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In situ magnesium isotope compositions of carbonates play an important role in tracing geological and biological processes.

The Laowan super-large (208 t Au) gold deposit is located in the Tongbai orogenic belt, along with a newly-discovered molybdenite deposit at its depth in the northern periphery. The gold deposit is a fault-controlled lode gold deposit featuring sulfide quartz vein-type and altered rock-type mineralization hosted within the metamorphic rocks, whereas the molybdenum deposit is a typical porphyry-type deposit. These two deposits have their respective paragenetic sequences and mineralization types without spatial overlapping in the ore field. Here, we present U–Pb dating of zircon, hydrothermal rutile, and REE phosphates, and Re–Os dating of molybdenite to constrain the relationship between the Au and Mo mineralization, and their relation to Mesozoic granitic magmatism. Textural features indicate that rutiles and associated phosphate minerals are of hydrothermal origin, generated by re-precipitation and dissolution of titanite crystals hosted in the metamorphic host rocks due to hydrothermal alteration during Au and Mo mineralization. LA-ICP-MS U–Pb dating of rutile from the auriferous altered rocks yields a 206Pb/238U age of 120.0 ± 6.7 Ma (MSWD = 1.4), consistent with the ages of the associated monazite (125.0 ± 2.4 Ma) and xenotime (126.3 ± 2.0 Ma), representing the timing of the gold mineralization, coeval with Laowan monzogranite (zircon U–Pb: 128.8 ± 0.7 Ma). Rutile from the molybdenum deposit show an older 206Pb/238U age of 141.0 ± 11 Ma (MSWD = 1.1), consistent with the molybdenite Re–Os age (141.5 ± 1.7 Ma; MSWD = 0.27) and the zircon U-Pb age (141.6 ± 0.8 Ma; MSWD = 1.5) of the Songpa porphyry. Hence, the Au and Mo mineralization in the Laowan district represent two episodic mineralization events related to the late Mesozoic granitic magmatism. Our study also suggested that multiple isotopic dating is helpful to precisely constraint the ages for complex hydrothermal deposits.

The South China Block underwent a tectonic switch from compression to extension between the Late Jurassic and Early Cretaceous, but the extension process has not been well understood. Here we report that the Meiziwo lamprophyres in northern Guangdong, formed in the Early Cretaceous ( c. 136 Ma; 40 Ar/ 39 Ar dating), are characterized by ocean-island basalt (OIB)-like geochemical signatures and Pb enrichment, together with moderately high ( 87 Sr/ 86 Sr) i (0.70642–0.70766), positive ε Nd ( t ) (+4.6 to +5.1) and intermediate ( 206 Pb/ 204 Pb) i (18.579–18.602), ( 207 Pb/ 204 Pb) i (15.727–15.733) and ( 208 Pb/ 204 Pb) i (38.871–38.909). The lamprophyres were derived from an asthenosphere-dominated source, with contributions from recycled oceanic crust and terrigenous sediments. In contrast, the previously reported c. 154 Ma mafic dyke in eastern Guangdong and the c. 165–155 Ma A-type granite belt in southern Hunan and nearby regions show arc-like signatures and unradiogenic Nd but moderately radiogenic Pb isotopes, suggesting magma derivation from a lithospheric mantle. Hence, the change from lithospheric to asthenospheric sources may be caused by progressive lithospheric extension and thinning associated with the rollback and tearing of the palaeo-Pacific plate. The 136 Ma Meiziwo lamprophyres, together with the 140 Ma asthenosphere-derived OIB-like mafic rocks nearby, signify the petrological response to regional extension in the South China Block from c. 140 Ma onward. Supplementary material: Tables S1–S3 and Figures S1–S4 are available at https://doi.org/10.6084/m9.figshare.c.5953720

Replacement of pyrite by copper-bearing sulfides is widespread in mineral deposits, with zonation of chalcocite, bornite, and chalcopyrite being a common result of this process. Copper occurs predominantly as Cu(I) in hydrothermal fluids, but the mechanistic details of reactions between pyrite and aqueous Cu(I) and their relevance to the zonation of Cu sulfides in hydrothermal deposits remain poorly understood, because of a lack of relevant experimental constraints. In this study, we investigated the reactions between pyrite and aqueous Cu(I) chloride solutions over a wide range of physicochemical conditions (100–250 °C; pH = 1–8; saturated vapor pressure). The experimental results show that Cu-bearing sulfides form at temperatures of >150 °C, and that pH exerts an important control on the mineralogy of the reaction products. In strongly acidic conditions (pH = 1.1), pyrite dissolution occurs; in acidic-to-neutral conditions (pH = 3.0–6.0), chalcopyrite and bornite are the main products; in weakly alkaline conditions (pH = 8.2), the replacement products are chalcocite and bornite. Chalcopyrite, bornite, and chalcocite generally occur in a zoned sequence outward from the pyrite reaction front to the bulk solution, and the replacement of pyrite by chalcopyrite is heterogeneous. In situ Raman observation and S isotope analyses suggest that pyrite replacement by chalcopyrite is a redox-coupled dissolution–precipitation reaction, with the oxidative dissolution of pyrite to form sulfate, generating the electrons that maintain the reductive replacement of pyrite by chalcopyrite. The sites of oxidative dissolution and reductive replacement can be spatially separated, but coupled by electron transfer. By contrast, the further replacement of chalcopyrite by bornite and chalcocite does not involve the oxidative dissolution of sulfur, but release of iron and H+, which could be promoted at higher pH. Notably, when the zonation of sulfides is established in a hydrothermal experiment of pyrite replacement by Cu(I) solution, gradients of H2S (or HS–), Cu(I), and Fe(II) are developed between the pyrite reaction front and bulk solution via diffusion through interstitial pore space. As such, the inner zones of chalcopyrite and bornite are not in equilibrium with the bulk solution as confirmed by thermodynamic calculations. The results imply that the zonation of Cu-bearing sulfides in mineral deposits records heterogeneous chemical environments, from the mineral interface- to the ore deposit-scale during dynamic mineralization processes.

At the Black Mountain porphyry Cu-Au deposit in the Baguio district, Northern Luzon (Philippines), pre- and synmineralized rocks preserve magmatic and hydrothermal minerals (e.g., plagioclase, amphibole, titanite, and epidote) spanning the complete paragenesis of the deposit. Strontium isotope values in early crystallized plagioclase phenocrysts from all felsic porphyries can be divided into two types. The type-I plagioclase crystals show relatively homogeneous Sr isotope values (0.7035–0.7038, 1σ

The southern Myanmar tin ore district is an important part of the well-known Southeast Asia tin belt (SATB), and hosts numerous economically important primary tin-tungsten ore deposits. However, the timing of formation of these deposits is unclear due to the scarcity of robust age data. The tectonic setting of tin mineralization in this area also needs to be further constrained. Most of the primary tin-tungsten ore deposits in southern Myanmar are typical hydrothermal quartz vein–type, with cassiterite and wolframite as the main ore minerals. Here, we present in situ U–Pb ages of cassiterite and wolframite from nine granite-related hydrothermal Sn–W deposits in southern Myanmar. Cassiterite samples from the Hermyingyi, Thitkhatoe, Thaling Taung, Kalonta, Taungphila, Pagaye, Bawapin, Kanbauk, and Letha Taung deposits yield common lead-corrected weighted mean 206Pb/ 238U ages of 61.6 ± 0.8 Ma, 61.9 ± 0.6 Ma, 60.4 ± 0.9 Ma, 63.0 ± 0.6 Ma, 62.9 ± 0.6 Ma, 69.5 ± 0.5 Ma, 63.6 ± 0.6 Ma, 61.3 ± 0.6 Ma, and 84.9 ± 0.5 Ma, respectively. Wolframite samples collected from these deposits also yield consistent ages with the cassiterite samples. These ages, combined with available tin mineralization ages from other deposits in the western part of the SATB, define three epochs of Sn metallogeny related to three contrasting geodynamic settings: (1) Early Cretaceous (~ 125–110 Ma) mineralization is related to post-collision slab break-off after collision between the West Burma terrane and the Sibumasu-Tengchong terrane; (2) Late Cretaceous to Paleocene (~ 90–60 Ma) mineralization developed in an Andean-type accretionary setting during subduction of the Neo-Tethys oceanic lithosphere; (3) Early Eocene (~ 50–40 Ma) mineralization may have formed in a post-collision setting after the India-Asia collision.

Owing to the superimposition of water-rock interaction and external fluids, magmatic source signatures of ore-forming fluids for vein-type tin deposits are commonly overprinted. Hence, there is uncertainty regarding the involvement of magmatic fluids in mineralization processes within these deposits. Tourmaline is a common gangue mineral in Sn deposits and can crystallize from both the magmas and the hydrothermal fluids. We have therefore undertaken an in situ major, trace element, and B isotope study of tourmaline from the Yidong Sn deposit in South China to study the transition from late magmatic to hydrothermal mineralization. Six tourmaline types were identified: (1) early tourmaline (Tur-OE) and (2) late tourmaline (Tur-OL) in tourmaline-quartz orbicules from the Pingying granite, (3) early tourmaline (Tur-DE) and (4) late tourmaline (Tur-DL) in tourmaline-quartz dikelets in the granite, and (5 and 6) core (Tur-OC) and rim (Tur-OR), respectively of hydrothermal tourmaline from the Sn ores. Most of the tourmaline types belong to the alkali group and the schorl-dravite solid-solution series, but the different generations of magmatic and hydrothermal tourmaline are geochemically distinct. Key differences include the hundredfold enrichment of Sn in hydrothermal tourmaline compared to magmatic tourmaline, which indicates that hydrothermal fluids exsolving from the magma were highly enriched in Sn. Tourmaline from the Sn ores is enriched in Fe 3+ compared to the hydrothermal tourmaline from the granite and displays trends of decreasing Al and increasing Fe content from core to rim, relating to the exchange vector Fe 3+Al –1. This reflects oxidation of fluids during the interaction between hydrothermal fluids and the mafic-ultramafic wall rocks, which led to precipitation of cassiterite. The hydrothermal tourmaline has slightly higher δ 11B values than the magmatic tourmaline (which reflects the metasedimentary source for the granite), but overall, the tourmaline from the ores has δ 11B values similar to those from the granite, implying a magmatic origin for the ore-forming fluids. We identify five stages in the magmatic-hydrothermal evolution of the system that led to formation of the Sn ores in the Yidong deposit based on chemical and boron isotope changes of tourmaline: (1) emplacement of a B-rich, S-type granitic magma, (2) separation of an immiscible B-rich melt, (3) exsolution of an Sn-rich, reduced hydrothermal fluid, (4) migration of fluid into the country rocks, and (5) acid-consuming reactions with the surrounding mafic-ultramafic rocks and oxidation of the fluid, leading to cassiterite precipitation.

The Dachang Sn-polymetallic ore district in South China is the second largest tin district in the world with a tin reserve of over one million tonnes. Zn-Cu skarn and stratiform, massive, and vein Sn-Pb-Zn ores are all present in this district. This has led to a debate as to whether the Sn orebodies were formed by Cretaceous magmatic-hydrothermal replacement or Devonian submarine exhalative-hydrothermal sedimentation. Here, we present a systematic investigation of the major, trace element, and boron isotopic compositions of different types of tourmaline in the Dachang ore district. Tourmaline disseminated in the Longxianggai granite and pegmatite veins belongs to the schorl series and has high contents of Li, Zn, and Ga. The δ 11B value of primary magma of the Longxianggai granite is estimated to be about −13‰, close to the global average δ 11B value (−11‰) for S-type granites. Tourmaline from quartz-tourmaline veins in the Longxianggai granite has similar chemical composition to the magmatic tourmaline and likely formed from hydrothermal fluids exsolved from the evolved granitic melt. The δ 11B value of the initial hydrothermal fluids is also calculated to be about −13‰. Tourmalines from the skarn and sulfide ores in the Lamo deposit have higher Mg/(Mg+Fe) and lower Na/(Na+Ca) ratios and higher contents of Be, Ge, Sr, and Sn than magmatic tourmaline. These patterns likely reflect input of elements derived from the host Devonian limestone. The δ 11B values of the hydrothermal fluids are estimated to be between −13 and −10‰, suggesting evolved magmatic-hydrothermal fluids related to the Longxianggai granite. Tourmalines from the stratiform and vein ores in the Changpo-Tongkeng deposit are extremely Mg-rich and mostly belong to the dravite series. They have high contents of Sc, V, Cr, Sr, and Sn and show positive Eu anomalies. The δ 11B values of these B- and Sn-rich fluids are estimated to be between −15 and −10‰, suggesting that the fluids also have a magmatic-hydrothermal origin. These fluids are most likely derived from the same granitic magma source, but may have interacted with the Devonian volcanic rocks.

Potassic volcanic rocks are characteristic of collisional tectonic zones, with recycling of continental crust playing an important role in their generation. Potassium-rich partial melts and/or fluids derived from subducted continental material initiate and/or mix with mantle-derived melts and then erupt at the surface with varying degrees of interaction with the overlying lithosphere. The details of how continental material incorporates into mantle melts are, however, uncertain. In particular, the depths from which the potassium-rich fluids and/or melts are released from the continental material and then react with the mantle-derived melts remain a subject of debate. We have measured the boron isotope composition of volcanic rocks from Western Anatolia (Turkey) that erupted between 52 and 0.1 Ma, and span the lifetime of collisional events from initial arc-type eruptions to post-collisional volcanism. These data and other geochemical indices show that ultrapotassic volcanism was mainly confined to a narrow window between ca. 20 and 15 Ma, consistent with recycling of high-pressure phengite, with the timing of the potassic volcanism coincident with slab rollback and breakoff.

Tourmaline, one of the most important hosts of boron (B) in crustal rocks, has rarely been found in natural high-pressure (HP) and ultra-HP (UHP) eclogites. Here, we report the first finding of tourmaline-bearing UHP eclogites and veins in the Dabie terrane, China. These distinctive samples occur exclusively in impure UHP marbles. Investigations on the eclogite-vein-marble system provide important insights into the origin, flow, and metasomatic effects of eclogite-facies, 11B-rich fluids in continental subduction zones. Petrologic and geochemical evidence indicates that tourmaline in the eclogites (Tur-E) formed by metasomatism due to the infiltration of a B-rich fluid under conditions of ca. 2.2–2.6 GPa and 610–660 °C. The HP veins, containing euhedral tourmaline (Tur-V) and occurring at the eclogite-marble contacts or in the interiors of eclogite lenses, represent the crystallized products of the infiltrating fluid. Systematic compositional variations along the profile from the interiors of the eclogite lenses to their margins and mass-balance calculations indicate large inputs of B, carbon, large ion lithophile elements, and light rare earth elements to the eclogites during fluid infiltration. All types of tourmaline, including the Tur-E and Tur-V as well as minor amounts of tourmaline in the marbles (Tur-M), have similar compositions (dravitic) with XMg values [= Mg/(Mg + Fe)] of 0.7–0.8. In situ analyses using laser ablation multicollector inductively coupled plasma mass spectrometry show that all of tourmaline has high δ11B values (ranging from +6 to +15‰), which suggest a 11B-rich isotope signature for the infiltrating fluid. The tourmaline B isotope data, together with the detailed field observations and whole-rock Sr-Nd isotopes, reveal that the infiltrating fluid was derived from the impure marbles. Influx of such fluid was highly channelized and was mainly achieved along lithologic boundaries between UHP marbles and eclogites or along fractures in the eclogites. This study indicates that impure marbles are an important reservoir of isotopically heavy B in deeply subducted continental slabs. This point may be of particular importance because most B reservoirs in subducted continental crust typically have light B isotopic compositions. Our results highlight that subducted metacarbonate rocks could liberate eclogite-facies, B-rich, high-δ11B fluids and thus might exert important effects on the cycle of B and its isotopes in subduction zones.

Magnetite (Fe3O4) is one of the most common accessory minerals in magmatic rocks, and it can accommodate a wide variety of major, minor and trace elements that can be measured by laser ablation ICP-MS. In this study, we investigate the chemical compositions of magnetite from four carbonatite complexes (Oka, Mushgai Khudag, Hongcheon and Bayan Obo). The minor elements (Mg, Ti, Al, Mn) in magnetite vary significantly both within and between different complexes. High field strength elements (Zr, Hf, Nb, Ta, U, Th) are generally depleted in magnetite from carbonatite complexes, whereas K, Rb, Cs, Ca and P are commonly below detection limits. V and Zn display significant variations from tens to thousands of ppm. Co, Ni and Ga are present in ppm or tens of ppm, whereas Cu, Sr, Y, Ba and Pb are characterized by sub-ppm levels. Mo and Ge are identified at the ppm level, whereas a consistent concentration of 2–5 ppm is observed for Ge. The determined chemical compositions of magnetite from carbonatite complexes are quite distinguishable compared to those formed in silicate and sulfide melts. This is clearly shown using multielement variation diagrams, and the distinct signatures of carbonatite-related magnetite include strong positive anomalies of Mn and Zn and negative anomalies of Cu, Co and Ga. The discriminant diagrams of Ti vs. Zr + Hf, Ti vs. Nb + Ta and Ni/Cr vs. Ti are applicable for distinguishing magmatic and hydrothermal magnetite in carbonatite-related environments. In addition, the discriminant diagram of Zn/Co vs. Cu/Mo and Cu vs. Zr + Hf can be used to distinguish carbonatite-related magnetite from magnetite that formed in other environments.

The large-scale, high-grade Sn ores and the Cu-Sn metal association in the volcanic massive sulfide (VMS) ores in Neves Corvo are unique among VMS deposits, not only in the Iberian Pyrite Belt but also worldwide. Thus, the exceptional nature of the Neves Corvo deposit calls for unusual metallogenic processes. Previous efforts to constrain these processes have been hampered by a lack of high precision ages for the mineralization. This has led to a debate as to whether tin mineralization occurred at the same time as the associated volcanism and VMS-style mineralization, or is the result of later processes events associated with the Hercynian orogeny. We report in-situ U-Pb dating results of hydrothermal cassiterite and sulfur isotopic compositions of sulfides in the Neves Corvo deposit that place tight constraints on the timing of mineralization and on the origin of the hydrothermal ore-forming fluids. The cassiterite samples yield U-Pb ages of the Sn mineralization of 363–366 Ma; identical to the age of the host volcanic rocks. δ34S values range from −32.3‰ to +17.4‰ among the different VMS ore types and are largely consistent with microbiological reduction of seawater sulfate, but with some positive values resulting from thermochemical sulfate reduction. In contrast, the Sn-rich ores have a limited range in δ34S that clusters near 0‰, which suggests derivation from magmatic fluids. Hence, the unusually high Sn grades at the Neves Corvo deposit are interpreted to be derived from fluids exsolved from a hidden granitic source essentially synchronous with formation of the volcanic rocks and VMS mineralization.

The Qiyugou district is one of the most important gold deposit distribution areas in the Xiong’ershan region, North China Craton. These deposits are hosted in Archean Taihua Supergroup rocks as gold-bearing breccia pipes. Here, we report a detailed in situ analysis of trace elements and S-Pb isotopes in sulfides from different ore stages, in combination with electron probe microanalysis of ore minerals from the gold-bearing J4 breccia pipe in the Qiyugou district, to unravel the gold distribution and their textural relationships to pyrite, the metal sources and S-Pb isotopic composition variations during the ore-forming processes. The Qiyugou breccia pipes hosted gold ore (over 70 t Au, average grade of 2–5 g/t) that formed in four mineralization stages, i.e., an early K-feldspar-biotite-magnetite-quartz-pyrite (Py-1) stage (I) that can be further divided into two substages, namely the Ia K-feldspar-biotite-magnetite stage and the Ib quartz-pyrite stage; a gold-pyrite (Py-2)-quartz stage (II); a gold-quartz-polymetallic sulfide (Py-3) stage (III); and a late quartz-carbonate stage (IV). The visible native gold and electrum grains occur as small inclusions and disseminations in the fractures within Py-2 and Py-3. Tellurides and Bi-Pb-minerals are widespread in the stage II stockworks and veins, as is intergrowth with visible native gold and Py-2. In situ LA-ICP-MS trace element analysis reveals the presence of invisible gold hosted in three types of pyrite with extremely low Au content (Py-1 ≤ 0.05 ppm; Py-2 ≤ 0.03 ppm; Py-3 ≤ 0.02 ppm). Concentrations of Te, Bi, and Pb in pyrite are high and correlate well with Au concentrations, but As content is low. Therefore, the Te, Bi and Pb played a significant role in gold mineralization in As-deficient ore fluids in the J4 gold-bearing breccia pipe from the Qiyugou district. High-precision in situ laser ablation multiple collector inductively coupled mass spectrometry (LA-MC-ICP-MS) lead isotope analyses indicate that the sulfides have 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios from 17.250 to 17.629, from 15.401 to 15.621, and from 37.649 to 38.290, respectively, which are similar to the granite porphyry in the district and indicative of their similar lead sources. High-precision in situ LA-MC-ICP-MS sulfur isotope analyses of pyrite show a large δ34S variation (e.g., from −18.1 to −11.1 per mil for Py-1, from −12.2 to − 6.6 per mil for Py-2, and from −4.9 to −1.6 per mil for Py-3) with a remarkable increasing trend from stage I, stage IIto stage III. This trend may record a decreasing oxygen fugacity of the ore-forming fluids during mineralization.

The Hermyingyi W-Sn deposit, situated in southern Myanmar, SE Asia, is a typical quartz-vein type W-Sn deposit. The ore-bearing quartz veins are mainly hosted by the Hermyingyi monzogranite which intruded into the Carboniferous metasedimentary rocks of Mergui Series. According to mineral assemblages and crosscutting relationships, four ore-forming stages are recognized: (1) silicate-oxide stage; (2) quartz-sulfide stage; (3) barren quartz vein stage; (4) supergene stage. Five molybdenite samples from the deposit yield Re-Os model ages ranging from 67.8±1.6 to 69.2±1.6 Ma (weighted mean age of 68.7±1.2 Ma), and a well-defined isochron age of 68.4±2.5 Ma (MSWD=0.18, 2σ). This Re-Os age is consistent with the previously published zircon U-Pb age of the Hermyingyi monzogranite (70.0±0.4 Ma) (MSWD=0.9, 2σ) within errors, which indicates a genetic link between the monzogranitic magmatism and W-Sn mineralization. The new high-precision geochronological data reveal that the granitic magmatism and associated W-Sn mineralization in southern Myanmar took place during the Late Cretaceous (70-68 Ma). The extremely low Re contents (22.9 ppb to 299 ppb) in molybdenite, coupled with sulfide δ34S values in the range of +1.9‰ to +5.6‰ suggest that ore-forming metals were predominately sourced from the crustal-derived granitic magma.

Early Cretaceous felsic volcanic-intrusive complexes are widespread in the Gan-Hang Volcanic Belt (GHVB) and accompany abundant uranium ore resources. However, the petrogenesis and tectonic...

The Li isotopic compositions of tourmalines can be used as a powerful geochemical tracer and provide valuable information regarding magma–volatile relationships and the magmatic-hydrothermal evolution of pegmatites. Laser ablation-multiple collector-inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS) is the method of choice for in situ Li isotopic analysis. In this study, we investigated the feasibility of Li isotopic analysis in tourmalines by both ns- and fs-LA-MC-ICP-MS with (tourmalines as calibration standards) and without (NIST 610 glass as the calibration standard) matrix-matched calibration. The Li isotopes of tourmalines can be accurately analyzed with matrix-matched calibration by ns- or fs-LA-MC-ICP-MS. However, inaccurate δ7Li values were obtained when tourmalines were measured against a non-matrix-matched standard by ns- (∼10.0‰ deviation) and fs-LA-MC-ICP-MS (∼1.5‰ deviation). Wet plasma conditions can significantly reduce the matrix effect in isotopic analysis. Furthermore, the deviation in fs-LA-MC-ICP-MS can be suppressed by water addition after the ablation cell. However, a relatively large deviation (∼4‰) still existed, even though the matrix effect during ns-LA can be largely suppressed by water addition after the ablation cell (∼6‰ deviation was reduced). Fortunately, with the water addition before the ablation cell, an accurate and precise Li isotopic analysis by ns-LA-MC-ICP-MS can be achieved with non-matrix-matched calibration. This study indicated that there was a serious matrix effect in the Li isotopic analysis of tourmalines by ns- and fs-LA-MC-ICP-MS, and water-assisted ns- and fs-LA-MC-ICP-MS were an appealing option for the in situ Li isotope analysis of tourmaline with non-matrix-matched calibration.

Tourmaline often occurs in boron-rich granites and its genesis is still in dispute either formed from residual boron-rich silicate melt or from magmatic hydrothermal fluids with or without external fluid involvement. Here, we present a systematic investigation of in-situ major, trace elemental and boron isotopic variations of tourmaline from the Sanfang granite in Guangxi Province of South China, which demonstrate both the magmatic and hydrothermal origin for the formation of the tourmalines. The tourmaline occurs mainly in quartz-tourmaline nodules and tourmaline pegmatitic segregations within the Sanfang granite. Four types of tourmaline are identified: (1) isolated and disseminated tourmaline (Tur-D type) distributed in granite; (2) euhedral and subhedral tourmaline in quartz-tourmaline nodules (Tur-N type); (3) the earlier stage tourmaline (Tur-PE type) in pegmatitic segregations and (4) the later stage tourmaline (Tur-PL type) which replaced the Tur-PE type tourmaline in pegmatitic segregations. All the tourmalines belong to the alkali group representing dravite-schorl solid solution series with the former three types being schorl and the Tur-PL type being dravite. Petrography, chemical discrimination diagrams and Al occupations in the Y-site suggest that the Tur-D, Tur-N and Tur-PE type tourmalines are of magmatic origin and the Tur-PL type tourmalines are of hydrothermal fluid origin. Elemental and boron isotopic composition variations of tourmalines reflect the compositional and environmental evolution from late boron-rich magma to exsolved hydrothermal fluids. Chemical variations from the Tur-D to the Tur-N tourmalines are controlled by magma differentiation. The increase of Mg/(Mg + Fe) and Ca/(Ca + Na) ratios from the Tur-N to the Tur-PE tourmalines suggests the contamination of surrounding strata (e.g. the Sibao Group). Hydrothermal tourmalines have higher Mg/(Mg + Fe) and lower Na/(Na + Ca) ratios than the magmatic tourmalines. There is clear correlation at least in some trace elements (e.g. Sr, Pb) with major elements for all tourmalines, indicating the potential crystal chemical effects on their incorporation. Other trace element incorporation in tourmaline is largely controlled by melt and fluid composition. Hydrothermal tourmalines have high and stable V, Co and Ni contents, indicating relatively constant partition coefficient between hydrothermal tourmalines and the fluid. Hydrothermal tourmalines exhibit lower total REE contents but more pronounced positive Eu anomalies than the magmatic tourmalines. The δ11B values of all tourmalines from the Sanfang granite vary from −14.4‰ to −9.3‰, which indicate the boron in the Sanfang granite was mainly derived from partial melting of the metasedimentary source rocks. Boron isotopic variations of tourmaline are controlled by fractionation between melt-fluid and Rayleigh fractionation.

The Xiwang uranium ore deposit is one large-scale granite-hosted U deposit in the Xiazhuang U orefield in South China. Uranium orebodies occur as thin veins along the fracture zones within the Maofeng granitic pluton. Pyrite is the main sulfide mineral in the ores. Textural observation suggested that formation of hydrothermal pyrite can be divided into three stages: pre-mineralization stage pyrite (Py I), mineralization stage pyrite (Py II) accompanying with U-minerals, post-mineralization stage pyrite (Py III). In this study, in-situ sulfur isotopic compositions and trace element contents of pyrite from different stages were analyzed by laser ablation (MC-) ICP-MS methods. The δ34S values of Py I vary from −28.5‰ to −12.0‰ with an average value of −18.4‰, Py II from −15.9‰ to −10.2‰ with an average value of −12.5‰ and Py III from −22.3‰ to −14.8‰ with an average value of −19.4‰. The variations of sulfur isotopic compositions of pyrites were caused by the changes of oxygen fugacity of hydrothermal fluids. The hydrothermal fluids at the pre-mineralization stage had relatively higher oxygen fugacity (ƒO2 > 10−34). The decreasing of oxygen fugacity (to 10−36–10−35) at the mineralization stage might promote the precipitation of uraninite. The mineralization was terminated as the increasing of oxygen fugacity of hydrothermal fluids back to 10−35. Pyrite from the Xiwang deposit generally contains high U contents (up to ten thousand ppm) and very low Th contents (mostly

The Middle-Lower Yangtze River Valley Belt (MLYRB) in South China contains many stratabound Fe-Cu-Pb-Zn deposits hosted in Middle-Upper Carboniferous carbonates. The origin and nature of the ore fluids are poorly constrained (syngenetic vs. epigenetic). Trace elements and sulfur isotope compositions of sphalerite and galena from the Qixiashan carbonate-hosted Pb-Zn deposit (Eastern of MLYRB) help to clarify the ore-fluid source and metallogenic processes. Three types of sphalerites have been distinguished (black sphalerite a, zoned sphalerite b and light color sphalerite c). High Fe and Mn contents of the early black sphalerite (Sp-a) were possibly derived from preceding Fe-Mn-rich sulfide layer or sediments from ore-bearing strata via replacement at 274–315 °C. The zoned sphalerite (Sp-b) has a dark Fe-Cu-rich core (321–348 °C) overgrown by a light Fe-Cu-poor rim (285–314 °C). The Sp-b rims are compositionally similar to Sp-a, Therefore, zoned Sp-b possibly represents the transition stage from poor copper (Sp-a) to rich copper (Sp-c) fluids. The light-color late sphalerite (Sp-c) is characterized by Fe-Mn depletion, as well as Ga, Cu, Cd and Sn enrichments. The Ga-rich Sp-c was possibly precipitated by the mixing of Ga-bearing sulfate and metalliferous fluid at 146–255 °C. We considered the Qixiashan Pb-Zn deposit to be of epigenetic origin that has undergone multistage ore-forming processes, in which the ore sulfur (δ34S: –3.7‰ to +7.8‰) was sourced from seawater sulfate (+22‰) via thermochemical sulfate reduction (TSR).

Alkaline igneous-related rare earth element (REE) deposits constitute a major global economic resource of REE. However, our understanding of their geodynamic settings and magmatic-hydrothermal processes remains uncertain. Here, we present an investigation of petrography, geochronology and mineral chemistry of newly discovered REE mineralization in the alkaline syenite and pegmatite from the Kohistan Batholith in the Kohistan Island Arc, Pakistan. The pegmatite contains abundant chevkinite and monazite (up to 10–35% in volume), which formed from crystallization of a REE-oversaturated evolved melt and are the main REE-bearing phases. U-Th-Pb isotopic dating of zircon from the syenite yields the emplacement age of 31.2 ± 0.3 Ma, which closely matches the ages of zircon and monazite from the pegmatite (30.1 ± 0.3 Ma and 30.9 ± 0.3 Ma, respectively). Zircons from the syenite and the pegmatite have similar ɛ Hf(t) values, ranging from + 0.2 to + 2.5, indicating that the syenite and the pegmatite are co-magmatic in origin. The alkaline magma likely formed by partial melting of the enriched lithospheric mantle induced by the asthenospheric upwelling, which was related to slab break-off at the post-collisional stage following the collision of the Kohistan Island Arc with the Indian Plate. Zircons show the evolutional trend in trace element compositions from the syenite to the pegmatite, marked by increases in REE, Hf, Y, U, volatiles and fo 2. These changes reflect prolonged fractional crystallization processes of the alkaline magma, which were responsible for the REE enrichment in the residual pegmatitic melt. Post-collisional alkaline magmatic rocks are widely distributed in many places along the Tethyan orogenic belt. These observations suggest that these post-collisional alkaline rocks may be good targets for REE exploration.

White mica is an important reservoir of boron (B) in subducted metasedimentary rocks. To quantify the effect of phengite breakdown on B release and transfer, we investigated the replacement processes of phengitic mica and associated element redistribution in exhumed ultra-high pressure (UHP) impure marbles from the Dabie terrane, China. Three types of microstructures, which are related to the liberation, transport, and precipitation of B, are recognized: (1) Type-I is the pseudomorphic replacement of phengite by the assemblage of biotite + plagioclase ± quartz ± epidote. The assemblage maintains a flaky shape of pre-existing phengite, which only rarely occurs as a relict phase in the product assemblages. Phase equilibria modelling indicates that the conditions of replacement reactions are 1.2–1.3 GPa at ~600 °C, with a relatively low XCO2 of 0.04–0.16. (2) Type-II is characterized by the local occurrence of fine-grained tourmaline (Tur-F) along the outer margin of Type-I texture domains, which represents the in situ precipitation of B released by the replacement reactions. (3) Type-III texture involves the irregularly shaped intergrowth of tourmaline (Tur-In) + quartz in the calcite matrix, isolated from the Type-I and Type-II texture domains. The Type-III minerals are in equilibrium with diopside and plagioclase and most likely represent the precipitation from a “transported”, B-bearing fluid. Mineral trace element analyses indicate that relict phengite in Type-I texture has significantly higher B contents (284–464 μg/g) than all of the product minerals (2–26 μg/g). A mass balance estimate indicates that the majority (>90%) of B in the reactants is lost during the process of phengite replacement. The calculations in terms of mineral-fluid partition indicate that the fluid involved in the replacement reactions has B contents of 1893–6858 μg/g. In situ B isotopic analyses indicate that Tur-F and Tur-In have a similar variation range of δ11B (+4 ~ +7‰). Both types of low-pressure tourmaline have lower δ11B values than the previously reported eclogite-facies tourmaline (reaching +15‰) from phengite-bearing marbles in the same study area. This result indicates two episodes of tourmaline growth and B transfer. Thus, a two-stage model of B loss from phengite during slab exhumation is proposed. Our results reveal that the breakdown of white mica in exhumed metasedimentary rocks can cause a strong release of B, which would largely influence the B budget at convergent plate margins.

The Guojialing and Aishan plutons in the northern Jiaobei Terrane represent the magmatic products of the lithospheric thinning of the North China Craton in the Early Cretaceous. The exhumation history of the terrane in response to the thinning process and its effect on the formation and preservation of coeval gold deposits remain poorly constrained. Granodiorites from the Guojialing pluton and monzogranites from the Aishan pluton contain zircon grains with U-Pb ages of ca. 130 Ma and ca. 116 Ma, respectively. Using the Al-in-hornblende barometry, the Guojialing and Aishan plutons had crystallization pressures of 3.2–5.4 kbar (∼12 km) and 1.5–2.6 kbar (∼5 km), respectively. Using the hornblende-plagioclase thermometry, the Guojialing and Aishan plutons had crystallization temperatures of 628–697 °C and 702–745 °C, respectively. Fluid inclusion microthermometric data show that auriferous quartz veins in the Daliuhang deposit formed at temperatures between 243 and 322 °C at a depth of 7–11 km which was similar to the emplacement depth of the Aishan pluton. These thermobarometric and geochronological data reveal ∼7 km uplift between 130 Ma and 116 Ma, but negligible exhumation for the gold deposits after its formation until 116 Ma. Combining previous results, we envisage that the exhumation magnitude of the Guojialing intrusions were nearly the same in the wide area with slight differences between the core and margin of a single pluton. Numerous gold deposits in the Jiaobei Terrane formed during or after the late stage of rapid exhumation of granitoids, and were uplifted with similar depths to the Aishan pluton since ca. 116 Ma. The rapid exhumation of the Guojialing pluton was with the regional extension, and might be genetically associated with the intensive delamination of destabilized lithospheric root and dense residues.

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.

The Jintingling gold deposit, located in the Jiaodong peninsula, north China, contains vein-, dissemination- and stockwork-style ores hosted in the Jurassic Linglong granitic pluton. Hydrothermal activities in this deposit are divided into seven stages, including pre-ore massive K-feldspar alteration, specularite-quartz vein (V1), milky quartz ± sulfide vein (V2), quartz-pyrite vein (V3), massive quartz-sericite-pyrite alteration and gold mineralization, quartz-polymetallic sulfide vein (V4), and quartz-calcite vein (V5). Rhenium-Osmium dating was conducted on molybdenite from V2, yielding an isochron age of 123.3 ± 3.6 Ma. LA-ICP-MS zircon U-Pb dating yielded 121.5 ± 1.5 Ma (1σ, MSWD = 0.010) for a pre-ore diorite porphyrite dyke and 117.6 ± 1.2 Ma (1σ, MSWD = 0.018) for a post-ore diorite porphyry dyke, respectively. Thus, gold mineralization occurred at 122–118 Ma. Four types of fluid inclusions were identified in quartz veins, including CO2-H2O ± CH4 inclusions (type I), pure CO2 inclusions (type II), mineral-bearing inclusions (type III) and aqueous inclusions (type IV). Fluid inclusion studies demonstrate that the primary ore-forming fluids contain CO2-rich vapor (357–420 °C, 7.2–11.3 wt% NaCl equivalent) and critical fluids (368–400 °C). The two phases were likely formed by immiscibility of magmatic-hydrothermal fluids. Later on, the fluids evolved to a H2O-CO2-NaCl ± CH4 system which had temperatures of 300–364 °C and salinities of 2.0–9.7 wt% NaCl equivalent. The H2O-CO2-NaCl ± CH4 fluid system may experience phase separation, forming coexisted CO2-H2O ± CH4 inclusions (homogenized to vapor or liquid at temperature of 265–309 °C and 265–287 °C, salinities of 3.1–7.1 wt% and 4.3–7.1 wt% NaCl equivalent, respectively) and aqueous inclusions (homogenized to liquid at temperature of 255–294 °C and 3.7–7.6 wt% NaCl equivalent). Along with further evolution, the fluids shifted to a H2O-NaCl system, with temperatures of 163–258 °C and salinities of 0.5–9.0 wt% NaCl equivalent. Pyrite from the Jintingling deposit has δ34S values (5.5‰–6.1‰) similar to those of pyrite from other gold deposits in the Jiaodong district, indicating that they were related to the same hydrothermal ore-forming system. The δ13CPDB values of calcite (−4.5‰ to −5.4‰) in V5 are generally located in the range of magmatic-derived carbon. Fluids of V2, V3, V4 have δD from −64.4‰ to −87.1‰, and δ18O from 8.4‰ to 0.2‰, located in the compositional fields between magmatic water and meteoric water. Collectively, microthermonetric results and isotopic data indicate that the primary ore-forming fluids were most probably magmatic in origin, with incorporation of meteoric water in the later ore-forming stage. Precipitation of gold was triggered by cooling of fluids, fluid immiscibility and decrease of sulfur in the fluids.

Mafic dykes are abundant and widely distributed in many granite-hosted uranium ore deposits in South China. However, their geochronology, petrogenesis and relationship with uranium mineralization were poorly constrained. In this study, apatite U-Pb dating, whole-rock major and trace element and Sr-Nd-Pb isotope analysis were conducted for the dolerite dykes from the Aigao uranium ore deposit. Apatite U-Pb isotopic data indicate that the mafic dykes were emplaced at Early Jurassic (189 ± 4 Ma), which provides new evidence for the rarely identified Early Jurassic magmatism in South China. Pyroxene from the dykes is mainly augite, and plagioclase belongs to albite. The dolerite samples have relatively low SiO2 contents (45.33–46.79 wt%), relatively high total alkali contents (K2O + Na2O = 4.11–4.58 wt%) and Al2O3 contents (13.39–13.80 wt%), and medium MgO contents (4.29–5.16 wt%). They are enriched in Nb, Ta, Ti, rare earth elements and depleted in Rb, K, Sr, Th, showing the typical OIB-like geochemical affinity. All the dolerite samples show homogeneous Sr-Nd-Pb isotopic compositions, with (87Sr/86Sr)i varying from 0.706049 to 0.707137, eNd(t) from +4.6 to +5.2, 206Pb/204Pb from 19.032 to 19.126 and 207Pb/204Pb from 15.641 to 15.653. The mafic dykes in the Aigao deposit should be derived from the partial melting of the asthenospheric mantle and formed in a within-plate extensional environment. The emplacement age of the mafic dykes is older than the uranium mineralization age. Therefore, CO2 in ore-forming fluids couldn't originate from the basaltic magma as suggested by previous studies. The dolerite dykes might only provide a favorable reducing environment to promote the precipitation of uraninite from oxidize hydrothermal fluids.

Study of the origin and chemical differentiation of silicic magmas can provide important insights into crustal evolution and rare metal metallogeny. Tin mineralization always tends to form in relatively reduced, highly fractionated granite systems. Recognition of distinctions between fertile and barren magmas is of enormous benefit to mineral exploration. The Yanbei caldera complex (YCC), is a typical inland volcanic-intrusive complex that also hosts a giant porphyry-type tin ore deposit in Southeast China. To study the origin and chemical differentiation of the YCC and constrain its relationship with tin mineralization, a comprehensive petrological, whole-rock major and trace element geochemical data, along with zircon U Pb ages, trace element and Hf isotopic data of the Yanbei caldera complex (YCC) and the Xiaoji granite (XG) near the YCC are carried out. LA-ICP-MS zircon U Pb dating indicates that the generation and evolution of the YCC and the XG took place in a short time (4 M.y.) of between 142.4 and 138.4 Ma. Distinct zircon Hf isotopic compositions of the volcanic and intrusive units from the YCC suggest that they were derived from different magma sources. The volcanic rocks and the XG have consistent and low zircon Hf isotopic compositions (eHf(t) = −14.9 ~ −9.0), implying that they were almost exclusively derived from melting of Paleoproterozoic crustal rocks. But the magma source of the intrusive units (the granite porphyry, GP and the biotite granite, BG) (eHf(t) = −6.0 ~ −0.8) contains a significant mantle-derived component input. The whole-rock and zircon compositions suggest that the compositionally zoned volcano of the YCC can be interpreted in terms of the “crystal mush model”. The rhyolite has the geochemical characteristics of highly evolved magmas which undergo crystal fractionation, while the dacite displays a complementary geochemical signature implying that it represents the residual crystal mush after extraction of the rhyolitic melts. The XG displays similar chronological, compositional, and isotopic features to the rhyolite, suggesting that it is the intrusive equivalent of the rhyolite. The intrusive units (GP and BG) of the YCC are highly-evolved granites with elevated tin contents, responsible for tin mineralization. By comparison of fertile and barren systems in the YCC, we suggest that simple crystal fractionation for the high-evolved/extracted granitic melt does not necessarily lead to tin mineralization. A tin-bearing and volatile-rich melt originated under high-temperature partial melting of crustal source induced by underplating/input of a hot mantle magma is an essential precondition for some magmatic-hydrothermal tin mineralization systems.

Triassic magmatism in Thailand provides the critical geological record for understanding the evolution of the Paleo-Tethys Ocean. This paper presents zircon U-Pb dating, zircon trace element compositions, elemental geochemistry and Sr-Nd-Hf isotopes for the newly identified Late Triassic granite intrusions in the Upper Peninsula of Thailand where voluminous Late Cretaceous-Paleogene granite intrusions occur. Zircon U-Pb dating results indicate that the two-mica granites were emplaced at ca. 217–216 Ma. The unaltered two-mica granite samples are high silicic (SiO2 = 74.03–75.06 wt%) and display strongly peraluminous characteristics, with A/CNK ratios of 1.21–1.33 and CIPW normative corundum contents of 2.86–3.88 wt%. They have fractionated REE patterns ((La/Yb)N = 5.64–7.34) and notable negative Eu anomalies (Eu/Eu* = 0.35–0.49), with enrichment of Rb, Th, U, Ta and Pb and depletion of Ba, Nb, Sr and Ti. The two-mica granites can be assigned as the highly fractionated S-type granites. They have negative whole-rock eNd(t) (−13.2 to −12.3) and zircon eHf(t) (−11.5 to −7.4) values with corresponding two-stage Nd and Hf model ages ranging from 1.99 to 2.06 Ga and from 1.72 to 1.98 Ga, respectively, indicating a Paleoproterozoic crustal source. The combined geochemical and isotopic data reveal that these rocks were derived by fluid-absent muscovite melting of metapelite at the middle-upper crustal depths and modified by fractional crystallization. In combination of the results in this study with regional geological data, it can be concluded that the two-mica granites were more likely formed during the post-collisional stage of the Sibumasu-Indochina collision, induced by slab break-off of the Paleo-Tethys Ocean. Based on the integrated consideration of a set of factors, including temporal and spatial proximity, source lithology and source enrichment, redox state, and fractional crystallization coupled with melt-fluid interaction, it is suggested that the ca. 216 Ma two-mica granites exhibit high Sn mineralization potential and could be helpful for exploring the primary Sn deposit of Late Triassic age nearby.

Apatite is a ubiquitous mineral in carbonatites, and incorporates a variety of trace elements including rare earth elements (REEs). In this study, the textural and chemical variations of apatite were examined in order to trace the magmatic and hydrothermal petrogenesis of three carbonatite-related REE deposits: Shaxiongdong, Miaoya, and Bayan Obo. Various apatite textures were revealed by cathodoluminescence and back-scattered electron imaging. Magmatic apatite, which occurs predominantly in samples from Shaxiongdong, is euhedral, and commonly shows oscillatory or growth zonation with a yellow–green luminescent core and a violet luminescent rim. Euhedral to subhedral metasomatic apatite from Miaoya and Bayan Obo has a turbid texture, with the majority of grains associated with exsolved monazite. Hydrothermal apatite from Bayan Obo, typically occurring as aggregates in close association with fluorite and barite, is anhedral, with green or light violet luminescence. The different apatite textures are characterised by distinct trace element compositions. Magmatic apatite contains the highest concentrations of Mn (avg. 457 ppm) and Sr (avg. 18,285 ppm) and is characterised by a steeply inclined REE chondrite-normalised pattern. Metasomatic apatite, which has undergone in situ dissolution–reprecipitation, contains lower Mn (avg. 272 ppm) and Sr (avg. 9945 ppm) concentrations. It is characterised by highly variable REE trends with an La/SmN ratio varying from 0.13 to 5.61, and lower average La/YbN, La/SmN, and Sr/Y ratios (46, 2.2, and 18, respectively) than magmatic apatite. Hydrothermal apatite that was precipitated from a fluid is characterised by convex upward chondrite-normalised REE distributions with the lowest La/YbN, La/SmN, and Sr/Y ratios (13, 0.69, and 5.8, respectively). The average concentrations of Mn and Sr in this apatite are 270 and 6610 ppm, respectively. There are no Eu anomalies (Eu/Eu* = 0.97) in the chondrite-normalised REE plots for any of the analysed apatite samples. The combined textural and compositional variations of apatite in the three deposits reflect diverse magmatic and hydrothermal processes, including: 1) mineral fractionation contributing to core–rim zoning within the Shaxiongdong magmatic apatite; 2) dissolution–reprecipitation inducing monazite precipitation in Miaoya and Bayan Obo metasomatic apatite; and 3) coprecipitation with fluorite and barite from fluids generating the Bayan Obo hydrothermal apatite. A compilation of published apatite compositions from other rock types demonstrates that trace element compositions of apatite can be used to differentiate crystallisation environments and differentiate apatite from other rock types. Apatite from carbonatite has high Sr, REEs, La/YbN, Th/U, and Sr/Y, and no Eu anomaly, compared with apatite from igneous silicate rocks (except ultramafic rocks), and iron-oxide copper gold (IOCG) or iron-oxide apatite (IOA) deposits.

Adakitic rocks in continental settings are commonly considered to be formed by partial melting of thickened or delaminated lower crust. Investigations on this kind of rocks can provide important information about crustal evolution complementary to information from other rocks. This paper reports adakitic granodiorite of the Lingxi pluton in the interior of the Cathayisa Block. LA-ICP-MS zircon U-Pb dating shows that it was formed in the late Early Cretaceous (100±1 Ma). The granodiorite has geochemical features of adakitic rocks derived from partial melting of the thickened lower crust, e.g., high SiO2 (mainly ranging from 64.4 to 68.9 wt.%) and Sr (624–894 ppm) contents, Sr/Y (49.9–60.8) and La/Yb (23.4–42.8) values, low Y (10.3–17.1 ppm), Ni (5.62–11.8 ppm) and MgO (mostly from 0.86 wt.% to 1.57 wt.%) contents and weak Eu anomaly. It has initial 87Sr/86Sr ratios of 0.7086–0.7091, e Nd( t ) values of −6.2 to −5.9 and zircon e Hf( t ) values mostly of −10.1 to −7.6. Based on the geochemical characteristics and simple modelling, it is suggested that the most likely generation mechanism of the Lingxi granodiorite is partial melting of a thickened Proterozoic lower continental crust at a pressure ≥12 kbar (or crust thickness ≥40 km), leaving a garnet-bearing amphibolite residue. Combining our results and previous studies of the tectonic evolution of the Cathaysia Block, we propose that the crust was thickened to over 40 km by a compressive event occurring during the late Early Cretaceous, which is supported by the observation that there is an angular unconformity between the Upper Cretaceous Series and the early Lower Cretaceous or the Jurassic rocks. After this event, the Cathaysia Block experienced a lithospheric extension and thinning probably driven by the high-angle paleo-Pacific subduction. With the attenuation of lithosphere, the lower crust was heated to partial melting by upwelling asthenospheric materials, resulting in generation of the Lingxi granodiorite and other coeval granitoids in the Cathaysia Block. This study provides new information on the crustal evolution of the Cathaysia Block during the Early Cretaceous.

Two Early-Middle Triassic magmatic arc belts occur in the Indochina Block within Thailand, namely the Lampang Volcanic Belt and the Loei-Phetchabun Volcanic Belt, which are about 150 km apart and run parallel to each other. The Lampang Volcanic Belt has been extensively studied and suggested to be induced by eastward Paleotethyan subduction, whereas the Loei-Phetchabun Volcanic Belt has not been well constrained due to the scarcity of geochronological and geochemical data. Here we report a detailed study on zircon U–Pb dating, elemental geochemistry and Sr–Nd isotopes for the Phu Rai diorites recently identified in Loei Province, NE Thailand. The Phu Rai diorites yield Middle Triassic (ca. 239 Ma) emplacement ages. They are calc-alkaline rocks characterized by arc-like trace element patterns and depleted Sr–Nd isotopic compositions ((87Sr/86Sr)i = 0.70371–0.70392; eNd(t) = +1.65 to +2.54). These geochemical and isotopic signatures reveal that the Phu Rai diorites were most likely derived from a depleted mantle wedge metasomatized by subducted sediment-derived melts and slab-derived fluids, and modified by limited degree of fractional crystallization involving clinopyroxene, amphibole and Fe–Ti oxides combined with weak plagioclase accumulation. Based on our results and others from the literature, we suggest the existence of an Early-Middle Triassic (ca. 250–239 Ma) magmatic arc belt in NE Thailand, which is not directly linked to eastward Paleotethyan subduction, but is possibly associated with eastward subduction of the Nan back-arc basin. Specifically, the ca. 239 Ma Phu Rai diorites and ca. 245–241 Ma adakites nearby form a rock association in response to slab break-off at that time, immediately after the initial stage of the Sukhothai-Indochina collision. The occurrence of this rock association could mark not only the cessation of eastward subduction of the Nan back-arc basin but also the initiation of the Sukhothai-Indochina collision.

The Gutian porphyry Cu–Mo deposit is a newly proved porphyry copper deposit in the coastal South China associated with granodioritic porphyries. In this study, zircon U–Pb ages and Hf isotope data, as well as geochemical and Sr–Nd–Pb–Re–Os isotopic compositions, are reported for these intrusions and minerals. Both zircon U–Pb and molybdenite Re–Os dating suggest that the Gutian granodiorite porphyries and related mineralization formed at ~ 160 Ma. The Gutian granodiorites show a low-Mg adakitic geochemical affinity, with relatively high K 2 O but low Cr and Ni contents. These rocks have initial ( 87 Sr/ 86 Sr) i ratios of 0.7085 to 0.7097, negative e Nd (t) values (− 12.5 to − 7.8), ( 206 Pb/ 204 Pb) t ratios of 18.048 to 18.241, ( 207 Pb/ 204 Pb) t ratios of 15.609 to 15.628, and ( 208 Pb/ 204 Pb) t ratios of 38.494 to 38.667. Zircons from the granodiorites have negative e Hf (t) values of − 15.7 to − 8.5, which are close to those of Cathaysia crust-derived melts. Geochemical and Sr–Nd–Pb–Hf isotopic compositions suggest that they may be derived from Late Jurassic thickened juvenile lower crust. These lower crustal magma sources may not only contain pre-Proterozoic basement rocks, but also involve Triassic and Middle–Late Jurassic arc magmas within the lower crust, which were likely derived from an enriched mantle source associated with paleo-Pacific Plate subduction from the Middle to Late Jurassic. The Gutian ore-related granodiorites represent a new example for significant contributions of ancient subduction melts and enriched mantle-derived sources for porphyry-type magmatism and Cu-Mo mineralization, which occurred in response to an arc regime during the Middle to Late Jurassic in South China.

We performed a detailed study of the stratigraphic transition of Oceanic Anoxic Event 1a (OAE1a) to oceanic red bed 1 (ORB1) from the classic Gorgo a Cerbara section in the Umbria region of central Italy. We focused on a 25.5-m-thick stratigraphic succession, from which we analyzed 305 samples for total organic carbon (TOC), CaCO 3 , magnetic susceptibility, diffuse reflectance spectrophotometry and the stable carbon and oxygen isotopic composition of both bulk samples and organic matter. In the Gorgo a Cerbara section, the Selli Level of OAE1a (∼1.81 m thick) consists of laminated to bioturbated dark gray to black mudstones and shales with medium to dark gray radiolarian-rich silty to sandy layers and a maximum TOC content of 20.22%. The carbon isotopic values show a negative excursion (C3 stage, ∼0.14 m) at the base of the Selli Level, followed by a stepwise positive excursion (C4–C6 stages, ∼1.67 m) in the upper part of the Selli Level. The transition from OAE1a to ORB1 (∼3.19 m thick) is characterized by bioturbated greenish gray cherty limestones and marly limestones with subordinate marls, corresponding to stable carbon isotopic C7 stage and lasts for ∼0.75 Ma. The ORB1 interval (∼13.15 m) consists of reddish marly claystones, dark-red marlstones, red marly limestones and red calcareous shales which indicate a highly oxic environment. Our results reveal a stepwise transition from a predominantly mesotrophic and dysoxic to anoxic environment at the time that the OAE1a black shales were deposited to an oligotrophic and oxic environment during the transitional interval and finally to highly oxic conditions during the ORB1 interval. The nannoconid crisis occurs at the top of the C2 stage, just 0.34 m below the negative excursion in δ 13 C isotopic values. The massive CaCO 3 dissolution phase occurs 0.25 m above the negative excursion; it persisted for 0.85 Ma and probably resulted from excess CO 2 , ocean acidification, and carbonate compensation depth (CCD) shoaling. Deposition of massive black shales occurs at the base of the C6 stage and lasted for 0.4 Ma.

The Miao'ershan uranium ore district is one of the most important granite-hosted uranium producers in South China. There are several Triassic granite plutons in the Miao'ershan batholith , but uranium ore deposits mainly occur within the Douzhashan granitic body. Precise zircon U–Pb dating indicated that these Triassic granite plutons were emplaced during 204 to 215 Ma. The Douzhashan U-bearing granite lies in the central part of the Miao'ershan batholith, and has higher U contents (8.0 to 26.1 ppm, average 17.0 ppm) than the nearby Xiangcaoping granite (5.0 to 9.3 ppm, average 7.0 ppm) and the Yangqiaoling granite (6.4 to 18.3 ppm, average 11.5 ppm) in the south part of the batholith. The Douzhashan granite is composed of medium-grained two-mica granite, whereas the Xiangcaoping and Yangqiaoling granites are composed of porphyritic biotite granite. Both the Xiangcaoping and Douzhashan granites have high A/CNK ratios (> 1.10), high (87Sr/86Sr)i ratios (> 0.720) and low eNd(t) values (− 11.3 to − 10.4), suggesting that they belong to strongly peraluminous S-type granites. The Douzhashan granite has low CaO/Na2 O ratios, high Rb/Sr and Rb/Ba ratios, indicating a partial melting origin of clay-rich pelitic rocks. In contrast, the Xiangcaoping granite formed from clay-poor psammite-derived melt. The Yangqiaoling granite shows different geochemical characteristics with the Douzhashan and Xiangcaoping granites, indicating a different magma source. The Yangqiaoling granite has higher e Nd(t) of − 9.4 to − 8.3 and variable A/CNK values from 0.98 to 1.19, suggesting a mixture source of meta-sedimentary rocks and meta-igneous rocks. Crystallization fractionation is not the main mechanism for U enrichment in the Douzhashan granite. We suggest that U-rich pelitic rock sources may be the key factor to generate peraluminous U-bearing granites in South China. Searching for those granites which are reduced, strongly peraluminous and were derived from U-rich pelitic rocks, is the most effective way for exploring granite-hosted U deposits.

The Pengshan Sn and Pb-Zn polymetallic deposits are located in the south margin of the Jiujiang-Ruichang (Jiurui) district of the Middle-Lower Yangtze River Metallogenic Belt in South China. Four large deposits include Huangjinwa, Zengjialong, Jianfengpo, and Zhangshiba, the former three are Sn-dominant deposits which occur as stratiform orebodies in the contact zones of the Pengshan granites and within the country rock strata, whereas Zhangshiba consists of stratiform Pb-Zn orebodies within the Precambrian metasedimentary strata. In this study, we present results on zircon U-Pb ages, major and trace elements, and mineral chemistry as well as Sr-Nd-Hf isotope data of the granites, Pb and S isotopes of both the Sn-dominant and Pb-Zn dominant deposits, and U-Pb dating of cassiterite from the Pengshan district. SHRIMP and LA-ICP-MS zircon U-Pb dating shows that the Pengshan granites were emplaced in the Early Cretaceous (129–128 Ma), which is in good agreement with the U-Pb dating (130–128 Ma) of cassiterite from the Jianfengpo Sn deposit. The Pengshan granites consist mainly of weakly peraluminous highly fractionated I-type affinity granitic rocks. Detailed elemental and isotopic data suggest that the granites formed by partial melting of Mesoproterozoic metamorphic basement materials with minor input of mantle-derived melts. The mineral chemistry of biotite demonstrates that the Pengshan granitic magma had a low oxygen fugacity, thereby precluding the tin dominantly partitioning into the rock-forming silicate minerals and favoring accumulation in the exsolved residual liquid during magma crystallization stages. Sulfur isotopes show a relatively heavy sulfur isotopic composition from 5.8 to 17.6 ‰, and no difference for sulfur isotopes between the Sn deposits (5.8–13.4 ‰, Huangjinwa, Zengjialong, Jianfengpo) and the Pb-Zn deposit (mostly 7.1–13.0 ‰, except for one 17.6 ‰, Zhangshiba). The sulfur isotope data of pyrite from the host sedimentary rocks show relatively higher δ34S values of 22.7–28.7 ‰. Lead isotopes indicate that the granites have higher 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios than the host Precambrian metasedimentary rocks, and the sulfide minerals from the orebodies fall in between them. Again, there is no difference for Pb isotopes between the Sn deposits (Huangjinwa, Zengjialong, Jianfengpo) and the Zhangshiba Pb-Zn deposit. The coincidence in S and Pb isotope compositions for Sn and Pb-Zn deposits suggests that similar sources for these mineralization, possibly derived from a mixed source of the granitic magmas and the Precambrian metasedimentary rocks. These data therefore favor of a magmatic-hydrothermal origin for both the Sn and Pb-Zn polymetallic mineralization in the Pengshan district.

The Early Paleozoic Orogen in South China has been a topic of hot debate; in particular with regard to the relative contributions of crustal and mantle sources to the generation of granites. To address this issue, we report geochronological and geochemical data for three related suites of granites (Tuantian, Suite 1, Nanlao, Suite 2, and Laochengpo, Suite 3) from the Laojunshan district in the southeast Yunnan Province, western South China Block (SCB). LA-ICP-MS U-Pb dating of zircons indicates magmatic crystallization ages of ~ 436Ma, ~ 430Ma and ~ 427 Ma for Suites 1, 2, and 3 granites, respectively. The eHf(t) values of magmatic zircons in all three suites are heterogeneous, ranging between + 3 and − 14. All three suites also contain inherited zircon cores with Proterozoic U-Pb and Hf model ages. Bulk compositions form well-defined mixing arrays, with Suites 1 and 2 being strongly peraluminous (A/CNK > 1.1), whereas Suite 3 is weakly peraluminous (A/CNK = 1.0–1.1). Suites 1 and 2 have lower TFe2O3, Al2O3, MnO, MgO, CaO, TiO2, Na2O, Mg# and Nb/Ta but higher K2O, Rb/Sr, Rb/Ba and eNd(t) than those of Suite 3. These results suggest that Suite 1 and Suite 2 were formed by partial melting of Proterozoic metasedimentary rocks with little or no input of mantle-derived materials, but Suite 3 was derived from a mixture of a crustal melt with mantle derived mafic magma. The apparent paradox that the mantle-derived component has lower eNd(t) values than the crustal components is consistent with the very low eNd(t) values found in mantle-derived basalts in the SCB. The Wuyi-Yunkai orogenic collapse may have caused lower crustal melting of the Cathaysia Block. The early Paleozoic granitoid magmatism with mafic magma input indicates an extensional environment in the western SCB, in response to post-collisional orogenic collapse. Asthenospheric upwelling and basaltic underplating probably contributed heat and melts triggering felsic magmatism in the western SCB.

Abundant Jurassic-Cretaceous W-Sn ore deposits are distributed in the Nanling Range in South China. However, the exact mineralization ages, relationships between mineralization and granitic rocks, and tectonic settings of these deposits remain controversial. As a giant quartz vein-type W-Sn deposit hosted in Devonian sedimentary strata, the Shanhu orebodies are featured by located about 4 km far away from the Yantianling muscovite granite. Zircon U-Pb dating of the Yantianling granite yielded ages of 101.0 ± 1.5 Ma and 100.4 ± 1.1 Ma, consistent with cassiterite U-Pb ages of quartz vein ores (100.2 ± 1.0 Ma and 100.5 ± 1.1 Ma), indicating a close genetic relationship between the granitic magmatism and quartz vein-type W-Sn mineralization. The Yantianling muscovite granite is characterized by highly silicious (72.01–74.62 wt%), high alkali (Na2O + K2O = 5.32–7.89 wt%) and strongly peraluminous (A/CNK = 1.11–1.81). The granite is enriched in Rb, Ta, Nd and U, and depleted in Sr, Ti and P. It displays right-declining chondrite-normalized REE patterns with strongly negative Eu anomalies, and has low Nb/Ta and Zr/Hf ratios, indicating that the granite experienced strong magmatic differentiation. The Yantianling granite has low whole-rock eNd(t) values (−9.5 to −9.3), zircon eHf(t) values (−12.7 to −7.8) and Paleoproterozoic model ages. The granite belongs to S-type and was derived from partial melting of meta-sedimentary crust. The low Ce4+/Ce3+ ratios (averaging 47) of zircon from the Yantianling granite indicated low oxygen fugacity, similar to other W-bearing granites in South China. This study indicated that Cretaceous granitic magmatism in the Nanling Range also has strong W-Sn mineralization potential. Combined with previous studies on coeval magmatic rocks and tectonic activities, we propose that the Yantianling S-type granite and associated W-Sn mineralization in the Nanling Range were formed during the regional lithospheric extensional environment.

Cretaceous mafic rocks mainly occur along the coast of South China. In comparison, coeval mafic rocks are distributed only sporadically in the inland region, and their petrogenesis and tectonic setting have not been well documented so far. Here we report a detailed study on 40Ar/39Ar dating, elemental geochemistry and Sr-Nd-Pb isotopes for the Yaoling diabases in northern Guangdong, South China. The Yaoling diabases yield a Late Cretaceous (101 ± 1 Ma) 40Ar/39Ar age. These rocks have variable (87Sr/86Sr)i (0.705023–0.709847), relatively uniform eNd(t) (+2.45 to +3.88) and intermediate (206Pb/204Pb)i (18.586–18.692), (207Pb/204Pb)i (15.743–15.764) and (208Pb/204Pb)i (38.300–39.137). These rocks exhibit geochemical affinity to both within-plate and arc magmatism, i.e., relatively high TiO2, Nb and Zr contents, and negative Nb anomalies with (Nb/La)PM of 0.65–0.82. Such dual features indicate that the Yaoling diabases were most likely generated through partial melting of a previously metasomatized lithospheric mantle at a shallow depth (75–85 km), and modified by crystal fractionation. It is likely that the ancient metasomatism may have occurred during the Neoproterozoic oceanic subduction beneath the Cathaysia Block. We suggest that the Yaoling diabases formed in an intraplate extension setting associated with asthenospheric upwelling, possibly in response to the far-field stress that propagated from the paleo-Pacific subduction during the Late Cretaceous (ca. 100 Ma).

The Jinwozi deposit is the most economically important gold (Au) deposit in the Beishan Orogen (Eastern Xinjiang, NW China). The Au orebodies occur as quartz veins or altered lodes in the Jinwozi Formation clastic rocks and the Jinwozi granite. The age, detrital source and tectonic setting of the Jinwozi Formation, however, have not been well understood. In this paper, we reported new LA–ICP MS detrital zircon U–Pb ages and Lu–Hf isotopes of ore-hosted clastic rock of the Jinwozi Formation. Detrital zircons from three samples yield 334 U–Pb ages varied from 330 to 2598 Ma, showing complex detrital sources. The youngest detrital zircon population suggests that the Jinwozi Formation deposited no earlier than 330 Ma in the Late Carboniferous or Permian. The majority of the detrital zircons (291 out of 334) have ages between 330 and 533 Ma, suggesting a dominant Paleozoic detrital source. Much of these age data (282 out of 334) range from 470 to 370 Ma, broadly coeval with the zircon U–Pb ages of the Jinwozi granite. Zircon Hf isotope data also implicate their similar origin to the Jinwozi granite. The source rocks, as well as the Jinwozi granite, may have formed in the Early Paleozoic Caledonian Orogeny, during which the supercontinents of Gondwana and Laurasia assembled. This orogeny process may have provided plenty of detritus for the clastic rocks of the Jinwozi Formation. Precambrian detrital zircon ages from the Jinwozi Formation cluster around 2400–2600 Ma, 1800–2100 Ma, 800–1300 Ma, which corresponds to the supercontinent assembly events of Kenor, Columbia and Rodinia, respectively. The age populations of 2200–2300 Ma and 600–660 Ma are possibly related to the breakup of Kenor and Rodinia supercontinents. This understangding is supported by zircon Hf isotope data.

Cretaceous tectono-magmatic evolution of the Cathaysia Block in South China is important but their mechanism and geodynamics remain highly disputed. In this study we carried out a detailed geochemical study on the recently found Kuokeng mafic dikes in the western Fujian Province (the Interior Cathaysia Block) to reveal the petrogenesis and geodynamics of the Cretaceous magmatism. Kuokeng mafic dikes were emplaced in three principal episodes: ~ 129 Ma (monzogabbro), ~ 107 Ma (monzodiorite), and ~ 97 Ma (gabbro). Geochemical characteristics indicate that the monzogabbros were derived from the unmodified mantle source, while gabbros were likely derived from metasomatized mantle by subducted slab (fluids and sediments). Sr–Nd isotope compositions indicate that the parental magmas of the monzodiorites were generated by mixing of enriched, mantle-derived, mafic magmas and felsic melts produced by partial melting of crustal materials. Until the Early Cretaceous (~ 123 Ma), the dominant ancient Interior Cathaysia lithospheric mantle exhibited insignificant subduction signature, indicating the melting of asthenospheric mantle and the consequent back-arc extension, producing large-scale partial melting of the crustal materials under the forward subduction regime of the paleo-Pacific plate. The monzodiorites and gabbros appear to be associated with northwestward subduction of Pacific plate under an enhanced lithospheric extensional setting, accompanying with mantle modification, which triggered shallower subduction-related metasomatically enriched lithospheric mantle to melt partially. After ca. 110 Ma, the coastal magmatic belts formed due to a retreat and rollback of the subducting Pacific Plate underneath SE China in the continental margin arc system.

The Pingshui Cu–Zn deposit is located in the Jiangshan–Shaoxing fault zone, which marks the Neoproterozoic suture zone between the Yangtze block and Cathaysia block in South China. It contains 0.45 million tons of proven ore reserves with grades of 1.03 wt.% Cu and 1.83 wt.% Zn. This deposit is composed of stratiform, massive sulfide ore bodies, which contain more than 60 vol.% sulfide minerals. These ore bodies are hosted in altered mafic and felsic rocks (spilites and keratophyres) of the bimodal volcanic suite that makes up the Neoproterozoic Pingshui Formation. Metallic minerals include pyrite, chalcopyrite, sphalerite, tennantite, tetrahedrite and magnetite, with minor galena. Gangue minerals are quartz, sericite, chlorite, calcite, gypsum, barite and jasper. Three distinct mineralogical zones are recognized in these massive sulfide ore bodies: a distal zone composed of sphalerite + pyrite + barite (zone I); an intermediate zone characterized by a pyrite + sphalerite + chalcopyrite assemblages (zone II); and a proximal zone containing chalcopyrite + pyrite + magnetite (zone III). A thin, layer of exhalative jaspilite overlies the sulfide ore bodies except in the proximal zone. The volcanic rocks of the Pingshui Formation are all highly altered spilites and keratophyres, but their trace element geochemistry suggests that they were generated by partial melting of the depleted mantle in an island arc setting. Homogenization temperatures of the primary fluid inclusions in quartz from massive sulfide ores are between 217 and 328 °C, and their salinities range from 3.2 to 5.7 wt.% NaCl equivalent. Raman spectroscopy of the fluid inclusions showed that water is the dominant component, with no other volatile components. Fluid inclusion data suggest that the ore-forming fluids were derived from circulating seawater. The δ 34 S values of pyrite from the massive sulfide ores range from − 3.6‰ to + 3.4‰, indicating that the sulfur was primarily leached from the arc volcanic rocks of the Pingshui Formation. Both pyrite from the massive sulfide ores and plagioclase from the spilites have similar lead isotope compositions, implying that the lead was also derived from the Pingshui Formation. The low lead contents of the massive sulfide ores and the geochemistry of their host rocks are similar to many VMS Cu–Zn deposits in Canada (e.g., Noranda) and thus can be classified as belonging to the bimodal-mafic subtype. The presence of magnetite and the absence of jaspilite and barite at the − 505 m level in the Pingshui deposit suggest that this level is most likely the central zone of the original lateral massive sulfide ore bodies. If this interpretation is correct, the deep part of the Pingshui Cu–Zn deposit may have significant exploration potential.

As a world-class tin–tungsten province, South China is well known for its extensive Mesozoic granitic magmatism. The Dulong district, located in the western Cathaysia Block of the South China tin–tungsten province, is characterized by widespread Mesozoic granitoids and accompanying Sn-polymetallic ore deposit (~ 30 Mt of Sn). It is one of the most important polymetallic tin ore districts in China. In this study, three mineralization-related granite types were identified in the Dulong district, including the Dulong coarse-grained granite (DCG), the Dulong fine-grained granite (DFG), and the Dulong porphyritic granite (DPG). Detailed studies are presented on zircon U–Pb ages, major and trace elements, mineral chemical and Nd–Hf isotopic compositions of the tin-bearing granites from the Dulong district. LA-ICP-MS U–Pb dating of zircon grains from these three granite bodies yields ages of 90.1 ± 0.7 Ma, 89.7 ± 0.8 Ma and 86.0 ± 0.5 Ma, respectively. Geochemically, the granites are strongly peraluminous, with high contents of alkalis, enrichment in P, Li, Rb, Cs, Ta, Sn, W and U, depletion in Ti, Mg, Co, Ni, Sr, Ba, Zr, Hf, Th and rare earth elements. Fractional crystallization of plagioclase and K-feldspar was the principal process of magmatic differentiation that controlled Rb, Sr, Ba and Eu concentrations, whereas rare earth elements were fractionated by accessory minerals, such as apatite and monazite. The geochemical data suggest that the rocks are highly fractionated S-type granites. The granites show bulk rock e Nd (t) values in the range of − 12.2 to − 10.8 and zircon e Hf (t) values from − 15.5 to − 2.5, with Meso-Paleoproterozoic T DM C ages for both Nd and Hf isotopes. Geochemical and isotopic data suggest that these highly fractionated S-type granites DCG, DFG and DPG were originated from the same episode of partial melting of the protolith, which have analogous components of metamorphosed pelitic rocks from the Meso-Paleoproterozoic continental crust. Extreme fractional crystallization resulted in enrichment of tin in the evolved granitic magma, and the reduced magmas (fO 2 below NNO) would efficiently remove Sn into a hydrothermal fluid, and lead to deposition of Sn-rich mineral phases. The association of Dulong and Gejiu magmatism in the western Cathaysia Block may be likely to mark the onset of back-arc extension or intra-arc rift in the region during Late Cretaceous. The upwelling of asthenospheric mantle may have triggered partial melting of metasedimentary rocks in the overlying crust to generate the S-type granitic magmas.