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[Display omitted] • Bega Batholith shows isotope-chemical correlations consistent with magma mixing. • Compositional zoning in Bega is strongly controlled by arc tectonic geometry. • Two discrete mantle sources are involved in granite petrogenesis in Bega. • Estimated ∼ 50 % of the batholith is constituted by juvenile-mantle material. • Bega Batholith represents an episode of crustal growth at ca 400 Ma. Cordilleran granitic batholiths represent significant episodes of crustal growth and differentiation, and commonly display lateral isotopic and chemical variations. Establishing the tectono-magmatic processes responsible for generating this compositional asymmetry is important for understanding crustal evolutionary processes throughout the Phanerozoic. The Bega Batholith, an example of a 'Cordilleran style' granite batholith, is the largest I-type Siluro-Devonian granite complex in the Lachlan Fold Belt (LFB) of southeastern Australia and comprises seven granite supersuites that display systematic lateral isotopic and chemical asymmetry. From west to east towards the present-day continental margin, an increase in the content of Na 2 O, Sr, Al 2 O 3 , and P 2 O 5 , with concomitant decreases in CaO, Sc, Rb, and V are observed. In the same direction, whole-rock initial 87Sr/86Sr decreases from 0.7098 to 0.7039, ε Nd values increase from −8.3 to +4.4, and δ18O decreases from 10.2 ‰ to 7.9 ‰. Depleted-mantle model ages also decrease from ca. 1800 Ma in the west to 600 Ma in the east. Here, we address whether these chemical and isotopic variations were generated by interaction between two distinct components (mantle-derived magmas and supracrustal sources) or were alternatively produced by partial melting of infracrustal source rocks formed sequentially by much earlier episodes of crustal underplating. Combined whole-rock Nd-Sr-O isotopic and geochemical analyses indicate that several I-type supersuites exhibit chemical and isotopic correlations consistent with two-component magma mixing. This new evidence challenges the long-held view that I-type granites derive exclusively from the melting of infracrustal sources, and that granite terranes represent wholesale crustal reworking rather than new crustal growth. Our results show that the compositional zoning within the Bega Batholith is multifaceted. Firstly, the presence of two discrete mantle sources endows chemically and isotopically distinct eastern and western segments in the batholith. Secondly, within these compositionally distinct regions the lateral compositional changes across supersuites derives from mixing between mantle-derived and supracrustal sources. Finally, progressive extension within a developing back-arc environment regulates the ratio of crust-mantle contributions and compositional architecture of each I-type supersuite. [ABSTRACT FROM AUTHOR]

[Display omitted] • We measured δ114/110Cd values of granite and sphalerite from a large skarn system. • Little to no Cd isotopic fractionation took place during the magmatic–hydrothermal processes. • S- and I-type granite-related deposits have distinguishable δ114/110Cd values. • Cd isotopes provide a potentially effective tool in skarn systems. Granite-associated deposits are one of the important ore types in the Earth's crust and can dominantly be subdivided into S-, I- and A-type granite-related deposits with different mineralization elements and isotopic signatures (e.g., sulphur and boron). The object of this study is to investigate whether Cd isotopic difference exists between I- and S-type granite-related deposits, and to provide new insights on geochemical behavior of Cd in such systems that have not been well constrained. The Dulong deposit in southwest China is a world-class skarn-type polymetallic Zn–Sn–In deposit that is thought to be genetically related to the emplacement of the highly fractionated S-type Laojunshan granite. The extremely negative δ114/110Cd values of sulfides (−0.82 ‰ to −0.42 ‰) within the Dulong deposit are all lower than those of sulfides from other Zn–Pb ore deposits globally. In comparison, representative sphalerites from I-type granite-related deposits yield heavier Cd isotopic compositions relative to the samples from the Dulong deposit. The Laojunshan granite samples are enriched in light Cd isotopes and have δ114/110Cd values that range from −0.73 ‰ to −0.40 ‰, overlapping with the δ114/110Cd values of sphalerite within the Dulong deposit and suggesting that the Cd in the deposit was derived from the Laojunshan granite. Similarly, I-type granite-related deposits elsewhere have Cd isotopic compositions that are similar to mafic–intermediate igneous rocks, suggesting little or no Cd isotopic fractionation took place during the magmatic–hydrothermal processes that formed these deposits. These results suggest that geochemical signatures of metal sources are the most likely control on Zn/Cd ratios and δ114/110Cd values of sulfides in these deposits, with different mineral deposit types having different Zn/Cd ratios and δ114/110Cd values. In summary, Cd isotopes provide a potentially effective tool for discriminating between different types of hydrothermal system and may also be useful in the investigation of granite petrogenesis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zircon U-Pb ages for the Siluro-Devonian Bega Batholith of the Lachlan Fold Belt. • Systematic east to west age progression from 420 to 385 Ma. • Bega Batholith may record an undocumented episode of crustal growth along the Gondwanan margin. Earth's continental crust is primarily composed of buoyant, felsic igneous (granitic) material that has been extracted from the mantle along convergent plate margins. Establishing the timescales of subduction-related granite batholith assembly is key to understanding the processes of magma generation, segregation, and transport that define the dynamics and rates of crustal growth. The 'Cordilleran' Bega Batholith is the largest I-type granite batholith in the Lachlan Fold Belt (LFB) of south-eastern Australia. The product of accretionary orogenesis along the Terra Australis Orogen, it has been extensively characterised by isotopic and geochemical studies yet lacks a robust geochronological framework. We present new ID-TIMS and SHRIMP U-Pb zircon ages for twenty-two plutonic rocks of the Bega Batholith. This geochronological survey indicates a prolonged duration for I-type magmatism, with crystallisation ages ranging from ca. 420 Ma in the west, to 385 Ma in the eastern Bega Batholith. These I-type granites collectively occupy ∼90,000 km3 and were emplaced over a period of ∼20–35 Ma, corresponding to a magma production rate of ∼8–15 km3/Ma km−1, considerably lower than that of S-type granites of the region and other subduction-related granite terranes globally. Fundamentally, the temporal overlap between the Bega I-type granites and S- and A-type granites also argues against a hiatus between each phase of granite magmatism in the LFB, suggesting a continuum between the granite types and derivation from common source components. This new geochronological data provides the first comprehensive compilation of U-Pb ages from across the Bega Batholith, establishing initial constraints on the development and evolution of I-type magmatism in south-eastern Australia. Our results demonstrate that I-type granite petrogenesis is linked with crustal growth processes, requiring the modification of global crustal growth curves during the Phanerozoic to account for new continental crust generated within I-type granite terranes of the Paleo-Pacific Gondwanan margin. [ABSTRACT FROM AUTHOR]

• I-type monzogranites in the East Kunlun Orogen Belt were emplaced at 251–221 Ma. • The studied monzogranites were generated by partial melting of ancient lower crust. • The Early Triassic monzogranites were formed in a localized extensional environment during a subduction-dominated stage. • The Late Triassic (ca. 232–221 Ma) monzogranites were formed in a post-collisional environment. The Triassic granitoids in the East Kunlun Orogenic Belt (EKOB) are crucial for understanding the tectonic evolution of the Paleo-Tethys Ocean. This study presents zircon U–Pb ages, Lu–Hf isotopes, whole-rock major and trace elements, and Sr–Nd isotope compositions from monzogranite plutons in the central segment of EKOB to constrain their petrogenesis and tectonic evolution. These monzogranites are dominant composed of mineral assemblages of K-feldspars, plagioclase, minor biotite and accessory minerals. U–Pb dating of zircons from the Xinle South (XLS), Nanshankou (NSK) and Changgou South (CGS) plutons yield ages of 251 Ma, 232 Ma and 221 Ma, respectively. The studied monzogranites have relatively high SiO 2 and Al 2 O 3 , but have low contents of TiO 2 , Fe 2 O 3 T, MgO relative to the coeval granodiorites. These monzogranites are classified as fractionated I-type granites, ranging from calc-alkaline to high-K calc-alkaline compositions. Their negative εNd(t) values (−4.2 to −6.3) and zircon εHf(t) values (−6.1 to −9.3) suggest that magma generation occurred through partial melting of ancient lower crust, followed by extensive fractional crystallization. Integrating our new data with regional geological evidence, we propose that the Early Triassic XLS monzogranite emplaced in a localized extensional environment linked to the northward subduction of the Paleo-Tethys oceanic plate. In contrast, during the post-collisional extensional phase of the Late Triassic, the formation of the NSK and CGS monzogranite plutons was directly influenced by asthenospheric upwelling, lower crust delamination, and subsequent continental rifting. [ABSTRACT FROM AUTHOR]

• A prominent episode of ca. 800 Ma magmatism in the southern Dabie Orogen identified. • The granitoids show I-type features. • An accretion-type orogeny in the northern Yangtze Block produced the ca. 800 Ma granitoids. • The 'edge model' of Rodinia reconstruction is favored. Large-scale Neoproterozoic granitoids occur widely in the Dabie Orogen of the northern Yangtze Block and provide significant clues to understanding the geological evolution of the Block within the Rodinia supercontinent. We present evidence for a prominent episode of granitoid intrusion at ca. 800 Ma in the southern Dabie Orogen (SDO), verified by new zircon LA-ICP-MS ages from four separate granitoid intrusions ranging from 807 Ma to 795 Ma in age. The granitoids are dominated by monzogranite and granodiorite with bulk-rock A/CNK and zircon δ 18O values of 0.90–1.10 and 5.03–6.45‰, respectively, corresponding to I-type affinity. This is also supported by negative correlations of SiO 2 vs. P 2 O 5 and Sr vs. P 2 O 5 , and positive correlations of SiO 2 vs. A/CNK, Rb vs. Y and Rb vs. Th. Low zircon ε Hf (t) values (−15.03 to −3.84) and relatively old two-stage Hf model ages (mainly between 1900 and 2200 Ma) for these granitoids are consistent with primary derivation of magma from partial melting of Paleoproterozoic metabasites. Relatively low Ga/Al ratios, Zr contents, and zircon saturation temperatures and consistently negative zircon ε Hf (t) and bulk-rock ε Nd (t) values are distinct from those of 780–720 Ma A-type granites in the Dabie Orogen that formed in a rift setting. We propose that the ca. 800 Ma granitoids in the SDO were products of variable degrees of partial melting of ancient mafic crust, promoted by heating of the upwelled asthenosphere due to oceanic slab breakoff in an accretion-type orogeny. Our observations suggest that the formation of the unified Yangtze Block was achieved by diachronous assembly of multiple micro-blocks during the Neoproterozoic, consistent with a peripheral location of the Yangtze Block in the Rodinia supercontinent. [ABSTRACT FROM AUTHOR]

• The ca.750 Ma I-type granitic melts formed in a back-arc setting from water-fluxed melting. • Thermodynamic modeling shows I-type melts can be formed at 725–875 °C, 9 kbar, 2.0–3.5 wt.% H 2 O. • Asthenosphere upwelling from slab rollback caused underplating of hydrous basaltic magmas. • Water content was crucial in generating granitic rocks of various compositions in a continental arc. Water is crucial in generating granitic systems; however, its role (i.e., dehydration, low to high water-fluxed melting) in granitic magmatism in continental arcs remains unsettled and poorly understood. Neoproterozoic arc-related igneous rocks are uncovered along the western margin of the Yangtze Block, presenting a complex compositional array ideal for deciphering the influence of water content within the continental arc and its geodynamic significance. The Jinping granites, in the Ailaoshan zone, are emplaced at 750 ± 4 Ma, as determined by zircon U-Pb dating. These medium to coarse-grained granites consist predominantly of plagioclase, quartz, K-feldspar, muscovite, and biotite. Characterized by high SiO 2 (71.2–73.5 wt%), alkalis (K 2 O+Na 2 O=7.54–9.56 wt%) and low Fe 2 O 3 T (1.01–1.66 wt%), MgO (0.53–0.85 wt%), and CaO (0.15–0.93 wt%) concentrations, they exhibit high-K calc-alkaline signatures. The negative correlation between P 2 O 5 and SiO 2 , alongside the positive correlation between Rb and Y, typifies the Jinping granites as I-type granites. Low La/Nb (1.96–3.43) and Nb/Ta (8.57–11.3) ratios, but high Th/La (0.28–0.46) and Zr/Sm (30.5–47.7) ratios, as well as whole rock ε Nd(t) (−0.4 to +1.3) and zircon ε Hf(t) values (+5.25 to +8.53) of the studied granites are similar to synchronous mafic rocks at the western margin of the Yangtze Block. These features suggest partial melting origin from the mafic lower crust. Thermodynamic modeling posits that the Neoproterozoic Ailaoshan I-type granitic rocks may have formed through water-fluxed melting (2.0–3.5 wt% H 2 O) under medium pressure conditions (9 kbar). It is postulated that slab rollback could have prompted water (as hydrous melt or fluids) release from hydrous minerals in the underlying cumulate mafic rocks, subsequently triggering water-fluxed melting in the lower crust. In contrast, high water-fluxed melting-generated adakitic granites with low K 2 O/Na 2 O ratios (<0.8) in the region, spatially and temporally associated with the Jinping granites, reflect higher water content in the deeper crust. This supports the notion that water was conveyed from depths to surface, facilitating the conversion of adakitic rocks into I-type granites as water content diminished. Thus, water content within the lower crust plays a pivotal role in the genesis of granitic rocks with varied compositions in a continental arc setting. [ABSTRACT FROM AUTHOR]

The Pamir orogen originated through the amalgamation of various arc terranes. Despite undergoing numerous studies, the subduction polarity and time regarding the accretion processes remain inadequately constrained. To address these issues, we carried out a detailed study of zircon and apatite U-Pb ages, zircon Hf isotopes, and whole-rock geochemistry for the Permian to Cretaceous gabbro, volcanic rocks and granitoids from the Southern Pamir and the Rushan-Pshart suture. Three stages of magmatism are identified, including 279–266 Ma gabbro and andesite to dacite, 209–208 Ma granitoids, and 108–103 Ma gabbro and granitoids, respectively. The Permian gabbro and basaltic andesite to dacite in Pshart Range are enriched in light rare earth elements (LREE) and large ion lithophile elements (LILE), but are depleted in Ta, Nb, and Ti, suggesting formation from an enriched mantle source in a subduction zone. The Late Triassic I-type granitoids are typical arc calc-alkaline magmatic rocks with ε Hf (t) values varying from −8.7 to −3.5, which mainly sourced from the partial melting of mixed crustal sources predominately consisting mafic rocks with minor metasedimentary rocks. The Early Cretaceous Pshart granites are I-type granites with relatively low ε Hf (t) values ranging from −14.6 to −2.9, suggesting that they were crust-derived rocks. The Early Cretaceous Bazardara granites are identified as A 2 -type granites with the ε Hf (t) values ranging from −18.3 to +5.3, and were derived from mixing of mantle-derived and crust-derived magmas, or interaction between mantle melts and old crustal rocks. The early Cretaceous gabbro exhibits -MORB-like geochemical characteristics with flat REE pattern (La/Yb N = 4.96), moderate enrichment of LILEs and weak depletion of Nb, Ta and Ti (Nb/La PM = 0.94). Thus, the early Cretaceous A 2 -type granite, E-MORB-like gabbro and volcanic rocks were formed in an extensional setting. Our new data indicate that the southward subduction of the Rushan-Pshart oceanic slab started in the Early Permian and continued to the Late Triassic. Moreover, combining the previous data, we conclude that the Early Cretaceous granites and gabbro in the Southern Pamir formed in an extensional environment due to the southward rollback after northward near-flat subduction of the Neo-Tethyan oceanic lithosphere. [Display omitted] • Permian, Triassic, and Cretaceous arc rocks are identified in the South Pamir. • Southward subduction of the Rushan-Pshart Ocean began before the Permian. • The southward subduction formed the late Triassic I-type granites. • Slab roll-back of the Shyok Ocean caused within-plate magmatism in the South Pamir. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ca. 800 Ma I-type granites were identified in the Feidong Complex. • The I-type granitic rocks were produced by partial melting of ancient lower crust. • Ca. 800 Ma I-type granites in the Feidong Complex suggests a post-collisional extensional setting. Neoproterozoic magmatic rocks are widely distributed along the periphery of the Yangtze Block, but their petrogenesis and tectonic setting remain controversial. This study involved an integrated geochemical and geochronological analysis of mid–Neoproterozoic granitic rocks from the Feidong Complex on the northeastern margin of the Yangtze Block. LA–ICP–MS zircon U–Pb dating of two granitic gneiss samples yielded weighted mean ages of 803 ± 7 Ma and 792 ± 11 Ma. Combined with published age data from other Neoproterozoic magmatic rocks, these new dates suggest that the Feidong Complex experienced a magmatic flare–up at ca. 800 Ma. Geochemically, the granitic gneisses exhibit the characteristics of highly fractionated I–type granites. All of the studied samples have negative ε Hf (t) values of –18.20 to –8.51 and corresponding two–stage Hf model ages (T DM2) of 2.82–2.23 Ga, indicating their derivation from remelting of ancient crust. Geochemical characteristics suggest that the granitic rocks formed in a syn–collisional or post–orogenic environment. Integrating published geochemical data from other magmatic rocks along the northern margin of the Yangtze Block, we suggest that a plausible petrogenetic model for mid–Neoproterozoic magmatic rocks within the Feidong Complex may be tectonic collapse and remelting of the early to mid–Neoproterozoic collisional orogenic belt. In this model, melting represents a tectonothermal response to lithospheric extension before the breakup of the Rodinia supercontinent. [ABSTRACT FROM AUTHOR]

Late Triassic granitoids containing abundant mafic microgranular enclaves (MMEs) occur widely in the Eastern Kunlun Orogenic Belt (EKOB). In this work, we present mineral chemistry, zircon U-Pb ages and L-Hf isotopes, whole-rock chemistry and S-Nd isotope compositions of the MMEs and host granodiorite from the Huda pluton in the Elashan area within the easternmost domain of the EKOB. These rocks contain inherited (Meso- to Neoproterozoic) and xenocrystic (ca. 240 Ma) zircon grains that yield apparent older ages, whereas the magmatic zircons from MMEs and granodiorite yield similar weighted mean ages around 224 Ma, which are interpreted as their crystallization ages. The MMEs have low SiO 2 but high TiO 2 , TFe 2 O 3 , CaO, MgO and MnO concentrations with relatively high Mg# values (48–54) and 100MnO/(MnO + MgO + TFe 2 O 3) ratios (1.2–1.6). They display identical Sr-Nd-Hf isotope compositions to the host granite. Combined with petrological evidence, we suggest that the MMEs are cognate cumulates that formed by pressure quenching during the late stage of magma evolution from the same parental magma of the host granodiorite, rather than a magma mixing origin. The granodiorite is calc-alkaline to high-K calc-alkaline, metaluminous I-type granite. They show relatively low SiO 2 and MnO, but high MgO, Al 2 O 3 , CaO and TFe 2 O 3 contents with Mg# values of 45–50. They are enriched in light rare earth elements (LREEs) and large ion lithophile elements (LILEs), such as Rb, Th, K and Pb, and are depleted in P and high field strength elements (HFSE) including Nb, Ta and Ti. These rocks display slightly negative Eu anomalies and low Sr/Y and La/Yb ratios. Together with the rim-ward chemically evolved nature of some phenocrysts, the comparatively high initial Sr isotope (0.70888–0.70912), low whole-rock ε Nd (t) (−5.6 to −6.0) and zircon ε Hf (t) (−3.3 to −0.1) values, and low Nb/Th (0.11–0.26) and Ta/U (0.53–0.68) ratios, we suggest that the granodiorite magma was sourced from the lower crust. Considering their comparatively young two-stage Nd and Hf model ages (1.42–1.49 Ga and 1.13–1.42 Ga, respectively) and same trace element character with the juvenile crust beneath the EKOB, we interpret the juvenile lower crust as the dominant source rocks for the granodiorite. Based on our data and regional geological evidence, we suggest that the partial melting of juvenile crust resulted from delamination-related asthenosphere mantle upwelling. The latter process resulted in extensive melting of the lower crust, producing a major Late Triassic magmatic flare-up event in the EKOB. Unlabelled Image • Mafic microgranular enclaves are cognate cumulates. • The 224 Ma granodiorite was derived from the partial melting of juvenile crust. • The Late Triassic magmatic flare-up event was associated with delamination process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Wolframite samples show a ferberite composition (H/F < 29), large and positive Eu/Eu* and negative Ce/Ce* anomalies. • U–Pb wolframite age of 315.2 ± 4.7 Ma (2σ) represents the first W deposition episode in the Iberian Massif. • Molybdenite Re–Os dating yielded absolute ages from 305.1 to 303.8 ± 2.2 Ma (2σ) • The 40Ar/39Ar mica ages (2σ) record isotopic resetting after E2 Gerês biotitic granite emplacement. The Borralha area (Iberian Massif, Portugal) reflects a long-lived and multiphase magmatism (ca. 316 to 300 Ma), characterized by three types of granite emplacement during two different extensional events (E1 and E2) and one compressional event (C3) within the Variscan orogeny. The W (Cu) mineralization styles correspond to veinlets and quartz veins (i.e., São António and Santa Helena), and disseminations in the Santa Helena breccia pipe. Molybdenite coexists with an Fe-bearing wolframite–quartz assemblage in the Venise breccia pipe and quartz veins (i.e., São José and São Paulo). The geochemistry and geochronology of wolframite and molybdenite samples were studied by electron probe microanalysis (EPMA), in-situ U–Pb laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) and Re–Os thermal ionization mass spectrometry (TIMS). The wolframite yields a U–Pb age (sample WBV1) of 315.2 ± 4.7 Ma (2σ), representing the first recognized episode of W deposition in the Iberian Massif. Wolframite samples (WBV1, WB1, and WB4) have a ferberite composition with a hübnerite/ferberite ratio of < 29. High amounts of Nb (up to 3703 ppm) with low Ta (up to 123 ppm) and REEs (up to 11.4 ppm) and conversely, low amounts of Nb (up to 471 ppm) with high Ta (up to 190 ppm) and REEs (up to 53.7 ppm) were measured in wolframite samples. The REEs normalized patterns of the wolframite samples record a mixed signature. Large and positive Eu/Eu* and Er/Er* anomalies were identified (sample WBV1), whereas negative Ce/Ce* and Nd/Nd* anomalies were observed in samples WB1 and WB4. Molybdenite Re–Os dating yields absolute ages ranging from 305.1 to 303.8 ± 2.2 Ma (2σ), which are coeval with the emplacement of E2 biotite granite (Penedos; I-type; <305 Ma). Low amounts of Re (<1 ppm), W, Co, Ni, As, Cu, Bi, Fe, Mn V and Se (<0.005 wt%) were detected in the molybdenite structure. Constraints between the timing of W- and Mo-deposition and a protracted cooling history of the host rocks are confirmed by 40Ar/39Ar white mica dating. The 40Ar/39Ar ages obtained for secondary white micas collected from Mo veins (Venise breccia pipe; 277 ± 3 and 287 ± 4 Ma 2σ) and W (Cu) dissemination (Santa Helena breccia pipe; 287 ± 2 and 279.0 ± 6 Ma 2σ) record the isotopic resetting by later hydrothermal overprints and cooling /exhumation history after E2 Gerês biotitic granite emplacement. The W-ore deposition did occurred during the final E1 extensional tectonic stage (315 Ma) and E2 extensional tectonic stage for Mo-ore deposition, where a temporal offset was needed for the adjustment of tectonic conditions after the C3 compressional and E2 extensional stage started. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Beila and Dongga granites emplaced at ca. 118 Ma and 110 Ma, respectively. • The formation of the Beila granites was in response to the Lhasa-Qiangtang collision. • The Dongga granites resulted from the breakoff of the Bangong-Nujiang oceanic slab. • The locally survived ancient basement beneath the northern Lhasa Terrane has affinity of that in the central Lhasa Terrane. Collisional orogenic belts serve as excellent places for investigating geodynamic process and growth mechanism of the continental crust. As one of the largest collisional orogenic belts worldwide, the Tibetan Plateau is formed by the amalgamation of multiple tectonic terranes. However, the nature and composition of the crustal basement beneath the northern Lhasa Terrane, located in central Tibetan Plateau, is still a matter of debate. Here, we investigated a series of Early Cretaceous granites in the Beila and Dongga areas, northern Lhasa Terrane. Zircon U-Pb dating reveals that the Beila and Dongga granites were emplaced at ca. 118 Ma and 110 Ma, respectively. These granites are characterized by high SiO 2 and K 2 O, low TiO 2 and P 2 O 5 contents and low Mg#. They exhibit enrichment in light rare earth elements, significant negative Eu anomalies, and depletion in Ba and Sr. These geochemical features suggest that they belong to highly fractionated I-type granites. Both the Beila and Dongga granites display similar and enriched whole-rock Sr-Nd and zircon Hf isotope compositions, implying a likely common ancient crustal origin. Given the temporal sequences and redox conditions during their formation, it is highly probable that the Beila and Dongga granites formed during the syn-collision stage between the Lhasa and Qiangtang Terranes and the breakoff of the Bangong-Nujiang oceanic slab, respectively. Integrated with coeval magmatism in the central Tibetan Plateau, our new data reveal the presence of a regionally preserved ancient basement beneath the northern Lhasa Terrane, analogous to the equivalent basement beneath the central Lhasa Terrane. [ABSTRACT FROM AUTHOR]

[Display omitted] • Middle Permian adakite, arc granitoids and high fractionated granite in the northern Qaidam Block have been identified. • Various magma sources contributed to the occurrence of these granitoids in the northern Qaidam Block. • The northern Qaidam Block was an active continental arc during the Middle Permian. • A five-stage model of subduction slab roll-back and subduction zone retreat for late Late Paleozoic to Early Mesozoic tectonic evolution of the northern Qaidam Block. Origin and tectonic setting of late Late Paleozoic to Early Mesozoic igneous rocks in the northern Qaidam Block (NQ) have long been a matter of debate. In this paper, we report new zircon U-Pb ages and Hf isotopic compositions and bulk rock major and trace elemental compositions for granitoids of the Yanchangbeishan area in the NQ. The granodiorite, tonalite, granodiorite, and syenogranite yielded zircon U-Pb ages of 271.9 Ma, 262.0 Ma, 272.4 Ma and 261.3 Ma, respectively, corresponding to ε Hf (t) values are 13.04–14.32, 8.14–10.77, 8.66–11.88, and 8.22–10.43, respectively. These granitoids are compositionally I-type granites and exhibit varying degrees of enrichment in Rb, Th, U, and K, and depletion in Nb, Ta, and Ti. According to field relationships, petrology, geochronology, and geochemistry, the granitoid types can be divided into three groups: (1) ca. 272 Ma granodiorites, which are formed through partial melting of metagreywackes and amphibolites derived from depleted mantle; (2) ca. 262 Ma tonalite, which represents a typical high-silica adakite derived from partial melting of subducted oceanic crust during the evolution of depleted mantle; and (3) ca. 261 Ma syenogranite, which is formed by the partial melting and high-degree fractional crystallization of mixed crustal materials. Considering our findings and the regional geological background, we propose a five-stage tectonic evolution model of subduction slab roll-back and subduction zone retreat for the late Late Paleozoic to Early Mesozoic of NQ. [ABSTRACT FROM AUTHOR]

S-type granitic magmas form essentially through partial melting of crustal metasedimentary rocks, so this eliminates many possibilities for the origins of chemical variations in their parental magmas. Global, whole-rock, major-oxide data show that S-type volcanic series have far less chemical variability (analytical scatter) than S-type plutonic rocks. On the other hand, published data show far smaller contrasts between metaluminous 'I-type' silicic plutonic and volcanic rocks. There are several possible explanations for these features, but sampling bias and analytical errors can be discounted. Likewise, the differences cannot be explained by plutonic S-types being crystal cumulates or products of wall-rock assimilation, nor can they be due to volcanic suites being products of magma mixing or having compositions controlled by a different differentiation mechanism to that which might control S-type plutonic compositions. Variations in major-oxide concentrations suggest that the most probable explanation is that S-type plutonic magmas are derived from somewhat more aluminous metasedimentary source rocks, with higher ratios of metapelites to metagreywackes. If so, there are complementary implications that plutonic S-type magmas may be formed at lower temperatures, that they may be more hydrous than the S-type volcanic magmas, and that the differences in emplacement mechanism reflect this. The weaker contrasts between 'I-type' volcanic and plutonic rocks may be due to their crustal magma sources being more homogeneous and the melting reactions stoichiometrically similar, regardless of source-rock type. • S-type volcanic series have much less chemical variability than S-type plutonic rocks. • Far smaller contrasts exist between metaluminous 'I-type' silicic plutonic and volcanic rocks. • Most probably S-type plutonic magmas are derived from more aluminous metasedimentary source rocks than the volcanic magmas. • Plutonic S-type magmas are probably be formed at lower temperatures and are more hydrous than the S-type volcanic magmas. • Weaker contrasts among 'I-type' rocks are due to more homogeneous magma sources and closely similar melting-reaction stoichiometry. [ABSTRACT FROM AUTHOR]

The closure of the Paleotethys ocean in the Tethyan orogenic belt in northeastern (NE) Iran, related to the collision between Gondwana-derived terranes in the south and Laurasia in the north, remains controversial due to the sparsity of Paleozoic ophiolitic outcrops but can be constrained by contemporaneous granitoids. The Late Triassic Torbat e Jam stock in NE Iran is composed of three intrusive suites: (1) the oldest gabbro to quartz diorite intruded at 215.5 ± 0.9 Ma; (2) granodiorite to monzonite; and (3) the youngest granite to alkali granite. All three suites are metaluminous to moderately peraluminous with enrichment in LILE, low LREE/HREE fractionation with (La/Yb) N  = 8.4–13.6, and small negative Eu anomalies. The Torbat e Jam stock without primary magnetite is characterized by very low magnetic susceptibility (5 × 10 −5 to 6 × 10 −4  SI unit), indicative of the I-type granitoids. Zircon Hf isotopic compositions show positive εHf (t) values of +2.6 to +5.7, indicative of a predominantly mantle source with minor crustal contamination. Hf model ages are consistent with the presence of Neoproterozoic juvenile sources (T DMC  = 0.88 to 1.09 Ga). These geochemical data and field relationships suggest that the Torbat e Jam stock formed in a late orogenic to post-collisional tectonic setting after the closure of a secondary Paleotethys ocean (Paleotethys II), which opened as an oceanic trough during the Late Palaeozoic in the Iranian block, and closed in the Late Permian-Early Triassic Indosinian orogeny. [ABSTRACT FROM AUTHOR]

The Lower Yangtze River Belt in eastern China preserves evidence for widespread Mesozoic magmatism. Geochronological and geochemical studies have been conducted on the magmatic rocks and their associated mineral deposits; however, the relationships and melting conditions of spatially associated I- and A-type granites remain poorly constrained. The Qingyang–Jiuhuashan granitic complex in southern Anhui Province, eastern China, comprises primarily hornblende-bearing granodiorite, monzogranite, alkali-feldspar granite, and granitic porphyry, which yield zircon U Pb ages of 142.2 ± 1.3, 134.6 ± 1.2, 126.4 ± 1.9, and 125.9 ± 1.2 Ma, respectively. Zircon grains from an enclave in the monzogranite yield an age of 134.5 ± 1.1 Ma, similar to that of the host rock. The ages are consistent with the timing of regional magmatic events in southern Anhui Province. Whole-rock geochemical compositions indicate that the granodiorite and monzogranite represent I-type granites, whereas the alkali-feldspar granite and granitic porphyry display A-type signatures. The I- and A-type granites yield similar whole-rock Sr Nd isotopic compositions, but distinct zircon δ 18 O values. We infer that the I-type granites were produced through water-fluxed melting of Mesoproterozoic basement during subduction of the paleo-Pacific plate. The A-type granites were generated through partial melting of the lower crust, triggered by extensional upwelling of mantle-derived magmas that provided heat and alkali-rich fluids. We identify three stages of Cretaceous tectono-magmatic activity that occurred in response to ridge subduction and subsequent slab rollback beneath eastern China. [ABSTRACT FROM AUTHOR]

The Shirenzhang tungsten deposit is a classic wolframite-quartz vein-type deposit located in northern Guangdong Province, eastern segment of the Nanling W-Sn polymetallic belt. The ore veins, controlled by the NW-striking fault system, are mainly hosted in the Ordovician metasedimentary rocks and can also be found with less amount in the cupola of the concealed granitic stock, displaying a typical five-floor vertical zonation proposed by the Chinese geologists. The concealed granitic stock mainly comprises two intrusive facies, the porphyritic biotite granite (G1) in the outer zone and the medium- to fine-grained monzogranite (G2) in the inner zone. In this paper, we report new cassiterite U-Pb ages and Pb isotopes of sulfides for the Shirenzhang tungsten deposit, combined with new zircon U-Pb ages and Hf isotopes, elemental geochemistry and Sr-Nd-Pb isotopes of the concealed granitic rocks, with aims to elucidate the origin of the ore-related granites and the link between the tungsten mineralization and granitic magmatism. LA-ICP-MS zircon U-Pb dating gives the weighted mean ages of 164 ± 2 Ma for G1 and 162 ± 4 Ma for G2, respectively. Cassiterite from the wolframite-bearing quartz vein and the drusy quartz vein yield the weighted mean ages of 164 ± 2 Ma and 160 ± 2 Ma, respectively. These ages suggest that both the granitic intrusion and related W-(Sn) mineralization in the Shirenzhang deposit were initiated during the late Jurassic (ca. 160 Ma). The Shirenzhang granitic rocks are weakly peraluminous highly fractionated I-type granites. Detailed elemental and isotopic data demonstrate that the granitic rocks were derived from partial melting of the Paleoproterozoic basement rocks at a relatively shallow depth of ~30 km triggered by underplating of basaltic magma, and underwent extensive fractional crystallization of hornblende, biotite, feldspar, and monazite and/or allanite. A continental arc setting induced by northwesterly subduction of the paleo-Pacific plate is suggested for the genesis of the Shirenzhang I-type granites. The comparable Pb isotopic compositions of feldspar and sulfides imply that the lead in the ore veins was of magmatic origin. Integrating the spatial-temporal relationship between the ore veins and the concealed granitic rocks with the Pb isotopes from the sulfides and granites, we suggest that the tungsten mineralization is genetically linked with the concealed granitic rocks in the Shirenzhang deposit. Fractional crystallization and melt-fluid interaction may play an important role on the formation of the granite-related tungsten mineralization. [ABSTRACT FROM AUTHOR]

Neoproterozoic intrusions are widespread in the northwestern margin of the Yangtze Block, and their petrogenesis was closely related to the assembly and breakup of Rodinia supercontinent. A combined study of zircon U–Pb dating, geochemistry and Sr–Nd–Hf isotopes was carried out for three types of intrusive rocks from the Hannan region, including the Beiba gabbros, the Tianpinghe and Taojiaba I-type granites and the Tiechuanshan and Huangguan A-type granites. LA-ICP-MS zircon U–Pb dating results show that the studied intrusions have crystallization ages ranging from ca. 880 to 770 Ma. The ca. 880 Ma Beiba gabbros have variable contents of MgO, Al 2 O 3 , Cr and Ni and extremely low high field strength elements (HFSE) concentrations that indicate a cumulate origin. These gabbros display subduction-related geochemical signatures with whole-rock initial 87 Sr/ 86 Sr ( I Sr ) = 0.704–0.705, ε Nd ( t ) = −0.4 to +0.6 and zircon ε Hf ( t ) = +6.9 to +8.4, suggesting that they were derived from the partial melting of an enriched lithospheric mantle that had been modified by slab-derived materials. The ca. 860 Ma Tianpinghe I-type granites have high I Sr (> 0.704) and negative ε Nd ( t ) (−5.6 to −3.5) values and zircon ε Hf ( t ) = −1.9 to +1.6, indicating their sources were mixtures of Neoproterozoic juvenile mafic crust and minor Paleoproterozoic crustal components, whereas the ca. 770 Ma Taojiaba I-type granites have relatively low I Sr (<0.704) and positive ε Nd ( t ) (+1.5 to +2.4) with zircon ε Hf ( t ) = +6.2 to +9.5, implying that they were dominantly sourced from the Neoproterozoic juvenile crustal materials. The geochemical and Sr–Nd–Hf isotopic data imply that the ca. 780 Ma Tiechuanshan A-type granites were crystallized from a reduced and peralkaline magma, which was generated by partial melting of a heterogeneous source involving Neoproterozoic juvenile and ancient mafic crust under dry and reducing conditions. In contrast, the parental magma of the ca. 774 Ma Huangguan A-type granites was oxidized, aluminous and calc-alkalic and resulted from the dehydration melting of tonalitic to granodioritic rocks under water-subsaturated and oxidizing environments. In combination with previous work, the ca. 880–860 Ma Beiba gabbros and Tianpinghe I-type granites are interpreted to be formed during the stage of initial back-arc extension that was caused by subduction-induced convection in the mantle wedge. Subsequently, the ca. 780–770 Ma Tiechuanshan and Huangguan A-type granites and Taojiaba granodiorites were formed in a continental back-arc rift setting related to the rollback of subducted oceanic slab. Our new results support that an arc-back-arc system developed in the northwestern Yangtze Block during the Neoproterozoic. [ABSTRACT FROM AUTHOR]

Located in a region rich in Cu-Ni and Mo mineralization, the Baishan granitic stock is barren for reasons that remain enigmatic. Whole rock elemental and Sr-Nd isotope analysis, major element analysis of a number of minerals, and zircon trace element, U-Pb and Hf isotope analysis were undertaken in order to reveal the petrogenesis of the granites. All granites show typical I-type characteristics including metaluminous to slightly peraluminous, calc-alkaline signatures with a strong depletion of Nb, Ta, Ti and P, enrichment of light rare earth elements and large ion lithophile elements (e.g., Cs, Rb, Th, U, K). In addition, a strong depletion in Ti and P, highly fractionated light rare earth element patterns and less fractionated heavy rare earth element patterns, and negative correlations between SiO 2 and TiO 2 , Al 2 O 3 , MgO, FeO T , P 2 O 5 , Zr and Hf suggest significant fractional crystallization of amphibole, apatite, zircon and Ti-bearing minerals. Whole rock Sr-Nd and zircon Hf isotopic compositions show wide variations with ( 87 Sr/ 86 Sr) i values of 0.70358 to 0.70505, εNd (t) of 3.8 to 7.2, and εHf (t) of 2.4 to 12.2 indicating derivation from partial melting of juvenile lower crust with obvious addition of ancient crust. Zircon U-Pb ages indicate a formation age of ~ 292 Ma, significantly older than the ore-forming granite porphyry and slightly older than the regional mafic-ultramafic, A-type and diabase magmatism of Eastern Tianshan. The granite stocks were likely derived during heating of ascending asthenospheric mantle above a mantle plume in the Early Permian. Mineral chemistry, saturation thermometry, mineral species and whole rock Fe 2 O 3 /FeO ratios indicate a crystallization temperature of > 980 to 665 °C, pressure of ~ 1.6 kbar and oxygen fugacity of ≤ NNO for the granite stock. Comparing the geochemistry, magma source and crystallization environment for the Early Permian barren granite and Late Triassic ore-related granite porphyry, the low ratios of Sr/Y and low (La/Yb) N , and reduced oxidation state (≤ NNO) in the granitic stock are signatures of infertility for the Early Permian granite. This study implies high Mo mineralization potential for granitic rocks with high Sr/Y, (La/Yb) N and highly oxidized conditions. [ABSTRACT FROM AUTHOR]

Arc-related intrusions may provide insights into the evolutionary history of orogenic belts. The Danzhou biotite monzogranite (DZG) batholith is situated adjacent to the Bangxi−Chenxing suture in central Hainan Island (South China), which represents the easternmost segment of the eastern Paleo-Tethys branch. Here, we document the zircon U Pb ages, major and trace elements, and Sr–Nd–Hf isotope geochemistry of the DZG to constrain the evolutionary history of the easternmost segment of the Paleo-Tethys. LA − ICPMS zircon U Pb geochronology yielded emplacement ages ranging from 263 ± 3 Ma to 262 ± 2 Ma. Bulk-rock geochemical affinities reveal that the granitic intrusion is a high-K calc-alkaline and weakly peraluminous (A/CNK = 1.04–1.09) granite, exhibiting high SiO 2 (70.08–73.33 wt%) and K 2 O (4.42–5.31 wt%) contents. The rocks are characterized by LIFE and LREE enrichment, and HFSE depletion, exhibiting negative Nb, Ta, P, and Ti contents. They also show remarkable negative Eu anomalies with Eu/Eu* = 0.35–0.53. The petrography and elemental compositions correlate the DZG with an I-type granite. The DZG has variable initial 87Sr/86Sr (0.7043 and 0.7109), negative ε Nd (t) values (−7.9 to −7.2), and negative to positive in-situ ε Hf (t) values (−4.3 to 7.5), which are similar to those of the Middle Permian I-type granitoids situated in southern Hainan. Geochemical data and Sr − Nd − Hf isotopic compositions indicate that the DZG might have been generated by magma mixing of the lower crust beneath the South China Block (SCB) and enriched mantle with a 60–75% mantle contribution. The DZG exhibits arc-granite affinities and is related to the northward subduction of the eastern Paleo-Tethys Ocean between the Indochina Block and SCB. The formation of the DZG suggests subduction of the easternmost segment of the Paleo-Tethys began during the Middle Permian and its closure occurred during the Middle Triassic. [Display omitted] • The Danzhou biotite monzogranite was emplaced at 263–262 Ma. • Magma mixed by the crust and mantle melting with a 60–75% mantle contribution. • Magmatism formed related to the northward subduction of the eastern Paleo-Tethys. • Subduction of the easternmost Paleo-Tethys began at the Middle Permian. [ABSTRACT FROM AUTHOR]

Late Silurian–early Devonian magmatism of the NW Junggar region in the Central Asian Orogenic Belt provides a critical geological record that is important for unraveling regional tectonic history and constraining geodynamic processes. In this study, we report results of Zircon U–Pb ages and systematic geochemical data for late Silurian–early Devonian largely granitic rocks in NW Junggar, aiming to constrain their emplacement ages, origin and geodynamic significance. The magmatism consists of a variety of mafic to felsic intrusions and volcanic rocks, e.g. adakitic granodiorite, K-feldspar granite, syenitic granite, gabbro and rhyrolite. U–Pb zircon ages suggest that the granitoids and gabbros were emplaced in the late Silurian–early Devonian (420–405 Ma). Adakitic granodiorites are calc-alkaline, characterized by high Sr (407–532 ppm), low Y (12.2–14.7 ppm), Yb (1.53–1.77 ppm), Cr (mostly < 8.00 ppm), Co (mostly < 11.0 ppm) and Ni (mostly < 4.10 ppm) and relatively high Sr/Y (31–42) ratios, analogous to those of modern adakites. K-feldspar granites and rhyolites are characterized by alkali- and Fe-enriched, with high Zr, Nb and Ga/Al ratios, geochemically similar to those of A-type granites. Syenitic granites show high alkaline (Na 2 O + K 2 O = 8.39–9.34 wt.%) contents, low Fe # values (0.73–0.80) and are weakly peraluminous (A/CNK = 1.00–1.07). Gabbros are characterized by low MgO (6.86–7.15 wt.%), Mg # (52–53), Cr (124–133 ppm) and Ni (84.7–86.6 ppm) contents. The geochemical characteristics of the gabbroic samples show affinity to both MORB- and arc-like sources. All granitoids have positive εNd(t) (+ 3.9 to + 6.9) and zircon εHf(t) (+ 9.8 to + 15.2) values and low initial 87 Sr/ 86 Sr ratios (0.7035–0.7043), with young T DM (Nd) (605–791 Ma) and T DM (Hf) (425–773 Ma) ages, suggesting significant addition of juvenile material. The adakitic granodiorites probably resulted from partial melting of mafic lower crust, leaving an amphibolite and garnet residue. The K-feldspar granites, rhyolites and syenitic granites probably formed from partial melting of the Xiemisitai mid-lower crust, while the gabbroic intrusion was probably generated by interactions between asthenospheric and metasomatized lithospheric mantle. Voluminous plutons of various types (adakites, A-type granites, I-type granites, and gabbros) formed during 420–405 Ma, and their isotopic data suggest significant additions of juvenile material. We propose that a slab roll-back model can account for the 420–405 Ma magmatic “flare up” in NW Junggar as well as an extensional setting. [ABSTRACT FROM AUTHOR]

I- and S-type granites comprise large areas and play a key role in global soil weathering patterns. I-type granites are originated from melting of igneous source rocks, whereas S-type granites result from melting of sedimentary sources. This gives rise to differences in mineralogical and geochemical characteristics of the rocks. The objective of this study was to address the effect of petrology and mineralogy of I- and S-type granites on weathering, pedogenesis and total organic carbon stocks across a climosequence. Significant differences in morphological, physical and chemical properties of soils derived from I- and S-type granites were observed and directly linked to petrological, mineralogical and geochemical signatures of the underlying granites, e.g., presence of more mafic minerals in the I-type granite, and therefore a higher clay and iron content in their derived soils. In addition, this higher iron content favored the hematite pathway and, thus, the red soil development. Despite the influence of the climate on weathering patterns, i.e., higher soil development in humid areas, parent material seems to play a decisive role in determining soils characteristics in the studied area. The type of parent material also governed the rates of carbon accumulation in soils. I-type granites originated soils with higher TOC stocks than soil profiles developed from S-type granites. This carbon accumulation is mainly due to soil chemical and physical characteristics driven by the type of granite, notably soil fertility and clay content. [ABSTRACT FROM AUTHOR]

The early Paleozoic Wuyi–Yunkai orogeny resulted in extensive magmatism in the Cathaysia and eastern Yangtze blocks, South China. Identifying the nature of related magmatism is essential for understanding the orogeny that remains enigmatic with regard to its tectonic setting and geodynamic driving force. The Zhangjiafang pluton (438 ± 3 Ma) in western Jiangxi province is composed of predominant granodiorite with abundant coeval mafic-intermediate microgranular enclaves (MMEs) (~ 433 ± 5 Ma). The granodiorite samples are weakly peraluminous (A/CNK = 1.05–1.09) and have low SiO 2 (61.9–64.9 wt.%) and high Fe 2 O 3 (4.6–5.6 wt.%), MgO (2.2–2.8 wt.%) and CaO (4.3–4.8 wt.%), belonging to I-type suite due to abundant amphibole in the rocks. They exhibit strongly negative whole-rock ε Nd (t) values (− 11 to − 9) and zircon ε Hf (t) values (− 14 to − 4), similar to the basement of the Cathaysia Block, but distinguishable from simultaneous I-type granites of the Banshanpu and Hongxiaqiao plutons in eastern Yangtze Block in much lower Sr, Ba, Th and U. The MME samples show pronounced negative Nb–Ta–Ti anomalies and have overall less negative whole-rock ε Nd (t) (− 9 to − 7) and zircon ε Hf (t) values (− 9 to − 4) than the host granodiorite, which are best interpreted as products of mantle-derived melts that mixed insufficiently with crust-derived magma. The block boundary between the eastern Yangtze and Cathaysia blocks should pass through the nearby west area (i.e., Pingxiang City) of the Zhangjiafang pluton. The Early Paleozoic I-type granitic rocks near the block boundary have all negative ε Nd (t) and ε Hf (t) values, demonstrating an overall ancient basement of the two blocks prior to the Wuyi–Yunkai orogeny, preferring an intracontinental orogeny model. However, the early Paleozoic mafic rocks and I-type granites with coeval MMEs were frequently present along the Jiangshan–Shaoxing–Pingxiang Fault zone, illustrating widespread modification of the ancient basement adjacent to the block boundary by mantle-derived melt during the orogenic collapse. The pre-existing block boundary might have promoted asthenosphere upwelling and basaltic underplating during the intracontinental orogenic collapse. [ABSTRACT FROM AUTHOR]

Post-collisional magmatic intrusions and their mafic microgranular enclaves (MMEs) can provide significant insights into granite petrogenesis, crust-mantle interaction, and the reworking and growth of the continental crust. A combined petrological and geochemical study was carried out on MMEs and their host Niubiziliang I-type felsic composite pluton (granite and granodiorite) and aluminous A 2 -type Datonggou biotite granite from the Niubiziliang batholith in the northwestern segment of the North Qaidam Orogenic Belt (NQOB), China. This study presents whole-rock major- and trace elements and Sr Nd isotopic compositions, electron probe microanalyses of plagioclase, hornblende, and biotite, and zircon U Pb dating and Hf isotopes. Zircon U Pb dating demonstrates that the studied rocks formed during the Late Devonian (ca. 382 Ma). The Niubiziliang composite felsic pluton samples yield a metaluminous calc-alkaline to high-K calc-alkaline I-type granitic composition. The MMEs from Niubiziliang composite felsic pluton have low SiO 2 (52–64 wt%) and high MgO (2.8–4.9 wt%) concentrations. Both MMEs and host granites are enriched in light rare earth elements (LREEs) and large ion lithophile elements (LILEs) and are depleted in P and high field strength elements (HFSEs). All MMEs and host granitoids samples from Niubiziliang have indistinguishable Sr-Nd-Hf isotopic compositions characterized by initial Sr isotope ratios of 0.70545–0.70633 (MMEs), 0.70555–0.70742 (host rock), whole-rock ε Nd (382 Ma) values of −2.95 to +1.6, −0.25 to +3.5, and zircon ε Hf(382Ma) values of +2.2 to +10.2, +1.3 to +10.4, respectively. The Niubiziliang composite felsic pluton is a product of mixing juvenile crust-derived and depleted mantle-derived melts in a 40:60 proportion. MMEs crystallized from the same source as the host granite, and they were formed by self-mixing with the earlier crystallized cumulates when they were affected by the emplacement of subsequent hot magmas. The Datonggou biotite granite has high TFe 2 O 3 /(TFe 2 O 3 + MgO), TiO 2 /MgO, Ga/Al, and Y/Nb ratios, high zircon saturation temperatures (802–846 °C), high HFSE concentrations (e.g., Zr, Nb, and Y), moderate (Na 2 O + K 2 O) concentrations, and low Eu and Sr concentrations. Interstitial biotite has high Fe 2 O 3 but low MgO concentrations, similar to those of aluminous A-type granite. The above-mentioned characteristics imply that the Datonggou biotite granite is an aluminous A 2 -type granite. Considering their high initial Sr isotopic composition (0.72218–0.72652), low ε Nd (382 Ma) (−6.73 to −6.31), and comparatively old two-stage Nd model ages (1640–1674 Ma), we suggest the biotite granite was generated by partial melting of Ordovician-Silurian granitoids with tonalitic compositions at H T -L P conditions. The formation of coeval I- and aluminous A 2 -type granitoids in this region was probably related to the lithospheric mantle delamination and associated asthenospheric upwelling at ca. 390 Ma. The I-type granitoids and MMEs from the Niubiziliang area represent a net addition of juvenile mantle to the crust and, given the wide distribution of contemporaneous I-type granitoids, the post-collisional magmatism has significantly contributed to the growth of the continental crust in the NQOB. [Display omitted] • The Niubiziliang granitoids, MMEs, and biotite granite were emplaced at 382 Ma. • Lithospheric delamination occurred at ca. 390 Ma in the North Qaidam belt. • The post-collisional granitoids contribute to the growth of the continental crust. [ABSTRACT FROM AUTHOR]

An initial Paleoproterozoic active continental margin formed along the northern margin of the Yangtze Craton. The early stages of this active tectonism involved the subduction of ocean crustal material and the formation of ca. 2.05 Ga Nb–enriched mafic dikes in the Kongling Complex, ca. 2.08 Ga arc–related granitoids in the Houhe area and arc–related I–type granite magmatism within the Feidong Complex. The final stages of subduction and the closure of the ocean in this area led to the collision of the South and North Yangtze cratons at 2.0–1.9 Ga, forming I– or S–type syn–collisional granites in the Kongling Lengshui, Hong'an, Tongbai, Susong, and Feidong complexes as well as granulite facies metamorphism in the Dabie Orogen and the Kongling and Douling complexes. [Display omitted] • Paleoproterozoic basement of the Yangtze Craton crops out within the Feidong Complex. • Ca. 2.0 Ga granitic rocks of the Feidong Complex have I-type affinities. • I–type granites in the Feidong Complex generated by the partial melting of older lower crustal material. • A ca. 2.0 Ga subduction-collision event is recorded within the northeastern Yangtze Craton. • The Yangtze Craton was a component of the Columbia supercontinent. The early history of the Yangtze Craton is not well constrained as a result of the lack of outcropping Archean to Paleoproterozoic rocks. This study presents new elemental and Laser Ablation–(Multicollector)–Inductively Coupled Plasma–Mass Spectrometry (LA–(MC)–ICP–MS) zircon U–Pb geochronological and Hf isotopic data for Paleoproterozoic granites of the Feidong Complex, located within the northeastern Yangtze Craton. Zircon U–Pb dating yields 207Pb/206Pb ages of 2054 ± 22 and 1994 ± 26 Ma for granite and granitic gneiss units in this area, respectively, confirming the existence of middle Paleoproterozoic basement rocks within the Feidong Complex and the northeastern Yangtze Craton. Zircons from the granite and granitic gneiss units have ε Hf (t) values ranging from –13.02 to –6.91, corresponding to two–stage Hf model ages (T DM2) of 3.44–3.07 Ga. The granites have whole–rock ε Nd (t) values from –0.25 to + 0.14 whereas the granitic gneisses have ε Nd (t) values that range from –8.90 to –8.12. This suggests that the granitic magmatism in this area was resulted from reworking of ancient crustal components but that the granites and granitic gneisses are derived from different magma sources. This is consistent with the fact that the granites in this area have volcanic arc affinities whereas the granitic gneisses have syn -collisional granite affinities, although all are classified as I–type granites. Combining these data with previous research on Paleoproterozoic magmatic and metamorphic events recorded elsewhere in the Yangtze Craton suggests that a middle–late Paleoproterozoic geological transition from plate subduction to collision occurred at ca. 2.0 Ga in the northeastern Yangtze Craton. This tectonism caused the partial melting of ancient crustal material, generating both the granites and granitic gneisses in the study area. [ABSTRACT FROM AUTHOR]

The North Qinling orogen, central China, formed above an ancient ocean-continent subduction zone and contains widespread early-Paleozoic I-type granites. Previous studies have shown that the mantle wedge beneath the north Qinling unit was significantly metasomatized and isotopically enriched relative to the lower crust in the early-Paleozoic. Therefore, material contributions from the mantle wedge and the lower continental crust can be readily distinguished in this geological setting. In this study, we show that the early-Paleozoic Zaoyuan I-type granite was emplaced at c. 417 Ma and zircon antecrysts are preserved. Our geochemical and isotopic results demonstrate that there is no evidence of a mantle source contribution in the Zaoyuan granite. Instead, it is argued that the granites formed solely by low-temperature fluid-fluxed melting of a mixture of lower and upper crustal material, in a continental arc setting. Cathodoluminescence images of magmatic zircons from the Zaoyuan granite reveal core to rim domains. Zircons from both domains are isotopically uniform and have consistent morphology. Increasing Th and U contents and δ18O zir and decreasing ε Hf (t) values from core to rim domains are explained by contamination of the melt during crystallization. Two granite samples have different Hf isotope compositions indicating some source heterogeneity during the formation process. Our results provide evidence for partial melting of a mixed crustal source and subsequent minor assimilation with upper crustal metasediments during crystallization. We further conclude that the suggested magma formation mode might be more common process for the generation of I-type granites in order to acquire their isotope mixing characteristics. • The Zaoyuan granite was of I-type affinity and emplaced at 417 ± 3.3 Ma. • They were formed by low-temperature fluid-fluxed melting of a mixture of different crustal sources in continental arc setting. • Zircon morphology and grain-scale Hf O isotope variations indicate contamination of upper crustal material. [ABSTRACT FROM AUTHOR]

The Neoproterozoic basement of Wadi Al-Baroud area located at the northern Eastern Desert (ED) of Egypt, at the northernmost segment of the Arabian–Nubian Shield (ANS), is comprised of two different granite suites. A large batholith ascribed to the Older Granite suite, extends across the boundary between the northern and central ED, and is intruded by two isolated plutons of the Younger Granite suite. The Older Granite suite includes gray-colored, massive to gneissose, granodiorites to tonalites typically containing microgranular mafic enclaves. These are calc-alkaline, magensian, metaluminous I-type granitoids, with high Sr contents, and depleted in Rb, Nb, Y and REE. The Younger Granite suite plutons are pink to red, biotite and two-mica monzogranites. These are peraluminous A-type granites exhibiting a high-K calc-alkaline nature, and varying between ferroan and magnesian type granites. The A-type granites of the Younger Granite suite are enriched in Ga, Y, HFSE and REE elements, and depleted in the LILE elements Ba, Sr and Rb and transition metals Cr, Ni, Co, Sc and V. Magmatic saturation temperatures indicate early crystallization of apatite at high temperature in the metaluminous I-type Older Granite suite, while in the peraluminous A-type Younger Granites its crystallization occurs later after separation of zircon and monazite. The plutons of the Younger Granite suite were generated during the post-collisional stage of the northern ANS, following collision between the juvenile ANS crust and the pre-Neoproterozoic continental blocks of west Gondwana. The emplacement of the Older Granite suite took place earlier, within a normally mature continental arc prior to the collision. These pre-collision granitoids evolved through assimilation-fractional crystallization processes from mantle-derived parental magmas, which have interacted with crustal materials during ascent and storage. The post-collisional Younger Granite suite seems to have been derived by high degree, partial melting of metasedimentary sources, particularly psammitic and pelitic metasediments. [ABSTRACT FROM AUTHOR]

New whole-rock major and trace elements, and zircon U–Pb and Hf–Nd isotope compositions are reported for the Karamay dikes, enclaves, and host granites in the West Junggar, NW China. Zircon U–Pb dating of the Karamay pluton yields an age of 300.7 ± 2.3 Ma for the enclave and 300.0 ± 2.6 Ma for the host granite, which was intruded by dike with an age of 298 Ma. The host granites exhibit relatively low SiO 2 contents and A/CNK and Ga/Al ratios, low initial 87 Sr/ 86 Sr ratios (0.703421–0.703526) and positive ε Hf ( t ) (5.5–14.1) and ε Nd ( t ) (7.3–8.1) values with a young model age, suggesting that they are I-type granites and were mainly derived from a juvenile lower crustal source. The enclaves and dikes belong to an andesitic calc-alkaline series and have high MgO concentrations at low silica content and positive ε Hf ( t ) (7.6–13.2, 14.2–14.9) and ε Nd ( t ) (6.8–8.3, ∼6.9) values. They are enriched in LILEs (Rb, Ba and U) and LREE and depleted in HFSEs (Nb and Ta) with insignificant negative Eu anomalies, indicating that the melts were derived from an enriched lithospheric mantle modified by subducted oceanic crust-derived melts and minor fluids, followed by fractional crystallization. The Karamay host granites and enclaves are of mixed origin and are most probably formed by the interaction between the lower crust- and lithospheric mantle-derived magmas, and were intruded by the unmixed dikes subsequently. The upwelling mantle through a slab window in an island arc environment might have triggered partial melting of the lithospheric mantle and its subsequent interaction with the granitic magma, further suggesting that the ridge subduction played an important role in the crustal growth of West Junggar. [ABSTRACT FROM AUTHOR]

Kashmar granitoids outcrop for ~ 100 km along the south flank of the Sabzevar ophiolite (NE Iran) and consist of granodiorite and monzogranite along with subordinate quartz monzonite, syenogranite and aplitic dikes. These granitoids intruded Early to Middle Eocene high-K volcanic rocks and can spatially be grouped into eastern and western granitoids. Five samples of granite have identical zircon U–Pb ages of ca. 40–41 Ma. The granitoids have quite high K 2 O (~ 1.3–5.3 wt.%) and Na 2 O (~ 1.1–4.6 wt.%) with SiO 2 ranging between ~ 62 and 77 wt.%. They are metaluminous to peraluminous, calc-alkaline and I-type in composition. Their chondrite-normalized REE patterns are characterized by LREE enrichment and show slight negative Eu anomalies. Kashmar granitoids have low whole rock εNd (− 0.43 to − 2.3), zircon εHf values (− 1.9 to + 7.2), and somewhat elevated δ 18 O (+ 6.1 to + 8.7‰) in the range of I-type granites. The Kashmar granitoids show Early Neoproterozoic zircon second-stage Hf and bulk rock Nd model ages at ca. 500–1000 Ma (associated with ca. 640 Ma old inherited zircons). Bulk rock Nd–Sr isotopic modeling suggests that 10–20% assimilation of Cadomian lower crust by juvenile mantle melts and then fractional crystallization (AFC process) can explain the Sr–Nd isotopic compositions of Kashmar granitoids. Kashmar granitoids are products of crustal assimilation by mantle melts associated with extension above the subducting Neotethyan Ocean slab beneath SW Eurasia. Similar subduction-related extension was responsible for the flare-up of Eocene–Oligocene magmatism across Iran, associated with core complex formation in central Iran. [ABSTRACT FROM AUTHOR]

Highlights: [•] Fengdingshan granites and Taoyuan Complex were formed in Silurian period. [•] Fengdingshan granites were formed by reworking of Neoproterozoic basaltic crust. [•] Taoyuan mafic rocks originated from a previously metasomatized lithospheric mantle. [•] The Fengdingshan and Taoyuan Plutons were formed in a post-orogenic collapse stage. [•] Nd–Hf decoupling may be a fingerprint of an ancient oceanic subduction. [ABSTRACT FROM AUTHOR]

Abstract: The early Paleozoic Wuyi–Yunkai orogeny represents the first extensive tectonothermal event in South China since the Neoproterozoic break-up of the Rodinia supercontinent. The early Paleozoic igneous rocks in the South China Block (SCB) are important for understanding the processes responsible for the orogeny. The Taishan Batholith in the inner Cathaysia Block consists dominantly of granodiorite and hornblende-bearing granite. Zircon U–Pb dating of four samples gives a consistent crystallization age of ca. 436Ma, synchronous with widespread late-orogenic S-type granitic intrusions in the Wuyi–Yunkai orogen. The Taishan granitoid rocks are metaluminous or peraluminous (A/CNK=0.94–1.15) and have variable SiO2 (61.5–74.9wt.%), MgO (0.4–2.4wt.%), Fe2O3 (1.8–7.4wt.%) and CaO (1.1–5.5wt.%), with gradually decreasing P2O5 from mafic to felsic components. Thus the Taishan Batholith displays the petrological and geochemical characteristics of I-type granites. Additionally, all samples have strongly negative εNd(t) values (−11 to −9), suggesting an overall ancient source. The early Paleozoic I-type granitoid rocks in the Taishan area were derived from partial melting of ancient middle to lower crust at a high thermal gradient (>35°C/km), and underwent extensive fractional crystallization of hornblende, plagioclase, and biotite. The Wuyi–Yunkai orogenic collapse may have been responsible for middle to lower crustal melting of the Cathaysia Block. The early Paleozoic I- and S-type granitoid magmatism lack significant input of a juvenile component, indicating that the processes accompanying orogenic collapse such as asthenosphere upwelling and basaltic underplating, contributed heat to trigger widespread early Paleozoic felsic magmatism in the SCB. An intraplate orogenic event, instead of continental or arc collision, may be the preferred model for the Wuyi–Yunkai orogeny. [Copyright &y& Elsevier]

Abstract: The Qorveh area is located in west Iran and belongs to the Sanandaj–Sirjan plutono-metamorphic zone. The igneous assemblage of Qorveh was generated by subduction of the Neo-Tethys Ocean beneath the Iranian microplate during the Mesozoic and Cenozoic. The Qorveh igneous activity produced several sequences of plutonic (subvolcanic) and volcanic rocks, which host iron deposits in the Qorveh area. Plutonic rocks in this area are comprised of a subvolcanic complex of granite, quartz-monzonite, quartz-monzodiorite, monzonite, diorite, and minor gabbros with a volcanic sequences comprised of rhyolitic rocks. The coeval suite of rocks are metaluminous to slightly peraluminous (A/CNK=0.64–1.16) and are calc-alkaline to alkaline. They also have moderate REE contents (∑REE=72–292ppm and La/Yb=2.6–9ppm for plutonic samples; ∑REE=177–209ppm and La/Yb=4.2–9ppm for volcanic samples) with negative (Eu/Eu*=0.4–0.8ppm) to positive Eu anomalies (Eu/Eu*=1.1–1.3ppm). The lithological, mineralogical, and geochemical studies together with field observations indicate that these rocks were generated by different magmatic processes. All these rocks have geochemical attributes of an active continental margin geodynamic environment (e.g. Cs, Th, K, Rb, and LREE enrichments; P, Nb, Ti, Y, and HREE depletions) and have I-type magmatic characteristics. Also granites, rhyolites, and rhyolitic–rhyodacitic tuffs possess some crustal A-type geochemical characteristics, indicative of local transpression in this dominantly convergent geodynamic environment. [Copyright &y& Elsevier]

Abstract: The granitic rocks of the Sierra de Ancasti represent one of the easternmost outcrops of the Famatinian arc of the Sierras Pampeanas. We report here new U–Pb SHRIMP and LA-ICP-MS Ordovician ages and a petrological and geochemical study of the Las Cañadas I-type granitic complex in the central sector of Sierra de Ancasti. Numerical modelling indicates that calc-alkaline and metaluminous monzogranites (SiO2 = 69.8–73.0 wt.%) were produced by fractional crystallization of plagioclase-rich tonalite (∼60% plagioclase and SiO2 = 60.9–62.5 wt.%) from an inferred parental magma of granodioritic composition (SiO2 = 67.4 wt.%). Sm–Nd isotopic data on the dated rocks indicate a dominant continental crustal input, as reported for other Ordovician granitic rocks (Famatinian magmatism) farther west in the Sierras Pampeanas. Combined ages and isotopic data are consistent with previous studies indicating that Famatinian magmatism was short-lived (∼20 Ma) and lacked a significant asthenospheric contribution. The occurrence of inherited zircon and the petrological and geochemical data from the Las Cañadas complex indicate that the parental magma was derived from mixed igneous and sedimentary material in the source or by partial melting of igneous rocks of different ages. Systematic dating of inherited zircon cores is required to clarify this issue. Zircon saturation geothermometry combined with geochemical data indicates that the onset of zircon crystallization, together with variable amounts of other minerals such as plagioclase, quartz, biotite, oxides and apatite, occurred when the parental magma reached 67 wt.% SiO2 with ∼440 ppm of Zr at ∼878 °C. [Copyright &y& Elsevier]

Abstract: The Sanandaj-Sirjan Zone (SSZ) trends northwestward in western Iran on the Precambrian to Paleozoic basement and exposes abundant I-type granitoids and calc-alkaline volcanic rocks that were most active during the Late Jurassic to Upper Cretaceous. The petrogenesis of the granitoids and associated volcanic rocks has been widely related to Neotethyan subduction beneath the Iranian plate. We report a geochronological and geochemical study of the Suffi abad granite (SLG) body that crops outs southeast of Sanandaj within the SSZ and is mainly composed of K-feldspar+quartz+plagioclase±hornblende. The SLG, which shows a high-K calc-alkaline affinity, has LA-ICPMS zircon U–Pb ages ranging between 149±2 and 144±3Ma and initial 87Sr/86Sr of ∼0.7024–0.7069 and 143Nd/144Nd of ∼0.5125–0.5127. These value correspond to an ɛ Nd (145Ma) of +1.5 and +4.9, suggesting that the SLG originated from the juvenile crust or depleted mantle with a young TDM (650–900Ma) over the subduction zone beneath the SSZ. Zircon saturation temperatures suggest that crystallization of the zircons, or emplacement of the host magmas, occurred at 560–750°C, consistent with an intergrowth texture of K-feldspar and quartz that implies crystallization around the K-feldspar-quartz eutectic at lower temperatures. Overall, geochemical data suggest that crystallization of the hornblende and plagioclase played a role in magma differentiation. These data allow us to conclude that the high-K SLG did not originate directly from the juvenile mantle source as do most I-type, calc-alkaline granitoids, but more likely was produced from the partial melting of pre-existing I-type granitoids in the upper continental crust under low pressure conditions. [Copyright &y& Elsevier]

Abstract: The Jinshajiang suture zone, located in the eastern part of the Tethyan tectonic domain, is noticeable for a large-scale distribution of Late Jurassic to Triassic granitoids. These granitoids were genetically related to the evolution of the Paleo-Tethys Ocean. Beiwu, Linong and Lunong granitoids occur in the middle zone of the Jinshajiang Suture Zone, and possess similar geochemical features, indicating that they share a common magma source. SIMS zircon U–Pb dating reveals that the Beiwu, Linong and Lunong granitic intrusions were emplaced at 233.9±1.4Ma (2σ), 233.1±1.4Ma (2σ) and 231.0±1.6Ma (2σ), respectively. All of these granitoids are enriched in abundances of Si (SiO2t =65.2–73.5wt.%), and large-ion lithophile elements (LILEs), but depleted in high field strength elements contents (HFSEs, e.g., Nb, Ta, and Ti). In addition, they have low P2O5 contents (0.06–0.11wt.%), A/CNK values ([molecular Al2O3/(CaO+Na2O+K2O)], mostly <1.1) and 10,000Ga/Al ratios (1.7–2.2), consistent with the characteristics of I-type granites. In terms of isotopic compositions, these granitoids have high initial 87Sr/86Sr ratios (0.7078–0.7148), Pb isotopic compositions [(206Pb/204Pb)t =18.213–18.598, (207Pb/204Pb)t =15.637–15.730 and (208Pb/204Pb)t =38.323–38.791], zircon δ18O values (7.3‰–9.3‰) and negative εNd(t) values (−5.1 to −6.7), suggesting they were predominantly derived from the continental crust. Their Nb/Ta ratios (average value=8.6) are consistent with those of the lower continental crust (LCC). However, variable εHf(t) values (−8.6 to +2.8) and the occurrences of mafic microgranular enclaves (MMEs) suggest that mantle-derived melts and lower crustal magmas were involved in the generation of these granitoids. Moreover, the high Pb isotopic ratios and elevated zircon δ18O values of these rocks indicate a significant contribution of the upper crustal composition. We propose a model in which the Beiwu, Linong and Lunong granitoids were generated under a late collisional or post-collisional setting. It is possible that this collision was completed before Late Triassic. Decompression induced mantle-derived magmas to be underplated and provided the heat for the anatexis of the crust. Hybrid melts including mantle-derived and the lower crustal magmas were then generated. The hybrid melts thereafter ascended to a shallow depth and resulted in some degree of sedimentary rock assimilation. Such three-component mixing magma source and subsequent fractional crystallization could be responsible for the formation of the Beiwu, Linong and Lunong granitoids. [Copyright &y& Elsevier]

Abstract: The Longwood Igneous Complex (LIC) is located in Southland, New Zealand on the eastern side of the Carboniferous to Cretaceous, I-type, Median Batholith. Intrusives of the Complex range in age from Permian to Jurassic and show trace element characteristics typical of subduction-related magmas. Gabbro, gabbroic diorite and basaltic dyke rocks show trace and minor element patterns and isotopic compositions indicating that they represent magmas generated in an intra-oceanic subduction system. Radiometric ages decrease across the LIC from 254Ma in the east to 142Ma in the west and mineral chemistry and mineral phase relationships indicate emplacement at depths between 15 and 25km. Thus the petrology and geochemistry of the LIC provides the basis for evaluating the composition of lower–middle crust assembled above a long lived intra-oceanic subduction system and we estimate this to be andesitic and similar to bulk continental crust. Rocks of the LIC range in composition from troctolite and gabbro through diorite to trondhjemite and granite. All of the ultramafic rocks and most of the gabbros have petrographic and geochemical features consistent with a cumulate origin and mineral chemistry shows similarities with arc cumulate sequences from elsewhere. Few of the plutonic rocks making up the LIC have direct analogues among modern intra-oceanic volcanic rocks. The latter are the end products and the former the leftovers from magmatic processes that included fractional crystallisation, crustal assimilation and magma mixing and mingling. Longwood intrusions do not represent magma chambers. They formed as crystal cumulates and mushes left over from the processes that generated magmas erupted at the contemporary volcanic arc. A correlation between decreasing age of emplacement and Sr and Nd isotopic compositions and inheritance in zircons dated by ion probe are indications of crustal recycling. The generation of felsic rocks in the Longwood intra-oceanic arc involved crustal anatexis and, over the 100million year history of the arc, the crust evolved towards a composition similar to bulk continental crust and average andesite. Dioritic rocks of the LIC contain abundant mafic enclaves, which are argued to represent fragments of mafic magma, derived by fractional crystallisation from basalt, which was intruded into a hot but solid or near solid diorite. Heating and remobilisation of the dioritic host disrupted and disaggregated the intruding mafic magma to form enclaves and zones of intrusion breccia that show every variation from liquid–liquid to liquid–solid mingling and mixing. They were then further modified chemically and mineralogically by diffusion of H2O, Na, P, Ba, REE, and, to a lesser extent, Rb. Mafic dykes occur throughout the Complex and a number of these are composite with compositions ranging from dolerite through andesite to dacite. The components of composite dykes do not define unequivocal linear mixing trends and hybridisation processes that took place within them have only localised significance; mingling and hybridisation in the composite dykes do not appear to have controlled geochemical variation among the major intrusive units of the Complex. [Copyright &y& Elsevier]

Abstract: The Xutai and Lujiagou plutons, exposed in the Songshan–Jishan area in the southern margin of the North China Craton (NCC), are studied to constrain the tectonic regime of the NCC between 2.5 and 2.4Ga. The Xutai pluton (dated at 2509±33Ma) mainly consists of tonalite and monzogranite with a calc-alkaline affinity (Rittmann Index (δ)<3.3). Low 10,000Ga/Al (1.15 to 1.38) and zircon saturation temperature (T Zr =612 to 779°C) and a negative correlation between P2O5 and SiO2 classify them as I-type granite. Enriched LREE, low Y and Yb with high Sr/Y ratios are attributed to garnet in the residue, indicating a deep source for the pluton. Zircon grains have positive ε Hf(t) values (+4.6 to +9.4) with T DM C ages ranging from 2708 to 2435Ma (average of 2502Ma), close to the crystallization age of the pluton, indicative of a juvenile crust source. Negative Nb, Ta and Ti anomalies of the pluton and its intrusive contact relationship with older subduction-related amphibolites are supportive of an arc setting. The Lujiagou pluton (dated at 2399±24Ma) mainly consists of syenogranite with a calc-alkaline affinity (δ<3.3). High SiO2 (73.25 to 75.21wt.%) and K2O (5.38 to 8.03wt.%) and low P2O5 (0.01 to 0.04wt.%) indicate that the primitive magmas of the rocks have experienced fractionation. The rocks have 10,000Ga/Al (0.71 to 2.55) and T Zr (614 to 796°C) lower than those for A-type granite and negative correlation between P2O5 and SiO2, consistent with highly fractionated I-type character. Zircon ε Hf(t) values (−0.2 to +4.4) with T DM C from 2909 to 2652Ma are indicative of mantle-derived components, contaminated by older crust. However, the rocks have high SiO2, K2O and low Mg#, precluding their derivation from a juvenile source. Considering the LREE enriched nature, low Y, negative Eu anomalies and zircon Hf and whole rock Nd isotopic components identical to TTGs, we propose that the Lujiagou pluton inherited from preexisting Songshan TTGs, consistent with formation in an extensional setting. We thus propose that the Xutai and Lujiagou plutons record a tectonic transition from compressive to extensional setting in the southern margin of the NCC during 2.5 to 2.4Ga. [Copyright &y& Elsevier]

Abstract: The Sakarya Zone is intruded by several Late Paleozoic granitoids, of which the Sarıcakaya intrusive rocks in the central Sakarya (Eskişehir) region, is the least-studied. The Sarıcakaya intrusive rocks consist mainly of quartz diorite-granodiorite, granodiorite and granite. They are, geochemically, divided into two groups: diorites and granites. The former is medium-K and calc-alkaline (mainly I-type), whereas the latter is high-K to shoshonite and calcic (I-type). Typical minerals for both rock types are plagioclase, K-feldspar, quartz, biotite, hornblende and Fe–Ti oxides. Chondrite-normalized REE patterns for the Sarıcakaya intrusive rocks are moderately fractionated and have small negative Eu anomalies. They are enriched in LILE and LREE relative to HFSE showing characteristics of arc-related granitoids. Geochemical characteristics of the Sarıcakaya intrusive rocks indicate a hybrid origin through partial melting of lower crustal source rocks. [ABSTRACT FROM AUTHOR]

The Deng-Deng intrusive complex belongs to the Central African Fold Belt (CAFB) in eastern Cameroon and includes granodiorite and diorite. Both rocks are classified as metaluminous to slightly peraluminous, high-K calc-alkaline, and I-type granitoids (A/CNK <1.1). Primitive mantle-normalized trace-element patterns display large-ion lithophile elements (LILE) enrichment, such as Rb, Cs, Ba and K, and depletion in high-field-strength elements (HFSEs), such as Nb, Ti, Ta and P. The studied rocks are enriched in LREEs relative to HREEs and exhibit weak negative Eu anomalies (Eu/Eu* = 0.61–0.92 and 0.59–0.67 for the granodiorite and diorite, respectively), suggesting active continental margin arc affinity. The emplacement temperatures of these granitoids are estimated between 775 and 806 °C. Combined with their diagnostic ratios (e.g., Th/Ta, Rb/Sr, Nb/La, and La/Sm), we propose that the Deng-Deng granitoids were sourced by mixing between mafic magma derived from the lithospheric mantle and felsic magma derived from partial melting of a lower crust in a convergent margin setting. • Pan-African granitoids investigated at Deng-Deng area in eastern Cameroon. • Deng-Deng granitoids comprise deformed granodiorites and undeformed quartz monzonites. • The studied granitoids display I-type and metaluminous signatures. • Deng-Deng granitoids derived from partial melting of mantle and lower crust sources. • Emplacement at 775–806 °C in convergent margin setting. [ABSTRACT FROM AUTHOR]

Abstract: Two granitoid complexes in the eastern Kyrgyz Tien Shan, situated north and south of the Southern Tien Shan Suture, were studied. The suture formed as a result of the closure of the Turkestan Ocean and collision of the Tarim microcontinent in the south with the Middle Tien Shan in the north. The timing of collision is still disputed. The deformed calc-alkaline Terektinsky complex, situated immediately north of the suture, represents one of the largest shear-zone related intrusions in the Tien Shan (130×5–15 km in size). Small stocks of evolved A-type granites of the Inylchek complex, hosting economic tin mineralization, were emplaced immediately south of the suture opposite the Terektinsky complex. Two samples from the Terektinsky complex and 3 samples from three A-type stocks were collected for U–Pb zircon SHRIMP-II geochronology. The ages at 2σ level obtained for the Terektinsky complex north of the suture (294+5 Ma and 291+5 Ma) and ages of the small granite bodies south of the suture (299+4 Ma, 295+4 Ma, 289+6 Ma; Tashkoro, Inylchek and Maida''adir intrusions, respectively) are nearly identical, within error limits. They show that the Southern Tien Shan Suture in the eastern Kyrgyz Tien Shan had already formed by ~295 Ma, and had evolved into a transcrustal mega-shear zone controlling emplacement of granitoids. Geochemical distinction between the two magmatic systems is based on 10 original bulk and trace analyses of rocks from this study and on a large dataset extracted from previously published research and unpublished reports. Geochemically, the rocks of the Terektinsky complex comprise calc-alkaline (high potassium I-type) series while the granites of the Inylchek complex are typical A-type granites with an elevated alumina saturation index and higher boron contents compared to a “standard” A-type rapakivi granite. Contrasting metallogenic features of the two granitoid complexes south and north of the Southern Tien Shan Suture are defined by their sources: a fertile fore-arc complex, and/or passive margin sediments of Tarim to the south, and barren metamorphic Precambrian basement of the Middle Tien Shan to the north. [Copyright &y& Elsevier]

Abstract: Neoproterozoic magmatism in the Yangtze Block of South China produced voluminous S- and I-type granites, and sparse A-type granites. The Daxiangling A-type granitic pluton is spatially associated with the Shimian I-type pluton at the western margin of the Yangtze Block. Both plutons have similar SHRIMP zircon U–Pb ages of ∼800 Ma and are slightly younger than the tonalite–trondhjemite–granodiorite (TTG) gneisses in the area. The Shimian pluton is composed of granite and monzogranite with high SiO2 (69.3–76.6 wt.%), Na2O (2.79–3.80 wt.%) and K2O (3.94–5.87 wt.%), and low Fe2O3 (0.96–3.06 wt.%) and MgO (0.12–0.50 wt.%). The Daxiangling pluton consists of alkali–feldspar granites with higher SiO2 (76.3–79.3 wt.%) and lower Al2O3 (10.6–11.9 wt.%) and CaO (0.21–0.55 wt.%) than the Shimian granites. Both plutons are slightly peraluminous (A/CNK=1.00–1.12) and belong to the high-K, calc-alkaline series. The Daxiangling alkali-feldspar granites have much higher Zr, Hf, Ga and HREE, and lower Sr than the Shimian granites. On the chondrite-normalized REE diagram, both plutons are enriched in LREE, but the rocks of the Daxiangling pluton show relatively flat patterns because of their higher HREE contents. Their primitive-mantle normalized spidergrams display negative Eu, Nb, Ta, Sr, P and Ti anomalies. Both plutons have nearly identical whole-rock Nd and zircon Hf isotopic compositions (ε Nd(t)=+1 and ε Hf(t)=+5 to +9), similar to the TTG gneisses. We suggest that the I-type granites of the Shimian pluton were produced by dehydration melting of the TTG rocks as a result of underplating of mantle-derived mafic magmas. The rocks above the I-type magma source may have been converted to charnockites by heating and dehydration. With increasing temperatures, the charnockites underwent partial melting at temperatures >900 °C to produce A-type magmas. Both the A- and I-type granites formed at an extensional active continental margin, perhaps in a back-arc environment. A-type granites with mantle-like isotopic signatures may be reworked or recycled from juvenile crustal rocks. The association of A- and I-type granites suggests that aluminous A-type granite is most probably derived from a charnockite source heated by large-scale magmatic underplating, rather than a tonalite source. [Copyright &y& Elsevier]

Abstract: In the Kyrgyz Tien Shan (also known as Tian Shan in literature) the Caledonian (Cambro-Silurian) intrusions comprise an extensive magmatic arc stretching from east to west for more than 1000km. The characteristic feature of the arc is its relatively homogeneous composition of rock types over the whole structure. The Kichy-Naryn and Djetim intrusions presented in this study are slightly elongated in an east–west direction and occupy an area of ca. 100km2. The main rock types are diorite, granodiorite and granite. Geological and geochemical features of the Kichy-Naryn and Djetim intrusions demonstrate characteristics of I-type granite series. Rocks of the two intrusions define a continuous high-K calc-alkaline series. Diorite and granite of the Kichy-Naryn intrusion yielded early Silurian crystallisation ages of 436±2Ma (U–Pb, zircon). Diorite from pebbles in the conglomerate sampled close to the contact of the Kichy-Naryn intrusion yielded a significantly older early Ordovician crystallisation age of 466±10Ma. The obtained ages of 466 and 436Ma match ages of two major regional magmatic pulses at ca. 435–440 and 460–470Ma which took place during continuous subduction from the Cambrian to the Silurian. The amount of granites in the Northern Tien Shan, their prolonged history of formation and pronounced I-type geochemical characteristics suggest their formation in an Andean-type active margin environment. [Copyright &y& Elsevier]

Abstract: The Upper Triassic Siah-Kuh granitoid stock is part of a series of Triassic-Cretaceous intrusions in the Phanerozoic Sanandaj-Sirjan zone in the Zagros orogenic belt, south-central Iran. The Siah-Kuh stock intrudes Lower Paleozoic amphibolites of the Abshur metamorphic complex and Upper Devonian-Lower Carboniferous greenschists of the Sargaz metamorphic complex. The Siah-Kuh granitoid stock consists mainly of coarse to medium grained leucogranodiorite, leucomonzogranite and alkali granite with subordinate syenite. It also contains a number of mafic enclaves of different sizes and is intruded by alkali granite and granophyre dikes along with monzonitic and a few dioritic dikes. The Siah-Kuh granitoid rocks are characterized by enrichment in large ion lithophile elements (LILE) such as Rb, Ba, K, Ce and depletion in high field strength elements (HFSE) such as Y, Nb and Zr. The chondrite normalized REE patterns are characterized by moderate LREE enrichment [(La/Yb)N =1.31–4.82] and unfractionated HREE [(Gd/Yb)N =0.50 to 1.33]. Granodiorites with the least fractionated HREE and a general absence of Eu anomalies suggest the involvement of plagioclase and absence of garnet during the melting processes. Alkali granites with the highest (La/Yb)N values and pronounced negative Eu anomalies are more differentiated products. Nd isotope analyses of the Siah-Kuh granitoids yield an “errorchron” age of 199±30Ma (MSWD=1.30), consistent with the field relationships and give Nd model ages (T DM) from 0.81 to 1.64Ga and εNd(T) values from +1.81 to +2.45 at 200Ma. These geochemical data suggest that the Siah-Kuh granitoid stock has characterisitics of metaluminous to slightly peraluminous, calc-alkaline, I-type granite formed in a volcanic arc setting. The onset of subduction of the Neotethys oceanic crust beneath the Central Iranian microcontinent in Triassic time could have accounted for the continental arc volcanism. Dehydration of subducted oceanic crust and partial melting of mantle wedge caused partial melting of subcontinental lithosphere, which resulted in the formation of metasomatised and enriched mafic arc magmas, at variable water fugacity and led to the formation of the Siah-kuh granitoid rocks. [Copyright &y& Elsevier]

Abstract: The Middle Jurassic Boroujerd Granitoid Complex of the Sanandaj-Sirjan Zone (with a U–Pb zircon age of 169–172Ma) was emplaced in an active continental margin setting. This complex consists of three main units: an elongate NW–SE extending granodioritic unit (SiO2 =58–71wt%), which is widespread throughout the area, a quartz-dioritic unit (SiO2 =52–63wt%), exposed as small stocks within the granodioritic body, and a monzogranitic unit (SiO2 =70–75wt%), widely scattered as separate small outcrops through the southern part of the area. A series of NW trending aplites and pegmatites are present in the granodioritic unit and its aureole. Geochemically this complex is metaluminous to slightly peraluminous, typical of I-type granites. It belongs to high-K calc-alkaline series and displays the geochemical characteristics typical of volcanic arc granites related to an active continental margin (e.g. significant Nb, Ti, P and Sr depletion). Isotopic data (Sri =0.7062–0.7074 and εNdt =−3.02 to −3.62) are consistent with a crustal protolith. In addition, fractional crystallization may have played an important role in the formation of the whole spectrum of the granitoid types that occur in the Boroujerd area. [Copyright &y& Elsevier]

Abstract: The Shah-Kuh granitic pluton of eastern Central Iran was emplaced ∼165Ma ago, in an active continental margin setting. It is made of two main units: a granodioritic unit (SiO2=63–71wt%) to the north–west and a syenogranitic unit (SiO2=73–77wt%) to the south–east. The former unit displays seriate medium-grained textures and contains locally abundant mafic enclaves. The latter unit is medium- to coarse-grained and porphyritic, with 0.5–3cm long K-feldspar megacrysts. Fine-grained granitic bodies are present in both units. The rocks are metaluminous to slightly peraluminous (I-type) and peraluminous (S-type) and belong to the ilmenite-series granites. Fractional crystallization appears to have been a very effective differentiation process in both units, and the fractionated mineral assemblages are determined by mass balance calculations. Isotopic data (Sri=0.7065 and εNdt=−2.5) are consistent with a young upper crustal protolith. Tin mineralization in sheeted quartz-tourmaline (-cassiterite) veins is spatially associated with the granodioritic unit. The veins formed by hydraulic fracturing when the granodioritic to monzogranitic magma became water-saturated and exsolved a fluid phase during crystallization. The reduced nature of this magma is responsible for the incompatible behaviour of Sn, likely to favour Sn concentration in the residual melt and then in the exsolved fluid. Another fluid phase was exsolved by the syenogranitic magma and was responsible for local greisenized granites, characterized by high Y and HREE-contents and non-fractionated REE distribution patterns. Field and mineralogical data show that the (B, Sn) vein-forming fluid was different from the (F, Li) greisen-forming fluid. [Copyright &y& Elsevier]

Northeastern (NE) China is the easternmost part of the Central Asian Orogenic Belt (CAOB), which is celebrated for its accretionary tectonics and the world''s most important juvenile crust production in the Phanerozoic era. Abundant granitoids occur in the Great Xing''an, Lesser Xing''an and Zhangguangcai Ranges in NE China. This paper presents partial results of a series of studies on the granitoids from this region, aiming to understand their role in the building of new continental crust in eastern Asia. Three composite granite plutons (Xinhuatun, Lamashan and Yiershi) were chosen for geochemical and isotopic study in order to determine their emplacement ages and petrogenesis. Petrographically, they range from granodiorite (minor), monzogranite, syenogranite to alkali-feldspar granite. Quartz and perthitic feldspar are principal phases, accompanied by minor amounts of plagioclase, biotite (<5%) and other accessory minerals. In addition, many contain abundant miarolitic cavities which suggest that they were emplaced at shallow levels with extensive fractional crystallization. Geochemically, the granites are silica-rich, peraluminous and have high contents of alkalis. They invariably show enrichment in light rare earth elements (LREE) and significant negative Eu anomalies. All the granitic rocks demonstrate the characteristic negative anomalies in Ba, Nb, Sr, P, Eu, and Ti, and a positive anomaly in Pb in the spidergram.The emplacement of the Xinhuatun pluton took place at 184±4 Ma as revealed by zircon SHRIMP U–Pb data. This is also supported by the slightly younger Rb–Sr whole-rock (WR) isochron age of 173±3 Ma. A whole-rock (WR) Rb–Sr isochron age of 154±3 Ma was obtained for the Lamashan pluton, which is interpreted as close to the time of emplacement. The Yiershi pluton was intruded at about 140 Ma as evidenced by a zircon U–Pb age of 137±2 Ma and WR Rb–Sr isochron age of 143±5 Ma. Biotite-WR Rb–Sr isochrons and 40Ar/39Ar ages of feldspars allow us to estimate the cooling rate of each pluton.Geochemical data suggest that the rocks are highly fractionated I-type granites. Fractionation of biotite and feldspars was the principal process of magmatic differentiation and responsible for major element variation. Rb, Sr and Ba concentrations were controlled by feldspar separation, whereas REE elements were fractionated by accessory minerals, such as apatite, allanite and monazite. [Copyright &y& Elsevier]

[Display omitted] • The Early Paleozoic I-type granites were generated through partial melting, magma mixing and fractional crystallization. • Mantle-derived magmas provided the heat and material for the formation of the granites. • The granites formed during an intracontinental orogeny. • The granites were related to the assembly of northern East Gondwana. The tectonic setting of the Early Paleozoic granites in the South China Block (SCB) remains enigmatic, and it is uncertain as to whether they are related to intracontinental orogenic processes or oceanic subduction. Previous studies mostly focused on Early Paleozoic S–type granitoids in the SCB, and relatively little attention has been paid to Early Paleozoic I–type granitoids. Here we present whole–rock major and trace elemental data and LA–ICP–MS zircon U–Pb age and Lu–Hf isotopic data for hornblende monzogranites, monzogranites, and mylonitic granites of I–type granites affinities that comprise the Daning and Guiling plutons in the southwest part of the Wuyi–Yunkai orogen in the SCB. These rocks contain zircon with U–Pb ages of 422–418 Ma, taken as the age of emplacement. They are rich in LREEs and moderately depleted in Eu (δEu = 0.49–0.64), with negative Ba, Sr, Nb, and Ti anomalies, and positive in Rb, Th, U, and Pb anomalies. Our studies of these granites and their abundant enclaves indicate that they formed via complicated petrogenetic processes, including the partial melting of a mixed source of meta–sedimentary rocks and meta–basalts in the lower crust, magma mingling and mixing of crust–mantle materials, and fractional crystallization. Mantle–derived magma played an important role in the formation of these Early Paleozoic granites. Although an ancient and enriched mantle source might have made a significant contribution to these Early Paleozoic granites, the input of juvenile mantle–derived magma might have been insignificant. Taking into account all the other geological evidence from the Wuyi–Yunkai region, we suggest that the tectono–magmatic events of the Early Paleozoic took place during intraplate orogenesis rather than oceanic subduction and collision, and that these events were triggered by a far–field tectonic response to the assembly of northern East Gondwana. [ABSTRACT FROM AUTHOR]

• Paleoproterozoic magmatism and sedimentation were first discovered in Susong area. • ∼2.0 Ga I-type granite was formed by reworking of ancient crust during orogenic event. • Metasedimentary strata and mafic dikes representing post-orogenic extensional environment. • Paleoproterozoic rocks represent the tectonic transition from collisional to extensional. Paleoproterozoic and Archean rocks in the poorly exposed Yangtze Craton provide a unique proxy for understanding early cratonic evolution. In this study, we report the newly discovered Paleoproterozoic granitoids, mafic dikes, and metasedimentary rocks in the Susong area near the northern margin of the Yangtze Craton. The zircon U–Pb analysis results of the Luohanjian granite (hereinafter referred to as LHJ-granite) and mafic dikes yielded 207Pb/206Pb ages of 2020–2002 Ma and 1837 ± 21 Ma, respectively. Metasedimentary strata that were intruded by the mafic dikes yielded detrital zircon 207Pb/206Pb ages of 2.55–2.32 Ga and 2.15–1.93 Ga, suggesting a depositional age of ∼ 1.90–1.85 Ga for the metasedimentary rock. The whole-rock ε Nd (t) and zircon ε Hf (t) values of the LHJ-granite were negative and ranged from − 10.4 to − 9.4 and − 11.4 to − 9.0, with corresponding T DM2 model ages of 3.3–3.2 Ga and ∼ 3.1 Ga, respectively. This implies that the granitic magma originated from the reworking of ancient pre-existing crustal components. The granitoids were weakly peraluminous (A/CNK = 1.00–1.18) with high SiO 2 concentrations of 71.98–76.00 wt%, LREE enrichment, high (La/Yb) N values of 26.55–100.49, and moderately negative Eu anomalies, characterized by the enrichment of Rb, Ba, Th, U, and Nd, and the relative depletion of Nb, Ta, Sr, P, and Ti. These granite samples exhibited a negative correlation between SiO 2 and P 2 O 5 and low Rb/Ba (0.15–0.33) and Rb/Sr (0.30–1.55) ratios. All these features indicate that the LHJ-granite is most likely belongs to I-type granite, which may have formed via the reworking of the TTG gneiss during subduction–collisional events. In combination with the mafic dikes and metasedimentary strata, our study proposes a mid–late Paleoproterozoic geological transition from a compressional to an extensional setting, indicating a tectonic shift from a collision orogeny (2.0 Ga) to a post-collision extensional environment (1.84 Ga) in the Susong region. [ABSTRACT FROM AUTHOR]

[Display omitted] • The granitic stock in the Xingluokeng W deposit was intruded at ca. 152 Ma. • Petrographic variations within the stock are ascribed to co-magmatic evolution via fractionation. • The granites show I-type affinity, mainly derived from Paleoproterozoic meta -igneous rocks. • Fractionation crystal and fluid-rock interaction have contributed to the W mineralization of the Xingluokeng deposit. The Xingluokeng deposit is the largest tungsten deposit discovered in the Wuyi metallogenic belt, with 30.43 Mt WO 3 reserves averaging at 0.23%. The main orebody mainly occurs in an altered granitic stock, comprising veinlet-disseminated and vein-type scheelite and wolframite mineralization. A comprehensive study of field investigations with whole-rock and in-situ geochemical and isotopic compositions was conducted on different intrusive phases of the Xingluokeng ore-bearing granitic stock, aiming to constrain the petrogenesis and its genetic link to W mineralization. The Xingluokeng stock is mainly composed of the porphyritic biotite granite (G1) as the upper part of the stock, intruded by the medium- to fine-grained biotite granite (G2) in the deep. Petrographic observations suggest that the stock experienced intense fractional crystallization as well as assimilation of country rocks close to stock margins. Zircon U − Pb geochronology and trace element analyses indicate that G1 and G2 were emplaced coevally at ~152 Ma at a relatively lower oxygen fugacity condition (Ce4+/Ce3+ = 44 ± 18 for G1, and 104 ± 41 for G2). Ti-in-zircon thermometer and AlT-in-biotite geobarometer reveal average crystallization temperature and depth at 762 ℃−740 ℃ and 7.3–7.0 km, respectively. Geochemically, obvious negative correlation between SiO 2 and P 2 O 5 and low A/CNK values (mostly < 1.1) indicate that they belong to the weakly peraluminous I-type granite, rather than S-type granite as proposed previously. Whole-rock geochemical compositions from G1 to G2 display systematic variations, with a general decrease in major oxides (such as Al 2 O 3 , TiO 2 , FeOT, MgO, CaO) and Zr/Hf ratio, but a gradual increase in DI value, Rb/Sr ratio and δEu with increasing SiO 2 , suggesting fractional crystallization is the major factor that controls the compositional variations between G1 and G2. They have consistent initial 87Sr/86Sr ratios of 0.71170 to 0.71477 and ε Nd (t) values of −12.5 to −10.8, as well as zircon ε Hf (t) values of −17.4 to −9.2 with Paleoproterozoic Nd − Hf model ages (1783–2081 Ma), suggesting a mixed crustal source of about 88% Paleoproterozoic meta -basaltic rocks and about 22% Paleoproterozoic gneissic granites, with minor assimilation of country rocks. These results favor that the Xingluokeng granites were formed by co-magmatic evolution via K-feldspar-dominated fractionation. High degrees of fractional crystallization have immensely enriched W in reduced magma, then intensive fluid-rock interaction liberated Ca from the G1 to form the scheelite and some Fe might come from the country rocks (biotite hornfels) to precipitate the wolframite. [ABSTRACT FROM AUTHOR]

• Three late Mesozoic (166–102 Ma) I-type granites identified in eastern Guangdong. • They were generated by mixing of crust- and mantle-derived magmas. • Variable Sr–Nd–Hf–O isotope data show a progressive crust–mantle interaction. • Changing subduction direction of the oceanic plate induced large-scale extension. Zircon U–Pb dating and in-situ Hf–O isotopic compositions, combined with whole-rock geochemical and Sr–Nd isotope data, are systematically presented to constrain the timing and petrogenesis of the late Mesozoic granitoids in eastern Guangdong Province, SE China. Zircon U–Pb chronology shows that two intrusions were emplaced from the Middle Jurassic to Early Cretaceous (166–144 Ma). All the granitoids are classified as calc-alkaline I-type granites with highly diverse elemental and isotopic compositions. The systematic variations in zircon Hf–O isotopes show that the granites can be categorized into three groups. The Donggang granitic porphyries (166 Ma) have the highest zircon δ18O values of 6.3–8.2‰ (average of 7.7‰) but the lowest ε Hf (t) values of −8.0 to −1.4, with the oldest Hf model ages of 1.30–1.70 Ga. The Liuzhoushan monzogranites (144 Ma) have intermediate zircon δ18O values of 6.0–6.9‰ (average of 6.4‰) and ε Hf (t) values of −5.0 to 0.3, with Hf model ages of 1.17–1.51 Ga. The late Early Cretaceous granitoids have the lowest δ18O values of 4.9–6.6‰ (average of 5.5‰) but the highest ε Hf (t) values of −3.2 to 3.3, with the youngest Hf model ages of 0.95–1.36 Ga. Zircon saturation temperatures of the Donggang, Liuzhoushan, and Xinwei (Sanrao) intrusions are calculated to be 642 °C, 722 °C, and 748 °C, respectively. Together with the variations in Sr–Nd isotopes, it appears that these granitoids were derived from the mixing of different proportions of mantle-derived components with Paleoproterozoic basement crust-derived magmas. The underplating of mantle-derived magmas into the continental crust, which supplied both heat and material contribution, was likely responsible for the generation of the most late Mesozoic I-type granites in eastern Guangdong. From Middle Jurassic to late Early Cretaceous, the increasing ε Hf (t) and ε Nd (t) values as well as the decreasing δ18O values and T DM 2 ages indicate a progressive role of the crust–mantle interaction, corresponding to a gradually enhanced extensional tectonic environment. The northeast (NE)-ward younging trend and the enhanced crust–mantle interaction along coastal SE China were probably induced by the changing direction of the subducted plate from oblique to parallel to the continental margin. [ABSTRACT FROM AUTHOR]