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Shamai tungsten deposit is a medium sized magmatic hydrothermal deposit located in Dong Ujimqin Banner of Inner Mongolia. The ore bodies mainly occur in biotite monzonite granite and biotite monzonite granite porphyry. In this study, the petrography, LA-ICP-MS zircon U-Pb chronology and petrogeochemistry of biotite monzonite granite and biotite monzonite granite porphyry are studied in order to clarify the genesis and age of the two rocks and provide further data for regional prospecting. The results show that the LA-ICP-MS zircon U-Pb ages of biotite monzogranite are 135. 6±1.6 Ma and 136.3±1.8 Ma, and the biotite monzonite granite porphyry is 138. 6±1.1 Ma. The main elements show they are peraluminous high potassium calc alkaline granite which are characterized by high SiO2(73.73%~78.23%), Na2O+K2O (7.56%~8.89%)and low MgO (0.09%~0.20%), CaO (0.51%~ 0.89%), Ti O2 (0.03% ~0. 12%). They are enriched in Rb, K, Th, U, and depleted in Sr, Ba, Nb, P, Ti, with strong negative Eu anomaly and high FeOT content, FeOT/MgO and FeOT/(FeOT+MgO) ratio indicating the characteristics of A-type granite. The zircon U-Pb age of the Shamai granite is consistent with the age range of the large-scale metallogenesis in eastern China. The tectonic environment discrimination diagrams indicate that it was formed in the extensional tectonics environment after the continental collision in the Yanshanian period, which is related to the lithospheric thinning of northern margin of the North China Craton. [ABSTRACT FROM AUTHOR]

The Xing–Meng Orogenic Belt hosts an amount of low-sulfidation epithermal gold deposits. However, the tectonic-magmatic setting remains problematic, which hinders understanding the factors that control the gold endowment in the region. Wulaga deposit is the largest low-sulfidation epithermal gold deposit in the northeastern Xing–Meng Orogenic Belt. Gold mineralization occurs in the crypto-explosive breccia zone of subvolcanic granodiorite porphyry. Zircon U–Pb ages of three granodiorite apophyses and previous pyrite Rb–Sr dating (113.8 ± 4.4 Ma) indicate granodiorite porphyry and gold mineralization was coeval. The ore-related granodiorite porphyry is moderate SiO2, high-K calc-alkaline, and metaluminous, suggesting an I-type granite. Moreover, Wulaga granodiorite porphyry displays low initial 87Sr/86Sr ratios and positive εNd(t) values with TDM2(Nd) of 799.7–897.4 Ma and εHf(t) values with TDM2(Hf) of 652–785 Ma, indicating that it was derived from partial melting of the Neoproterozoic juvenile mafic lower crust. Ti-in-zircon thermometry, medium–high Sr/Y ratio, high Ba/La, and fO2 value indicate that Wulaga granodiorite porphyry formed at relatively low temperatures (∼700 °C), rich water, and high fugacity within the stability field of garnet in the juvenile lower crust. Combined with ore-related tectonic-magmatic activities in the Wulaga, Dong'an, and Sandaowanzi gold deposits, the Early Cretaceous low-sulfidation epithermal gold deposits in the Xing–Meng Orogenic Belt were formed from magmatic-hydrothermal events triggered by mutual interaction between post-orogenic lithospheric extension related to the closure of the Mongol-Okhotsk Ocean and arc-back extension associated with rollback of the Paleo-Pacific Ocean plate. These data indicate the potential existence of the Early Cretaceous epithermal gold deposits that are related to the contemporaneous igneous activity.

The Xing-Meng Orogenic Belt is characterized by intense and widespread Mesozoic granitic magmatism related to large-scale W mineralization. Three periods of W-mineralized granitic magmatism can be distinguished: Early Triassic, Early–Middle Jurassic, and Late Jurassic–Early Cretaceous. Early Mesozoic W-mineralized granitoids are I-type granites with metaluminous to weakly peraluminous characteristics, with higher Rb concentrations and lower K/Rb ratios than coeval W-barren granitoids. Late Mesozoic W-mineralized granitoids belong to highly fractionated A-type granites, enriched in Rb, Th, and U, and depleted in Ba, Sr, P, Ti, and Eu. They have higher Rb/Sr and U/Th ratios, and lower (La/Yb)N, LREE/HREE, Eu/Eu*, K/Rb, Zr/Hf, Nb/Ta, and Y/Ho ratios than contemporary W-barren granitoids. Mesozoic W-mineralized granitoids mainly originated from the partial melting of juvenile lower crust, whereas Early Mesozoic W-mineralized granitoids encompassed minor reworked ancient crustal material. Triassic W-mineralized granitoids formed in a syn- and/or post-collision setting related to the closure of Paleo-Asian Ocean. Early–Middle Jurassic W-mineralized granitoids formed in a compressional setting created by the subduction of Paleo-Pacific Ocean plate in the east and the closure of Mongol-Okhotsk Ocean in the west. Late Mesozoic W-mineralized granitoids formed in a post-orogenic extensional setting controlled by the MOO and PPO tectonic regimes. [ABSTRACT FROM AUTHOR]

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The end-Permian to Early-Middle Triassic magmatic rocks in Inner Mongolia can provide valuable insights into the relationships between the collisional processes and the magmatic responses during the final orogenic evolution of Xing-Meng orogenic belt (XMOB). This paper presents zircon U-Pb ages and Hf isotopes, whole rock geochemical and Sr-Nd-Pb isotopic data for the Early-Middle Triassic diabases and monzogranites from the Langshan area, southwestern XMOB. Our results suggest that the studied diabases and monzogranites were respectively formed during Early Triassic and Middle Triassic. The Early Triassic diabases are characterized by "arc-like" geochemical signatures, including enrichment in Rb, U and K, and depletion in Nb, Ta, P and Ti. They have negative to weak positive εNd (t) values (−3.1 to +1.5) and relatively high initial ratios of 208Pb/204Pb (35.968–37.346), 207Pb/204Pb (15.448–15.508) and 206Pb/204Pb (16.280–17.492), indicating a subduction-metasomatized enriched lithospheric mantle source. Their low Ba/Rb (2.72–6.56), Ce/Y (0.97–1.39) and (Tb/Yb)N ratios (1.31–1.45) suggest that the parental magma was likely originated from low degree partial melting of the phlogopite-bearing lherzolite in a spinel-stability field. The Middle Triassic monzogranites show high Sr/Y ratios, low MgO, Cr and Ni contents, high Zr/Sm ratios (40–64), negative zircon εHf(t) values (−25.8 to −8.8), as well as relatively flat heavy rare earth element patterns. They were likely derived from low degree partial melting of a moderately thickened ancient lower crust. The diabases and the slightly postdated high Sr/Y granites in this study represent the magmatic responses to the final orogenic evolution in the southwestern XMOB. Together with regional works, we propose that the slab break-off of the Paleo-Asian oceanic lithosphere following the terminal collision between the North China Craton and the South Mongolia terranes triggered asthenospheric upwelling, and the ongoing convergence further initiated moderately crustal thickening and uplift in the XMOB. [ABSTRACT FROM AUTHOR]

The Xing-Meng Orogenic Belt (XMOB) hosts significant Au-dominant polymetallic mineral deposits. Although these deposits mostly formed in the Mesozoic, Permian Au deposits are also present but less well studied. In the Bilihe and Hadamiao gold mining areas, granitic intrusions that are associated with gold mineralization were dated by LA-ICP-MS at 272.7-259.7 Ma. These intrusions consist of granodioritic porphyry and quartz diorite that both represent calc-alkaline metaluminous I-type granites. These granitoids exhibit enrichment in LREEs and LILEs, depletion in HREEs and HFSEs, and low Sr/Y ratios, suggesting that these rocks have an island-arc affinity. The εHf(t) values of the Bilihe granodioritic porphyry and Hadamiao quartz diorite range from −0.3 to +8.9, with TDM2 values ranging from 0.7 to 1.3 Ga, and from +2.5 to +13.5, with TDM2 values ranging from 0.4 to 1.1 Ga, respectively. The zircon δ18O values of the granitic porphyry and quartz diorite range from 6.9 to 7.6‰ and from 5.0 to 6.4‰, respectively. A simple binary Hf-O isotope mixing model shows that the assimilation of 10-15% sediments by MORB could have generated the Bilihe granodioritic porphyry, and that the assimilation of less than 5% sediments by MORB could have generated the Hadamiao quartz diorite. Combined with previous studies of the Late Carboniferous to Permian igneous rocks in the southern region of the XMOB, these new data suggest that the Bilihe and Hadamiao ore-related intrusive rocks formed in a continental-arc setting associated with the subduction of the Paleo-Asian oceanic slab. This setting indicates the potential existence of subduction-related gold deposits that are related to contemporaneous igneous activity. [ABSTRACT FROM AUTHOR]

We undertook zircon U-Pb dating and geochemical analyses of the Weitingchagan (WT) pluton in the Dong Ujimqi area, Northeast China, with an aim of determining their ages, petrogenesis and sources, which are important for understanding the Late Palaeozoic tectonic evolution of the Xing-Meng Orogenic Belt. The WT pluton consists of coarse- to medium-grained porphyritic granites in the core and medium- to fine-grained monzogranites in the rim, contains abundant microgranular enclaves and is intruded by small amounts of muscovite monzogranites. The results of LA-ICP-MS zircon U-Pb dating indicate that the WT composite pluton formed during the Late Carboniferous-Early Permian with the ages ranging from 289 Ma to 312 Ma. Petrological and geochemical characteristics of the WT pluton were derived from the partial melting of crustal materials, and the AFC process played an important role in the magmatic evolution. The porphyritic granites are I-type granite, and the monzogranites and muscovite monzogranites are highly fractionated I-type granite. Combined with previous studies on the contemporaneous magma-tectonic activities in the Uliastai Continental Margin, the study suggests that the WT pluton formed in an extensional environment, which may relate to the closure of the Palaeo-Asian Ocean. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Zircon U–Pb dating and whole-rock geochemical data for Carboniferous–Permian (meta-) sedimentary sequences, igneous rocks, and Precambrian amphibolite in the eastern Xing-Meng Orogenic Belt (XMOB) were used to constrain the final stage evolution and the position of closure of the Paleo-Asian Ocean (PAO). Detrital zircons from Late Paleozoic strata range in age from Archean to Late Paleozoic, with major age groups at ~ 1.0–0.7 Ga and ~ 0.5–0.25 Ga in the northern part and at ~ 2.7–2.5 Ga, ~ 2.1–1.8 Ga, and ~ 0.5–0.25 Ga in the southern part of the XMOB. Striking changes in zircon age distribution patterns indicate inputs to these strata were separated by the Paleo-Asian Ocean (PAO) in the Late Paleozoic. The PAO closed along the Solonker–Linxi suture. The Late Paleozoic formation ages (~ 346 Ma, ~ 303 Ma, and ~ 269 Ma) of the igneous rocks with arc-like geochemical features south to the PAO, together with previously published data on the regional igneous rocks and ophiolites, indicate double-side subduction of the PAO in the Late Paleozoic. [ABSTRACT FROM AUTHOR]

The eastern Xing'an-Mongolian (Xing-Meng) Orogenic Belt (XMOB) is one of the important areas of porphyry copper (Cu)-molybdenum (Mo) deposits in China. However, studies on the exact ages of mineralization and their geodynamic significance are very limited. In this study, granodioritic rocks from the Duobaoshan Cu deposit and Daheishan Mo deposit were selected to make zircon SHRIMP U-Pb analyses in order to constrain their mineralization ages. Geochronological data indicate that two episodes of mineralization took place in the Duobaoshan Cu deposits. The granodiorite related to the Duobaoshan porphyry Cu deposit was formed in the Early Paleozoic with zircon U-Pb age of 485±8 Ma, whereas the granodiorites related to the Sankuanggou skarn-type Cu deposit were emplaced in the Jurassic with zircon U-Pb ages of 176±3 and 177±3 Ma. In the Daheishan area of Jilin Province, the emplacement age of the granodiorite porphyry related to the porphyry Mo deposit was dated at 170±3 Ma, and the unmineralized monzogranite at 178±3 Ma. Therefore, two episodes of Cu-Mo mineralization were developed in the eastern XMOB, at ∼485 Ma and ∼175 Ma, respectively. Based on the geological history and spatial-temporal distribution of the granitoids in northeastern (NE) China, it is proposed that the Duobaoshan Cu deposit was related to the collision of the Xing'an and Erguna blocks in the Early Paleozoic, and the Sankuanggou Cu and Daheishan Mo deposits were related to subduction of the Paleo-Pacific plate during the Jurassic. [ABSTRACT FROM AUTHOR]

The boundary region of the North China Craton (NCC) and Xing-Meng Orogenic Belt (XMOB), including the northern boundary of the NCC and the southern XMOB, is the ideal area to investigate the spatially uneven lithospheric deformation and associated tectonic evolution in the boundary region of the craton and orogen. The depths and structures of the lithosphere–asthenosphere boundary (LAB) and mid-lithosphere discontinuity (MLD) are the key information to describe the nature and deformation pattern of the lithosphere, and thus can provide basic constraints on the associated tectonic processes and mechanism of the lithospheric deformation. Based on waveform data collected from 226 broadband seismic stations, high resolution spatial variations in the LAB and MLD depths were obtained by using the wave equation migration method for the S-receiver functions. The migrated images show a lateral variation in the LAB depth from 100–120 km in the northern boundary of the NCC to 120–140 km in the southern XMOB. The imaged LAB within the NCC is much shallower than that revealed by mantle xenoliths enclosed in the nearby Early Paleozoic kimberlites (~180 km), suggesting that the cratonic lithosphere of the area may have undergone significant thinning during the Phanerozoic evolution. Furthermore, a coherent MLD is identified at depths of 70–90 km beneath the northeastern NCC, which corroborates the speculation that the MLD probably existed in the eastern NCC before lithospheric destruction in the Mesozoic. The spatial variations in the LAB and MLD depths probably reflect complex lithospheric deformation and thinning around the boundary region of NCC and XMOB. The properties, including the gradient thickness and S-wave velocity contrast, of the two discontinuities further indicate that lithospheric deformation and thinning might be related to partial melting induced by the Big Mantle Wedge associated with the subducting Paleo-Pacific plate and its stagnation during the Late Mesozoic. • Lithospheric structure beneath the boundary region of North China Craton and Xing Meng Orogenic Belt were obtained. • Distribution of MLD provides the speculation that the MLD existed in the eastern NCC before its destruction in the Mesozoic. • Lithospheric deformation and thinning might be related to partial melting associated with the subducting Paleo-Pacific plate. [ABSTRACT FROM AUTHOR]