No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
The SHRIMP zircon U-Pb dating and geological features of Bairendaba diorite in the Xilinhaote area, Inner Mongolia, China
Abstract
The diorite in Bairendaba Ag polymetaHic ore district was studied with SHRIMP zircon U-Pb and geochemical method. It has yielded a Hercynian emplacement age of 326.5±1.6 Ma (MSWD=1.7), and the geochemical data suggest a volcanic arc setting genesis for the diorite, there was significant contamination with Xilinhaote complex in the magma evolvement. Combined with the geological and geochronological features of granitods in the nearby area, it shows that there has been an intensive Hercynian tectonic-magmatic event in this area, and the volcanic arc setting may extend from Sunid area to northern Hexigten.
... The main minerals of the rocks are composed of plagioclase, quartz, biotite, and hornblende. Zircon U-Pb dating shows that the quartz diorite was emplaced at 326.5 ± 1.6 Ma (Liu et al., 2010a;Liu et al., 2010b;Liu et al., 2010c). ...
... Arsenopyrite and wolframite are often considered as high temperature minerals according to previous statistics (Hsu, 1976;Pokrovski et al., 2002;Liu and Xiao, 2020). Dark sphalerite is mostly formed in high temperature environment, Fe has the ability of strong isomorphism to replace Zn in sphalerite at high temperature, and the ability of Fe to replace Zn in sphalerite decreases with the decrease of forming temperature (Liu et al., 2010a;Liu et al., 2010b;Liu et al., 2010c). Arsenopyrite may form earlier than the cassiteritesphalerite-mica quartz vein that cut through the early arsenopyritebearing quartz vein (Fig. 8c, d). ...
... Each analysis incorporated a background acquisition of approximately 20-30 s followed by 50 s of data acquisition from the sample. The raw data were processed offline by ICPMSDataCal software version 9.9 (Liu et al., 2010a;Liu et al., 2010b;Liu et al., 2010c). ...
Weilasituo ore field is located in the southern part of Great Xing’an Range, Inner Mongolia of northeastern China with two main ore deposits, one is previously found Cu-Zn deposit and another is recently found Sn-Li-Rb deposit. Sphalerite occurs in both deposits with multiple generations from early magmatic to later hydrothermal origin, and five types (sph-I to sph-V) were distinguished in the Sn-Li-Rb deposit. A combination of electron microprobe and LA-ICP-MS analysis indicates that the Weilasituo sphalerite is rich in In, Cd, Sn, and poor in Fe, Ga and Ge. The ore-forming temperature of sphalerite ranges from 220°C to 320°C, indicating a medium-temperature environment for ore formation. Sphalerite from the Weilasituo Cu-Zn deposit shows high-Fe content, whereas the Fe content is low in the Sn-Li-Rb deposit. The difference in Fe content may not be solely related to the temperature, but also controlled by local deposition environments. It is proposed that in the Sn-Li-Rb deposit, the Fe in the host rock of biotite-plagioclase gneiss was extracted into the ore-forming fluid by greisenization to form zinnwaldite. Overall, the critical metals including Nb and Ta in columbite-group minerals, Li in zinnwaldite, Rb in feldspar and micas, and In and Cd in sphalerite, should be mined together for a comprehensive utilization of these associated elements in the Weilasituo mining area.
... The Weilasituo Sn-polymetallic deposit is divided into sections with some hosting vein-type Cu-Zn and some with vein-type and disseminated Sn mineralization (Fig. 1c). The whole deposit is hosted within the Paleoproterozoic Baoyintu Group comprising plagioclase-amphibole gneiss and biotite-plagioclase gneiss belonging to the Ordovician to Silurian Xilinhot complex (Shi et al., 2003), Carboniferous quartz diorite (~327-308 Ma, Liu et al., 2010;Wang et al., 2013aWang et al., , 2013b and Early Cretaceous porphyritic alkali granite (139-138 Ma, Liu et al., 2010;Yang et al., 2019). The biotite-plagioclase gneiss is composed of plagioclase (45-50 vol%), quartz (25-30%), biotite (20-25%), amphibole (2-5%), and accessory (<1%) zircon and apatite. ...
... These show narrowly-distributed negative δ 34 S isotopic features and a magmatic origin, suggesting the ore fluids were H 2 S-dominant and reducing when the majority of sulfide mineralization occured. Alternatively, the variation in Fe / (Fe + Mg) ratios in Weilasituo micas could be explained by the distinctly different Mg and Fe contents and Fe/(Fe + Mg) ratios between granitic intrusions (mean MgO content as 0.12 wt% and total FeO content as 0.87 wt%, Liu et al., 2010;Yang et al., 2019) and wall rocks (quartz diorite with MgO as 10.3 wt% and FeO as 8.92 wt %, unpublished data). The wall rocks could have provided different background levels of Mg and Fe during greisenization via fluid-rock interaction (Heinrich, 1990), resulting in the widespread distribution of zinnwaldite (Fe-rich mica) and iron sulfides (pyrite and pyrrhotite) from the addition of large amounts of Fe to the fluid. ...
... High temperature has been thought of as an essential factor in the formation of Ba-rich phlogopite (Solie and Su, 1987) in metamorphic rocks and Ti-rich micas (Kwak, 1968). At Weilasituo, fluid cooling was indicated in previous fluid inclusion studies (Ouyang et al., 2014;Liu et al., 2016Liu et al., , 2018, but wall rock composition may have also played a key role during fluid circulation at this deposit (averaged TiO 2 contents in quartz diorite is 0.80 wt %, unpublished data; TiO 2 contents in causative granites as 0.10 wt%, Liu et al., 2010;Yang et al., 2019). ...
Spatial-temporal compositional variations in hydrothermal mica from different mineralization stages were determined across a single cross-section at the Weilasituo tin-polymetallic deposit, Northeast China. Hydrothermal mica from the magmatic-hydrothermal transitional stage (unidirectional solidification textures), hydrothermal tin-tungsten stage, molybdenum stage and copper-zinc stage was analysed in situ for major and trace element composition. Weilasituo mica is enriched in Li, Rb, Cs and Zn, has a moderate W and Sn content and a low Cu content. The temporal variation in mica composition shows that the Li content decreased slightly from the early to the late stage, while Zn concentration showed the opposite trend. Other elements in mica are relatively constant between stages, with only Sn, Rb and Cs being slightly enriched in the hydrothermal tin-tungsten stage mica. According to the spatial variations in mica composition, mica with a high W, Sn, Nb and Ta content occurs in granite, while mica enriched in volatile elements like Li and F is distributed within the main tin ore vein, or adjacent to the breccia pipes. The results suggest that mica W-Sn-Nb-Ta enrichments are genetically related to an early high-temperature magmatic fluid linked to the granitic intrusions at Weilasituo, while volatile elements were enriched by successive evolution of lateral fluid migration. The trace-element content of the Weilasituo mineralizing fluid (estimated from mica composition and rough estimates of mica-fluid partition coefficients) suggests that the fluid related to different mineralization originated from the same source, and does not support obvious magmatic-meteoric fluid mixing. Finally, the results suggest that spatial-temporal variations in mica compositions can be taken as a potential indicator of ore fluid compositional evolution in a hydrothermal system.
... Late Palaeozoic magmatism developed extensively in the study area and can be divided into two stages according to zircon U-Pb ages: late Carboniferous and early Permian. Late Carboniferous igneous rocks are mainly calc-alkaline intrusions of diorite, quartz diorite, and granodiorite (Bao et al. 2007a(Bao et al. , 2007bLiu et al. 2009;Xue et al. 2010;Liu et al., 2010a), thought to be the northeastward extension of the Baolidao arc rocks in Sunid Zuoqi and Xilin Hot (Chen et al. 2000(Chen et al. , 2009Hu et al. 2015). Early Permian igneous rocks include intrusive and volcanic rocks. ...
... Late Carboniferous Baolidao arc rocks in central Inner Mongolia represent the products during the northward subduction of the Palaeo-Asian Ocean plate under the southern margin of the Siberian palaeoplate (Chen et al. 2000(Chen et al. , 2009Liu et al. 2009;Xue et al. 2010;Liu et al., 2010a). ...
... Except for the Bairendaba diorite that intruded the Xilin Gol complex (Liu et al., 2010a), most of the granitoids in the Baolidao arc have positive ε Nd (t) and zircon ε Hf (t) values ( Figure 8) (Chen et al. 2000(Chen et al. , 2009Liu et al., 2010a;our unpublished data). The ε Nd (t) values of the early Permian felsic rocks generally fall within the ε Nd (t) variation range of most dioritic rocks of the Baolidao arc (Figure 8). ...
The petrology, geochronology, and geochemistry of the early Permian volcanic rocks from Houtoumiao area, south Xiwuqi County in central Inner Mongolia of China, are studied to elucidate the early Permian tectonic setting of the region. The volcanic rocks, which are interbedded with sandstone, feature both mafic and felsic compositions and show a bimodal nature. Zircon U–Pb dating reveals that the volcanic rocks formed at 274–278 Ma, similar to the ages of bimodal magmatism in neighbouring areas. The mafic rocks are composed of tholeiitic basalt, basaltic andesite, basaltic trachyandesite, and trachyandesite. They are rich in Th, U, and LILEs, depleted in HFSEs Nb, Ta, and Ti, and have positive εNd(t) values (+3.6 to +7.9). Geochemical analyses indicate that the mafic rocks originated from metasomatized lithospheric mantle. The felsic volcanic rocks are mainly rhyolite, with minor trachyte and dacite. They have different evolutionary tendencies of major elements, chondrite-normalized REE patterns, and isotopic compositions from the mafic volcanic rocks, which preclude formation by fractional crystallization of mafic melts. The εNd(t) values of the felsic rocks are similar to those of the Carboniferous Baolidao arc rocks in the region. It is suggested that Permian felsic melts originated from the partial melting of Carboniferous juvenile arc-related rocks. By comparison with typical Cenozoic bimodal volcanism associated with several tectonic settings, including rift, post-collisional setting, back-arc basin, and the Basin and Range, USA, the bimodal volcanic rocks in central Inner Mongolia display similar petrological and geochemical characteristics to the rocks from back-arc basin and the Basin and Range, USA. Based on the analysis of regional geological data, it is inferred that the early Permian bimodal volcanic rocks in the study area formed on an extensional continental margin of the Siberian palaeoplate after late Carboniferous subduction–accretion.
... The Sr-Nd isotopic mixing model from DePaolo and Wasserburg (1976) and the parameters from Wu, Jahn, Wilde, and Sun (2000) except for ε Nd (t) and I Sr take 9.3 and 0.703. Also shown are data for the Paleozoic gneiss (Liu, Jiang, & Y., Z., 2010), mafic rocks (Chen, Jahn, et al., 2000;Dolgopolova, Seltmann, & Armstrong, 2013), intermediate rocks (Chen, Jahn, et al., 2000;Dolgopolova et al., 2013;Liu et al., 2010;Wang, 2009), felsic rocks (Guo, Zhang, Jia, & Huang, 2013), and Hegenshan ophiolites (Miao et al., 2008) from the Great Hingan Range, Baoyintu Gp. (Xu, Liu, Wang, Zheng, & Tian, 2000), Ailigemiao Gp. (Xu et al., 2008), Duobaoshan Fm. (Wu et al., 2015), Ondor sum Fm. (Zhang & Wu, 1998), Baoligaomiao Fm. (Fu et al., 2016) and Baolige Fm. (Li et al., 2014, calculated back to t = 310 Ma; (d) Plot of ε Nd (t) versus ε Hf (t). Data sources: MORB, OIB and the terrestrial array are from Vervoort, Patchett, Blichert-Toft, and Albarède (1999); pelagic sediments and Fe-Mn nodules from Blichert-Toft and Arndt (1999); hyperbola of mixing between components MORB and pelagic sediments after Liu et al. (2007) [Colour figure can be viewed at wileyonlinelibrary.com] ...
... The Sr-Nd isotopic mixing model from DePaolo and Wasserburg (1976) and the parameters from Wu, Jahn, Wilde, and Sun (2000) except for ε Nd (t) and I Sr take 9.3 and 0.703. Also shown are data for the Paleozoic gneiss (Liu, Jiang, & Y., Z., 2010), mafic rocks (Chen, Jahn, et al., 2000;Dolgopolova, Seltmann, & Armstrong, 2013), intermediate rocks (Chen, Jahn, et al., 2000;Dolgopolova et al., 2013;Liu et al., 2010;Wang, 2009), felsic rocks (Guo, Zhang, Jia, & Huang, 2013), and Hegenshan ophiolites (Miao et al., 2008) from the Great Hingan Range, Baoyintu Gp. (Xu, Liu, Wang, Zheng, & Tian, 2000), Ailigemiao Gp. (Xu et al., 2008), Duobaoshan Fm. (Wu et al., 2015), Ondor sum Fm. (Zhang & Wu, 1998), Baoligaomiao Fm. (Fu et al., 2016) and Baolige Fm. (Li et al., 2014, calculated back to t = 310 Ma; (d) Plot of ε Nd (t) versus ε Hf (t). Data sources: MORB, OIB and the terrestrial array are from Vervoort, Patchett, Blichert-Toft, and Albarède (1999); pelagic sediments and Fe-Mn nodules from Blichert-Toft and Arndt (1999); hyperbola of mixing between components MORB and pelagic sediments after Liu et al. (2007) [Colour figure can be viewed at wileyonlinelibrary.com] ...
The Solonker zone is widely accepted as the suture between the North China Craton and the Siberia-Mongolia continental plate. The Baolige granite complex is located to the north side of the Solonker Suture and is mainly composed of monzogranite and granite. Zircon U-Pb ages, geochemistry, and Sr-Nd-Hf isotopic data of the Baolige granites were presented to constrain their petrogenesis and tectonic settings. Two monzogranite samples from Baolige yielded weighted mean zircon 206 Pb/ 238 U ages of 310.7 ± 2.1 Ma (mean square of weighted deviates (MSWD) = 1.3) and 307.4 ± 1.6 Ma (MSWD = 0.77), whereas the granite intruded into the monzogranite yielded an age of 296.2 ± 2.0 Ma (MSWD = 1.2). Both the Baolige monzogranite and granite contain high contents of SiO 2 , K 2 O, and Al 2 O 3 , low contents of TiO 2 , MgO, and CaO, and are peraluminous high-K calc-alkaline. These rocks are characterized by enrichments of K, Rb, U, Pb, Th, and light rare earth elements and depletions of Nb, Ta, Ti, and heavy rare earth elements and contain slightly negative or no Eu anomalies, similar to typical arc-related granit-oids. The Ti-in-zircon thermometry yielded 650-759°C for the monzogranite and 645-796°C for the granite. The monzogranite shows positive zircon ε Hf (t) values (4.7-13.2) and whole-rock ε Nd (t) values (3.6-5.2), with T DM2(Hf) ages of 1,324-557 Ma and T DM2(Nd) ages of 1,015-821 Ma, and I Sr of 0.70363-0.70386. The granite shows ε Hf (t) values of 15.6-20.9 and ε Nd (t) values of 4.0-5.1, with T DM2(Nd) ages of 957-832 Ma, and I Sr of 0.70364-0.70406. Geochemical evidence indicates that the Baolige granite complex is highly fractionated I-type and was likely formed by partial melting of the Neoproterozoic juvenile crust in a continental arc setting. We concluded that the Paleo-Asian Ocean may have undergone north-dipping subduction beneath the Siberia-Mongolia continental plate during the Late Carboniferous, and the subduction may have continued to the Early Permian (ca. 296 Ma).
... In this paper, by systematically studying their geochemical characteristics, the relationship and differences in ore-forming processes between Sn-Fe and Sn-Pb-Zn deposits are discussed. [14,17,18,[20][21][22][23]. The age data on Sn-polymetallic deposits are from References [3,[5][6][7][8]11,12,[24][25][26][27][28]. ...
... The most important characteristics of the southern Great Khingan Range are the large amount of polymetallic deposits, including Sn-Fe, Cu, Pb-Zn-Ag, and Mo deposits (Figure 1b), which can be classified into three systems: (1) Sn-polymetallic systems, including most Sn-W deposits and Pb-Zn-Ag deposits, which are closely associated with the Late-Yanshanian granitoid in time and space (Figures 1b, 2, and 3a); (2) Mo-polymetallic systems, including many porphyry Mo-polymetallic deposits such as Aolunhua and Nianzigou [27,29], mainly formed during the Indosinian-Yanshanian [14,17,18,[20][21][22][23]. The age data on Sn-polymetallic deposits are from References [3,[5][6][7][8]11,12,[24][25][26][27][28]. ...
Skarn Sn-polymetallic deposits, located in the southern Great Khingan Range, can be divided into Sn–Fe and Sn–Pb–Zn deposits. By systematically studying the geochemical characteristics of source granitoid and deposits, the ore-forming mechanisms were established, and the differences in ore-forming processes between Sn–Fe and Sn–Pb–Zn deposits are discussed. The main findings are as follows: (1) these two deposits were formed in the Late-Yanshanian period; (2) the source granitoid evolved at an early stage in a reducing environment, while the oxygen fugacity increased at a late stage through the influence of a deep-seated fault; (3) fine-grained syenogranite from Dashishan showed a higher degree of evolution than the syenogranite from Damogutu; (4) the Damogutu Sn–Fe and Dashishan Sn–Pb–Zn deposits shared a source of ore-forming fluid, and Fe, Sn, Pb, and Zn all derived from Late-Yanshanian granitoids; and (5) the ore-forming fluid experienced a continuous evolution process from the magmatic to hydrothermal stage, and the magmatic–hydrothermal transitional fluid played a very important role in skarnization and mineralization.
... The Sr-Nd isotopic mixing model from DePaolo and Wasserburg (1976) and the parameters from Wu, Jahn, Wilde, and Sun (2000) except for ε Nd (t) and I Sr take 9.3 and 0.703. Also shown are data for the Paleozoic gneiss (Liu, Jiang, & Y., Z., 2010), mafic rocks (Chen, Jahn, et al., 2000;Dolgopolova, Seltmann, & Armstrong, 2013), intermediate rocks (Chen, Jahn, et al., 2000;Dolgopolova et al., 2013;Liu et al., 2010;Wang, 2009), felsic rocks (Guo, Zhang, Jia, & Huang, 2013), and Hegenshan ophiolites (Miao et al., 2008) from the Great Hingan Range, Baoyintu Gp. (Xu, Liu, Wang, Zheng, & Tian, 2000), Ailigemiao Gp. (Xu et al., 2008), Duobaoshan Fm. (Wu et al., 2015), Ondor sum Fm. (Zhang & Wu, 1998), Baoligaomiao Fm. (Fu et al., 2016) and Baolige Fm. (Li et al., 2014, calculated back to t = 310 Ma; (d) Plot of ε Nd (t) versus ε Hf (t). Data sources: MORB, OIB and the terrestrial array are from Vervoort, Patchett, Blichert-Toft, and Albarède (1999); pelagic sediments and Fe-Mn nodules from Blichert-Toft and Arndt (1999); hyperbola of mixing between components MORB and pelagic sediments after Liu et al. (2007) [Colour figure can be viewed at wileyonlinelibrary.com] ...
... The Sr-Nd isotopic mixing model from DePaolo and Wasserburg (1976) and the parameters from Wu, Jahn, Wilde, and Sun (2000) except for ε Nd (t) and I Sr take 9.3 and 0.703. Also shown are data for the Paleozoic gneiss (Liu, Jiang, & Y., Z., 2010), mafic rocks (Chen, Jahn, et al., 2000;Dolgopolova, Seltmann, & Armstrong, 2013), intermediate rocks (Chen, Jahn, et al., 2000;Dolgopolova et al., 2013;Liu et al., 2010;Wang, 2009), felsic rocks (Guo, Zhang, Jia, & Huang, 2013), and Hegenshan ophiolites (Miao et al., 2008) from the Great Hingan Range, Baoyintu Gp. (Xu, Liu, Wang, Zheng, & Tian, 2000), Ailigemiao Gp. (Xu et al., 2008), Duobaoshan Fm. (Wu et al., 2015), Ondor sum Fm. (Zhang & Wu, 1998), Baoligaomiao Fm. (Fu et al., 2016) and Baolige Fm. (Li et al., 2014, calculated back to t = 310 Ma; (d) Plot of ε Nd (t) versus ε Hf (t). Data sources: MORB, OIB and the terrestrial array are from Vervoort, Patchett, Blichert-Toft, and Albarède (1999); pelagic sediments and Fe-Mn nodules from Blichert-Toft and Arndt (1999); hyperbola of mixing between components MORB and pelagic sediments after Liu et al. (2007) [Colour figure can be viewed at wileyonlinelibrary.com] ...
The Solonker zone is widely accepted as the suture between the North China Craton and the Siberia–Mongolia continental plate. The Baolige granite complex is located to the north side of the Solonker Suture and is mainly composed of monzogranite and granite. Zircon U–Pb ages, geochemistry, and Sr-Nd-Hf isotopic data of the Baolige granites were presented to constrain their petrogenesis and tectonic settings. Two monzogranite samples from Baolige yielded weighted mean zircon ²⁰⁶Pb/²³⁸U ages of 310.7 ± 2.1 Ma (mean square of weighted deviates (MSWD) = 1.3) and 307.4 ± 1.6 Ma (MSWD = 0.77), whereas the granite intruded into the monzogranite yielded an age of 296.2 ± 2.0 Ma (MSWD = 1.2). Both the Baolige monzogranite and granite contain high contents of SiO2, K2O, and Al2O3, low contents of TiO2, MgO, and CaO, and are peraluminous high-K calc-alkaline. These rocks are characterized by enrichments of K, Rb, U, Pb, Th, and light rare earth elements and depletions of Nb, Ta, Ti, and heavy rare earth elements and contain slightly negative or no Eu anomalies, similar to typical arc-related granitoids. The Ti-in-zircon thermometry yielded 650–759 °C for the monzogranite and 645–796 °C for the granite. The monzogranite shows positive zircon εHf(t) values (4.7–13.2) and whole-rock εNd(t) values (3.6–5.2), with TDM2(Hf) ages of 1,324–557 Ma and TDM2(Nd) ages of 1,015–821 Ma, and ISr of 0.70363–0.70386. The granite shows εHf(t) values of 15.6–20.9 and εNd(t) values of 4.0–5.1, with TDM2(Nd) ages of 957–832 Ma, and ISr of 0.70364–0.70406. Geochemical evidence indicates that the Baolige granite complex is highly fractionated I-type and was likely formed by partial melting of the Neoproterozoic juvenile crust in a continental arc setting. We concluded that the Paleo-Asian Ocean may have undergone north-dipping subduction beneath the Siberia–Mongolia continental plate during the Late Carboniferous, and the subduction may have continued to the Early Permian (ca. 296 Ma).
... Multiple volcanic and plutonic rocks covered or intruded older rocks during Mesozoic to Cenozoic times. Fortunately, a few magmatic rocks with similar age and tectonic background to the Sonidzuoqi-Xilinhot magmatic arc were reported in southern Xi Ujimqin of the southern DXAM and Longzhen of the northern DXAM (Fig. 2) ( Chen et al., 2000Chen et al., , 2009aBao et al., 2007a;Liu et al., 2009Liu et al., , 2010Zhang et al., 2010a). In consideration of Miao et al. (2008)'s model (the coupling relation between the Sonidzuoqi-Xilinhot magmatic arc and the ''Hegenshan Ocean''), we acquired conception from our earlier work, which suggests that the detrital zircons from Permian sandstones in the south of Hegenshan area originated in the Sonidzuoqi-Xilinhot magmatic arc ( Han et al., in preparation). ...
... Wu et al. (2002) and Sun et al. (2001), as stated above, proposed an eastward extension of the Erenhot-Hegenshan suture zone for the northern 280 Ma-granite belt. The $320 Ma-age group, which is unique in the DXAM, has been interpreted as a subduction-related magmatic arc from Oyu Tolgoi of southern Mongolia (north of Solon Obo) (Wainwright et al., 2011), Mandula (Jian et al., 2010), Sonidzuoqi ( Chen et al., 2000Chen et al., , 2009a, southern Xi Ujimqin in the east of Inner Mongolia ( Bao et al., 2007a;Liu et al., 2009Liu et al., , 2010 and at Longzhen in the southeast of Nenjiang (northern DXAM) (Zhang et al., 2010a) ( Fig. 4 and Table 4). Furthermore, many previous studies represented similar data of magmatic events along the northern margin of the North China craton ( Zhang et al., 2004aZhang et al., , 2007aZhang et al., ,b,d, 2009aMa et al., 2004;Cope et al., 2005;Yuan and Wang, 2006;Wang et al., 2007a;Zhao et al., 2007;Luo et al., 2007Luo et al., , 2009 (Fig. 4). ...
... The Sr-Nd-Hf isotope indicates that it originated from partial melting in the source area of the depleted mantle under the background of regional extension (Pang et al., 2018). Several late early to late Carboniferous granite (325-309 Ma) have been reported from Sonidzuoqi, Xilinhot and Daqing areas Bao et al., 2007;Liu et al., 2009Liu et al., , 2010Xue et al., 2010). Some authors suggest they were formed in a late-to post-orogenic extensional setting (Bao et al., 2007;Xue et al., 2010). ...
According to sedimentary structure, petrology and sequence analysis from seven sections (S1–S7) across the West Ujimqin basin, the late Carboniferous to Permian sedimentary facies have been recognized and summarized as four sedimentary systems, i.e. the late Carboniferous-early Permian sedimentary system (SA) comprising the alluvial fan–delta–littoral facies, the late Carboniferous sedimentary system (SB) including the littoral facies–delta facies–platform margin facies, the early Permian sedimentary system (SC) characterized by delta front and prodelta facies, and the middle Permian sedimentary system (SD) with alternations of littoral and delta facies. According to the spatial and temporal distribution of the four sedimentary systems, the basin filling process can be divided into three stages. The first stage (324–290 Ma) is dominated by bidirectional terrigenous sediments containing the SA from alluvial fan to delta and littoral facies in the northwestern and the SB from littoral–delta to platform margin facies in the southern, respectively. The second stage (290–270 Ma) is characterized by delta front and prodelta facies of the SC marked by thick-bedded matrix-supported conglomerate, rapid accumulation of terrigenous sediments and volcanic debris, syn-sedimentary deformation and slump. The third stage (270–255 Ma) formed the SD with the alternations of littoral and delta facies, which is represented by complex terrigenous clasts and intra-basin carbonate. These shallow and proximal sedimentary systems from fan delta to littoral facies indicate that there was not oceanic sedimentary system in the eastern CAOB during the late Carboniferous to Permian except for some small red sea basins, which provides convictive evidence that the Paleo-Asian Ocean (PAO) had closed before the late Carboniferous. Detrital zircon dating reveals bidirectional provenances of the West Ujimqin basin, indicating that it was a limited basin between two uplifts, which implies presence of the late Paleozoic “basin and uplift” tectonic framework that developed on the eastern CAOB during the late Paleozoic.
... (d) Epsilon Nd (t) versus Th/Sc (after George and Ray, 2017). Also shown are the data of the Late Paleozoic intermediate-felsic arc magmatic rocks (Chen et al., 2000Chen et al., , 2009Zhang et al., 2008;Guo et al., 2009;Fu et al., 2016;Li et al., 2016c;Shi et al., 2016;Liao et al., 2017) and ophiolites (Miao et al., 2008;Wang et al., 2008;Jian et al., 2012;Song et al., 2015;Yang et al., 2017), the Xilin Gol complex (Liu et al., 2010), and the Heilongjiang and Mashan complexes (Wu et al., 2000) in central Inner Mongolia. ...
Late Paleozoic sedimentary strata outcrop extensively in central Inner Mongolia, and are a key to understanding the tectonic evolution of the southeastern Central Orogenic Belt. A combined analysis of petrography, whole-rock major and trace element, and Nd isotope is carried out on representative sandstones from the Late Paleozoic sedimentary strata (420–270 Ma). The sandstones are mainly wackes and litharenites in lithology, with low SiO2/Al2O3 of 2.85–9.47 (averagely 5.22) and poor textural and compositional maturities, implying short sediment transportation between the depositional basins and provenances. The trace element compositions are generally comparable to that of the average upper continent crust (UCC), with negatively-sloping chondrite-normalized rare earth element distribution patterns ((La/Yb)N = 3.43–11; averagely 6.94) and flat UCC-normalized trace element distribution patterns. The Nd isotopic compositions show great variation (ԐNd(t) = −5.01 to 5.35) with depositional time of the sandstones, and coincide well with the arc magmatic phases in central Inner Mongolia. The geochemical signatures of the sandstones indicate that the dominant provenances are intermediate to felsic arc magmatic rocks that have ages approximating the deposition, although old, recycled sediments may have made a minor contribution. An active continental arc setting during the Late Paleozoic in central Inner Mongolia, controlled by the northward subduction of the Paleo-Asian oceanic slab, was the most likely depositional tectonic setting of the sandstones. This active continental arc setting continued to at least 270 Ma, implying that the final closure of the Paleo-Asian Ocean along the Solonker suture zone most likely occurred sometime during the Late Permian to Early Triassic. The northward subduction of the Paleo-Asian Ocean is likely of West Pacific-style, in which the present-day Baolidao arc has a close genetic link with the South Mongolian microcontinent and, likely, the former originally formed as the arc margin of the latter.
... The early phase (330-292 Ma) magmatism mainly consists of volcanic rocks ( Xin et al. 2011;Liu et al. 2013a;Li et al. 2014Shao et al. 2015), I-and A-type acidic magamtic rocks Bao et al. 2007a;Liu et al. 2009;Xue et al. 2009;Cheng et al. 2012;Xu et al. 2012;He et al. 2013;Li et al. 2014). Those rocks were considered as post-collisional setting and usually associated with large-scale mineralization ( Liu et al. 2010Liu et al. , 2012Xue et al. 2010;Yun et al. 2011;Liang et al. 2013;Wang et al. 2013). The late phase magmatism includes alkaline granite (such as the Erenhot-Hegenshan alkaline granite belt, which were emplaced in a short time from 292 to 273 million years; Hong et al. 1996;Zhang et al. 2009cZhang et al. , 2013Zhang et al. , 2014Tong et al. 2015), A-type granitoids (Shi et al. ...
We undertake zircon U–Pb dating, Hf isotopes, and geochemical analyses of the Houtoumiao pluton in the Xilinhot microcontinent (XLMC) in the central Inner Mongolia with an aim of determining their ages, petrogenesis, and sources, which are important for understanding the late Palaeozoic tectonic evolution of the Xing’an-Mongolia Orogenic Belt. The Houtoumiao pluton consists of medium-grained granodiorite, coarse- and medium-grained syenogranite. Mafic microgranular enclaves (MMEs) are common in the Houtoumiao pluton. Zircon U–Pb dating has yielded ages of 303 ± 2 and 301 ± 2 Ma for the granodiorite, 295 ± 2 Ma for the syenogranite, and 292 ± 1 Ma for the MMEs. The granodiorite and syenogranite have features of high-K high silica content, rich in Rb, U, and Th, but low content of HFSE, belong to calc-alkaline series. The P2O5 concentration decreases with the increasing SiO2 content, suggesting I-type affinity. The MMEs, which are characterized by low SiO2, relatively high and variable TiO2, Al2O3, FeOT, MgO, CaO, Ni, and Cr contents, also have much higher total rare earth element concentrations that the REE patterns are subparallel to those of the host rocks. Zircons from the host rocks have εHf(t) values from +3.91 to +7.73 and TDM2 values of 820–1067 Ma, suggesting that the granitoids were probably dominated by remelting of juvenile crust materials. The MMEs are of εHf(t) value ranging from +6.23 to +11.04 and TDM1 values from 490 to 693 Ma, suggesting that the primary magma probably was derived from partial melting of a depleted lithospheric mantle, the mafic mineral fractional crystallization and crustal contamination occurred during the magma evolution. Combined with previous studies on the contemporaneous magma-tectonic activities in the Uliastai Continental Margin and XLMC, we suggest that the Houtoumiao pluton formed in a post-orogenic setting.
... The deposit is now worked by the Inner Mongolia Yindu Mining Co. Ltd. and has proven reserves of 1.4 million t Zn, 0.6 million t Pb, and 4.6 thousand t Ag. Recent studies have examined geological features, alteration, sulfur isotopes, dating of mineralization, and the origin of ore-forming fluids [12][13][14][15][16][17][18][19][20]. However, additional data are necessary to better characterize the mineralizing fluids and understand ore deposition in the different stages of mineralization. ...
The Bairendaba deposit is the largest Ag-Zn-Pb deposit in Inner Mongolia. Vein and disseminated ores occur in biotite-plagioclase gneiss and quartz diorite along regional EW trending faults. Microthermometric data for H 2 O-NaCl ± CH 4 ± CO 2 fluid inclusions record a decrease in homogenization temperature and salinity of ore-forming fluids with time. Early and main-stage mineralization have homogenization temperatures of 242°–395°C and 173°–334°C, respectively, compared with 138°–213°C for late-stage mineralization. Fluid salinities for early mineralization have a bimodal distribution, dominantly 4.2–11.8 wt.% NaCl equivalent, with 35.2–37.8 wt.% NaCl equivalent for a small population of halite-bearing inclusions. Main- and late-stage fluids have salinities of 2.1–10.2 wt.% NaCl equivalent and 0.7–8.4 wt.% NaCl equivalent, respectively. Oxygen and hydrogen isotope data indicate the interaction of a magmatic fluid with wall rocks in early mineralization, followed by the introduction of meteoric water during late-stage mineralization. Values of –15.9 ‰ to –12 ‰ ( δ¹³CPDB ) for hydrothermal quartz indicate that organic-rich strata were the source of carbon. Sulfur had a magmatic source, based on values of –0.1 ‰ to 1.5 ‰ ( δ³⁴SV-CDT ) for sulfide minerals. The Bairendaba deposit is a typical mesothermal system with mineralization controlled by structure.
... Province I is characterized by the youngest T DM (0.8-0.2 Ga) with high positive ε Nd (t) values ranging from + 0.1 to + 8.8 (+ 2.7-+8.4 for the Paleozoic and +0.1-+8.8 for the Mesozoic granitoids) (Figs. 9, 10, 11, 12 and 13). The main part of Province I is located to the north of the Nengjiang-Erenhot fault, and extends to the nearby Saynshand- Li and Yu, 1994;Liu et al., 1994;Liu et al., 2005Liu et al., , 2010Liu et al., , 2012aLiu et al., , 2014Liu et al., , 2015aNie et al., 1995;Wu et al., 1999Wu et al., , 2001Wu et al., , 2002Wu et al., , 2003Wu et al., , 2009Wu et al., , 2015Chen et al., 2000Chen et al., , 2003Chen et al., , 2008aChen et al., , b, 2010Chen et al., , 2011Chen et al., , 2013Yan et al., 2000;Jahn et al., 2001;Wei et al., 2001;Qian et al., 2002;Cai et al., 2003Cai et al., , 2004Cai et al., , 2005Han et al., 2004;Jiang, 2005Jiang, , 2007Jiang, , 2009Jiang, , 2011Hu et al., 2006;Li et al., 2007Luo et al., 2007;Yang et al., 2007Yang et al., , 2008aYang et al., , 2009Yang et al., , 2012Yang et al., , 2015aYing et al., 2007Ying et al., , 2011Zhang et al., 2007bZhang et al., , 2008aZhang et al., , b, d, 2009bZhang et al., , c, 2010bZhang et al., , c, 2012aZhang et al., , b, c, d, e, 2013Zhang et al., , 2014bZhang et al., , 2015bMiao et al., 2008;Qin et al., 2008;Xiao et al., 2008;Xu et al., 2008a, b;Feng et al., 2009;Wan et al., 2009;Wang, 2009;Batkhishig et al., 2010;Hou et al., 2010Hou et al., , 2011Hou et al., , 2015Jian et al., 2010;Sui and Xu, 2010;Niu et al., 2011Niu et al., , 2012Wainwright et al., 2011;Chu et al., 2012;Fu et al., 2012a, b;Guo et al., 2012Guo et al., , 2013Guo et al., , 2014Li, 2012;Shen et al., 2012;Wang et al., 2012Wang et al., , 2013Wang et al., , 2014aWang et al., , 2015bZeng, 2012;Zeng et Xiguitu-Xinlin suture and to the north of Linxi. The granitoids in this province were emplaced during 479-110 Ma. ...
There is a long-standing controversy regarding the tectonic division, composition and structure of the continental crust in the Da Hinggan Mountains and adjacent areas, which are mainly part of the southeastern Central Asian Orogenic Belt (CAOB). This paper approaches these issues via neodymium isotopic mapping of Paleozoic-Mesozoic (480 to 100 Ma) granitoids. On the basis of 943 published and 8 new whole-rock Nd isotopic data, the study area can be divided into four Nd isotopic provinces (I, II, III and IV). Province I (the youngest crust, Nd model ages (TDM) = 0.8-0.2 Ga) is a remarkable region of Phanerozoic crustal growth, which may reflect a major zone for closures of the Paleo-Asian Ocean. Province II (slightly juvenile crust, TDM = 1.0-0.8 Ga), the largest Nd isotopic province in the southeastern CAOB, is considered to reflect the recycling of the initial crustal material produced during the early stage (Early Neoproterozoic) evolution of the Paleo-Asian Ocean. Province III (slightly old crust, TDM = 1.6-1.1 Ga) is characterized by ancient crustal blocks, such as the central Mongolian, Erguna, Dariganga and Hutag Uul-Xilinhot blocks, which represent micro-continents and Precambrian basements in the southeastern CAOB. Several parts of Province III are located along the northern margin of the North China Craton (NCC), which is interpreted as a destroyed cratonic margin during the Paleozoic and Mesozoic. Province IV (the oldest crust, TDM = 2.9-1.6 Ga) mainly occurs within the NCC and reflects its typical Precambrian nature. These mapping results indicate that the boundary between Provinces II and III (the northern margin of the NCC) along the Solonker-Xar Moron Fault can be regarded as the lithospheric boundary between the CAOB and NCC. Provinces I and II account for 20% and 44% of the area of the southeastern CAOB, respectively, and therefore the ratio of continental growth is 64% from the Neoproterozoic to the Mesozoic, which is typical for this part of the CAOB and distinguishes the CAOB from other Phanerozoic orogens in the world.
... The quartz diorite is slightly foliated, and is subparallel to the regional foliation in the complex. SHRIMP zircon U-Pb dating indicates that the quartz diorite intruded the complex at ca. 327 ± 2 Ma (Liu et al., 2010b), predating the 40 Ar/ 30 Ar muscovite ages of ca. 133 ± 1 Ma yielded at the Weilasituo deposit (Pan et al., 2009b) and 135 ± 3 Ma yielded at the Bairendaba deposit (Chang and Lai, 2010). ...
The Weilasituo and Bairendaba Zn–Pb–Ag–Cu–(Sn–W) sulphide deposits are located in the southern part of Great Xing'an Range of Inner Mongolia in China. The deposits are located at shallow depths in the newly discovered Weilasituo porphyry hosting Sn–W–Rb mineralization. The mineralization at Weilasituo and Bairendaba consist of zoned massive sulphide veins within fractures cutting the Xilinhot Metamorphic Complex and quartz diorite. The Weilasituo deposit gradually zones from the Cu-rich Zn–Cu sulphide mineralization in the west to Zn-rich Zn–Cu sulphide mineralization in the east. The Bairendaba deposit has a Cu-bearing and Zn-rich core through a transitional zone devoid of copper to an outer zone of Zn–Pb–Ag mineralization. Three main veins contain more than 50 wt.% of the contained metal in the two deposits with their metal ratios displaying a systematic and gradual increase in Zn/Cu, Pb/Zn and Ag/Zn ratios from the western part of Weilasituo to the eastern part of Bairendaba.
Three stages of vein-type mineralization are recognized. Early, sub-economic mineralization consists of a variable proportion of euhedral arsenopyrite, pyrite, quartz, and rare wolframite, scheelite, cassiterite, magnetite and cobaltite. This was succeeded by main stage mineralization with economic concentration of zoned Cu, Zn, Pb and Ag sulphide minerals along strike within the veins. The zones consist of the assemblages: (1) pyrrhotite–Fe-rich sphalerite–chalcopyrite(–quartz–fluorite) at west Weilasituo; (2) pyrrhotite–Fe-rich sphalerite–chalcopyrite(–galena–tetrahedrite–quartz–fluorite) at east Weilasituo; (3) pyrrhotite–Fe-rich sphalerite–chalcopyrite(–galena–tetrahedrite–quartz–fluorite) in the centre of Bairendaba; (4) pyrrhotite–Fe-rich sphalerite–galena(–chalcopyrite–tetrahedrite–quartz–fluorite) in the transition zone of Bairendaba; and (5) pyrrhotite–Fe-rich sphalerite–galena–tetrahedrite(–chalcopyrite–falkmanite–argentite–pyrargyrite–quartz–fluorite) in the outer zone at Bairendaba. Post-main ore stage is devoid of sulphides and characterized overprinting of fluorite, sericite, chlorite, illite, kaolinite and calcite.
Zircon SHRIMP U–Pb dating, Zircon LA–ICP–MS U–Pb dating, molybdenite Re–Os isochron dating, and muscovite Ar–Ar dating indicate the Beidashan granitic batholith was intruded at 140 ± 3 Ma (MSWD = 3.3), the porphyritic monzogranite from marginal facies of the Beidashan batholith was intruded at 139 ± 2 Ma (MSWD = 0.75), the mineralized quartz porphyry was intruded at 135 ± 2 Ma (MSWD = 0.91), the greisen mineralization occurred at 135 ± 11 Ma (MSWD = 7.2), and the post-main ore stage muscovite deposited at 129.5 ± 0.9 Ma. The new geochronology data show the porphyry Sn–W–Rb and vein-type sulphide mineralization are contemporaneous with granitic magmatism in the region.
The metal zonation at the Weilasituo and Bairendaba deposits is a result of progressive metal deposition. This was during the evolution of a metal-bearing fluid along the strike of the veins and during the main stage of ore formation at the upper part of the deep-seated porphyry Sn–W–Rb system. This progressive zonation indicates that the deposits represent end-numbers formed from one ore-forming fluid, which moved from west to east from the porphyry. The metal zonation patterns of the major veins are consistent with metal-bearing fluid entering the system with the precipitation of chalcopyrite proximally and sphalerite, galena and Ag-bearing minerals more distally. We show that the mechanism of metal deposition is therefore controlled by thermodynamic conditions resulting in the progressive separation of sulphides from the metal-bearing fluid. The temperature gradient between the inflow zone and the outflow zone appears to be one of the key parameters controlling the formation of the metal zonation pattern. The sulphide precipitation sequence is consistent with a low fS2 and low fO2 state of the acidic metal-bearing fluid. The metal zonation pattern provides helpful clues from which it is possible to establish the nature of fluid migration and metal deposition models to locate a possible porphyry mineralization at depth in the Great Xing'an Range, which is consistent with the geology of the newly discovered porphyry Sn–W–Rb system.
... One-quarter of zircons yield ages from 320 to 358 Ma with a peak age of 336 Ma, which is unique in the Solonker-Hegenshan-Heihe belt and has been interpreted to reflect a subduction-related magmatic event. The evidence is supported by recent zircon ages obtained for igneous rocks in the study area, including SHRIMP U-Pb zircon ages of 339 ± 2 Ma for an andesite in the Oyu Tolgoi of southern Mongolia (Wainwright et al., 2011), 323.9 ± 2.7 Ma for trondhjemite in the Mandula (Jian et al., 2010), 325 ± 3 Ma and 322 ± 3 Ma for quartzdiorite plutons in the southern Xi Ujimqinin the east of Inner Mongolia (Liu et al., 2010b), and 313 ± 5 Ma to 323 ± 4 Ma for quartz-diorite and quartz-biotite-diorite in the Xinlin Gol complex (Bao et al., 2007). These new ages suggest that~330 Ma subductionrelated magmatim widely occurred in the Solonker-Hegenshan-Heihe belt. ...
The Weilasituo-bairendaba district is located at the eastern end of the Central Asian Orogenic Belt, which is an important component of the Cu-Pb-Zn polymetallic metallogenic belt on the Western slope of the Greater Xing’an Range in Inner Mongolia, China. The known Cu-Zn deposits such as the Weilasituo Cu-Zn deposit and the Bairendaba Ag-Pb-Zn deposit are the same tectonic-magmatic product. The district’s structure framework consists of the NE-trending regional faults, while the secondary faults provide channels and space for mineralization. The ore-bearing rocks are either Baoyintu Group gneisses or quartz diorites. The typical Cu-Zn deposits exhibit obvious Cu, Pb, Zn geochemical anomaly as well as obvious magnetic anomaly. The district-scale two-dimensional (2D) mineral prospectivity modeling has been reported. Nowadays, three-dimensional (3D) mineral prospectivity modeling is necessary and urgent. Integrated deposit geology and accumulated exploration data, the above four exploration criteria (regional fault, secondary fault, geochemical anomaly and magnetic susceptibility) are used for 3D mineral prospectivity modeling. Filtering (upward continuation, low pass filtering, two-dimensional empirical mode decomposition), magnetic inversion and 3D modeling techniques were used to construct geological models. Excellent machine learning algorithms such as random forest (RF) and XGBoost are applied. The two machine learning methods confirm each other to improve the accuracy of 3D mineral prospectivity modeling. In this paper, repeated random sampling and Bayesian optimization are combined to construct and tune models. This joint method can avoid the contingency caused by random sampling of negative samples, and can also realize automatic optimization of hyperparameters. The optimal models (RF28 and XGBoost11) were selected among thirty repeated training models for mineral prospectivity modeling. The obtained areas under the ROC curves of RF28 and XGBoost11 were 0.987 and 0.986, respectively. The prediction-area (P-A) plot and C-A fractal were used to delineate targets and grade targets. The targets were divided into Ⅰ-level targets and Ⅱ-level targets. The I- and II-targets are not only highly consistent with the known Cu-Zn deposits, but also exhibit obvious ore-forming geological features. The 3D targets are beneficial for Cu-Zn exploration in the Weilasituo-bairendaba district.
The Xingmeng Orogenic Belt evolved through a long-lived orogeny involving multiple episodes of subduction and accretion. However, there is a debate on its tectonic evolution during the Late Paleozoic. Here, we report geochemical, geochronological, and isotopic data from strongly peraluminous granites and gabbro-diorites from the Sunidzuoqi–Xilinhot region. Zircon U–Pb ages suggest that the intrusive rocks were emplaced during the Early Carboniferous (333–322 Ma). The granites exhibit geochemical characteristics similar to S-type granites, with high SiO2 (72.34–76.53 wt.%), Al2O3 (12.45–14.65 wt.%), and A/CNK (1.07–1.16), but depleted Sr, Nb, and Ta contents. They exhibit positive εNd(t) and εHf(t) values (-0.3 to 2.8 and 2.7–5.7, respectively) and young Nd and Hf model ages (TDM2(Nd)=853–1110 Ma and TDM2(Hf)=975–1184 Ma), suggesting that they may be the partial melting products of heterogeneous sources with variable proportions of pelite, psammite, and metabasaltic rocks. The meta-gabbro-diorites from the Maihantaolegai pluton have low SiO2 (47.06–53.49 wt.%) and K2O (0.04–0.99 wt.%) contents, and demonstrate slight light rare earth element (REE) depletion in the chondrite-normalized REE diagrams. They have high zircon εHf(t) values (14.41–17.34) and young Hf model ages (TDM2(Hf)= 230–418 Ma), indicating a more depleted mantle source. The variations of the Sm/Yb and La/Sm ratios can thus be used to assess the melting degree of the mantle source from 5% to 20%, suggesting a quite shallow mantle melting zone. We propose that the petrogenesis and distribution of the strongly peraluminous granites and gabbro-diorites, as well as the tectonic architecture of the region, can be explained by a ridge subduction model. Based on these results, and previous studies, we suggest a southward ridge subduction model for the Sunidzuoqi–Xilinhot region.
The Wulanba granite, consisting of biotite monzogranite and syenogranite, is located in the southern part of the Great Xing’an Range, NE China. Whole-rock major- and trace-element geochemistry suggests the Wulanba granite is a high-K–shoshonitic, slightly peraluminous and highly differentiated I-type granite. The Sr–Nd–Hf isotopes indicate that it originated from partial melting of juvenile crust derived from the depleted mantle with a minor input of old crust. The relatively young T 2DM and t DM2 ages indicate it was most likely derived from a Late Neoproterozoic to Early Palaeozoic source. We have demonstrated that the biotite monzogranite is the ore-related intrusion of the Haobugao Zn–Fe mineralization based on the following geological, geochronological and geochemical evidence: (1) the chalcopyrite/pyrite in the biotite monzogranite and the continuous mineralization of drill core ZK2508; (2) the consistence of the emplacement age of the biotite monzogranite (~141–140/138 Ma) with the skarn mineralization age (~142 Ma); and (3) the presence of rich ore-forming elements (Fe–Zn–Cu) in the biotite monzogranite, and the similar Pb compositions of the sulfides from the Haobugao deposit and the biotite monzogranite. Compared to the barren syenogranite, the fertile biotite monzogranite is more oxidized, while the edges of the apatite grains in the biotite monzogranite are more oxidized than the centres. The average F/Cl ratio of the fertile biotite monzogranite (~123.45) is much higher than that of the barren syenogranite (~73.98). We conclude that these differences reflect unique geochemical signatures, and the geochemical composition of the apatite can be used to infer the economic potential of granites.
China's W–Sn resources are dominant on a global scale. A series of Sn–polymetallic deposits has been found in recent years at depth on the flanks of known volcanic–subvolcanic Cu–Pb–Zn–Ag deposits in the Southern Great Xing'an Range, NE China. The large-scale Weilasituo tin–polymetallic deposit, formed at the depth of the Weilasituo Cu–Zn deposit, is most typical of these types of deposit. Tin–polymetallic orebodies are hosted in the early Paleozoic Xilingol Complex, and their mineralization is closely related to Early Cretaceous quartz porphyry. In this contribution, bulk-rock and mica chemical compositions, Re–Os geochronology, and He–Ar isotopic analyses are described in addressing the ore-formation mechanism of the deposit. Geochemical characteristics indicate that the ore-bearing quartz porphyry corresponds to the I-type granite serie. Five types of mica have been identified in the study area based on detailed petrography and EPMA and LA–ICP–MS analyses: (i) early magmatic Fe–Li mica in albitized quartz porphyry; (ii) late magmatic Fe–Li mica in mineralized quartz porphyry; (iii) hydrothermal Fe–Li mica in a cryptoexplosive breccia pipe (distributed around breccia fragments); (iv) Fe–Li mica in quartz veins; and (v) Fe–Li mica in plagioclase gneiss (wall rock). Magmatic zinnwaldite from the upper mineralized part of the quartz porphyry is enriched in Nb (100–160 ppm) and Ta (100–150 ppm). Hydrothermal zinnwaldite from the explosive breccia, quartz veins, and surrounding gneiss is unusually rich in Mg (up to 3.4 wt% MgO) and Sn (up to 200 ppm). ³ He/ ⁴ He ratios of the Weilasituo tin–polymetallic and Cu–Zn deposits are in the ranges 3.38–4.91 Ra and 4.8–4.9 Ra, respectively, indicating ore-forming fluids sourced from mixed crustal and mantle materials. Molybdenite Re–Os dating of W mineralization yielded an isochron age of 129.0 ± 4.6 Ma, similar to the porphyry crystallization and mineralization ages of the Weilasituo tin–polymetallic deposit, and also consistent with the mineralization age of the Cu–Zn deposit. We propose a new metallogenic model, with all subtypes of W–Sn–Cu–Pb–Zn–Ag mineralization in the Weilasituo area belonging to a single complex metallogenic system. Compared with other ore districts, ore-related granitoids in the Southern Great Xing'an Range display relatively uniform emplacement ages and were derived from partial melting of juvenile lower crust rather than old basement. Their ore-forming fluid source was greater influenced by mantle fluids than which found in South China.
We conducted zircon U–Pb dating and geochemical analyses for the Qianjinchang (QJC) pluton in the Xi Ujimqi, Northeast China, with an aim to determine their ages, petrogenesis, and sources. The QJC pluton consists of coarse/medium-grained biotite monzogranite in the core and fine-grained biotite granodiorite in the rim; those rocks intrude into quartz diorite but are intruded by minor intrusive phases, including small biotite syenogranite, diorite bodies, late diorite, granodiorite, granite, and pegmatite dykes. Our new laser ablation inductively coupled plasma mass spectrometry zircon U–Pb data indicate that the QJC composite pluton composed of 2 phases of magmatic activities, with the ages of 301~313 Ma for the quartz diorite, 283 ± 1 Ma for the biotite granodiorite, 280 ± 1 Ma for the biotite syenogranite, and 280 ± 2 Ma for the diorite dyke. Hf isotopic analyses for the quartz diorite sample show εHf (t) = 3.75 to 11.72, with 2-stage Hf model age (TDM2) ranging 568–1,078 Ma. The biotite syenogranite sample also shows a depleted εHf (t) = 4.47 to 8.71, with TDM2 ranging 745–1,015 Ma, suggesting the major involvement of juvenile crustal components. The various εHf values of the QJC pluton indicate a hybrid magma source of juvenile material with old crustal component, and the TDM2 values increase from the Carboniferous to Permian, which suggests an increasing proportion of old continental material during this period. Petrological and geochemical characteristics of the biotite granodiorite and biotite monzogranite samples suggest that they are S-type granites and derived from partial melting of the clay-poor, plagioclase-rich psammitic source, produced at low-medium pressure. The biotite syenogranite sample belongs to alkaline and shoshonitic series and probably formed by a hybridization process between basaltic magma and old continental components. Combined with previous studies on the contemporaneous magma-tectonic activities in the Xilinhot microcontinent, we suggest that the QJC pluton formed in a postcollisional setting.
The recently discovered Weilasituo Sn-polymetal deposit is located in the southern part of the Great Xing'an Range of Inner Mongolia, NE China, which is belonged to the eastern part of the Central Asian Orogenic Belt (CAOB). Sn-polymetal mineralization is closely related to the emplacement of the Early Cretaceous fine- to medium-grained quartz porphyry. Three types of mineralization have been recognized at Weilasituo with the disseminated and stockwork Sn-polymetal mineralization mainly hosted by the quartz porphyry, the vein-type Sn-polymetal mineralization hosted by NE-trending and WE-trending fractures and faults in the upper and outer part of the porphyry, and breccia mineralization occurred within a steep cryptoexplosive breccia pipe. The ore-related alteration typically consists of Na-Ca-Sr alteration and greisen.
The Hegenshan ophiolite in the Solonker-Hegenshan belt is the largest ophiolite in the Central Asian Orogenic Belt (CAOB). Despite its significance in constraining regional tectonic evolution, the emplacement time of the Hegenshan ophiolite is still under debate. In this study, we provide new detrital zircon ages of the Paleozoic sedimentary rocks that unconformably overlie the Wusinihei ophiolite (northeastern part of the Hegenshan ophiolite) to constrain the lower limit emplacement time of the Hegenshan ophiolite. The zircon ages obtained from the Paleozoic sedimentary rocks range from 298 ± 8 to 363 ± 7 Ma, and show bimodal distribution at 300-320 Ma (peak at 308 Ma) and 320-360 Ma (peak at 330 Ma). The age group of 300-320 Ma coincides with the age range of the volcanic rocks of the Late Paleozoic Gegenaobao Formation. The age group of 320 to 360 Ma with a peak at 330 Ma may be linked to local mafic-ultramafic rocks of the Hegenshan ophiolite. Accordingly, we suggest that the emplacement time of the Hegenshan ophiolite should have occurred earlier than the deposition of the Gegenaobao Formation, most likely during the time between 308 and 330 Ma, instead of the Silurian, Devonian or Mesozoic as previously considered.
The super-large Shuangjianzishan Pb–Zn–Ag deposit is a newly discovered deposit located in the Huanggang–Ganzhuermiao polymetallic metallogenic belt of Inner Mongolia, NE China. The deposit's resource includes 0.026 Mt Ag, 1.1 Mt Pb, and 3.3 Mt Zn. The deposit is controlled by a NW-trending ductile shear zone and NE- and NW-trending faults in black pelite assigned to the lower Permian Dashizhai Formation. LREE enrichment, HREE depletion, Nb, Ta, P, and Ti depletion, and Zr and Hf enrichment characterize felsic magmatic rocks in the Shuangjianzishan Pb–Zn–Ag district. The ages of porphyritic monzogranite, rhyolitic crystal–vitric ignimbrite, and porphyritic granodiorite are 254–252, 169, and 130 Ma, respectively. Pyrite sampled from the mineralization has Re–Os isochron ages of 165 ± 7 Ma, which suggest the mineralization is associated with the ca. 169 Ma magmatism in the Shuangjianzishan district.
Zircons extracted from the porphyritic granodiorite yield εHf(t) values of − 11.34 to − 1.41, with tDM2 dates of 1275–1901 Ma. The εHf(t) values of zircons in the rhyolitic crystal–vitric ignimbrite and the ore-bearing monzogranite porphyry are 7.57–16.23 and 10.18–15.96, respectively, and their tDM2 ages are 177–733 and 257–632 Ma, respectively. Partial melting of depleted mantle resulted in the formation of the ca. 254–252 Ma ore-bearing porphyritic monzogranite and the ca. 169 Ma rhyolitic crystal–vitric ignimbrite; dehydration partial melting of subducted oceanic crust resulted in the formation of the ca. 130 Ma porphyritic granodiorite. The porphyritic monzogranite was emplaced during the late stages of closure of the Paleo-Asian Ocean during the transformation from a collisional to extensional tectonic setting. The ca. 170 and ca. 130 Ma magmatism and mineralization in the Shuangjianzishan district are related to subduction of the Mongolia–Okhotsk Ocean and subduction of the Paleo-Pacific Ocean Plate, respectively.
The Bianjiadayuan Pb-Zn-Ag deposit in the Southern Great Xing’an Range consists of quartz-sulfide vein-type and breccia-type mineralization related to granite. Vein orebodies are localized in NW-trending extensional faults. Hydrothermal alteration is well developed and includes silicification, potassic alteration, chloritization and sericitization. Three stages of mineralization are recognized based on field evidence and petrographic observation and are marked by assemblages of quartz-arsenopyrite-pyrite (stage I), quartz-pyrrhotite-chalcopyrite-sphalerite (stage II) and quartz-galena-silver minerals (stage III). The granite, with a zircon age of 143.2 ± 1.5 Ma (n = 14, MSWD = 0.93), is subalkaline, peraluminous and is classified as A2-type granite originating in a post-orogenic extensional setting during the opening of suture zone between the North China Craton and the Siberia Craton from the Late Jurassic to the Early Cretaceous. The δ34SCDT values of sulfides, ranging from 3.19 to 10.65‰, are not consistent with the majority of magmatic hydrothermal deposits in the SGXR, possibly implying accessory source in addition to magmatic source. Microthermometric measurements show that ore minerals were deposited at intermediate temperatures (347.8-136.4 °C) with moderate salinities (2.9-14.4 wt% NaCl). Ore-forming fluids were derived largely from magmatic hydrothermal processes, with addition of meteoric water in late stage. Successive precipitation of Pb, Zn and Ag occurred with changes of physicochemical conditions. Overall considering mineralization features, ore-forming fluids and materials and tectonic setting and comparing with adjacent deposits, the Bianjiadayuan deposit is a mesothermal magmatic hydrothermal vein-type Pb-Zn-Ag deposit controlled by fractures and related to A2-type granite in response to the tectonic/magmatic/hydrothermal activity in late Jurassic. Besides, the explosive breccias in the west area require more attention in future exploration.
A selected suite of fresh volcanic rocks from the New Britain island arc has been analyzed for 143Nd/144Nd, 87Sr/86Sr, major and trace elements to investigate relationships between isotopes, trace elements and petrology, and depth to the underlying Benioff zone. From these relationships inferences about magma generation are made utilizing Nd and Sr isotope systematics in possible source materials. Lavas ranging in composition from basalt to rhyolite show minimal variation of 143Nd/144Nd. Small variations in 87Sr/86Sr do not correlate with depth to the Benioff zone, but are related to magma type. Nd-Sr isotopes suggest that island arc lavas in general are derived from a mixture of suboceanic mantle and hydrothermally altered mid-ocean ridge-type basalt, but the New Britain magma source appears homogeneous with little indication of either the involvement of oceanic crust or mantle inhomogeneity. Trace element patterns in New Britain lavas are not consistent with Nd isotope data for currently accepted petrologic and trace element models of magma genesis. Mafic lavas from New Britain and other island arcs have anomalously high Sr/Nd, possibly due to components derived from subducted oceanic crust.