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Granitic rocks forming in the syn- to post-orogenic stages can trace the compositional and structural complexity of the crust beneath an orogenic belt. The Qinling orogenic belt undertook multiple stages of tectonics and magmatism, resulting in the multifaceted evolution and compositional diversity of the crust. In the present study, the Guangtoushan and Miba plutons in South Qinling were chosen to reveal the crustal heterogeneity in study area via isotopic geochemistry and zircon geochronology. The Guangtoushan pluton was emplaced between ~215 Ma and ~202 Ma and the Miba pluton formed at ~213 Ma, as constrained by zircon U-Pb isotopic dating. Granitic rocks of the Miba pluton are characterized by amphibole bearing and homogeneous composition, with relatively depleted Sr-Nd isotopic compositions (initial 87Sr/86Sr values of 0.7060 to 0.7084 and initial εNd values of −5.4 to −9.5) and high Pb isotopic values. The Guangtoushan pluton contains muscovite and complex inherited zircon grains and has variable Sr-Nd isotopic composition (initial 87Sr/86Sr values of 0.7050 to 0.7091 and initial εNd values of −4.5 to −12.9) and low Pb isotopic values. Felsic magmas of the Guangtoushan pluton should be derived mainly from meta-sedimentary rocks beneath South Qinling, while the Miba pluton originated primarily from partial melting of meta-igneous rocks. The compositional diversity recorded in the Early Mesozoic plutons was caused by the heterogeneous crust, and partial melting was induced by heating of the up-welling asthenosphere in a post-collision setting. [ABSTRACT FROM AUTHOR]

Yanshanian magmatisms are intensive in the eastern Jiangnan orogen and can be divided into early (150–136 Ma) and late (136–120 Ma) stages. About these granitic rocks, the petrogenesis and associated tectonic setting are still hotly debated. The Taiping–Huangshan complex, a representative granitic rock in this region, is selected to perform geochemical studies. Three lithologic units have been identified in the Taiping–Huangshan complex: granodiorite, monzogranite, and alkali‐feldspar granite with zircon U–Pb dating results of 149–144 Ma, 148 Ma, and 135–131 Ma, respectively, belonging to the early stage for the granodiorite and monzogranite, and late stage for the alkali‐feldspar granite. The granodiorite and monzogranite have similar major and trace element characteristics with intermediate‐acidic SiO2 contents ranging from 65.9 to 69.7 wt.%, low Mg# values of 35.8–38.4, enriched LREE, Pb, Th, and U contents, and weak Eu anomalies (δEu = 0.71–0.79). The alkali‐feldspar granite is characterized by high SiO2 contents (73.3–76.6 wt.%), low Mg# (2.6–10.0), enriched Th, U, Ta, Pb, and Nd, depleted high‐field‐strength elements, and pronounced negative Eu anomalies (δEu = 0.01–0.19). The granodiorite and monzogranite have consistent εHf(t) (−5.38 to −9.41) and δ18O (7.18‰ to 11.00‰) values, while the alkali‐feldspar granite has elevated εHf(t) values (−0.96 to −6.48) and δ18O values (6.27‰ to 8.34‰). Integrated geochemical characteristics and batch partial melting modelling constrain that the early stage granitic rocks derived from ca. 8% batch melting of the Neoproterozoic juvenile crust, and the late‐stage granites derived from a similar crust source with a little contribution from mantle. From early to late stage, the tectonic setting translated from post‐orogenic to anorogenic and the later corresponded to a back‐arc extensional setting as increasing of the slab subducted angle of the Palaeo‐Pacific Plate. [ABSTRACT FROM AUTHOR]

Numerous late Mesozoic (Late Jurassic to Early Cretaceous) granitic plutons are present along the southern margin of the North China Craton (s-NCC), which belongs to the northernmost tectonic unit of the eastern Qinling orogenic belt. This tectonic unit records multiple tectonothermal and metallogenic events that occurred after continental collision of the North and South China Cratons in the late Early to Middle Triassic. This study reports the zircon U-Pb ages and the whole-rock and apatite geochemical compositions of the Taishanmiao granite, one of the largest late Mesozoic plutons in eastern Qinling. Three phases of this granite, emplaced between ∼125 and ∼113 Ma, are characterized by uniformly high SiO2 and K2O but low CaO, TFe2O3, and MgO contents and enriched Nd isotopic composition with initial ε Nd values of −13.5 to −12.7. Geochemical features reveal that these are A-type granites derived from partial melting mainly of ancient crust. Temperatures obtained from Ti-in-zircon thermometry and oxygen fugacity (f O2) data indicate that the magma(s) formed at high crystallization temperatures (∼800°–840°C) and f O2 levels (fayalite–magnetite–quartz [FMQ] buffer −1.5 to +1.5). Comparison with neighboring granites, such as the ∼150–130 Ma adakitic Heyu granite and the ∼115 Ma Donggou ore-bearing granite porphyry, implies that the Heyu granite formed from thickened crust and that the Donggou granite porphyry and Taishanmiao granite likely originated from a consistent magma system during the crustal thinning that occurred ∼125–113 Ma, except the porphyry rock was more evolved. This finding implies that their uniform magma chamber could provide sufficient metals and associated materials and even energy for the Donggou Mo deposit. [ABSTRACT FROM AUTHOR]

Mesozoic granitoid rocks in the eastern Qinling terrane along the southern margin of the North China Craton are significant for understanding geodynamics processes related to lithospheric delamination in the Late Mesozoic. In addition, these rocks have close genetic association with the largest Mo-(Au-Ag) polymetallic mineralization belt in China. In the present study, zircon U-Pb ages and elemental and Sr-Nd-Pb isotopic geochemistry are reported for two representative granite plutons (Heyu and Lantian) exposed in the eastern Qinling terrane. Granitoid rocks from both plutons are metaluminous to weakly peraluminous and are classified as I-type granite with formation ages of 145 ~ 135 Ma and 150 Ma, respectively. These rocks are characterized by adakite-like affinity without significant Eu anomalies. Both plutons have relatively high initial 87Sr/86Sr ratios ranging between 0.7063 and 0.7109 and variable εNd(t) values of – 29.2 to – 6.5. Their Pb isotopic compositions are comparable to those of old high-grade metamorphic basement rocks from the North China Craton but are different from those of country rocks from the Xiong'er and Taihua groups. These features indicate genesis via reworking of the lower crust beneath North China and partial involvement of juvenile crustal material to different extents. Occurrences of ca. 1000-Ma-old inherited zircon in the Lantian granites imply the contribution of the Qinling Group in North Qinling to the magma source(s). This magmatism occurred intensively in a transitional setting from compression to extension and was likely induced by lithosphere thinning and asthenosphere upwelling beneath eastern China during the Cretaceous. [ABSTRACT FROM AUTHOR]

The Longwangzhuang pluton is a typical example of Paleoproterozoic A-type granite intrusions at the southern margin of the North China Craton. This pluton is composed of arfvedsonite granite and minor aegirine–augite granites. Samples from both granite types display similar zircon U-Pb ages with 207U-206Pb ages of 1612 ± 19 Ma [mean square weighted deviation (MSWD) = 0.66] and 1609 ± 24 Ma (MSWD = 0.5), respectively. The granites exhibit similar high silica (SiO2 = 71.1–73.4 wt.%), high alkaline (Na2O + K2O = 8.10–9.26 wt.%, K2O/Na2O > 1), and low Al2O3 (11.8–12.8 wt. %) contents and metaluminous to weakly peraluminous bulk chemistry. The chemical variations of the Longwangzhuang pluton suggest the effects of mineral fractionation. In addition, all samples show typical characteristics of A-type granites, such as high 10000Ga/Al ratios (4.10–7.28), high FeOtot/(FeOtot + MgO) ratios (0.88–0.99), and high Zr (484–1082 ppm), Ce (201–560 ppm), and Y (78–156 ppm) contents. The εNd(t) values and the (206Pb/204Pb)t, (207Pb/204Pb)t, and (208Pb/204Pb)t ratios of the arfvedsonite granite samples vary from −4.6 to –5.3, 15.021 to 17.349, 15.241 to 15.472, and 33.206 to 36.905, respectively, and those for the aegirine–augite granite sample amount at −0.2, 14.421, 15.175, and 33.706. The distinct and variable Nd and Pb isotope values indicate the presence of heterogeneous protoliths. Based on its geochemistry, its low initial Pb isotope ratios, and its enrichment in Nd isotopes, we infer that the Longwangzhuang A-type granite is the partial melting product of basement rocks such as the Taihua Group gneisses accompanied by some involvement of juvenile material from the mantle. Together with published data from other Paleoproterozoic A-type granite plutons exposed at the southern margin of the craton, our findings suggest that these granites had a similar origin. Furthermore, geochemically, they can be divided into two groups: A2-type, which formed earlier (~1.8–1.6 Ga), and A1-type, which formed later (~1.6–1.5 Ga). Combining this information with the variations in whole-rock Nd and zircon Hf isotopic composition at ca. 1.6 Ga, we propose that tectonic transformation from post-orogenic to anorogenic magmatism occurred at the southern margin of the North China Craton at that time. [ABSTRACT FROM AUTHOR]

The aim of this article is to examine the geochemistry and geochronology of the Cadomian Mishu granites from northwest Iran, in order to elucidate petrogenesis and their role in the evolution of the Cadomian crust of Iran. The Mishu granites mainly consist of two-mica granites associated with scarce outcrops of tonalite, amphibole granodiorite, and diorite. Leucogranitic dikes locally crosscut the Mishu granites. Two-mica granites show S-type characteristics whereas amphibole granodiorite, tonalities, and diorites have I-type signatures. The I-type granites show enrichment in large-ion lithophile elements (e.g. Rb, Ba and K) and depletion in high field strength elements (e.g. Nb, Ti and Ta). These characteristics show that these granites have been formed along an ancient, fossilized subduction zone. The S-type granites have high K, Rb, Cs (and other large ion lithophile elements) contents, resembling collision-related granites. U–Pb zircon dating of the Mishu rocks yielded238U/206Pb crystallization ages of ca. 550 Ma. Moreover, Rb–Sr errorchron shows an early Ediacaran age (547 ± 84 Ma) for the Mishu igneous rocks. The two-mica granites (S-type granites) show high87Sr/86Sr(i)ratios, ranging from 0.7068 to 0.7095. TheirɛNd values change between −4.2 and −4.6. Amphibole granitoids and diorites (I-type granites) are characterized by relatively low87Sr/86Sr(i)ratios (0.7048–0.7079) and higher values ofɛNd (−0.8 to −4.2). Leucogranitic dikes have quite juvenile signature, withɛNd values ranging from +1.1 to +1.4 and Nd model ages (TDM) from 1.1 to 1.2 Ga. The isotopic data suggests interaction of juvenile, mantle-derived melts with old continental crust to be the main factor for the generation of the Mishu granites. Interaction with older continental crust is also confirmed by the presence of abundant inherited zircon cores. The liquid-line of descend in the Harker diagrams suggests fractional crystallization was also a predominant mechanism during evolution of the Mishu I-type granites. The zircon U–Pb ages, whole rock trace elements, and Sr–Nd isotope data strongly indicate the similarities between the Mishu Cadomian granites with other late Neoproterozoic–early Cambrian (600–520 Ma) granites across Iran and the surrounding areas such as Turkey and Iberia. The generation of the Mishu I-type granites could be related to the subduction of the Proto-Tethyan Ocean during Cadomian orogeny, through interaction between juvenile melts and old (Mesoproterozoic or Archaean) continental crust. The S-type granites are related to the pooling of the basaltic melts within the middle–upper parts of the thick continental crust and then partial melting of that crust. [ABSTRACT FROM AUTHOR]

The article talks about the orogenic event of North Qinling Terrain, understanding the evolution of tectonic plates before the amalgamation of North China Block and South China Block along the Mianxian-Lueyang suture zone. It talks about the spread of the oceanic crust, subduction, collision that leads to the closure of Shang-Dan Paleotethys, different types of granites, leucogranite and felsic intrusion linked to continental crust.

The Hai Van granitoid complex constitutes an important part of the Indosinian batholith of the northern Kontum massif in central Vietnam. The Kontum massif is a key region for understanding the palaeo-Tethyan accretionary history and the crustal evolution of the Indochina terrane. In this study, zircon U–Pb ages and geochemical data on the Hai Van complex are reported to shed more light on these geological processes. Zircon U–Pb isotopic analyses of six representative samples by the LA-ICP-MS technique show that granitoids from this complex crystallized between 242 and 224 Ma, indicating a prolonged period of magmatism in a late orogenic stage. Rocks from the Hai Van complex have S-type geochemical characteristics with high SiO2, Na2O + K2O, and Zr contents as well as typical S-type minerals such as cordierite and muscovite. Trace elements of the samples are depleted in Ba, Nb, P, Sr, and Ti and enriched in Rb, K, Th, U, and Pb. Negative Eu-anomalies indicate feldspar fractionation during magma crystallization. The Hai Van granitoids exhibit Nd–Hf isotopic features similar to Proterozoic rocks exposed in South China, with low initial ɛHf and initial ɛNd values and two-stage Hf model ages of 1.9–1.7 Ga. It is suggested that during the palaeo-Tethyan orogeny, central Vietnam experienced strong early Mesozoic magmatism that originated from partial melting of crustal material similar in composition to the basement of the South China block. [ABSTRACT FROM AUTHOR]

The eastern Qinling belt is characterized by widespread Mesozoic post-orogenic magmatism and abundant Mo–(Au–Ag) polymetallic mineralization. Most Mo deposits in this belt are genetically related to Mesozoic granitoids. The tectonic context of this close spatial and temporal relationship is still debated. This study reports U–Pb ages and Hf isotopic composition of zircons, major and trace element and Sr–Nd–Pb isotopic composition of the Donggou granite porphyry, host rock to one of the important Mesozoic Mo deposits in this orogen. Based on geochemical results, the Donggou granite porphyry is a silica-supersaturated, high-K metaluminous A-type granite showing enrichment in light REEs, depletion in middle REEs and significant negative Eu, Ba, Nb, Sr, P, and Ti anomalies. Negative initial ϵNdvalues of −17.0 to −13.2 for whole-rock and negative initial ϵHfvalues of −19.9 to −7.8 for zircon suggest that the magma was derived from a mixture of Archaean/Proterozoic crustal rocks and mantle-derived or newly added crust. Its Pb isotopic composition is similar to the lower crust of the North China block, but different from superjacent country rocks (Xiong'er and Taihua Groups). Zircon U–Pb dating yields a late Mesozoic emplacement age of 118–117 Ma, identical with the third episode of Mo mineralization in the eastern Qinling–Dabie belt. We postulate that the Donggou Mo-related porphyry granite formed by reworking of North China lower crust with significant input of juvenile material. The magmas formed in an extensional tectonic setting, induced by lithospheric thinning and asthenospheric upwelling beneath eastern China during Cretaceous time. [ABSTRACT FROM AUTHOR]

Abstract: Mesozoic granitoids are ubiquitous in China and have attracted the interests of many geologists not only because of their mineralization potential but also because they carry information on source material, emplacement mechanisms and crustal architecture. Most of the plutons were created by multi-stage magma emplacement and offer particular challenge for unraveling the emplacement and cooling history. A multi-isotope approach combined with single grain dating analyses provides a means to understand magma geneses even in complex magmatic settings. This study presents Rb–Sr isotope data for K-feldspar megacrysts and U–Pb ages and Hf isotopic composition for zircons from the composite Heyu pluton exposed in eastern Qinling orogen, central China. Zircon U–Pb concordia ages of 150 and 140Ma and single K-feldspar Rb–Sr isochron ages between 133 and 121Ma were obtained from early and late magmatic stages, respectively, consistent with slow cooling or isotopic re-equilibration of the Rb–Sr K-feldspar system. The distinct K-feldspar morphology of early and late intrusive phases is controlled largely by the emplacement depth, likely to be associated with a gravity-driven sinking model. Corresponding zircon εHf(t) values are −21.8 to −18.0 and −17.2 to −10.3 for early and late intrusive phases, respectively, indicating different magma sources. [Copyright &y& Elsevier]

• Recognition of two distinct stages of A-type magmatism at 1.65 Ga and 1.60 Ga in the North China Craton. • Geochemical and isotopic compositions of the two stages A-type granites indicate gradual crustal extension and asthenosphere upwelling processes. • Tectonic transition from post-orogenic to anorogenic settings took place at the late Paleoproterozoic. Paleoproterozoic and Mesoproterozoic A-type granites occur on many cratons and possess important information for our understanding of the formation and breakup history of the supercontinent Columbia. It was argued previously, that Proterozoic A-type granites (∼1.8–1.5 Ga), exposed along the southern margin of the North China Craton formed in a post-collisional or anorogenic setting related to the final amalgamation of the North China Craton or to the breakup of Columbia. In the present study, we report zircon ages and geochemical data of the Maping A-type granite. This intrusion consists of a quartz monzonite porphyry and a granite porphyry that, based on U-Pb age dating, formed at ∼ 1.65 and ∼ 1.60 Ga, respectively. The granites show high contents in alkaline and high field strength elements, high Ga/Al and Fe/Mg ratios. The quartz monzonite porphyry of the early stage is metaluminous and relatively depleted in Hf-Nd isotopic compositions (whole-rock initial ε Nd values −5.4 to −4.5; zircon initial ε Hf values −8.5 to −1.5), while granite porphyry of the late stage is peraluminous and has lower initial ε Nd and ε Hf values (−6.4 to −5.9; −9.6 to −3.3). Inherited zircon grains in the Maping intrusion have relatively high initial ε Hf values (>-0.7), likely originating from juvenile crust. The Pb isotopes of the quartz monzonite porphyry show characteristics similar to the lower crust, whereas the granite porphyry has more radiogenic Pb isotopic compositions. Apatite grains from the quartz monzonite porphyry have initial 87Sr/86Sr ratios of ∼ 0.7109–0.7133 and those from the granite porphyry have noticeably high initial 87Sr/86Sr ratios of ∼ 0.7862–0.8812. These isotopic characteristics imply the presence of various crustal rocks underneath the North China Craton with variable isotopic compositions. From the early to late magmatic stages, the Sr/Y ratios of granitic rocks decrease from 1.6 – 7.6 to 0.2–0.4, while the estimated magma temperatures, calculated from whole-rock compositions, slightly increase from approximately 900 °C to about 930 °C. These concurrent changes in temperature and chemical composition reflect ongoing asthenospheric mantle upwelling during crustal extension. This suggests a transition in the southern margin of the North China Craton from a post-collisional setting before 1.65 Ga to an anorogenic setting by 1.6 Ga. [ABSTRACT FROM AUTHOR]

Magma mixing or mingling between mafic and felsic magmas is a common phenomenon in granitoid magmatism, and chemical and mechanical interactions between the magmas are frequently observed in granitic rocks. The Dongjiangkou pluton is an example of magma mixing among the numerous early Mesozoic granitoid plutons that are exposed in eastern South Qinling. This pluton is predominantly composed of granodiorite and contains abundant mafic/intermediate microgranular enclaves (MMEs) and is sporadically intruded by mafic dykes. Both the granodiorite and MMEs were crystallized at 224–214 Ma and have inherited zircons of similar age ranges. The granodioritic rocks had metaluminous to weak peraluminous features and adakitic signatures and belong to the high-K calc-alkaline series, whereas the MMEs and dioritic dykes had low SiO 2 contents and metaluminous features and belong to the high-K calc-alkaline to shoshonite series. All of the rocks had high Mg# values and similar geochemical characteristics regarding trace elements and Sr isotopes, but they had diverse whole-rock Nd-Pb and zircon Hf isotopic compositions. The Dongjiangkou granodiorite was produced by partial melting of old basement rocks and Paleozoic juvenile crust beneath South Qinling triggered by asthenospheric upwelling. Magma(s) of the Dongjiangkou MMEs may have been derived from deep mantle and injected into and mixed with the magma(s) of the granodiorite, but chemical and isotopic homogenization was not achieved during the magma mixing process. Clastic rocks may have played a major role in the formation of crust-derived magma(s), causing strong Nd-Hf isotopic decoupling of several granitoid plutons in South Qinling. • Dongjiangkou granite witnesses insufficient mixing of felsic and mafic magmas. • Nd and Hf isotopic equilibrium did not reach during the magma mixing. • Felsic magma originated from old basement and Paleozoic rocks in South Qinling. • Input of clastic rocks to granitic magma source caused Nd-Hf isotopic decoupling. [ABSTRACT FROM AUTHOR]

The geochemical compositions and zircon U-Pb ages of the Muhuguan and Mangling plutons of the North Qinling Terrane (NQT), China, provide insights into the basement rocks involved in magma genesis and the Mesozoic tectonic evolution of the NQT. Monzogranites from the two plutons are characterized by high SiO 2 contents (69.3–77.0 wt%), low Mg numbers (0.21–0.38), enriched light rare-earth elements, Th, U, and Pb, depleted high-field-strength elements, and negative Eu anomalies. The source of the Mangling monzogranite is interpreted to have been deeper than that of the Muhuguan monzogranite, on the basis of its higher Sr/Y, (Dy/Yb) N , and (La/Yb) N ratios and lower SiO 2 content. Sr-Nd isotopic compositions indicate similar but heterogeneous magma sources for the two granites: 87Sr/86Sr i = 0.7070–0.7103 and ε Nd (t) = −7.0 to −15.0 for the Muhuguan granite, and 87Sr/86Sr i = 0.7054–0.7083 and ε Nd (t) = −7.9 to −16.0 for the Mangling granite. The zircon U-Pb age results fall into two groups: (1) syn -magmatic zircons (153 to 140 Ma); and (2) inherited zircons that define five age clusters, namely Neoarchean-Paleoproterozoic (2633–2103 Ma), Paleoproterozoic to Mesoproterozoic (1988–1377 Ma), Neoproterozoic (975–605 Ma), Paleozoic (535–382 Ma), and Late Paleozoic – Early Mesozoic (329–187 Ma). These data are consistent with a derivation of the granites by mixing between melted underplated juvenile crust within the NQT and melts from basement rocks similar to those of the Xiong'er Group within the southern margin of the North China Craton (S-NCC). The involvement of S-NCC material is also supported by the unradiogenic whole-rock Pb isotopic composition of the Muhuguan and Mangling granites, which is similar to that of the S-NCC basement rocks. These results suggest that the widespread Late Jurassic to Early Cretaceous granitoid intrusions within the NQT were generated in an extensional geological setting associated with mantle upwelling. Melts were derived from underthrust S-NCC basement material and juvenile Neoproterozoic basaltic rocks. • Inherited zircons of Mesozoic granites indicate heterogeneous magma sources. • Basement rocks of North China were involved in the granitic magmas. • Low-silica diorite originated from enriched mantle source. [ABSTRACT FROM AUTHOR]

The Qinling orogen records the prolonged amalgamation history between the North China Block (NCB) and the South China Block (SCB) accompanied by major granitoid intrusions during the Triassic. However, the petrogenesis of these granitoids, especially that of the peraluminous granites, remains a matter of debate. Detailed study of these peraluminous granites, which are the products of crustal melting, will give insights into the melting process and petrogenesis of peraluminous magmas and will further constrain the regional geological evolution. In this study, Xiahe (XH) tourmaline-bearing two-mica granite and Baijiazhuang (BJZ) two-mica granite were selected for systematic analysis of their mineralogy, petrology, zircon U-Pb geochronology, and geochemistry. The zircon U-Pb dating showed that the XH and BJZ granites were emplaced at approximately 242 Ma and approximately 214 Ma, respectively. The presence of muscovite and tourmaline, high peraluminosity at >1.1, low oxygen fugacity (ƒO 2) conditions below the fayalite–magnetite–quartz (FMQ) buffer, and low zircon saturation temperatures indicate sedimentary protolith (S-type) granitic affinity. The low CaO/Na 2 O ratios <0.4 suggest that the granites formed by partial melting of a pelitic source. The low heavy rare earth element (HREE) concentration and weak negative Eu anomaly in the XH granite implies garnet residue in the magma source, whereas an obvious Eu anomaly in the BJZ granite indicates no residual garnet. The Rb/Sr ratios remained constant in the XH granite with decreasing Sr and Ba concentrations; however, these ratios increased in the BJZ granite. This observation reflects that the XH (BJZ) granite was the product of fluid-present (fluid-absent) muscovite melting. This finding is in accord with the different geochemical features and the estimates of zircon and monazite saturation temperature between the XH and BJZ granites. In western Qinling, low-Sr/high-REE (group A) and high-Sr/low-REE (group B) peraluminous granites have been identified. We propose that the former were generated during fluid-absent muscovite melting, whereas the latter were derived from fluid-present muscovite melting. This hypothesis was further confirmed by higher zircon and monazite saturation temperature estimates in addition to higher REE, Th, Nb, and Ta concentrations in the group A granitoids. From regional geological considerations, it can be concluded that the Middle Triassic granitoids in western Qinling formed during subduction of the A'nimaqing–Mianlue oceanic crust, whereas the Late Triassic granitoids are related to syn - or post-collisional processes. • Τwo types of peraluminous Early Mesozoic granite recognized in western Qinling. • Generation of low–Sr/high–REE from water–absent muscovite partial melting. • Generation of high–Sr/low–REE from water–present muscovite partial melting. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Multi-stage magmatic activities of southern Anhui province, can be subdivided to three magmatics stages, i.e., ca. 152–136 Ma mainly of granodiorites, ca. 136–130 Ma mainly of mongranites, ca. 130–120 Ma mainly of K-feldspar granites. • Older granitoids of the Qingyang pluton originated from the mixing sources of mantle material and old crustal rocks, were related to the Paleo-Pacific subduction. • While younger A-type granite formed by the anatexis of more juvenile crustal rocks, were due to rollback of the Paleo-Pacific subduction. Abstract Late Mesozoic magmatic rocks are widely distributed in southern Anhui province, and are represented by the Qingyang-Jiuhuashan granitic complex, which consists dominantly of the Qingyang pluton of granodiorite and monzogranite, and the Jiuhuashan pluton of K-feldspar granite. These two plutons have zircon U-Pb ages of 138 Ma–128 Ma. Combining the new data with previously reported age data, the magmatism in southern Anhui province can be subdivided into three stages: early stage of ∼152–136 Ma, middle stage of ∼136–130 Ma, and latest stage of ∼130–120 Ma. Granodiorite (early stage) and monzogranite (middle stage) of the Qingyang pluton have SiO 2 contents of 66–68 wt%, total alkali contents of 7.5–8.6 wt%, K 2 O/Na 2 O ratios of 1.1–1.3, A/CNK ratios of 0.9–1.1, and low FeOT/(FeOT + MgO) values of 0.71–0.73. These rocks show depletion in Nb, Ta, and Zr and slightly negative Eu anomalies. K-feldspar granite (late stage) of the Jiuhuashan pluton is characterized by high SiO 2 contents (>75 wt%), K 2 O/Na 2 O ratios of 1.1–1.3, and A/CNK ratios of 0.9–1.2, and high FeOT/(FeOT + MgO) values of 0.88–0.93. They have high concentrations of Nb, Ta, and Zr, and strongly negative Eu anomalies. Initial ε Hf values of zircon grains from the granodiorite and monzogranite range from −8.01 to −6.71 and −11.40 to −9.43, with δ18O values varying from 7.16‰ to 8.04‰ and 7.26‰ to 8.06‰, respectively. Zircon grains from K-feldspar granites have relatively high initial ε Hf values of −7.62 to −4.78, but similar δ18O values of 7.03–8.84‰. Geochemical features of granodiorite and monzogranite point to an I-type signature, whereas those of K-feldspar granite show an A-type affinity. We propose that the granodiorite and monzogranite originated from mixing melts produced by partial melting of lithospheric mantle metasomatized by fluids and crustal rocks induced by underplating basaltic magmas, related to subduction of the Paleo-Pacific oceanic crust, whereas the K-feldspar granite formed from crustal anatexis in an extension setting caused by rollback of the subduction. [ABSTRACT FROM AUTHOR]

Migmatites provide a record of melt formation and crustal rheology. In this study we present zircon U-Pb ages and geochemical composition of migmatites from the Foping dome and granites from the Wulong pluton. U-Pb results from migmatite zircons indicate two episodes of partial melting. Rim domains from a leucosome in the Longcaoping area yield an age of ca. 209 Ma. Migmatites collected from the Foping dome yield U-Pb zircon ages of ~ 2910 to ~ 190 Ma, suggesting the involvement of meta-sedimentary source components. Rim domains of the zircons with low Th/U ratios (< 0.1) give ages of ~ 225–190 Ma and the youngest age domains (ca. 195 Ma) are characterized by low contents of heavy rare earth elements, which is related to crystallization of garnet. Magmatic rocks from the Wulong pluton can be subdivided into high Sr/Y and low Sr/Y granites. U-Pb zircon ages vary from 219 to 214 Ma for the high Sr/Y granites and from 214 to 192 Ma for the low Sr/Y granites. High Sr/Y granites have higher Na 2 O and Sr contents than the low Sr/Y granites. They also lack negative Eu anomalies and are depleted in HREE compared to the low Sr/Y granites. Initial 87 Sr/ 86 Sr ratios and ε Nd values of all the samples roughly overlap with those of Neoproterozoic basement rocks exposed in South Qinling. Including previous studies, we propose that the high and low Sr/Y granites formed by melting of thickened and normal crust, respectively. Close temporal-spatial relationship of the high and low Sr/Y granites with the two-stage migmatization events implies variation of crustal thickness and thermal overprints of the orogenic crust in post-collisional collapse. Following the collision of South Qinling and the Yangtze block prior to 219 Ma, partial melting of the deep crust occurred. The melts migrated upwards to form the high Sr/Y granites. This process occurred rapidly and caused collapse of the thickened crust and carried heat upwards, leading to further partial melting within the shallower crust and formation of the low Sr/Y granites. [ABSTRACT FROM AUTHOR]

In this contribution, we investigate the suitability of three igneous rock standards distributed by the Chinese Academy of Geological Sciences as international standard reference materials for Hf–Fe isotope determinations. We report Lu–Hf concentrations and Hf–Fe isotope compositions of Chinese National Standards (CNS) GSR-1 (granite), GSR-2 (andesite), and GSR-3 (basalt) in order to assess their homogeneity and give the first benchmark values. Experiments using spiked (isotope dilution) and non-spiked samples reveal an overall homogeneous Hf isotope composition for CNS GSR-2 and GSR-3 with 176 Hf/ 177 Hf = 0.282641 ± 6 (MSWD = 1.5, n = 10) and 0.282985 ± 04 (MSWD = 0.48, n = 10), respectively. In contrast to GSR-2 and GSR-3, two out of ten analyses of GSR-1 show elevated Hf concentrations in conjunction with less radiogenic Hf isotope compositions, considerably lower to −10.6 and −16.8 ɛ Hf units, respectively, compared to the average of the remainder analyses. We ascribe this heterogeneity to inherited zircon grains so often observed in granitic rocks. Iron isotope determinations on a subset of samples yields values of δ 57 Fe = +0.35 ± 0.02, +0.22 ± 0.05, +0.43 ± 0.02 (relative to IRMM-014, n = 3) for GSR-1, GSR-2, and GSR-3, respectively. Our results indicate that GSR-2 and GSR-3 appear suitable standards for Hf–Fe isotope analyses, but advise caution when using GSR-1 as a measure for quality control for Hf isotope compositions and concentrations. [ABSTRACT FROM AUTHOR]

The present study of the Lincang pluton in the western Yunnan Tethyan belt reveals that its compositional variation is largely inherited from a mixed igneous–sedimentary source. Geochemical composition analyses show that this pluton has a wide range of normative corundum values (0.5–3.1 %). With increasing mafic character [molar (FeO + MgO)/100g], the A/CNK values decrease at mafic character < 0.09; and they start to increase at mafic character > 0.09. As silica increases, P 2 O 5 contents become less scattered and decrease at SiO 2 > 69 wt.%. These characteristics indicate the transitional I-S-type affinity of this pluton, which is further supported by zircon trace element and oxygen isotopic features. Inherited zircons from the Lincang pluton display similar age–ε Hf (t) distributions to those of zircons from metavolcanic and metasedimentary rocks of the Lancang Group, suggesting that the Lancang Group served as source rock for the granite. Variable melting proportions of metavolcanic rocks, meta-arkoses, and mica schists of the Lancang Group can explain the positive correlation between 1000/Sr and initial 87Sr/86Sr ratios for the Lincang pluton. The melting of such mixed igneous–sedimentary source rocks is also in line with the negative correlation between CaO/Na 2 O and initial 87Sr/86Sr ratios as well as with the transitional I-S-type affinity of the Lincang pluton. Modeling of Sr–Nd ternary mixing shows that generation of the Lincang pluton requires the admixture of ~30–70 % metavolcanic rocks and variable proportions of meta-arkose and mica schist. The protracted emplacement period (ca. 30 million years) and heterogeneous initial 87Sr/86Sr ratios of the Lincang pluton suggest an incremental assembly of magmas. It is likely that individual magma batches were derived from a mixed igneous–sedimentary source, emphasizing the importance of source lithology on the compositional diversity of the granite. Unlabelled Image • The Lincang pluton has a transitional I-S-type granitic affinity. • Compositional diversity of the granite is controlled by igneous–sedimentary source. • Large-volume pluton formed by long-term assembly of individual magma batches. [ABSTRACT FROM AUTHOR]

The Early Miocene high-K I-type plutonic rocks constitute the early products of the Neogene to Quaternary magmatism, and the youngest exposed intrusions in the East Anatolian plateau. Here we deal with the petrogenesis of the Early Miocene Taşlıçay intrusion covering an area of ∼62 km2. The intrusion comprises leucogranite, and minor gabbro-monzodiorite and rhyolite porphyry. U-Pb dating of zircons from the leucogranite, monzodiorite and rhyolite porphyry yielded identical igneous crystallization ages of ∼19 Ma (Early Miocene). According to the modified alkali-lime index, the leucogranite and the rhyolite porphyry are alkali-calcic, while the gabbro-monzodiorite is transitional calcic to calc-alkalic. On variation diagrams, the gabbro-monzodiorite and the leucogranite as well as rhyolite porphyry form distinct bimodal groupings, whereby the leucogranite display well-defined linear differentiation trends, in contrast to the gabbro-monzodiorite. The leucogranite has relatively fractionated rate earth element (REE) patterns with concave-upward shapes and significant negative Eu anomalies; middle REEs are hardly fractionated with respect to heavy REEs. The gabbro-monzodiorite is characterized by high abundances of incompatible elements, slightly fractionated chondrite-normalized REE patterns with feebly negative Eu anomaly. The rhyolite porphyry is compositionally similar to the leucogranite. The geochemical features imply a fractionating mineral assemblage of hornblende, plagioclase and biotite for the leucogranite, and hornblende and ± plagioclase for the gabbro-monzodiorite. All the rock types display a narrow Sr and Nd isotopic variation (initial 87Sr/86Sr = 0.7053 to 0.7065; initial εNd = −0.5 to −3.8). The leucogranite and rhyolite porphyry exhibit gradually slightly higher initial 87Sr/86Sr and lower initial 143Nd/ 144Nd ratios relative to the gabbro-monzodiorite. Similarly, δ18O and initial εHf values of zircons suggest slightly increasing amount of crustal component from the leucogranite to the rhyolite porphyry. The gabbro-monzodiorite is probably related to partial melts from the slightly enriched lithospheric mantle. The magmas of the leucogranite and the rhyolite porphyry, on the other hand, probably resulted from the remelting of a middle- to high-K basic to intermediate rocks, compositionally similar to the gabbro-monzodiorite, and assimilated gradually slightly increasing amount of old high-silica crustal material. Several lines of evidence such as (i) presence of the well-developed dike swarm of rhyolite porphyry at the north eastern margin of the intrusion, (ii) exhumation of the intrusion at the earth's surface by Middle Miocene, (iii) widespread apatite fission tract ages between 22 and 16 Ma from literature, and (iv) the absence of the exposed intrusions younger than the Early Miocene suggest that the Early Miocene represents probably a time of continental extension and exhumation in Eastern Anatolia and NW Iran. • The Taşlıçay intrusion occurs in the East Anatolian Plateau in the Tethyan realm. • It comprises middle to high-K gabbro-diorite, leucogranite and rhyolite porphyry. • All the rock types formed during Early Miocene (ca. 19 Ma). • Formation and exhumation occurred in an extensional setting. • The high-K leucogranite formed mainly by melting of newly underplated mafic rock. [ABSTRACT FROM AUTHOR]