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Research on the geological process of the Xing'an -- Mongolia Orogenic Belt has attracted the attention of scholars both domestically and internationally. Its genesis and tectonic location may help revealing the geological processes asscoaited with the evolution of the Xing'an -- Mongolia Orogenic Belt. This study focuses on the development of the Permian granitic complex in Jielin Ranch, and we conduct systematic geological, petrographic, zircon U-Pb chronology, Hf isotope, and geochemical tracing of rock elements for evidence. The results show that the granitic complex is mainly composed of monzogranite and syenogranite, which obtained zircon U-Pb ages of 291.1 ± 1.1 Ma and 260.8 ± 1.1 Ma, respectively. The monzogranite and syenogranite are all acidic and aluminum rich rocks, and the monzogranite is a potassium rich, high potassium calcium alkaline rock series with relatively low REE content, high degree of fractionation, and insignificant europium anomalies, enriched with LILE (Rb, Th, U, K), deficient elements such as Ba, Sr, Nb, Ti, and P, εHf(t) values are from +4.1 to +7.0 (TDM2=1130-920 Ma). Geochemistry shows that the monzogranite belongs to high fractionation of I-type granite, which formed in a subduction-compressional or extension tectonic environment, and Middle Neoproterozoic lower crust rocks as the major source material of magma. The syenogranite is a potassium high potassium transitional rock series with a high rare earth content (214 x 10-6~325 x 10-6), low LREE/HREE (2.54-6.41), δEu (0.04-0.15) and the typical "four component effect" fractionation mode is enriched in large ion lithophilic elements such as Rb, Th, K, and strongly depleted in elements such as Ba, Sr, Nb, Ta, Ti, P, εHf(t) values are from +4.2 to +8.6 (TDM2=738-1228 Ma), suggesting the characteristics of an "A2 type" granite. The magma originated from partial melting of the lower crust of the Middle and Neoproterozoic with the participation of mantle derived melts, and was formed in a back-arc extensional environment. This suggests that the study area experienced a subduction-compressional or extension tectonic environment during the early Permian and a brief backarc extension process in the late Permian. [ABSTRACT FROM AUTHOR]

Integrated geochemical, U-Pb zircon, and Pb isotopic data from granitoids of the Wulandele porphyry molybdenum deposit, northeastern Inner Mongolia, are reported to disclose the possible magmatic process and Mo ore-forming process. LA-ICP-MS zircon U-Pb dating constrains the timing of the quartz diorite and monzonitic granite to 282 ± 2.4 Ma and 135.4 ± 2.1 Ma, respectively. The ages are accordant with geological facts which state that the shallow Permian granitoids are only the ore-hosting rock while the concealed Cretaceous fine-grained granite is the causative intrusion. Whole-rock geochemical data show that the granitoids belong to the high-K calc-alkaline series, and are enriched in LILEs, but depleted in HSFEs. Permian granitoids exhibit I-type characteristics, while Cretaceous granite is akin to A-type granite. Pb isotopic ratios are consistent between Permian granitoids and Cretaceous granite with ratios of 206Pb/204Pb = 18.048–18.892, 207Pb/204Pb = 15.488–15.571, and 208Pb/204Pb = 37.066–38.441. Considering geological and geochemical features together, Permian granitoids are interpreted as subduction-related continental margin high-K calc-alkaline rocks, while Cretaceous granite may be the result of the remelting of the relic Permian arc in an extensional environment induced by the rollback of the Paleo-Pacific plate. Different from classical porphyry-type deposits, the Wulandele Mo deposit, which formed in an intraplate tectonic setting, indicates that the intraplate porphyry Mo deposit should be one of the important exploration targets in the Central Asian Orogenic Belt, especially its eastern segment. [ABSTRACT FROM AUTHOR]

The Zhunsujihua porphyry Mo-Cu deposit is located in the Erenhot–East Ujimqin metallogenic belt in northeastern China. Granodioritic intrusions in the mining area are dominated by granodiorite and granodiorite porphyry, but the Mo mineralization is limited within the granodiorite. Zircon LA-ICP-MS U-Pb dating yields crystallization ages of 301.5 ± 3.0 Ma for granodiorite and 296.0 ± 3.0 Ma for granodiorite porphyry. These ages constrain the magmatic activity at the Zhunsujihua deposit that took place during the subduction of the Paleo-Asian oceanic plate. Whole-rock geochemical data suggest that the granodioritic intrusions belong to calc-alkaline and high-K calc-alkaline series, and are characterized by enrichment in K, Rb, U, Th, and Pb, and depletion in Nb, Ta, Ti, and P. The negative Eu, Ba, and Sr anomalies suggest that they have experienced extensive fractionation of plagioclase. Trace element compositions of zircons from the Zhunsujihua deposit provide constraints on the oxygen fugacity (ƒO2) of the magma, which is shown to high values with ∆FMQ = +0.5 to +5.6. The wide range of zircon εHf (t) (+1.3~+9.4) values, positive whole-rock εNd (t) (+2.5~+3.9) values, and relatively low initial (87Sr/86Sr)i (0.70367~0.70561) ratios indicate that the magmas mainly originated from a juvenile lower crust source derived from depleted mantle, but mixed with pre-existing crustal components. Moreover, the juvenile lower crust represents the main source of Mo for the Zhunsujihua deposit. A high magmatic oxygen fugacity and fractional crystallization played key roles in forming the Zhunsujihua deposit. [ABSTRACT FROM AUTHOR]

[Display omitted] • The mineralization of the Quanzigou Mo deposit is closely related to the quartz porphyry. • The Hongniangshan complex mainly originated from partial melting of a Paleoproterozoic lower crust. • Both the medium–coarse-grained granite and the porphyritic granite experienced magmatic mixing. • Magma of the complex experienced fractional crystallization in different extent. • The Hongniangshan complex emplaced in a post-collisional tectonic setting. The Quanzigou porphyry molybdenum deposit is located in Fengzhen County, Inner Mongolia, China, belonging to the northern margin of the North China Craton. A Yanshanian granitic complex, namely the Hongniangshan complex, is exposed in the deposit, mainly composed of medium–coarse-grained granite, porphyritic granite, and quartz porphyry. The Mo orebodies occur mainly in the porphyritic granite as ore-bearing quartz veins or veinlets. Previous study on molybdenite Re–Os and zircon U–Pb dating suggests that the Hongniangshan complex emplaced during 173–160 Ma and that the Quanzigou Mo deposit formed at ca. 160 Ma. Geochemical analyses in this study show that all these Middle–Late Jurassic granites are peraluminous, high-K calc-alkaline granite, featured by enrichment in Rb, Th, U, Hf, and Zr and depletion of Ba, P, and Ti, with high K 2 O/Na 2 O ratios. Nearly all the samples from the medium–coarse-grained granite and the porphyritic granite show weakly negative Eu anomalies, whereas the negative Eu anomalies of the quartz porphyry are moderate or strong. The Hongniangshan complex has low zircon ε Hf (t) values (−14.4 to − 6.7), old single-stage and two-stage model ages (1099–1471 Ma and 1637–2124 Ma, respectively), and low K-feldspar Pb isotopic compositions (206Pb/204Pb = 17.019–17.590, 207Pb/204Pb = 15.365–15.489, 208Pb/204Pb = 37.002–37.670), with K-feldspar δ18O values of 8.0–10.4‰, suggesting that the granitic complex was predominantly originated from a Paleoproterozoic lower crust source. Geochemical characteristics, combined with results from previous studies, show that the Quanzigou Mo mineralization was closely related to the quartz porphyry. The Middle Jurassic medium–coarse-grained granite was likely formed in the back-arc extension environment triggered by the subduction of the Mongol–Okhotsk Ocean and the Paleo-Pacific plate, and the formation of the Late Jurassic porphyritic granite and the quartz porphyry was controlled by both the post-collisional process of the Mongol–Okhotsk orogenic belt and the coeval subduction of the Paleo-Pacific plate. [ABSTRACT FROM AUTHOR]