Field investigations, petrology, geochemistry, zircon U-Pb geochronology and Hf isotope analysis were performed to investigate the petrogenesis of Ningjiawan pluton, in an attempt to shed light on its geodynamic significance. LA-ICP-MS zircon U-Pb dating from two samples yielded ages of 2364±6 Ma (MSWD=0.13) and 2360±23 Ma (MSWD=4.0) respectively, indicating that the magma emplaced and crystalized in Paleoproterozoic. The pluton contains high concentrations of alkaline, K and Si, had elevated FeO^T/MgO ratios and high field strength element (HFSE) contents, was enriched in Rb, Ba, Th and U elements, was depleted in Ca, Mg, P and Ti, and possessed a “seagull-type” chondrite-normalied REE pattern with significantly negative Eu anomalies (δEu=0.13−0.36) and enrichment in the LREE relative to the HREE, exhibiting the traits of the highly fractionated Itype granite. Relatively high whole-rock Y/Nb values (1.2−2.8), together with positive ε_Hf(t) values (+1.6−+6.4), and t_DM1(Hf) and t_DM2(Hf) ages of 2449−2629 Ma and 2474−2711 Ma respectively on the zircon grains, signified that they were products derived from magma mixing between crust and depleted mantle sources. Moreover, distinctive negative Nb, P and Ti anomalies and positive Ce, Nd and Zr anomalies, characteristics of continental margin arc, combining with the regional geological background, indicate that Ningjiawan pluton is very likely to form in island arc setting.

Zircon SHRIMP U-Pb ages and LA-MC-ICP-MS Lu-Hf isotopic compositions of a rhyolite sample and a tuff sample of Baoligaomiao Formation from Baiyinwula region and Qinggelebaolage region respectively in the middle Inner Mongolia were determined. Zircon U-Pb dating gives the eruption age of rhyolite from the Baiyinwula region as 300.0±2.9 Ma, indicating that the volcanic member of Baoligaomiao Formation formed during the Late Carboniferous. The Qinggelebaolage tuff, which was considered as a part of Baoligaomiao Formation, has a zircon SHRIMP U-Pb age of 159.6±1.4 Ma, belonging to Late Jurassic Manketouebo Formation, with three ages of captured zircons (291.8±3.4, 304.0±3.3 and 734.7±9.2 Ma, respectively). In-situ zircon LA-MC-ICP-MS Hf analyses show that magmatic zircons from Baiyinwula rhyolite and Qinggelebaolage tuff have ε_Hf(t) values of +10.5?+12.9 and +10.1?+13.1, with T_DM^C of 493?645 Ma and 369?563 Ma, respectively. Thus, the Baiyinwula rhyolite should be derived from partial melting of Late Paleozoic juvenile crust with involvement of ancient crustal materials whereas the Qinggelebaolage tuff should be generated by partial melting of Late Paleozoic crust. Integrating previous studies, the results review that the Mesozoic and Paleozoic volcanic rocks in the Uliastai continental margin might be derived from similar sources, revealing that there was an important crustal accretion event in Late Paleozoic. Moreover, two Paleozoic captured zircon grains in Qinggelebaolage tuff, which have U-Pb ages of ca. 300 Ma, are similar in Hf isotopic features to the magmatic zircons from both the Baiyinwula rhyolite and the Qinggelebaolage tuff, signifying significant crust reworking during formation of the Late Jurassic Qinggelebaolage tuff. These results, together with previous data from the literature, indicate that in the Inner Mongolia Orogenic Belt, a transition from island arc to post-collision extension related to evolution of Paleo-Asian Ocean occurred at ca. 300 Ma, whereas the influence of the Mongol-Okhotsk tectonic regime was responsible for the Mesozoic volcanism (ca. 160 Ma).

In order to understand the Late Paleozoic tectonic setting of eastern part of Central Asian Orogenic Belt more deeply, the Permian volcanic rocks from Xi Ujimqin Banner, Inner Mongolia were selected to study their geochronology and geochemistry. The contents of major elements, the age, the contents of trace elements and REEs and the Sr-Nd isotopes of the volcanic rocks were measured by X-ray fluorescence spectrometry (XRF), SHRIMP zircon U-Pb, ICP-MS and ISOPROBE-T, respectively, and the results are as follows. The volcanic rocks consist of subordinate basaltic andesites and dominant rhyolites, with the SiO₂ content ranges of 53.54%?54.71% and 72.61%?80.81%, respectively. The SHRIMP zircon U-Pb age of one rhyolite specimen is about 279 ± 4.3 Ma, indicating that the rhyolites erupted in Early Permian. The basaltic andesites are characterized by slightly enriched LREE, depleted HREE, slightly negative Eu, Nb, Ta and Sr anomalies, and high abundances of LILE and HFSE, with the (La/Yb)_N ratios of 2.06 to 2.34. The mafic rocks may be inferred to generate from deep non-primitive mantle largely mixed by crustal source according to these features above. The rhyolites are characterized by slightly enriched LREE, depleted HREE, intensively negative Eu, Sr, P and Ti anomalies, slightly depleted Nb and Ta, and high abundances in K, Zr and Hf, with the (La/Yb)_N ratios ranging from 1.70 to 3.81, relatively high positive ε_Nd(t) values (+3.98?+5.62) and relatively young T_DM (490?690 Ma). The felsic rocks show an A-type affinity and may be inferred to come from a juvenile crustal source. According to their geochemistry, regional geology and previous studies, these bimodal volcanic rocks were generated by intra-plate volcanism and formed in a post-collisional extensional setting.

Tongchang dioritic pluton in Southern Shaanxi Province is located in the tectonic domain of the Mianxian-Lueyang-Yangpingguan triangle block, northern margin of Yangzi Craton, and consists mainly of diorite, quartzdiorite and granodiorite. Zircon grains separated from these rocks are dated using LA-ICPMS and SHRIMP U-Pb isotopic methods. The dating results indicate three intrusive stages of the Tongchang dioritic pluton, and early diorite emplaced at 879±7 Ma; middle quartz diorite at 848±5 Ma to 840 ±7 Ma, with copper ore-bearing albitite emplced at 834±7 Ma, which is consistent with the crystallization age of quartz diorite within error range, and the last granodiorite at 824±5 Ma. These zircon U-Pb isotopic dating results reveal that the emplacements of the Tongchang diorites and related copper deposit did not occur in Paleozoic but in Jinning stage of Neoproterozoic era. The magmatic activity and related copper deposit mineralization are important responses to the breakup event of global Rodinia supercontinent( 860-750 Ma).

To study the petrogenesis and tectonic setting of Langao mafic volcanic rocks in South Qinling orogenic belt, basalts and volcanic breccias are sampled from Langao County for petrography, major elements, trace elements and REE analysis. The results show that they are classified to alkaline basalts, and characterized by strong differentiation between LREE and HREE, Rb,K depletion relative to Th, Hf and no Nb, Ta, Zr, Ti negative anomalies. All of the samples display highly consistent REE patterns and trace elements spider diagrams with OIB. Petrogenenis studies reveal that they were derived from a congenetic primitive magma which was the product of low-degree partial melting of the spinel-garnet lherzolites and garnet lherzolites. These rocks mainly underwent fractional crystallization of clinopyroxene with minor plagioclases and were not accompanied by contamination of continent crustal materials during their magmatic evolution processes. Tectonic discrimination for mafic volcanics, using trace elements, and regional geological analysis demonstrate that Langao mafic volcanic rocks were most likely formed in the ocean basin plateau or ocean island setting.

Zhashui granitoids and Dongjiangkou granitoids in the South Qinling tectonic domain of the Qinling orogen, ShanXi province, are composed of porphyry-like granodiorites and porphyry-like monzogranites. LA-ICP-MS zircon U-Pb dating,in conjunction with CL-i magery, reveals that the Zhashui porphyry-like monzogranite (sample ZS01-01) emplacedfrom209±2 Mato 199±2 Ma, and Dongjiangkou porphyry-like monzogranite (sample ZS04-01) from219±2 Mato 209±2 Ma. Integrated with the previous studies in regional tectonic setting and geochemical characteristics, the two granitoids formed in one geological event. Emplacement of the Dongjiangkou instrusion is slightly earlier than Zhashui intrusion, and second emplacement of the Dongjiangkou intrusion occurred at synchronous time with the main emplacement of the Shashui intrusion. These new dating data of these two intrusions indicates existing three stages of the tectono-magma activities during ～219 Ma to ～199 Ma along Shangdan suture belt in the north margin of the South Qinling tectonic domain.

Xiba granitoids are located in the South Qinling tectonic belt, Shaanxi province, which consist of granodiorite, monzogranite and tonalite. LA-ICP- MS zircon U-Pb dating yields two concordant ages, 219 ±1 Ma for monzogranite sample XB01-2, and 218±1 Ma for granodiorite sample XB06-1. The ages for two samples are uniformintest errors, indicating a crystallization age of ～218 Ma. This result, together with the previous studies concerning regional tectonic setting and geochemical characteristics of Xiba granitoids, show that they are produced in the magmatism event of the main orogenic stage of the Qinling orogenic belt.

Guangtoushan granitoids are locatedin the north of Mianlue suture zone, which consist of tonalites and monzogranites. Thetonalites display gneissic feature, which are locally mylonitized into granitoid mylonites. The weakly gneissic to massive monzogranites with a little garnet emplaced after the mylonite zone. LA-ICPMS zircon U-Pb isotope dating reveals that Guangtoushan granitoidpluton experiencedtwo stages of emplacement. The earlier gneissic tonalite, sample GT18-01, emplaced at 221±6 Ma and the later monzogranite, sample GT11-01, yields a crystalline age of 199±4 Ma. Integrated with the previous studies in regional tectonic setting and geochemical characteristics, the early tonalites of the Guangtoushan granitoids were most likely to emplace at ～221 Ma, which possibly represents the arc magmatism of oceanic crust subduction before Mianlue ocean basin closed. Then, Mianlue ocean basin closed andthe Yangtze Craton was amalgamazed with Qinling micro-block, which formed Mianlue suture zone. The S-type monzogranitic magmatismprobably occured in the syn-collision tectonic setting during the main orogenic stage of the Qinling orogenic belt at ～199 Ma. The closure event of the Mianlue ocean basin, which formed the Mianlue suture zone, occured between ～221 Ma and ～199 Ma.

The Paleoproterozoic Wangjiahui granitoid intrusion, west segment of Wutai mountains, consists mainly of quartz monzodiorite, granodiorite, monzogranite and adamellite. Petrochemical analysis of these rocks indicates that they are of metaluminous calc-alkaline feature (A/CNK<1.1). These rocks are characterized by the negative anomalies of Nb, Ta, Sr, P and Ti, and LILEs-enriched in primitive mantle normalized trace-element patterns. Especially, they display obviously high K₂O and negative Sr and Eu anomalies, which are significantly different from the island arc granitoids. Combined with their ε_Nd(2.1Ga) range of -3.82 to -2.80 and T_DM = 2.6 ~ 2.7Ga, these granitoids are most likely to be derived from the partial melting of hybrids both ~ 2.6Ga metavolcanic materials in Archean Wutaishan magmatic arc and older continent crustal materials under lower than 1.2GPa. Petrological and geochemical characteristics of Wangjiahui granitoid intrusion suggest that is probably fored under post-collisional tectonic background. Integrated with other late Paleoproterozoic granitoids within the Central Tectonic Zone, it indicates that there was a tectonic transitional process from extension to compression during late Paleroproterozoic in the southern segment of the Central Zone of NCC.

Neoarchean Wutaishan granitoids (～2.540 Ga) are mainly consisted of granodiorite, monzogranite, a little tonalite, trondhjemite. The geochemistry in whole rocks indicates that they have the characters of middle to high potassium calc-alkaline granitic magma. They exhibit the LILE enrichments and higher w(Rb)/w(Sr) ratios (Rb/Sr), relatively lower w(Sr)/w(Y) and w(La)_n/w(Yb)_n ratios, w(Nb)/w(Ta) and w(Zr)/w(Hf) ratios are similar to Chondrite, right inclined REE patterns, and Nb, Ta, Ti depletion, but all of them have the neodymium T_DM＝2.54～2.72 Ga and the evidently positive ε_Nd(t) values. These important geochemical features indicate that the calc-alkaline granitic magma formed in the Neoarchean oceanic island arc tectonic environment, derived from the partial melting of the juvenile original basaltic crust, and underwent some crystallization fractionation. The Neoarchean oceanic crust subducted to the oceanic island arc and dehydrated, caused the partial melting of the overlain mantle wedge, formed the underplating basaltic rocks underlain the island arc. These basaltic rocks were partially melted in the environment of less 37km crustal depth and formed the Neoarchean Wutaishan calc-alkaline granitic magma.