Kalamaili belt, shed from the rising Kalamaili orogen, record the orogenic history. The strata consist of proximal conglomerate thinning to distal fi ne-grained sandstone and mudstone. Poorly sorted conglomerate is composed of dominant pyroclastic rocks with lesser andesitic, granitic, and ophiolitic clasts. Imbricated clasts indicate that the paleocurrents were directed to the present-day southwest to west-southwest. Laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) detrital zircon U-Pb dating of sandstones from both formations confi rms that the Yemaquan arc northeast of the Kalamaili orogenic belt was the main source. Two granitic cobbles with zircon sensitive highresolution ion microprobe (SHRIMP) U-Pb ages of 432.2 ± 7.8 Ma and 428.1 ± 6.8 Ma indicate the presence of Silurian magmatism in the Yemaquan arc. The SHRIMP U-Pb age of volcanic rocks from the Batamayineishan Formation, which overlies the molasse on both sides of the Kala maili belt, is 349.5 ± 6.0 Ma. The depositional age of molasse is confi ned to between 343.5 Ma and 345 Ma, based on the 2σ range of possible ages for the youngest detrital zircons and the overlying volcanic rocks. Combined with the previously dated plagiogranite and biostratigraphic ages on chert in the Kalamaili ophiolite as the lower age limit, the Kalamaili collision is restricted to 373.8-343.5 Ma, taking into account 2σ error, suggesting that the termination of Kala maili paleo-ocean subduction and the final amalgamation in East Junggar occurred before the Visean.
... In the earliest Devonian, extension in the East Junggar resulted in the formation of the Kalamaili oceanic crust represented by the KOB, which separated the Yemaquan block in the north and the Junggar block in the south (Fig. 16A). At the end of the Early Devonian, the Kalamaili oceanic crust began to subduct northward beneath the Yemaquan block approximately along the Qingshui-Sujiquan fault zone, resulting in the formation of the Yemaquan arc (Li et al., 1990Li, 2004; Fig. 16B). The closure of the Kalamaili Ocean and the collision between the Yemaquan arc and the Junggar block occurred around the end of the Early Carboniferous to the beginning of Late Carboniferous (Li et al., 1990;Luo et al., 2016;Fig. ...
... At the end of the Early Devonian, the Kalamaili oceanic crust began to subduct northward beneath the Yemaquan block approximately along the Qingshui-Sujiquan fault zone, resulting in the formation of the Yemaquan arc (Li et al., 1990Li, 2004; Fig. 16B). The closure of the Kalamaili Ocean and the collision between the Yemaquan arc and the Junggar block occurred around the end of the Early Carboniferous to the beginning of Late Carboniferous (Li et al., 1990;Luo et al., 2016;Fig. 16C). ...
There are many lode gold deposits and occurrences in the Kalamaili area of the East Junggar, northwestern China. However, little is known about the specifics of ore geology and geochemistry of these gold deposits because of very limited exploration and research work in this region. Field geology, fluid inclusions, stable isotopes, trace elements in quartz, and hydrothermal zircon U-Pb dating are combined in this study to constrain the nature and source of ore fluids, the timing of mineralization, and the mechanism of gold precipitation in Kalamaili. The gold deposits are confined to a narrow zone between two regional NW- to NWW-trending shear zones and are structurally controlled by secondary, high-angle faults of the shears. The orebodies occur in the Middle Devonian and Lower Carboniferous, zeolite to lower greenschist facies clastic sedimentary and pyroclastic rocks. Gold mineralization occurs as auriferous quartz-sulfide ± tourmaline veins/veinlets and disseminated ores in the immediate altered wall rocks. The ore mineralogy is relatively simple and dominated by quartz with minor to trace amounts of sulfides (pyrite and arsenopyrite), sericite, calcite, and native gold. Quartz of various generations contains three types of fluid inclusions, including predominant H2O-CO2-NaCl inclusions and subordinate H2O-NaCl inclusions and CO2 ± CH4 ± N2 inclusions. The mineralizing fluid is uniformly characterized by a medium to high homogenization temperature (mostly 240−330 °C), low salinity (typically <6 wt% NaCl equivalent), reduced, and CO2-rich-H2O-NaCl ± CH4 fluid. The hydrogen and oxygen isotope data (δ18OH2O = +5.6‰ to +14.3‰, δDH2O = −99‰ to −62‰) indicate a metamorphic origin for the mineralizing fluid. The majority of sulfide δ34S values range between 0‰ and +10‰, indicative of a largely sedimentary rock reservoir of sulfur in the ore-forming fluids. Geochemically, the auriferous quartz is characterized by low concentrations of most trace elements including Ti, Al, Li, Ge, and Sb. Laser ablation−inductively coupled plasma−mass spectrometry U-Pb isotope dating of hydrothermal zircons from the auriferous quartz vein yielded a weighted mean 206Pb/238U age of ca. 313 Ma. Phase separation of ore fluids and fluid-rock interaction are suggested as key mechanisms for the gold precipitation. Integrated geological and geochemical evidence indicates that formation of the orogenic gold system in Kalamaili is related to the transition from compressional to transcurrent deformation during the Late Carboniferous. Target gold exploration in this region should focus on the northeast side of the Kalamaili fault zone, where there exist suitable structural and stratigraphic trap sites with high fluid flux and potential gold mineralization.
... Both the Junggar and Yemaquan blocks are underlain by the juvenile arc crust and lack Precambrian basement rocks (Table S4; Chen & Jahn, 2004;, and references therein), demonstrating that they probably evolved as two Paleozoic intraoceanic arcs. It has been suggested that the northern Junggar block represented a passive margin during the middle Devonian, whereas the southern Yemaquan block corresponded to an active margin, which were intervened by the Karamaili Ocean (Li et al., 1990). The gabbro from the ophiolites along the Karamaili fault gave a zircon U-Pb age of 329.9 ± 1.6 Ma (Wang et al., 2009), indicating that the ocean basin was still open in the Early Carboniferous. ...
... Thus we propose a new tectonic model to elucidate the dynamic links between the arc-arc collisional processes and the accretionary tectonics in the southern Junggar area. In the Middle Devonian, northward subduction of the NTO and Karamaili Ocean plates generated the magmatic arc and/or arc basin system at the southern margins of the Junggar and Yemaquan blocks (Figure 13a; Xiao et al., 2004;Li et al., 1990). Slab rollback of the subducting NTO plate possibly initiated the retreating mode at the accretionary margin of the Junggar intraoceanic arc at ∼ 353 Ma, leading to the formation of extensional structures (Figures 4i and 5) and the development of ∼350-330 Ma intraarc rift sequences (Figure 13b). ...
Understanding the tectono‐sedimentary evolution of the Karamaili orogenic belt and reflective collisional processes between the Junggar and Yemaquan blocks in NW China is critical for assessing the role of arc‐arc collision during accretion forming Central Asian Orogenic Belt. An integrated multidisciplinary investigation has been conducted on the Carboniferous strata across the Karamaili suture zone. Three Carboniferous tectonostratigraphic units in the Karamaili orogenic belt were identified, that is, Early Carboniferous clastic sequences, clastic‐volcanic sequences, and Late Carboniferous carbonate‐clastic sequences. The deposition of the Early Carboniferous strata in the northern Junggar block was controlled by normal faults in an extensional setting, accompanied with sediment supplies from the Junggar block. The Upper Carboniferous is distributed in the Junggar block and at the southern margin of the Yemaquan block, unconformably overlain by rift sequences. This unit shows a foreland‐type depositional pattern typical for a contractional regime and gained the detritus from the Yemaquan block. Such tectono‐sedimentary evolution corresponds to a ∼350–330 Ma rifting event in the Junggar arc and a ∼330–320 Ma collision event between the Junggar and Yemaquan arcs prior to the onset of intraplate rifting at ∼320 Ma. Given the temporal‐spatial distributions of the arc and rift magmatism in the southern Junggar area, we propose that two phases of rifting were likely associated with slab rollback of the subducting North Tianshan oceanic plate. The Karamaili collision may transfer crustal shortening to the southern margin of the Junggar arc resulting in coupling across the plate boundary, implying that arc‐arc collision is a possible mechanism for driving accretionary orogenesis.
... Even this subduction-related setting may continue into the Late Carboniferous as a slab break-off model that was supported by geological events and geochemical data (Su et al., 2007;R.J. Wu et al., 2009;Zhang et al., 2009;Chen and Guo, 2010;Li et al., 2010;Yang et al., 2010Yang et al., , 2012. However, there is not much data concerning the weathering, provenance and tectonic setting of volcanic rocks within the Junggar Basin that has been published, which consequently leads to different interpretations regarding the basement type of the Junggar Basin: continental crust (Li et al., 1990(Li et al., , 2000Liang et al., 2004;Zhang et al., 2004), oceanic crust (Coleman, 1989;Xiao et al., 1992) or Early Paleozoic arc Carroll et al., 2001;Li et al., 2007) and arc splicing terrane (Zheng et al., 2000;Long et al., 2006;Yuan et al., 2006). Furthermore, the question of whether or not the Precambrian basement exists is still a point of controversy (Coleman, 1989;Feng et al., 1989;Kwon et al., 1989;Yuan, 1995;Hsu, 1998). ...
... Therefore, it is difficult to analyze the basement characteristics of the superimposed basin only depending on comparison and inference. b) Continental crust (Wu, 1987;Li et al., 1990Li et al., , 2000Zhang et al., 2004;Li et al., 2007). Li et al. (2000) obtained the Ar-Ar age (~462 Ma) of the Laojunmiao quartz schist in the East Junggar, showing the existence of the Ordovician continental basement. ...
The Well Moshen-1, the deepest well in the Junggar Basin, is located in the Mosuowan Uplift of the Central Depression. Andesitic magmatic rocks (including the vitric clastic tuff, tuffite and crystal tuff with volcanic–sedimentary rocks) are common in the Carboniferous of the Well Moshen-1. In-situ SHRIMP zircon U–Pb dating and Hf isotope analysis together with geochemical data, seismic profile and magnetic anomaly were carried out on these andesitic tuffs at a depth of 7000 m in the Well Moshen-1 in order to reveal the basement character and the evolution of the Junggar Basin and the crustal accretionary process of this region in the Late Paleozoic. By using high-accuracy dating techniques, we obtained the zircon SHRIMP U–Pb age of the andesitic tuff of 331.7 ± 3.8 Ma. Geochemical data has also shown that the rocks have typical arc-like geochemical characteristics (low TiO2, Mg#, enrichment in large-ion lithophile elements and depletion in high-field-strength elements, especially Nb, Ta and Ti), suggesting that they are crystallization differentiation products of intra-oceanic arc magmatism. The Carboniferous strata from the Well Moshen-1 are divided into three tectonostratigraphic units with eight periods of volcanic activities, showing a change in the compressional stress of the Mosuowan Uplift from strong to weak and its ending during the Early Permian. The Hf model ages and the formation ages of the zircons from these andesitic tuffs are similar, with 176Hf/177Hf ratios ranging from 0.282906 to 0.283030 and εHf (t) values from 11.7 to 15.2, implying a lateral growth of juvenile crust in the Junggar Basin during the Early Carboniferous. Based on the analysis of regional geologic settings of the Junggar region, the Mosuowan Uplift is considered to be a Carboniferous intra-oceanic arc that resulted from a northward subduction of the South Junggar Ocean, which suggests that the lateral accretion of arcs played an important role in crustal growth in this part of Central Asia.
... In geochemical discrimination diagrams, the Karamaili ophiolite plots in the island arc basalt and mid-ocean ridge basalt (MORB) fields, suggesting ridge-subduction affected island arc or fore-arc setting Liu et al., 2007). The Yemaquan arc, located at the northern part of the Karamaili suture zone, consists of Devonian to Carboniferous and minor Ordovician-Silurian volcanic and volcaniclastic rocks (Li et al., 1990), whereas the Jiangjunmiao region at the southern part of the tectonic zone is composed of a well-developed succession of Middle Devonian to Lower Carboniferous clastic sedimentary rocks. These sedimentary rocks are overlain by predominantly terrestrial volcanic rocks of the Carboniferous Batamayineishan Formation (BS Formation) (Zhang et al., 2013). ...
... It is generally accepted that northward subduction of the Karamaili Ocean beneath the Yemaquan arc and Wulungu terrane took place during the Devonian-Early Carboniferous in the East Junggar terrane (Fig. 16a) Zhang et al., 2009;Xiao et al., 2011;Long et al., 2012;Su et al., 2012). The Karamaili ophiolitic mélange contains the Late Devonian to Early Carboniferous radiolarian chert (Shu and Wang, 2003), and is unconformably overlain by Lower Carboniferous strata (Li et al., 1990) and intruded by late Carboniferous A-type granites (Li, 1995;Han et al., 2006), indicating that the closure of the Karamaili suture zone occurred in the Early Carboniferous. During the Late Carboniferous (Fig. 16b), the Karamaili oceanic basin was closed, and a foreland basin formed to the south of Karamaili suture zone. ...
The Luliang Uplift preserves relatively complete Carboniferous strata and is an important region to study the spatio-temporal framework and tectonic evolution of the Junggar Basin. Here we report new SHRIMP/SIMS U-Pb ages, whole rock Sr-Nd data, and in-situ zircon Hf isotopic compositions for Carboniferous strata samples in the eastern Luliang Uplift. The gravity and magnetic data suggest that the Carboniferous volcanics are distributed as NW-trending bands and also bring out N-S oriented parallel amalgamation. The sedimentary units and structural deformation of the eastern Luliang Uplift suggest that the basin evolution involved Late Carboniferous extensional graben stage and latest Carboniferous-Early Permian compressional stage. The Carboniferous Batamayineishan Formation is divided into the lower volcanic unit followed up sedimentary unit and an upper volcanic unit as inferred from the lithology and unconformities. The lower volcanic unit from the drill cores mainly consists of andesite, dacite, rhyolite and tuff intercalated with minor basalt. The middle sedimentary unit is made up of sandstone and mudstone with tuff and tuffaceous sandstone, and the upper volcanic unit is composed of basalt, rhyolite, tuff and breccia with minor clastic sedimentary rocks. Zircon SHRIMP U-Pb age (337.2 Ma) for the tuff and SIMS U-Pb age (308.6 Ma) for basalt suggest that the lower and upper volcanic units belong to Lower Carboniferous and Upper Carboniferous, respectively. The basalts from upper volcanic unit in the eastern Luliang Uplift show typical calc-alkaline affinity with low Nb/Y ratios (0.17-0.28) and SiO2 contents (47-54%) and moderate Th abundances (0.45-3.74 ppm), enrichment in LREE and LILEs and depletion in Nb, Ta and Ti. They have low initial 87Sr/86Sr ratios (0.703571-0.705122) and positive εNd(t) values (5.5-8.6) and constant Sm/Yb ratios (1.56-2.03), and variable trace element ratios (e.g., Ba/Th, Ba/La and Ba/Nb), suggesting that the parental magmas were mainly derived from 2 to 8% partial melting of a spinel Iherzolite mantle source metasomatized by hydrous fluids and melts of subducted sediments. Furthermore, relatively high TiO2 (1.52-3.76%) and Zr contents (172-414 ppm) indicate that they were formed in an extensional setting. Taking into account the occurrence of coeval island arc-related volcanics, we propose an intra-arc rift basin model for the eastern Luliang Uplift. The eastern Luliang Uplift and East Junggar terrane display different tectonic features during the closure of the Junggar Ocean. During the Late Carboniferous, continued northward subduction prevailed and generated a fault-controlled intra-arc basin in the eastern Luliang Uplift. Intra-arc basin contraction in Permian is probably indicative of the closure of Junggar Ocean in the northern Junggar Basin. Our study confirms the important role of subduction-accretion process associated with the Carboniferous crustal growth in the Junggar terrane.
... The Chinese Altay-East Junggar domain marks the site where one branch of the Paleoasian ocean, the Junggar ocean, was consumed (Sengör et al. 1993; Filippova et al. 2001). Although different terranes in this region have been distinguished (Li et al. 1990Li et al. , 2003 Xiao et al. 1991; Windley et al. 2002; Xiao et al. 2004a), they are all similar in that all have an island arc/subduction zone with a brief southward younging (Li et al. 1990Li et al. , 2003 O'Hara et al. 1997; Niu et al. 1999; Xu et al. 2001; Xiao et al. 2004a). Based on terrane analysis and zircon geochronology in the Chinese Altay region, Windley et al. (2002) concluded that the Chinese Altay was a Cambro-Ordovician continental magmatic arc. ...
... The Chinese Altay-East Junggar domain marks the site where one branch of the Paleoasian ocean, the Junggar ocean, was consumed (Sengör et al. 1993; Filippova et al. 2001). Although different terranes in this region have been distinguished (Li et al. 1990Li et al. , 2003 Xiao et al. 1991; Windley et al. 2002; Xiao et al. 2004a), they are all similar in that all have an island arc/subduction zone with a brief southward younging (Li et al. 1990Li et al. , 2003 O'Hara et al. 1997; Niu et al. 1999; Xu et al. 2001; Xiao et al. 2004a). Based on terrane analysis and zircon geochronology in the Chinese Altay region, Windley et al. (2002) concluded that the Chinese Altay was a Cambro-Ordovician continental magmatic arc. ...
The geology and tectonics of North Xinjiang can be divided into the Chinese Altay-East Junggar, West Junggar, and Tianshan-Tarim domains, each of which is composed of Andean-type magmatic arc or island arc, accretionary wedge,and ophiolitic slice, showing archipelago paleogeography.The Chinese Altay-East Junggar domain was more closely located to the Angaran craton (Siberia), while the Tianshan-Tarim domain was near the opposite side of the early Paleozoic Paleoasian ocean.The West Junggar domain occupied an intermediate position near the Kazakhstan block in the early Paleozoic Paleoasian basin.The Tianshan-Tarim and West Junggar domains drifted northwards and approached the Chinese Altay-East Junggar active margin of the Angaran craton in the late Paleozoic. Subsequent amalgamation of these domains squeezed the archipelago systems of these domains, leading to termination of the Paleoasian ocean and formation of a complicated orogenic collage between Angaran craton and the Tarim block by the late Carboniferous or the early Permian. These multiple accretion processes significantly contributed to the lateral growth of Central Asia.
... These discoveries, together with the preservation of Ordovician passive-margin deposition in the Harlik domain (Li et al., 2009a), indicate that the two arcs were probably separated by the Karamaili Ocean at that time and evolved as independent tectonic elements. Despite numerous studies, controversy remains about the timing of their amalgamation, with major proposals ranging from the Devonian to Permian (Li et al., 1990Zhang et al., 2013;Long et al., 2012;Xiao et al., 2009). Additionally, an Ordovician-Silurian amalgamation viewpoint has been proposed based on regional geological investigation in the Junggar area (He and Li, 2001). ...
Arc-arc amalgamation occurs during the evolution of composite orogens at convergent plate margins and plays a critical role in controlling accretionary patterns and processes. The eastern Junggar terrane in the southern Central Asian Orogenic Belt underwent a long-lived subduction-accretion process in the Paleozoic, but whether and how the Yemaquan and Dananhu-Harlik arcs were amalgamated remain debatable. A systematic U-Pb–Hf-O isotopic study was conducted on zircons from Silurian granitic rocks in the Yemaquan arc. The U-Pb dating results suggest that these rocks were emplaced at 433–422 Ma and inherited abundant 536–435 Ma zircons representing a predominant magmatic episode in the Yemaquan arc. Their positive εHf(t) values and young Hf model ages indicate that the Yemaquan arc is dominated by juvenile basement with significant crustal growth during the Neoproterozoic to early Paleozoic. The variations in zircon Eu/Eu*, εHf(t), and δ18O values reveal that the Yemaquan arc experienced remarkable crustal thickening and remobilization at ca. 450 Ma, similar to the northern Dananhu-Harlik arc, and this was followed by extension that initiated at ca. 420 Ma. These features support the amalgamation of these two arcs occurring ca. 450–420 Ma. Integrated with regional data, we correlated this amalgamation event in the eastern Junggar terrane with the orogenic event in the Chinese Altai terrane, and we propose a middle Paleozoic tectonic evolution model in the eastern Junggar–Altai area from arc assembly to dispersal in association with a transition in accretionary mode. This scenario probably took place as a response to plate reorganization during the breakup of the northern margin of Gondwana.
... The western margin is bounded by the western Junggar orogenic belt, the NE margin by the Altai orogenic belt along the southern edge of the Siberian plate, and the southern margin by the northern Tianshan orogenic belt ( Figure 1). The branches of the Paleo-Asian Ocean in the Junggar Basin began to narrow during the Middle Ordovician, following which small back-arc oceanic basins extended and then separated during the Devonian; the Junggar oceanic basin narrowed and closed completely during the Carboniferous; and cratonic depression basins formed during the Carboniferous to Permian (Li et al., , 1992(Li et al., , 1990Wu et al., 2008;Yu et al., 2010). ...
Several Carboniferous deep-marine-sandstone reservoirs have recently been discovered in the Junggar Basin, NW
China. These reservoir sandstones were deposited by sediment-gravity flows that occurred on the continental slope of the
Junggar Basin, and they have high hydrocarbon exploration potential. In this study, careful observations and
petrological and geochemical analyses of samples from outcrop sections of Carboniferous rocks from the Junggar Basin
were conducted to establish the deep-marine sedimentary characteristics, depositional environments, and mechanism of
these gravity-flow deposits, as well as a sedimentary model for their occurrence. The deep-marine, gravity-flow deposit
types include those of turbidity currents, debris flows, and slumps. The debris-flow deposits can be divided into pebbly
debris-flow deposits and sandy debris-flow deposits. Results allow the relationship between the type and nature of
gravity flows and ocean basin evolution to be established. During the early Carboniferous, the ocean basin had sufficient
space to accommodate incoming sediment, and the sediment transport distance was long. The gravity-flow sediments of
this period are dominated by sandy debris-flow deposits and turbidity-flow deposits characterised by thin individual
layers but thick accumulations of multiple deposits. With continuous narrowing of the oceanic basin during the late
Carboniferous, the basin had a smaller accommodation space. The main types of gravity-flow deposition during this
period were pebbly and sandy debris flows, with rare thin turbidity-flow deposits. These deposits were coarser grained
than their early Carboniferous equivalents, and their cumulative thicknesses were smaller. The results of the study
provide insights into the prediction of deep-marine reservoir sandstones and the distribution of hydrocarbons in the
Junggar Basin.
... The final closure time of the Karamaili Ocean ranges from the Early Carboniferous (Bai, Chen, Tang, & Zhang, 2018;Li et al., 1990Li et al., , 2009Zhang et al., 2013), through the later Early Carboniferous (Long et al., 2012), to the Late Carboniferous to the Early Permian Xiao et al., 2008Xiao et al., , 2018. The youngest ophiolite age (329.9 ± 1.6 Ma, Wang et al., 2009) from lithological units in the Karamaili ophiolite demonstrated that the Karamaili F I G U R E 1 0 Comparison between the U-Pb age probability distribution for the detrital zircons from the Moqinwula area and adjacent terranes. ...
The recognition of unconformities is important for stratigraphic subdivision and correlation and for determining the timing of tectonic activity and the ocean‐continent transition process. Here, we have identified a Late Palaeozoic disconformity in the Moqinwula area of the northern Junggar Block, NW China. Integrated field relationship observations and sedimentological, biostratigraphical, geochemical and detrital zircon geochronological data, suggest that the underlying Hongliugou Formation is of Devonian age and was deposited in a passive continental margin setting. The overlying Tamugang Formation formed in the Early Carboniferous and was deposited in a foreland basin setting. Integrating the published data and our new work, we suggest a new tectonic evolution model related to the Karamaili ocean‐continent transition process. During the Early Devonian, northward subduction of the Karamaili Ocean plate beneath the East Junggar Belt formed the Yemaquan arc. At this time, a passive margin sequence was deposited on the northern Junggar Block. During the Early Carboniferous, the closure of the Karamaili Ocean resulted from the collision between the Junggar Block and the East Junggar Belt. Foreland basins subsequently developed, forming an extensive unconformity in the accretionary wedge to the north and a disconformity in the relatively rigid and stable Junggar Block to the south. This significant difference in stratigraphic contact relationships confirms that regional convergence‐induced shortening deformation had no significant influence on the northern margin of the Junggar Block, suggesting the existence of a relatively rigid basement, probably an oceanic plateau, under the cover sediments of the Junggar Block.
... The Yemaquan Arc is located between the Almantai and Kalamaili ophiolite belts and is a part of the eastern Junggar orogenic belt (Figure 1). The folded basement of the Yemaquan continental block is a flysch volcanic basin, and its southern continental margin volcanic arc is covered with Devonian acid volcanic and pyroclastic rocks, neritic terrigenous clastic rocks from the late Early Devonian to the Early Carboniferous, and post-collisional alkaline granite bedrock (Li et al., 1990). This arc is located in the larger Kalamaili area, where gold deposits represented by the Jinshuiquan, Shuangquan, Nanmingshui and Sujiquandong deposits are developed, forming a set of metallogenic gold systems related to the late Paleozoic collisional orogeny. ...
Altaids in the Central Asian Orogenic Belt (CAOB) is one of the world’s largest orogenic belts containing mineral deposits. Together with the Junggar terrain they open an important window to study the Paleozoic tectonic evolution of the CAOB. In this paper, we analyze a 637-km-long wide-angle refraction/reflection seismic profile across the Altai-Eastern Tianshan orogenic belt in the southern Altaids, conducted in September 2018 using 10 large explosive charges fired in drilled holes. We use a traveltime inversion method to reconstruct the lithospheric P-wave velocity structure along the profile. The lithosphere is composed of a 43-55-km-thick crust, a ∼10-km-thick crust-mantle transition layer beneath the Altai Mountain, and a ∼25-km-thick layer of lithospheric mantle. The results clearly reveal: a prominent Moho uplift beneath the Yemaquan Island Arc, two major crustal-scale low-velocity anomalies (LVAs) beneath the Yemaquan Arc and Bogda Mountain, and three high-velocity anomalies (HVAs) near the surface around the Kalatongke, Yemaquan and Kalatage mining areas. We hypothesize that the subduction of the Paleo-Asian Ocean occurred with strong mantle upwelling. We suggest that continued compression of the Paleo-Asian Ocean causes the delamination of lithosphere, as well as asthenospheric material upwelling and magma underplating into the crust. Consistently, Paleozoic mafic-ultramafic rocks and mantle-derived minerals related to gold, copper and nickel deposits, are widely extended in the area. Our results show that the P-wave velocity-depth curves for deeper depths (>30 km) in the southern Altai and Junggar Basin are close to those of the continental arcs and global continent average. Despite powerful Paleozoic subduction activity, orogeny and volcanism strongly modified the lower crust in the region, part of ancient continental crust was still preserved below the southern Altai and Junggar Basin. In addition, the upper part (depth 5–30 km) of the velocity-depth curve for the Junggar Basin is close to that of the Costa Rica volcanic front and the British Columbia accreted terrain, suggesting that Paleozoic orogenic activity has intensively reconstructed the upper-middle crust beneath the Junggar Basin.
... The >800-km-long, east-west-trending Junggar Basin, located between the Siberian, Kazakhstan, and Tarim cratons (Ş engör et al., 1993;Jahn et al., 2004;Xu et al., 2014;He et al., 2018), is an important tectonic feature of the southern part of the Central Asian Orogenic System (Windley et al., 2007;Xiao et al., 2009;Xiao et al., 2015;Yin and Nie, 1996;Wu et al., 2016aWu et al., , 2016bŞ engör et al., 2018;Chen et al., 2022) ( Fig. 1A). Much is known regarding the geology and tectonic evolution of the Junggar Basin and adjacent mountain belts, such as compositional differences of basement rocks exposed in the surrounding Bogda Shan, Kelameili Shan, and Tianshan (Jiang, 1984;Xiao et al., 1992;Han et al., 1998;Xu et al., 2014), the distribution of oceanic and continental Paleozoic rocks (Li et al., 2012;Xu et al., 2014), the number and orientation of accretionary orogens (Li et al., 1990, the development of proto-basins Zhao et al., 2008;Yi et al., (caption on next page) X. Li et al. 2018; Zhang et al., 2020), the stratigraphy, provenance, and depositional environments of Carboniferous-Permian strata, and hydrocarbon prospects and conditions (Wu et al., 1996;Chen et al., 2005;Tang et al., 2015;He et al., 2018;Zhang et al., 2018). However, critical unknowns regarding the tectonic development of the Junggar Basin region include the timing of closure of the Paleo-Asian Ocean (Xia et al., 2004;Li et al., 2006;Xu et al., 2006;Briggs et al., 2007;Xiao et al., 2008Xiao et al., , 2009Li et al., 2010;Li, 2016), the stratigraphy and prevalence of volcanic rocks in the Carboniferous basin section (Xia et al., 2004(Xia et al., , 2008Ru, 2012), and the overall tectono-stratigraphic framework of the basin (Xu et al., 2014), especially at basin-mountain interfaces . ...
The late Paleozoic development of the East Junggar Basin and adjoining mountain belts was critical to the construction of the larger Central Asian Orogenic System, yet the structural framework of basement rocks and overlying strata of the basin and their spatio-temporal relationship with adjacent thrust-bounded ranges remain poorly constrained. In this study, we conducted reflection seismology and compiled existing geologic observations of the East Junggar Basin and adjacent Bogda Shan to the south and Kelameili Shan to the north to construct cross sections depicting the tectono-stratigraphic framework and evolution of the region. Our work shows that Carboniferous–Permian strata overlying basement rocks in the East Junggar Basin occur in structural uplifts and depressions and feature at least five major unconformities. The structure of the East Junggar Basin is characterized by: (1) horsts and grabens involving basement rocks and overlying Carboniferous–Jurassic strata; (2) series of stratigraphic depressions marked by Jurassic–Cretaceous strata; and (3) a south-dipping monocline in uppermost Neogene–Quaternary strata. Mesozoic–Cenozoic strata are absent along the northern margin of the East Junggar Basin at the Kelameili Shan. Strata are generally older from the Kelameili Shan to the northern East Junggar Basin where Devonian–Carboniferous strata are thrust southward over younger strata. In contrast, thicker sequences of Cretaceous–Quaternary strata are present in the southern portion of the East Junggar Basin. Strata of the East Junggar Basin were deposited in a foreland depression formed in the footwall of a leading, north-directed thrust of the Bogda Shan. The overall tectono-stratigraphic framework of the East Junggar Basin is a product of tectonic activity varying in time and space along the northern and southern basin-mountain interfaces since the late Paleozoic.
... The East Junggar Orogenic Belt (EJOB) is located in the northeastern Junggar basin and comprises the Dulate arc, Armantai ophiolite belt, Yemaquan arc, Karamaili ophiolite belt, and the Halic-Dananhu arc from north to south [13][14][15][16]. The available data have suggested that the formation and evolution of the EJOB are related to the closure of the Junggar Ocean between the Junggar and Altai plates during the Paleozoic [17][18][19]. ...
The Huangyangshan super-large graphite deposit is located in the Qitai area of East Junggar in Xinjiang Province, China. This deposit is well known for its distinguishing properties, including the alkaline granite complex that hosts the graphite ore, the dominantly orbicular structure developed in the graphite ore, and the association of graphite with metal sulfides in the orbicular ore. This study aims to determine the genetic relationship between graphite and metal sulfides in order to better understand the graphite mineralization process of the Huangyangshan deposit. The methods applied in the study include X-ray micro-CT scanning and scanning electron microscopy (SEM) analyses of the orbicular graphite ore and in situ inductive laser ablation-coupled plasma mass spectrometry (LA-ICP-MS) trace element analyses of the pyrrhotite and chalcopyrite associated with the graphite. The analytical results show that the graphite ore is composed of crystalline graphite, K-feldspar, albite, quartz, biotite, amphibole, and metal sulfides. The metal sulfides in the orbicular ore include pyrite, pyrrhotite, pentlandite, and chalcopyrite. According to the color, crystalline shape, texture, and occurrence, pyrrhotite can be classified into four types (I, II, III, and IV), and chalcopyrite into two types (I and II), of which types I, II, and III pyrrhotite and type I chalcopyrite have a close genetic relationship with graphite. The granular types (I, II, and III) of pyrrhotite are enriched in Co, Ni, Se, Ge, and Te and are depleted in As, Sb, Ag, and Au; they also have a high value of Co/Ni, indicating that these types of pyrrhotite have a magmatic origin. Low values of Co/Ni suggest that type IV pyrrhotite has a hydrothermal origin. The similar contents of Co and Ni and the values of Co/Ni compared with the chalcopyrite from the magmatic Co–Ni sulfide deposits imply that type I chalcopyrite has a magmatic origin. In summary, the metal sulfides of the Huangyangshan deposit are genetically related to graphite mineralization and formed predominantly by magmatic processes.
... 6.2 and 6.3; Xiao et al., 2004;Zhang et al., 2013;Xu et al., 2020). The Dulate Arc is mainly composed of Devonian-Carboniferous volcanic and sedimentary rocks (Li et al., 1990;Zhang et al., 2005Zhang et al., , 2008Zhang et al., , 2009, as well as granitoids with ages of 390-370 Ma and~330-320 Ma (Tong et al., 2014;Tang et al., 2017;Song et al., 2019). The Yemaquan Arc extends along the Kalamaili ophiolite and borders the Harlik Arc in the east (Fig. 6.2). ...
The Central Asian Orogenic Belt (CAOB) lies between the Baltica, Siberia and Tarim-North China cratons, and is one of the largest Phanerozoic orogenic belts on Earth. The development of the CAOB initiated in the Neoproterozoic and it further grew during the Paleozoic via the accretion of various island arcs, seamounts, accretionary wedges and micro-continents. This vast orogenic system was eventually amalgamated by the final closure of the Paleo-Asian Ocean during the late Paleozoic, resulting in the docking of the Tarim-North China craton from the south. Since the late Paleozoic, parts of the CAOB (e.g., the Tianshan and Altai) have served as typical examples of intra-continental orogens where the relationship between plate margin processes and the occurrence of compressive intra-plate deformation can be studied. Throughout the Mesozoic, the southwestern (SW) part of the CAOB experienced several major periods of intra-continental deformation, which have been interpreted to be related with a series of Cimmerian collisions (e.g., the collisions of Qiangtang, Lhasa and Karakorum blocks with Eurasia) occurring along the southern Eurasia margin. The evolution of the SW CAOB continued with active deformation in response to far-field effects of the convergence between the Indian plate and the Eurasia continent throughout the Cenozoic.
Stress-fields as a result of these distal tectonic events propagated through the inherited Paleozoic structures of the CAOB resulting in progressive and punctuated exhumation and mountain building events that shaped the prominent Tianshan and Altai-Sayan mountainous landscapes that are seen today. This study focuses on the intricate intra-continental evolution of the Chinese Tianshan and Junggar orogenic collage, a key component of the SW CAOB. After the initial establishment in the late Paleozoic, this orogenic belt was immediately reworked by the movement of several deep-rooted strike-slip faults probably until the earliest Triassic, then subjected to large-scale reactivation events during the Meso-Cenozoic. As the architecture of the Tianshan and Junggar orogenic belt is complicated and its intra-plate evolution long-lasting, several issues regarding its thermo-tectonic history since the late Paleozoic remain unclear. Main objectives of this research are to better unravel late Paleozoic tectonic wedging due to strike-slip movements and to further elucidate the Meso-Cenozoic reactivation history of the Tianshan and Junggar systems, focusing on some of their uninvestigated or poorly constrained key regions.
Regarding the late Paleozoic strike-slip faults system developed along the Chinese Tianshan belt, we carried out structural and geochronological studies on the poorly investigated Xiaergou and Wulasitai shear zones around and in the Central Tianshan block (Chapter 4). The Xiaergou shear zone is the connecting segment between the North Tianshan fault and Main Tianshan shear zone along the northern margin of the Yili - Central Tianshan blocks, it strikes NW-SE with a width of ~3-5 km and shows predominant dextral kinematics. Zircon U-Pb ages of pre- and syn-kinematic granitic dykes within the Xiaergou shear zone indicate that the dextral shearing was active at ~312-295 Ma. The Wulasitai shear zone is a high-strain belt occurring in the interior of the Central Tianshan block, it extends NW-SE for more than 40 km with variable widths of ~1-5 km, steep mylonitic foliations and sub-horizontal stretching lineation are well developed and various kinematic indicators suggest prevailing sinistral shearing. New biotite 40Ar/39Ar ages of two meta-sedimentary rock units, together with the published metamorphic zircon U-Pb ages constrain the timing of the sinistral shearing at ~312-301 Ma. Our new results combined with the previous studies reveal that the dextral strike-slip shear zones framing the Central Tianshan formed almost simultaneously in the latest Carboniferous (~310 Ma) and lasted until the middle to late Permian. They resulted from the eastward tectonic wedging and relative rotations between continental blocks in the SW CAOB. The sinistral shearing of the Wulasitai shear zone within the Central Tianshan was likely generated due to differential eastward motions of the northern and southern parts of the Central Tianshan.
New apatite fission track (AFT) data on the Paleozoic rocks in and adjacent to the Chinese Central Tianshan were obtained, including two age-elevation profiles in the Alagou and Gangou areas. Inverse thermal history modeling reveals that the basement of the Central Tianshan experienced regional slow to moderate cooling during most of the Mesozoic, and that the present-day topography was mainly built by Cenozoic surface uplift and erosion. Geomorphological observation reveals several remnant fragments of flat, low-relief surfaces within the Central Tianshan, which were likely to have formed in the Mesozoic as evidenced by thermal history modeling of the Alagou age-elevation profile. Furthermore, the new data suggests that the Chinese Central Tianshan and its adjacent terranes did not undergo intensive relief building during its long-term Mesozoic evolution, as several pre-Mesozoic deep-rooted regional faults did not record evidence for a significant Mesozoic reactivation. Finally, differential exhumation of the basement in the western Chinese Tianshan and Junggar has been studied, and shows that the development of regional brittle faults significantly influences the processes of intra-continental deformation (Chapter 5).
The Chinese Eastern Tianshan and East Junggar orogenic belts are major constituents of the SW CAOB, and low-temperature thermochronology was applied to constrain the thermo-tectonic history of these two domains (Chapter 6). AFT dating of Paleozoic basement samples from the region dominantly yields Cretaceous (~126-70 Ma) AFT ages, except for two granitic samples from the East Junggar with older ages of ~239 and ~157 Ma, respectively. Thermal history modeling reveals that the Eastern Tianshan and southern part of the East Junggar experienced moderate to rapid basement cooling throughout the Cretaceous. We interpret this as a far-field effect of accretion and collision along the southern Eurasia margin since the Early Cretaceous. Major faults were reactivated and thus may have played an important role in controlling localized rapid basement uplift and cooling. We also dated seven Mesozoic sandstone samples collected from the eastern margin of the Junggar Basin. The detrital AFT age peaks, together with inverse thermal history modeling of the basement, reveal that the East Junggar underwent late Permian to Early Jurassic basement cooling episodes. These cooling events are thought to be related to post-orogenic transpression along major faults as a distal effect of the coeval Qiangtang-Eurasia collision. Combined with already published evidence, our new data suggests that the Eastern Tianshan and East Junggar did not undergo significant exhumation (> ~2-3 km) during the Cenozoic.
The Yili block in the western Chinese Tianshan forms the easternmost part of the Kazakhstan paleocontinent, and exploring its thermo-tectonic history is important to reconstruct the intra-continental evolution of the Tianshan belt. We report new AFT data from the basement rocks from the northern (i.e. the Wenquan complex) and southern (i.e. the Dahalajunshan - Nalati range) margins of the Yili block (Chapter 7). Thermal history modeling reveals that the Wenquan complex underwent moderate basement cooling in the Cretaceous, possibly due to far-field effects of the Tethys closure and convergent deformation and the ensuing Lhasa-Qiangtang collision. These events at the southern Eurasian margin propagated tectonic stress to the northern Yili and triggered localized deformation. Early Triassic-middle Jurassic moderate cooling is also identified in the Dahalajunshan - Nalati range, and is interpreted to be related to the post-orogenic strike-slip motion along the major shear zones and the effects of the Qiangtang and Kunlun-Qaidam collision. Combined with the published thermochronological data, it is suggested that the northern and southern parts of the Yili block experienced a distinctly different Mesozoic thermo-tectonic evolution. Basement cooling of the northern Yili block generally took place before the Cretaceous, exhuming shallower crustal levels as compared with the southern one. The intermontane Yili basin may have accommodated substantial propagated contraction induced by the Cretaceous collisional events, resulting in less strain reaching the northern Yili. Based on our new results and the previously published thermochronological data, it is suggested that the intra-continental reactivation of the North Tianshan and Nalati faults probably did not invoke significant regional exhumation during the Meso-Cenozoic. Instead, small-scale brittle faults controlled localized enhanced denudation.
In general, the research conducted in this dissertation provides new constraints and valuable improvements on our knowledge of the timing and nature of intra-continental deformation and reactivation of the Chinese Tianshan and Junggar orogenic collage since the late Paleozoic. Meanwhile, it lays the framework for a systematic review of low-temperature thermochronological data that could now be undertaken as many of the regional gaps in the Tianshan-Junggar have been filled (Chapters 8 and 9).
... The Kalamaili Formation is dominated by gray-green clastic rocks (BGMRX, 1999;Cai et al., 2018). The early Carboniferous deltaic sediments disconformably overlies Devonian rocks along the northeastern margin of the Junggar block (Li et al., 1990;Wang G C et al., 2019) (Fig. 2b-e), whereas contemporaneous terrestrial molasse or lava overlying unconformably on the Devonian volcanic-clastic strata are widely distributed in the other regions Cui et al., 2015a;Bai et al., 2018a;Li D et al., 2020). ...
The Paleozoic sediments on micro-blocks in the southwestern Central Asian Orogenic Belt record the tectonic evolution of the Paleo-Asian Ocean and accretionary processes of the south Siberian Craton. However, the absence of detailed stratigraphic studies and sedimentary basin analyses has led to disputes on Paleozoic arc-basin relationships and the tectonic evolution of the Junggar block and East Junggar belt. In this contribution, some Devonian marine-dominated lithostratigraphic units are recognized from the previously identified Huangcaopo Group, using zircon U-Pb data and fossils. To constrain the tectonic setting of the sedimentary basin between the Junggar block and Eastern Junggar belt, seven facies associations including 14 lithofacies were identified from two lithostratigraphic units of the Hongliugou Formation and Kalamaili Formation by detailed petrological and sedimentological studies. Combined with interpretations of detrital provenance and regional contemporaneous magmatism, the Silurian to Devonian successions located along the northeastern margin of the Junggar block could be considered as back-arc basin sediments. Integrated geological characteristics suggest that the Tuva-Altai-Junggar orogenic collage located on the southern margin of Siberian craton was formed during the Ordovician, and the spatial-temporal distribution of the ophiolitic mélange, subduction zone and back-arc extension zone indicate that opening of the Kalamaili Ocean developed on this collage and was related to northward subduction of the North Tianshan Ocean during the Silurian to Devonian.
... The Junggar Basin, located in the north of the Xinjiang Uygur Autonomous Region (Fig. 1), NW China, and surrounded by mountain ranges, has a basement composed of pre-Carboniferous micro-blocks, ocean basins and island arcs (Bian et al. 2010). During the Late Carboniferous, the ocean basin between the Junggar Block and the Siberian Block to the north and the basin between the Junggar Block and the Tarim-Middle Tianshan Block to the south both closed (Li et al. 1990;Carroll et al. 1995). Consequently, seawater retreated from the Junggar Basin area, with seawater remaining only in the Bogda Rift in the southeast and connecting with the open ocean in the Early Permian (Wartes et al. 2002). ...
The Middle Permian Lucaogou Formation in the Jimusar Sag, eastern Junggar Basin, NW China, was deposited in a salt lake within an intracontinental rift basin with intense hydrothermal activity. Hydrothermal-sedimentary dolomite in the form of three types of dolostones, namely, analcime-feldspar dolostone (AFD), silicic dolostone (SD) and buddingtonite-albite dolostone (BAD), related to syn-sedimentary hydrothermal activity at lake bottom was discovered. The characteristics and formation mechanism of the dolomite were studied based on micron-scale petrographic and isotopic geochemical research. The syn-depositional formation of these dolostones was indicated by their rock-mineral features and syn-sedimentary deformation stage. The dolomite was composed of relatively poorly ordered proto-dolomite crystals with micron-sized spherical or sub-spherical morphology and coexisted with hydrothermal minerals, including analcime, buddingtonite, albite and chalcedony. Albite clasts were replaced by the dolomite, indicating high-temperature conditions during formation. The remarkably low strontium isotopic compositions of the dolostones (87 Sr/ 86 Sr with an average of 0.705687) indicated that mantle-derived materials might have involved in the ore-forming fluid. The dolostones had positive δ 13 C PDB values (with an average of 6.94‰) and negative δ 18 O PDB values (with an average of − 8.12‰). Based on the δ 18 O PDB values, the formation temperatures of the dolomite were at least~25°C higher than those of the penecontemporaneous dolomite in the Lucaogou Formation in the study area. It is concluded that the dolomite precipitated from hydrothermal fluid erupting at the lake bottom. The possible genetic models are described. We suggest that the hydrothermal-sedimentary dolomite is an important genetic type, and this study may help increase the awareness of this understudied type of dolomite.
... As a result of subduction and closure of the Paleoasian Ocean, the continent closure during a collision between the Siberia plate and Tarim-Sino-Korean plate showed the scissors-like pattern from west to east [17]. Based on studies on several ophiolite zones developed in Northern Xinjiang [18,19], the oceanic lithosphere in Northern Xinjiang disappeared generally towards the end of the Late Devonian-Early Carboniferous where the continent collision happened. Xia et al. [6,20] presented that the ocean basin of the Paleoasian Ocean closed in Northern Xinjiang at the beginning of Early Carboniferous, on the basis of many geologic pieces of evidence such as isotopic dating for ophiolite, high-pressure metamorphic rock, and stratigraphic contact relationship. ...
The tectonic settings of Northern Xinjiang, Songliao Basin, and its peripheral areas all belong to the Paleoasian orogenic region. Their main structures are all composed of multiple continental segments and peripheral fold belts. Similar tectonic setting and complicated basement structure give rise to the similarities and differences in the forming environment and geochemical characteristics of volcanic rocks in the two regions. The similarities include lack of typical calc-alkalic volcanic rocks, inconsistent covariant relationship between oxide content and SiO2 in contents calc-alkalic volcanic rock in the consuming zone, the distribution pattern of trace elements featuring the enrichment of highly incompatible elements, Nb negative anomaly, La positive anomaly, Ba partially positive anomaly, as well as different enrichment degrees of light rare earth. The differences between the Northern Xinjiang and Songliao Basin are characterized by the developed alkalic basalt, rich and highly incompatible elements, and light rare earth. Volcanic rocks in Northern Xinjiang shows an increase in both total rare earth and light rare earth enrichment from south to north, whereas the total rare earth and light rare earth enrichment in Songliao Basin are also higher than the adjacent Daxing'anling. Generally, both the Carboniferous-Lower Permian volcanic rock in Northern Xinjiang and Mesozoic volcanic rock in Songliao Basin and its peripheral areas developed in the post-collision intracontinental extensional tectonic environment, indicating that the post-collision extensional basin in Junggar-Xingmeng Paleoasian Ocean orogenic region has promising oil-gas exploration potential for volcanic reservoirs.
... (b) Simplified geological map showing the tectonic framework and distribution of early Palaeozoic iron deposits in Chinese Eastern Tianshan (modified in accordance with Ma et al. 1997). Ophiolitic mélanges: a -Erqis accretionary complex: SHRIMP zircon age at 372 ± 19 Ma ) and 352 ± 4.4 Ma (Wu et al. 2006b) with Ordovician-Silurian radiolarian cherts and Silurian-Devonian turbidites (Xiao et al. 1992); b -Armantai ophiolititic mélange: SHRIMP zircon age at 503 ± 7 Ma (Xiao et al. 2009a) and 481 ± 5 Ma (Ping et al. 2005) with Ordovician (Li et al. 1990) and Middle to Late Devonian radiolaria (Xiao et al. 1992;Liang et al. 1999) radiolarian cherts; c -West Junggar ophiolitic mélange: Zircon U-Pb age from 510 to 320 Ma (Ren et al. 2014 and reference there in); d -Kelameili ophiolititic mélange: SHRIMP zircon age at 403 ± 9 Ma (Ping et al. 2005) with Early Devonian and Early Carboniferous radiolaria (Ma et al. 1997;Shu and Wang 2003); e -North Tianshan ophiolititic mélange: granulite Sm-Nd isochron age at 538 ± 24 Ma and amphibole 40 Ar-39 Ar plateau age at 432.0 ± 0.7 Ma with Silurian ophiolite (Shu et al. 2002; f -South Tianshan ophiolititic mélange: SHRIMP zircon age at 425.5 ± 2.3 Ma in the east (Li et al. 2002) and 378 ± 6 Ma in the west (Jiang et al. 2001a) with Ordovician-Silurian radiolarian (Jiang et al. 2001b); g -Beishan ophiolititic mélange: Cameca SIMS zircon age at 533 ± 1.7 Ma (Ao et al. 2012) the Precambrian basement (Ma et al. 1997;Shu et al. 2002). Granitoid intrusions of various ages, mostly belonging to the Palaeozoic, are widespread in the Central Tianshan zone (Liu et al. 2004;Gu et al. 2006;Wang et al. 2006;Hu et al. 2007;Wu et al. 2010Wu et al. , 2011Lei et al. 2013). ...
The stratabound Tianhu iron deposit, with a reserve of 104 Mt at 42% Fe, is located in the eastern part of the Central Tianshan zone in the southern part of the Central Asian Orogenic Belt. The deposit hosts schist, quartzite, marble, amphibolite, and granitic gneiss belonging to the Tianhu Group. Laser ablation inductively coupled plasma mass spectrometry was used to perform zircon U–Pb geochronology, bulk-rock geochemistry, and in situ zircon Hf isotope analyses of the metavolcanic host rocks for constraining the timing and genesis of the Tianhu iron deposit. According to the newly determined age constraints of 452 ± 3 and 477 ± 4 Ma, the iron deposit was concluded to be Ordovician in age. Geochemistry and zircon Lu–Hf isotope analyses suggested that the host rocks of the deposit represent metamorphosed arc-type volcanic rocks generated by the partial melting of a lower crustal source. Combined with geological and ore petrographic characteristics, the Tianhu iron deposit is interpreted to be of volcano–sedimentary origin with enrichment during subsequent metamorphism. The early Palaeozoic marks a critical iron mineralization epoch in the Eastern Tianshan area. The results also support the model of the Central Tianshan area as a volcanic-arc during the early Palaeozoic, associated with the subduction of the Northern Tianshan Ocean.
... SHRIMP zircon dates of gabbros from Zhaheba yielded ages of 489 AE 4 Ma and 406 AE 4 Ma, and of an anorthosite of 481 AE 5 Ma (Ping et al., 2005). Some of these ages are consistent with the presence of Ordovician radiolarian cherts (Li et al., 1990;He et al., 2001). However, other cherts yield middle to late Devonian radiolaria (Xiao and Tang, 1991;Xiao et al., 1992;Liang et al., 1999). ...
How ophiolitic mélanges can be defined as sutures is controversial with regard to accretionary orogenesis and continental growth. The Chinese Altay, East Junggar, Tianshan, and Beishan belts of the southern Central Asian Orogenic Belt (CAOB) in Northwest China, offer a special natural laboratory to resolve this puzzle. In the Chinese Altay, the Erqis unit consists of ophiolitic mélanges and coherent assemblages, forming a Paleozoic accretionary complex. At least two ophiolitic mélanges (Armantai, and Kelameili) in East Junggar, characterized by imbricated ophiolitic mélanges, Nb-enriched basalts, adakitic rocks and volcanic rocks, belong to a Devonian-Carboniferous intra-oceanic island arc with some Paleozoic ophiolites, superimposed by Permian arc volcanism. In the Tianshan, ophiolitic mélanges like Kanggurtag, North Tianshan, and South Tianshan occur as part of some Paleozoic accretionary complexes related to amalgamation of arc terranes. In the Beishan there are also several ophiolitic mélanges, including the Hongshishan, Xingxingxia-Shibangjing, Hongliuhe-Xichangjing, and Liuyuan ophiolitic units. Most ophiolitic mélanges in the study area are characterized by ultramafic, mafic and other components, which are juxtaposed, or even emplaced as lenses and knockers in a matrix of some coherent units. The tectonic settings of various components are different, and some adjacent units in the same mélange show contrasting different tectonic settings. The formation ages of these various components are in a wide spectrum, varying from Neoproterozoic to Permian. Therefore we cannot assume that these ophiolitic mélanges always form in linear sutures as a result of the closure of specific oceans. Often the ophiolitic components formed either as the substrate of intra-oceanic arcs, or were accreted as lenses or knockers in subduction-accretion complexes. Using published age and paleogeographic constraints, we propose the presence of (1) a major early Paleozoic tectonic boundary that separates the Chinese Altay-East Junggar multiple subduction systems of the southern Siberian active margin from those of the northern Tarim; and (2) a major Permian suture zone that separates the Tianshan-Beishan from the northern active margin of the Tarim Craton. These new observations and interpretations have broad implications for the architecture and crustal growth of central Asia and other ancient orogens as well. © 2014, China University of Geosciences (Beijing) and Peking University.
... The Zhaheba-Armantai ophiolite has zircon SHRIMP U-Pb ages ranging from 406 to 503 Ma (Jian et al., 2003;Xiao et al., 2009). Gabbros and anorthosite from the Zhaheba ophiolite have zircon SHRIMP U-Pb ages of 406-489 Ma, which is consistent with the presence of Devonian-Ordovician radiolarian cherts (Li et al., 1990;Xiao and Tang, 1991;Xiao et al., 1992;He et al., 2001). Plagiogranites of the Armantai ophiolite have a zircon SHRIMP U-Pb age of 503 ± 7 Ma ). ...
The Altay Range is an important part of the Central Asian Orogenic Belt (CAOB) that contains A-type granites that have been attributed to a post-collisional setting during the Late Carboniferous–Permian. However, our new LA-ICP-MS zircon U–Pb age data demonstrates that there were two episodes of A-type granite magmatism in the southern Altay Range. A Late Carboniferous to Early Permian (308–291Ma) suite does occur in the vicinity of Qiakuerte but a distinct Late Devonian (382–367Ma) suite is present in the Kouan area. The early Kouan A-type granites are mainly composed of alkali-feldspar granites, which are approximately synchronous with adakites, boninites, high-Ti basalts, picrites, ophiolitic rocks, and high temperature-low pressure metamorphic rocks, whereas the late Qiakuerte A-type granites mainly consist of arfvedsonite and aegirine-bearing granites, which are approximately coeval with some mafic–ultramafic rocks in the southern Altay Range. A-type granites are commonly classified as A1 and A2 sub-types, which are considered to be generated in anorogenic (rift or plume-related) or post-collisional settings, respectively. Both suites of the southern Altay Range are geochemically similar to typical A2-type granites, e.g., high K2O+Na2O, FeO/MgO, and Ga/Al, and Y/Nb values, and low CaO, Ba, Sr, and Eu contents. The Kouan A-type granites have relatively low (La/Yb)N (2.7–5.9), high εNd(t) (+6.7 to +7.7) and Nb/La (0.59–1.67), and variable εHf(t) (+5.0 to +14.1) values, whereas the Qiakuerte A-type granites have comparatively high (La/Yb)N (4.2–9.2), low εNd(t) (+5.3 to +6.0) and Nb/La (0.33–0.74), and variable εHf(t) (+10.0 to +18.7) values. The early Kouan A-type granites may have been generated by partial melting of a mafic source containing more depleted mantle-derived components than the late Qiakuerte A-type granites. We suggest that the Late Carboniferous to Early Permian Qiakuerte granites were formed in a post-collisional extensional setting, as is typical of A2-type granites. However, the Late Devonian Kouan A-type granites were more plausibly generated in an extensional setting as a result of slab window caused by a ridge subduction. In this case, the upwelling of asthenosphere through the slab window provided the source of parental magmas, or the heat for the generation of Devonian magmas. Therefore, our results suggest that A2-type granites can also form in a ridge subduction-related extensional setting.
... Xiao et al. (2009b) have pointed out that a mature arc setting in the Carboniferous is suggested by the presence of felsic tuff, basalt, andesite and porphyry copper ore deposits. The geochemistry of granites and volcanic rocks from the Yamaquan arc suggests a calc-alkaline affinity (Li et al., 1990). The Permian volcanic rocks in the southeastern Armantai ophiolite have also been interpreted as subduction-related products (Lin et al., 1997). ...
Late Paleozoic magmatic rocks (including basic dykes, basaltic andesite, rhyolite, keratophyre and syenite-porphyry with minor tuff) are widespread in the western margin of the East Junggar terrane. In-situ zircon U–Pb dating and Hf isotope analyses were carried out for these magmatic rocks from the Baijiangou and Zhangpenggou localities of East Junggar, integrating with geochemical data, to investigate their tectonic evolution as well as crustal accretionary process of this region in the Late Paleozoic. Inherited zircons from basic dykes range in age from 435Ma to 300Ma. The Zhangpenggou rhyolite and keratophyre have typical arc-like geochemical signatures and were formed in the Early Carboniferous (332Ma and 336Ma, respectively), suggesting they are products of subduction-related magmatism. The Baijiangou rhyolites were formed in the Late Carboniferous (315Ma and 323Ma) and their formation ages are similar to those of the syenite-porphyries (307Ma and 312Ma). The Hf model ages and the formation ages of zircons from these magmatic rocks are alike, with positive εHf(t) values vary from +0.7 to +16.6, implying that voluminous growth of juvenile crust happened in the East Junggar terrane during the Late Paleozoic. The absence of Precambrian inherited zircons in basic dykes indicates the lack of Precambrian basement beneath the East Junggar terrane. Taking geochronological studies on regional ophiolites into account, the East Junggar terrane is considered as a Devonian–Carboniferous oceanic island arc which has been continuously accreted to the southern active margin of the Siberian Craton since the Early Carboniferous.
... It is generally accepted that the Zhaheba-Armantai suture zone formed earlier than the Kalamaili suture zone (e.g., Xiao et al., 1992;Xiao et al., 2008). For the development of the Kalamaili suture zone, the upper-age bound can be constrained by Visean sediments that unconformably overlie the ophiolite (Li et al., 1989) and early Carboniferous molasse deposits, and the lower-age bound may be defi ned by a U-Pb zircon age of 373 ± 10 Ma for a plagiogranite of the Kalamaili ophiolite (Tang et al., 2007b), and Famennian to Tournaisian radio larian cherts asso ciated with the ophiolite (Li et al., 1990;Shu and Wang, 2003). The suturing event was related to the late Tournaisian to early Visean collision between the Junggar terrane and the Yemaquan arc, after which all of the terranes were intruded by late Carboniferous to Permian granitoids and Cu-Ni-sulfi de-bearing, mafi c-ultramafi c magmatic complexes (B.F. ...
The Central Asian orogenic belt is the largest tectonic assembly of continental and oceanic terranes on Earth due to closure of the paleo-Asian Ocean in the Phanerozoic. Among major suture zones in the North Xinjiang region of western China, the North Tian Shan suture zone, because of collision between the Yili terrane in the south and the Junggar terrane in the north, contains the youngest ophiolitic rocks and may represent the terminal stage of development of the Central Asian orogenic belt in western China, but the timing of the suture zone remains poorly constrained. A sensitive high-resolution ion microprobe (SHRIMP) zircon U-Pb age of 316 ± 3 Ma (i.e., the beginning of the late Carboniferous) from the undeformed Sikeshu pluton, which crosscuts the suture zone, places a crucial upperage bound for the time of collision between the Yili and Junggar terranes. This event occurred later than, or nearly concurrent with, other accretion-collision events in the North Xinjiang region, implying that final terrane amalgamation was completed in the late Carboniferous. The Sikeshu pluton shares geochemical characteristics of the widespread late Carboniferous to Permian postcollisional A-type and I-type granitoids with depleted-mantle-like Sr-Nd isotopic signatures in the North Xinjiang region. They all occurred during a protracted (ca. 320-270 Ma) episode of postcollisional magmatism that may have been induced by basaltic under plating due to either slab breakoff or delamination of thickened mantle lithosphere beneath the Central Asian orogenic belt. The same postcollisional magmatism also generated Cu-Ni-sulfide-bearing, mafic-ultramafic magmatic complexes, adakites, and porphyry-type coppermolybdenum-bearing magmatic rocks in the North Xinjiang region.
... Parallel to the A-type granite belts, two ophiolite belts, Aermantai and Karamaili, occur sporadically along deep faults. The Karamaili ophiolite has been considered to be a remnant of a small oceanic crust (Li et al., 1990; Li, 1995), but its age is still controversial. Shu and Wang (2003) and Tang et al. (2007) suggested a middle-late Devonian age. ...
Several types of granites including alkaline granites and alkali feldspar granites are distributed in the Karamaili tec- tonic belt of East Junggar, Xinjiang, China. Some medium-small tin deposits are located within or near the contact zones of the granitic intrusions. The alkaline granites share all the features commonly observed in peralkaline A-type granites. They contain alkalic mafic minerals such as riebeckite and aegirine; have high contents of SiO2, alkalis, Rb, Th, Zr, Hf, REE (except Eu), and high ratios of FeO*/MgO and Ga/Al; and show strong depletions in Ba, Sr, Eu in the spidergrams. Laser ablation-ICPMS U-Pb zircon geochronology indicates a crystallization age of ca. 305 Ma for the granites; TIMS analyses of the granites found high εNd(T) values of +5.9 to +6.5. Considering their geochemical features, alkaline gran- ites most likely formed by fractional crystallization of granodioritic magmas, which were probably produced by partial melting of lower crustal basaltic to andesitic rocks formed from oceanic crustal materials that were deeply buried during late Paleozoic subduction and accretion. Six molybdenite samples from the Sareshike tin deposit in East Junggar yielded an isochron age of 307 ± 11 Ma (2σ) and a weighted mean model age of 306.5 ± 3.4 Ma, consistent with zircon U-Pb ages of the alkaline granites. Low Re contents (0.323-0.961 ppm) in the molybdenite suggest that they originated from crustal sources related to the alkaline granites. Considering their identical ages, close spatial distribution, and similar sources, we argue that the A-type granites have a genetic relationship with the tin mineralization, and that the same association may be important elsewhere.
The East Junggar is a key to understanding the accretionary history of the southern Altaids. However, the tectonic setting and amalgamation history of the East Junggar during Carboniferous–Permian remain controversial. Here we report new field, geochronological, and geochemical data for the Carboniferous–Permian volcanic and sedimentary rocks from the Jiangjun unit and the Hongliugou ophiolitic complex of East Junggar to constrain its tectonic evolution. Carboniferous volcanic rocks, with zircon and apatite U–Pb ages from 337 ± 2 to 303 ± 32 Ma, display arc-related geochemical characteristics. Carboniferous–Permian sedimentary rocks predominantly consist of Carboniferous–Permian detrital zircons and have maximum depositional ages from 318 ± 5 to 281 ± 6 Ma. Provenance analysis indicates that the sediments from the west Jiangjun unit were sourced from the Yemaquan arc and those from the east Jiangjun unit may be sourced solely from a new intra-oceanic arc. Integrated data indicate that Carboniferous–Permian strata in the Jiangjun unit were formed in the intra-oceanic arc setting that remained until the middle Permian. These analyses suggest an amalgamation process of multiple convergence and accretion for the southern Altaids during the formation of the northeast Pangea in the late Paleozoic.
The Huangyangshan super-large graphite deposit, located in the East Junggar area of the Xinjiang Province, is hosted in and has closely temporal, spatial, and genetic relationships with the Huangyangshan alkaline granites. There are such silicate minerals as amphibole, biotite, pyroxene, and plagioclase occurring in the graphite-bearing granites. The integration of the electron microprobe analysis (EMPA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) enabled us to reveal the physicochemical conditions and evolution process, as well as the relationship of alkaline magmatism with graphite mineralization. The results show that the amphiboles generally have low Al and high Ti, K, Si, and Fe contents, as well as similar rare-earth elements (REEs) patterns and trace element distribution patterns to granites with significantly negative Eu anomalies. In the analyzed samples, primary biotite belongs to Fe-biotite and has characteristics of high Si and Fe and low Al and Mg contents. In the graphite orbicules, the pyroxene phenocrysts develop multiple zonal structures and are characterized by high Si and low Ca and Fe contents. The dominant plagioclase phenocrysts in the graphite orbicules are oligoclase and andesine, with normal and occasionally oscillatory zoning. The calculated crystallization temperature of the pyroxene, amphibole, and primary biotite in graphite orbicules are 840–1012 °C, 681–761 °C, and 658–720 °C, respectively, corresponding with their crystallization order. The pressure and depth calculation results of the amphibole, representing those of the magmatism, are 157–220 Mpa and 5.95–8.32 km, respectively. Both amphibole and biotite crystallized in a reducing environment with extremely low oxygen fugacity. The elemental compositions of these silicates indicate that the Huangyangshan pluton experienced significant mixing of mafic mantle-derived magma and felsic crust-derived magma. The cores of graphite orbicules were formed in a relatively earlier magmatic stage, while the granites and their dioritic enclaves were formed in a later magmatic stage. During magmatism, the mixing of mantle-derived basic magma had an important influence on the evolution and differentiation of the melts. According to the coexisting sulfides with graphite and compositional difference of amphibole and biotite in the granites and graphite ores, the graphite mineralization might be triggered by a magma mixing process.
The Eastern Tianshan and East Junggar orogenic belts are major constituents of the southwestern Central Asian Orogenic Belt. This study applies low-temperature thermochronology to constrain the thermo-tectonic history of these two domains. Apatite fission track (AFT) dating of Paleozoic basement samples from the Eastern Tianshan and East Junggar dominantly yield Cretaceous (∼126-70 Ma) AFT ages, except for two granitic samples from the East Junggar with older ages of ∼239 and ∼157 Ma, respectively. Thermal history modeling reveals that the Eastern Tianshan and southern part of the East Junggar experienced moderate to rapid basement cooling throughout the Cretaceous. We interpret it as a far-field effect of accretion and collision along the south Eurasia margin since the Early Cretaceous. Major faults were reactivated and thus may have played an important role in controlling localized fast uplift and cooling. We also dated seven Mesozoic sandstone samples collected from the eastern margin of the Junggar Basin. The detrital AFT age peaks, together with inverse thermal history modeling of the basement, reveal that the East Junggar underwent late Permian to Early Jurassic cooling episodes. These cooling events are thought to be related to post-orogenic transpression along major faults and distal effect of Qiangtang-Eurasia collision. Combined with already published evidence, our new data suggest that the Eastern Tianshan and East Junggar did not undergo significant exhumation during the Cenozoic.
The Huangyangshan alkaline pluton is located within the southern part of the Eastern Junggar orogenic belt in Xinjiang Province, and forms part of the Kalamaili alkaline granite belt. The pluton hosts the Huangyangshan super-large graphite deposit, which develops unique spherical structure and coexists with metal sulfides. This study examines the genetic relationship between the alkaline magmatism that formed the pluton and the graphite mineralization using zircon LA–ICP–MS U–Pb dating, geochemical analysis for representative rock types in the Huangyangshan pluton, and new Re–Os isotope dating for the graphite in the Huangyangshan graphite deposit. Zircons from medium-grained arfvedsonite granite, medium–fine-grained amphibole granite, medium-grained biotite granite, and fine-grained biotite granite phases of the Huangyangshan pluton yield weighted mean U–Pb ages of 322.7 ± 4.5, 318.3 ± 4.0, 303.9 ± 2.1, and 301.1 ± 3.6 Ma, respectively, indicating that all of the granite phases were emplaced during the Late Carboniferous over a period of around 20 Myr. Six graphite samples from the deposit yield a Re–Os isochron age of 332 ± 53 Ma. Combining these ages with the genetic relationship between the graphite mineralization and magmatism in the study area and the relatively large uncertainty on the Re–Os isochron age for the graphite suggests that the mineralization formed at ca. 320 Ma. The graphite samples yield an initial ¹⁸⁷Os/¹⁸⁸Os value of 0.38 ± 0.2, indicative of carbon derived from a mixture of organic and mantle-derived sources. The different granite phases in the Huangyangshan pluton are geochemically similar with relatively high SiO2 (75.6–78.2 wt%) and Na2O + K2O (8.01–9.04 wt%) and relatively low CaO (0.18–0.7 wt%), MgO (0.06%–0.13 wt%) and Fe2O3 (TFe2O3 = 1.08–2.06 wt%) contents. The granites are enriched in light rare earth elements (LREE), large-ion lithophile elements (LILEs) (e.g. Rb, Th, and K), and high field strength elements (HFSEs) (e.g. Zr and Hf), depleted in heavy rare earth elements (HREEs), and have negative Ba, Sr, P, Ti, and Eu anomalies. These geochemical characteristics are indicative of derivation from juvenile basaltic oceanic crustal materials in the lower crust. This suggests that the Huangyangshan pluton formed from magmas generated by partial melting caused by mantle-derived magma underplating, with the magmas then undergoing mixing, separation, and significant fractional crystallization. Diorite enclaves within the granites have weaker trace element anomalies that are indicative of magma mixing. In addition, the mantle-derived intermediate–basic end-member involved in the magma mixing is likely one of the important carriers of carbon and metal. In summary, the Late Carboniferous Huangyangshan pluton and its associated graphite mineralization formed in a post-collision extensional tectonic setting in the Kalamaili area.
The Karamaili ophiolite belt is located on the northeastern margin of Junggar Basin, which is a very important tectonic unit in northern Xinjiang and Central Asia area. The evolution of Karamaili oceanic basin remains controversial due to hot-debated issues on the ages and characteristics of Karamaili ophiolite. This study focuses on the Paleozoic tectonic setting in the Karamaili tectonic zone revealed by a comparative study of the Silurian-Carboniferous tectono-sedimentation on its north and south sides. To the north of the Karamaili ophiolitic belt, the angular unconformities are widely developed between Upper Silurian, Lower Devonian and underlying Middle-Upper Ordovician strata and Caledonian granitoids. The Lower Silurian strata are generally absent and the underlying Middle-Upper Ordovician strata mainly consist of andesite with greenschist facies. The Middle, Upper SilurianDevonian-Lower Carboniferous sedimentary deposition system to the north of Karamaili ophiolitic belt is similar to that to the south, including conformable contact, flat occurrence and undeveloped folds, faults and metamorphism. Anticlines or synclines are mainly of short axis, which is apparently different from strong deformation shown in the Karamaili ophiolitic mélange. Besides, pyroclastics-dominated rock associations, widely existent inclined beddings and cross-beddings and abundant kinds of animals and plants fossils indicate a littoral-shallow marine environment. Therefore, during Late Paleozoic, no ocean existed in the Karamaili tectonic zone and the oceanic basin represented by the Karamaili ophiolitic mélange had been closed before Middle Silurian.
Junggar basin is an important part of the Central Asian Orogenic Belt (CAOB) which is also one of the key areas of researches about formation and evolution of the CAOB. Recently, a question of whether the Junggar basin has a Precambrian basement is one of the hottest topics. We undertook LA-ICP-MS zircon U–Pb dating from Carboniferous pyroclastic rocks and Mesozoic sedimentary rocks in northern Xinjiang Province, NW China, with the aim of constraining the evolution and features of the basement of the north Junggar basin and adjacent areas. (1) The zircon U–Pb age analysis of the Carboniferous pyroclastic rock samples clustered in the 1447∼1410 Ma and 885∼559 Ma showed that the basement of the north Junggar basin was continental crust that formed 1.4 Ga ago. The zircon U–Pb ages clustered in the 536∼420 Ma, 401∼360 Ma, and 359∼303 Ma indicated a multiple evolution of basement. (2) The zircon trace element analysis of different age groups from the Carboniferous pyroclastic rock samples showed that the basement of the north Junggar basin was continental crust composed of acid rocks and intermediate-basic intrusive rocks, which were mainly the granitoids, syenite, basalt, dolerite, and larvikite. (3) The zircon U–Pb ages and trace element analysis of the Mesozoic sedimentary rock samples clustered in the 3022∼2102 Ma, 1747∼1202 Ma, 996∼915 Ma, 885∼544 Ma, 539∼420 Ma, 419∼356 Ma, and 354∼300 Ma revealed that not only 3.0-Ga continental crust existed in the north Junggar basin and adjacent areas but also multiple crustal material evolution that occurred during the formation of the basement. (4) The evolution of sedimentary cover experienced 299∼250 Ma, 210∼176 Ma, 175∼148 Ma, and 147∼132 Ma with the corresponding peak age of ca. 290, 180, 163, and 140 Ma, respectively, indicated that the sedimentary cover of the northern Junggar basin experienced a complex tectonic evolution from Permian.
The compressional (VP) and shear wave velocities (VS) of typical granitoids (alkali-feldspar granite, alkaline granite, granodiorite, monzogranite and quartz diorite) from Kalamaili granite belt and Yemaquan body in Eastern Junggar, Xinjiang were experimentally measured at pressures up to 1.0 GPa (room temperature) and temperatures up to 700°C (1.0 GPa) by ultrasonic reflection-transmission method. The results show that both VP and VS of the granitoids present a linear velocity increase with the pressure at room temperature from 0.4∼1.0 GPa, which is interpreted in terms of closure of the microcracks in rocks under this pressure range. The VP and VS of the granitoids are 5.79∼6.84 km·s−1 and 3.26∼3.85 km·s−1 respectively at room temperature and 1.0 GPa. On the basis of the linear relationship between pressure with VP and VS, we derived the pressure derivatives of VP and VS as 0.1568∼0.4078 km/(s·GPa) and 0.0722∼0.3271 km/(s·GPa) respectively, and the reference velocities VP0 and VS0 are 5.62∼6.47 km·s−1 and 3.15∼3.75 km·s−1 respectively. At 1.0 GPa, VP and VS of the granitoids show a linear decrease with temperature from room temperature to 700°C, and temperature derivatives of velocities are (−3.41∼−4.96) × 10−4 km/(s · °C) and (−0.88∼−3.22) × 10−4 km/(s · °C), respectively. Taking advantage of derivatives of velocities and reference velocities of the granitoids obtained from our experiments, and combining regional geothermal resources of East Junggar area, VP and VS-depth profiles were calculated. From the comparison of velocity-depth profiles with geophysical exploring results, we infer that the VP and VS of the alkali-feldspar granite, alkaline granite, monzogranite and part of granodiorite in Eastern Junggar of Xinjiang are coherent well with the velocity of the upper crust, and the average Poisson's ratio of several rocks are also consistent with the Poisson's ratio of the upper crust. Therefore, we suggest that these kinds of rocks are important parts of the upper crust in this region. In addition, the VP and VS of the quartz diorite are both in accord with the middle crust, suggesting that it may be one kind of rocks in the middle crust of this region.
Abstract Studies show that the Tianshan orogenic belt was built in the late stage of the Paleozoic, as evidenced by the Permian red molasses and foreland basins, which are distributed in parallel with the Tianshan belt, indicating that an intense folding and uplifting event took place. During the Triassic, this orogenic belt was strongly eroded, and basins were further developed. Starting from the Jurassic, a within-plate regional extension occurred, forming a series of Jurassic-Paleogene extensional basins in the peneplaned Tianshan region. Since the Neogene, a collision event between the Indian and the Eurasian plates that took place on the southern side of the Tianshan belt has caused a strong intra-continental orogeny, which is characterized by thrusting and folding. Extremely thick coarse conglomerate and sandy conglomerate of the Xiyu Formation of Neogene System were accumulated unconformably on the Tianshan piedmont. Studies have revealed that the strong compression caused by the Indian-Eurasian collision had a profound influence over the orogenic belt in the hinterland, and Mesozoic-Cenozoic brittle deformed structures superposed on the ductile deformed Paleozoic rocks. The Mesozoic extensional basins were converted into Cenozoic compressional basins. The deformation in the basins is featured by step thrusts and fault-related folds. Statistics of joints show that the principal compressive stress since the Neogene is in a N-S direction. Meanwhile, owing to the underthrusting of the basin toward the orogenic belt, the Paleozoic strata were thrust on the Meso-Cenozoic rocks as tectonic slices, revealing distinct kinematic features in different geologic units. The basin-range coupling zones are characterized by intensive compression, folding and thrusting, accompanied by local sub-E-W-trending strike-slip faults. In the Tianshan region, Cenozoic thrusting is the most common basin-range coupling mode. The folding and faulting of Mesozoic sedimentary rocks, spontaneous combustion of Jurassic coal layers and formation of sintered rocks, the Cenozoic earthquakes and active faulting, and the unique mosaic pattern of basin-range framework of Xinjiang are all products of tectonism since the Neogene.
Northeast China and adjacent regions are located in the central East Asian continent and consist tectonically of both the Paleo-Asian and Paleo-Pacific orogens between the Siberian platform and Sino-Korean (North China) block. This paper discusses some hotly-debated issues concerning the Permian geodynamic setting of these regions, based on a comprehensive analysis of available geological, geochemical, paleobiogeographical and paleomagnetic data. Spatial and temporal distribution of ophiolites and associated continental marginal sequences, Permian sedimentary sequences, spatial distribution and geochemistry of Permian magmatic rocks, and the evolution of paleobiogeographical realms imply: (1) that the Permian marine basins in northeast China and adjacent regions include remnants of the Paleo-Asian Ocean in southeastern Inner Mongolia and central Jilin Province, and active continental margins of the Paleo-Pacific Ocean; (2) that the suture between the Siberian and Sino-Korean paleoplates was finally emplaced in the Permian and is located in areas from Suolunshan (Solonker) eastwards through regions north to the Xar Moron river in southeastern Inner Mongolia, and then central Jilin province to the Yanji area; and (3) that the Permian crustal evolution of northeast China and adjacent regions, as well as parts of the Siberian paleoplate, was influenced by subduction of the Paleo-Pacific oceanic plate. Finally, the Permian tectonic framework and paleogeography of northeast China and adjacent regions in central East Asia are discussed briefly, and Early and Late Permian palinspastic reconstruction maps are provided.
Kalamaili suture zone is an important plate boundary in north Xinjiang, with plenty of Neopaleozoic volcanic rocks around. These volcanic rocks are enriched in LILEs and relatively depleted in HFSEs, and they are characterized by high Nb, Zr, TiO2 contents and Zr/Y, Nb/Y ratios, and display depleted Sr-Nd isotopic characteristics. The characteristics of these volcanic rocks suggest that they were produced in post-collisional period. The post-collisional volcanic rocks around Kalamaili suture zone became younger from west to east, which indicated that this suture zone entered post-collisional period gradually from west to east, and this reflected that the Kalamaili Ocean had been closed gradually from west to east. As to the Kalamaili suture zone in post-collisional period, the lithosphere extended and thinned, and the asthenospheric materials upwelled and partially melted. In the case of the intensive mantle convection, the suture zone was underplated by plenty of mantle-derived magmas. The lithospheric mantle metasomatized by fluid in subduction period partially melted under decompression and high temperature, the resulting melts contaminated the underplating asthenospheric materials, and the erupted lavas came into being the Neopaleozoic post-collisional volcanic rocks.
The northern Xinjiang of China is a composite orogenic belt in the south central part of the Altaids formed by subduction-accretion mainly during the Paleozoic. Geochronologic and geochemical data from the Paleozoic ophiolites and associated assemblages are reported here to place constrains on the tectonic evolution of this region and to reconstruct its history, using a model of subduction-accretion plus large-scale map-view strike-slip faulting. Geologic and geo-chronologic review indicates that the Paleozoic ophiolites and associated assemblages of the western and eastern Junggar regions are tectonically related, occurring as a pattern with the early Paleozoic Tangbale-Mayile-Hongguleleng-Aermantai complexes in the center, the late Paleozoic Darbut-Karamaili and the northern Tianshan complexes in the south, and the late Paleozoic Kekesentao-Qiaoxiahala-Kuerti com-plexes in the north. Available geochemical data suggest that the Paleozoic ophiolites of the northern Xinjiang are mainly oceanic fragments of these three types: mid-ocean ridge basalt, oceanic island basalts, and island arc basalts. The Paleozoic subduction-accretion complexes grew mainly along different segments of the Kipchak arc, and in associated with migration of magmatic arc. The Paleozoic ophiolite-associated sedimentary sequences and subduction-related volcanic rocks exhibit an evolution history from intraoceanic (early Paleozoic) to marginal settings (late Paleozoic), implying coeval strike-slip stacking with subduction-accretion processes, and by which to transport the respective complexes together and further to amalgamate with neighboring units of the Altaids. Subduction-accretion processes terminated in the mid-Carboniferous in this region. In the late Permian-early Triassic, a counterclockwise rotation of fault blocks in a giant sinistral strike-slip and extension domain between Altay and Tianshan, lastly generated present configuration of the Paleozoic subduction-accretion complexes in the northern Xinjiang.
Five nearly E-W-trending alkali-rich igneous rock belts are distributed from north to south in northern Xinjiang, and they are composed mainly of riebeckite, K-feldspar granite and high-K and medium-K calc-alkaline volcanic rocks and shoshonite. They were mainly emplaced or erupted between the Carboniferous and Permian. The compositions of Sr, Nd, Pb, and O isotopes imply that their principal resource materials are derived from the upper mantle or juvenile crust, indicating obvious continental growth in the Phanerozoic. The trace element association implies that their tectonic settings are within plate and volcanic arc for alkali-rich granites, and post-collisional are, late oceanic are and continental are for alkali-rich volcanic rocks. An archipelago model was suggested for the tectonic evolution in northern Xinjiang. It can be named the central-Asia-type orogeny, which is different from the so called circum-Pacific ocean-continent-type tectonics or the Alpine-Himalayan continent-continent-collisional orogeny.
Abstract As a typical Palaeozoic island arc system, the eastern Tianshan area, Xinjiang, is different from eastern China but similar to the Meso-Cenozoic island arc metallogenic provinces along the coast of the Pacific Ocean in metallogenic environment, geology and geochemistry. Three types of gold deposits, ductile shear zone-hosted gold deposits (Kanggur'), magmatic hydrothermal gold deposits (Jinwozi) and volcanic- or subvolcanic-hosted gold deposits (Xitan and Mazhuangshan), have been identified in this area. Regionally, gold deposits are structurally controlled by the Kanggur Tag ductile shear zone, Shaquanzi fault, Hongliuhe fault and Yamansu fault. Generally, gold mineralization occurs in the transition zones from volcanic rocks to sedimentary rocks. The horizon bearing well-developed jasper is an important indicator for gold mineralization. Each of the three types of gold deposits has its distinctive metallogenic background and geological-geochemical characteristics.
Abstract According to the study on the peripheral orogenic belts of the Junggar basin and combined with the interpretation of geophysical data, this paper points out that there is an Early Paleozoic basement of immature continental crust in the Junggar area, which is mainly composed of Neoproterozoic-Ordovician oceanic crust and weakly metamorphosed covering sedimentary rocks. The Late Paleozoic tectonism and mineralization were developed on the basement of the Early Paleozoic immature continental crust. The Junggar metallogenic province is dominated by Cr, Cu, Ni and Au mineralization. Those large and medium-scale deposits are mainly distributed along the deep faults and particularly near the ophiolitic mélange zones, and formed in the Late Paleozoic with the peak of mineralization occurring in the Carboniferous-Permian post-collisional stage. The intrusions related to Cu, Ni and Au mineralization generally have low Isr and positive ɛENd(t) values. The δ34S values of the ore deposits are mostly near zero, and the lead isotopes are mostly of normal lead. All these indicate that the ore-forming material comes either directly from the mantle-derived magma (for chromite and Cu-Ni deposits) or from recirculation of the basement material of the Early Paleozoic immature crust (for most Cu and Au deposits).
This paper deals with the various tectonic units in the Chinese Eastern Tianshan orogenic collage in the Central Asian Orogenic Belt, and discusses the Paleozoic geological history of the several periods of accretion and collision of archipelago systems lying between the Tarim and southern Angaran continental margins. The Late Ordovician-Silurian to Early Devonian Eastern Tianshan archipel-ago was characterized by (a) the Harlik-Dananhu subduction system with a S-dipping polarity in the north; (b) a southerly N-dipping subduction system beneath the Central Tianshan arc in the middle; and (c) the South Tianshan ocean against Tarim in the south. During the Devonian to Early Carboniferous, N-dipping subduction led to the Harlik-Dananhu arc and the Kanggurtag forearc basin/accretionary complex. In the Early to Mid-Carboniferous, the magmatic front associated with the N-dipping subduc-tion beneath the Dananhu-Harlik arc migrated southwards, forming the Yamansu arc constructed upon the Kanggurtag accretionary forearc. By the Late Carboniferous the Dananhu-Harlik arc was attached northwards to the Angaran margin, resulting in lateral enlargement of the Angaran continent. In the latest Carboniferous to Early Permian a multiple soft collision left wide suture zones in the south that include the ophiolite-strewn Aqikkuduk-Shaquanzi and Kumishi accretion-collision complexes, which were stitched by Early Permian post-collisional plutons. By re-defining and re-interpreting the various tectonic terranes, this paper presents a new, improved model for the Paleozoic evolution of this part of Central Asia.
The formation and development of the southern Altaids is controver-sial with regard to its accretionary orogenesis and continental growth. The Altay-East Junggar orogenic collage of North Xinjiang, China, offers a special natural laboratory to resolve this puzzle. Three tectonic units were juxtaposed, roughly from North to South, in the study area. The northern part (Chinese Altay), composed of variably deformed and metamorphosed Paleozoic sedimentary, volcanic, and granitic rocks, is interpreted as a Japan-type island arc of Paleozoic to Carboniferous-Permian age. The central part (Erqis), which consists of ophiolitic mélanges and coherent assemblages, is a Paleozoic accretionary complex. The southern part (East Junggar), characterized by imbricated ophiolitic mélanges, Nb-enriched basalts, adakitic rocks and volcanic rocks, is regarded as a Devonian-Carboniferous intra-oceanic island arc with some Paleozoic ophiolites, superimposed by Permian arc volcanism. A plagiogranite from an imbri-cated ophiolitic mélange (Armantai) in the East Junggar yields a new SHRIMP zircon age of 503 7 Ma. Using published age constraints, we propose the presence of multiple subduction systems in this part of the Paloasian Ocean in the Paleozoic. The intraoceanic arcs became accreted to the southern active margin of the Siberian craton in the middle Carboniferous-Permian. During the long accretionary processes, in addition to large-scale southward-directed thrusting, large-scale, orogen-parallel, strike-slip movements (for example, Erqis fault) in the Permian translated fragments of these intraoceanic arcs and associated accretionary wedges. This new tectonic model has broad implications for the architecture and crustal growth of Central Asia and for other ancient orogens.
The Ulungur River granites from North Xinjiang, China, display two petrological trends: (1) a peralkaline trend, composed of alkali amphibole- and alkali pyroxene-bearing granites and dykes, and (2) an aluminous trend, represented by alkali granites, monzogranites and aluminous granite dykes within the peralkaline granites. Rb–Sr whole-rock isochron dating yielded an age of 300 Ma for the emplacement of the peralkaline granites and 270 Ma for the aluminous granites. The Ulungur River granites share all the geochemical features common to A-type granites of the world. The Ulungur River granites are post-orogenic and emplaced in a post-collisional extensional environment.
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