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The Dongyang gold deposit is a recently discovered large gold deposit located within the Dehua–Youxi–Yongtai mining camp in central–east Fujian Province, southeast China. The deposit contains two individual ore sections: the northwestern Jitou section and the southeastern Dadongkeng section. Most of the mineralization is hosted by rhyolite porphyry and volcanic rocks of the Nanyuan Formation. The locations of subvolcanic intrusions in this area are controlled by NE–SW and NW–SE trending faults that are also closely related to mineralization. Detailed drillhole logging and adit mapping indicates that the deposit contains massive, polymetallic quartz–sulfide veins, and cryptoexplosive breccia type ores. Ore minerals consist of gold, electrum, silver minerals, pyrite, marcasite, and arsenopyrite with lesser amounts of sphalerite and chalcopyrite. The mineralization is hosted by quartz, sericite, illite, chalcedony, and calcite gangue and is associated with sericite and argillic alteration as well as silicification. Fluid inclusion microthermometry indicates that the inclusions within quartz from auriferous quartz–sulfide veins formed during the main stage of mineralization and homogenize at temperatures (Th) of 172 °C–217 °C (average of 192 °C) and have salinities of 0.4–2.6 wt% NaCl equivalent. These low to moderate temperatures and low salinities suggest that the mineralization occurred in an epithermal environment. The precipitation of gold mineralization at Dongyang was most likely caused by the mixing of a large amount of meteoric fluid with a smaller amount of magmatic fluid. Quartz-hosted fluid inclusions have H and O isotope compositions (δDH2O = −63.1 to −54.2‰; δ18OH2O = −5.7‰ to −3.8‰) that are indicative of derivation from a predominantly meteoric source. The S isotope values of pyrite vary from a narrow range of −3.4‰ to 0.9‰, suggesting that the S within the deposit was derived from a homogeneous magmatic source. The mineralization and alteration, gangue and ore mineral assemblages, fluid inclusion and H–O–S isotope compositions indicate that the Dongyang gold deposit is a low-sulfidation epithermal-type deposit. The estimated ore formation depth of Donyang is nearly identical to its actual depth, indicating minor denudation in the region. These results imply a great prospecting potential for other epithermal mineralization at the Dehua–Youxi–Yongtai mining camp.

The Ancun gold deposit is located in the Dehua–Youxi–Yongtai ore region of Fujian Province, southeast China. The orebodies are mainly hosted in early Paleozoic quartz diorite and structurally controlled alteration zones along NW- and NE-trending faults. Based on the characteristics of mineralization, alteration mineral assemblages, fluid inclusions, and H–O–S isotope data, the Ancun gold deposit can be classified as an intermediate-sulfidation epithermal deposit. The primary metallic minerals are gold, electrum, pyrite, sphalerite, chalcopyrite, and galena, and the principal gangue minerals are quartz, calcite, sericite, and illite. The main types of wall rock alteration include sericitization, argillization, silicification, beresitization, and carbonation. Fluid inclusion studies were carried out on quartz and sphalerite from Au-bearing silicified massive ores and auriferous polymetallic-sulfide-bearing quartz veins from the main ore stage. Microthermometric measurements of fluid inclusions yielded homogenization temperatures (Th) of 152–255 °C and salinities of 0.9–5.3 wt% NaCl equivalent in quartz, and Th of 175–236 °C and salinities of 1.6–5.0 wt% NaCl equivalent in sphalerite. The low to moderate temperatures and salinities imply that the ore-forming fluids formed in epithermal environments. Gold deposition at Ancun is inferred to have been caused mainly by mixing of magmatic and diluted meteoric waters. The H and O isotopic compositions (δDH2O = −76.4‰ to −61.2‰; δ18OH2O = −6.1‰ to 4.0‰) of inclusion water in quartz imply that ore-forming fluids were derived mainly from magmatic sources. Sulfur isotopic values of sulfide minerals vary over a narrow range from −3.9‰ to −0.6‰, suggesting that S was derived from a homogeneous magmatic source. Based on the close temporal and spatial relationship between intermediate-sulfidation epithermal deposits and porphyry deposits, along with the alteration and mineralization characteristics of the Ancun gold deposit, potential exists in this region to drill into deeper-seated porphyry deposits.

The Dehua gold ore-field, located in the central-eastern Fujian Province, SE China, is an important part of the renowned Dehua-Youxi-Yongtai gold ore production area. The ore-field contains several low-intermediate sulphidation epithermal gold deposits and numerous gold-bearing mineralized bodies. The extensive presence of intensely altered rocks, suitable structural environment, acidic intrusions and volcanic-subvolcanic rocks indicates an important potential for epithermal gold mineralization. In this work, fluid inclusion homogenization temperature and alteration mapping was carried out by fluid inclusion microthermometry in quartz and identification of alteration minerals closely related to the known mineralization. The result shows the trend of temperature contour curves as well as the shape of low argillic alteration zones implying that the area north of Qiucun might be profitable for future mineral exploration. The fluid and alteration mapping, in combination with soil geochemical mapping, defines the architecture of the epithermal-porphyry ore-forming system in the Dehua ore-field. Finally, the presence of intensely altered areas, high value zones of hydrothermal fluid flows and combined anomaly areas of multi-element association indicate that the region north of Qiucun has an important potential as a preferred target area for gold prospecting in the Dehua ore-field.

The Wuhe area in eastern Anhui province, hosting 23 metric tons of gold, has been recognized as a new gold ore cluster in the North China Craton (NCC) since the Hekou gold deposit was discovered in 2017. Its metallogenic setting and ore-forming process remain unclear. In this contribution, we perform a combined geology, cathodoluminescence, fluid inclusion, H-O isotope and pyrite Rb-Sr geochronologic studies on the Hekou gold deposit of the Wuhe area. In order to perform detailed fluid inclusion petrography study, we used scanning electron microscope-cathodoluminescence (SEM-CL) on a well preserved sulfides-bearing quartz grain from the auriferous quartz vein. In this quartz grain, generation A barren quartz in the core zone (QA, CL-white), minor sulfides bearing generation B (QB, CL-light gray) in intermediate zone and sulfides rich generation C (QC, CL-dark gray) in the distal zone and fractures were revealed. Only in QC, the higher carbonic proportion (50–80 vol%) inclusions (CC) coexist with the two-phase liquid-rich aqueous fluid inclusions (LC) and sulfides, meanwhile the CC and the LC show a similar Th of 258–313 °C and 249–308 °C, but different salinities of 1.4–5.3 wt% NaCl equivalent and 6.0–10.9 wt% NaCl equivalent, respectively. It suggests that dominating fluid immiscibility recorded in QC is responsible for the prime deposition of gold and sulfide minerals. The δ18O (-4.1 to −6.5‰) and δD (-67.1 to −81.3‰) values of fluid inclusions in quartz suggest that ore-forming fluids were mainly derived from magmatic water which could related to mantle source. Gold-bearing pyrites yield an Rb-Sr isochron age of 128.1 ± 2.7 Ma, which is 8 m.y. earlier than the peak value of gold mineralization ages (ca. 120 Ma) at Jiaodong in response to the Early Cretaceous lithospheric thinning of the NCC and the reactivation of the Tan-Lu Fault zone (TLFZ). The Wuhe area shares similar characteristics of geology, fluid inclusions, H-O isotopes, and ore-forming ages with the Jiaodong gold ore cluster, highlighting the exploration potential in this region.

The Shuangqishan gold deposit is the largest gold deposit in the Dehua ore cluster of Fujian Province. The gold orebodies are located in the metamorphic rock of Neoproterozoic Daling Formation. Representative genetic models of Shuangqishan gold deposit include epithermal gold deposit, orogenic gold deposit and granitoid-related gold deposit. Based on the comprehensive research of pyrite Rb-Sr geochronology, telluride mineralogy and pyrite LA-ICP-MS trace element, we intend to discuss the genesis of the Shuangqishan gold deposit. The Rb-Sr isotopic dating of gold-bearing pyrite indicates that mineralization age of the Shuangqishan gold deposit is 153.5 ± 2.4 Ma, which is the same as that of the granite porphyry dyke (zircon U-Pb age = 153.4 ± 1.2 Ma) in the mining area. The main gold-bearing mineral is native gold, with a fineness of >920, additional gold-bearing mineral is electrum, with a fineness of 677 ~ 741. The gold-bearing polymetallic sulphide quartz veins contain a large amount of tellurbimuth (Bi2Te3), rucklidgeite (PbBi2Te4) and tetradymite (Bi2Te2S). The Shuangqishan gold deposit’s characteristic combination of Au-Bi-Te elements is analogous to that of typical magmatic-hydrothermal deposit. The estimated log f Te2 versus log f S2 conditions of telluride mineralization at 250 °C are –13.0 ~ –9.5, –14.7 ~ –10.5, respectively. LA-ICP-MS trace element analysis of gold-bearing pyrite shows that the pyrite is As-poor and has high content of Te, Bi, Pb, Co and Ni, but has low content of Au and As. The typical As-poor pyrite indicates that the Shuangqishan gold deposit is the magmatic hydrothermal gold deposit. Te displays a high positive correlation with Bi and Pb, indicating that Te, Bi and Pb occur as Bi-telluride micro-inclusion in pyrite. Our research shows that the Shuangqishan gold deposit is the magmatic hydrothermal gold deposit formed in the late Jurassic.

The Dehua Au-polymetallic ore cluster, as one of the most important area in the Wuyi Au-Cu-Mo metallogenic belt, consists of many large to middle sized epithermal Au deposits and recently discovered porphyry Cu-Mo deposits. We first study the geochronology and geochemistry characteristics of the Cu-Mo mineralization-related Xianyang granite porphyry to constrain its petrogenesis, tectonic setting and metal endowment. LA-ICP-MS zircon U-Pb dating yield a precise age of 157.2 ± 0.8 Ma for the Xianyang granite porphyry, indicating that the granite porphyry was emplaced during the Late Jurassic. The Xianyang granite porphyry was suggested to be generated under continental arc setting, associated with subduction of the paleo-Pacific slab beneath the South China Block. The Xianyang granite porphyry belongs to the high-K calc-alkaline series, with SiO2 of 71.16–72.02 wt% and K2O of 4.28–4.69 wt%. It shows light rare earth element-enriched distribution patterns with (La/Yb)N of = 9.74–13.93, enrichment in large ion lithophile elements, but depletion of high field strength elements, with negative Nb, Ta and Ti anomalies, suggesting an arc magma geochemical affinity. It has lower initial 87Sr/86Sr ratios of 0.7079–0.7086 and relatively higher eNd(t) and eHf(t) values of −8.03 to −7.69 and − 8.86 to −5.48, respectively, than those of basement rocks of the Cathaysia block, suggesting that it was most likely generated by partial melting of the regional ancient crustal materials, with the involvement of asthenosphere mantle-derived materials. The Xianyang granite porphyry has remarkably high zircon Ce4+/Ce3+ values of 119–404 (mean = 245) and EuN/EuN* values of 0.37–0.60 (mean = 0.51), indicating a high oxygen fugacity, which is favor of the formation of the Xianyang porphyry Cu-Mo mineralization. Combining with published research results for regional subvolcanic rocks-related epithermal Au deposits, the porphyry Cu-Mo deposits and epithermal Au deposits in the Dehua ore cluster share similar petrogenetic-metallogenic ages and magma sources in the continental arc setting during the Late Jurassic period. The identification of the coeval porphyry-epithermal Cu-Mo-Au metallogenic system in the Dehua ore cluster highlights the possibility of finding the hidden porphyry Cu-Mo orebodies beneath the discovered epithermal Au deposits.

The Cathaysia Block is the southeastern part of the South China Block in Southeast (SE) China, and it hosts voluminous late Mesozoic I-, S-, and A-type granitoids, as well as minor highly fractionated granites. We present here zircon U–Pb age data and Nd–Hf isotopic data for the Dayang and Juzhou granites, together with new petrological and geochemical analyses. The Dayang pluton consists of fine-grained two-mica monzonitic granites in which the plagioclases exhibit zoning and poikilitic textures. In contrast, the Juzhou pluton consists of medium- to coarse-grained biotite K-feldspar granites that lack zoning and poikilitic textures. The emplacement ages are 143 ± 2.3 Ma for the Dayang pluton and 133 ± 2.1 Ma for the Juzhou pluton according to zircon U–Pb isotope analyses. The Dayang and Juzhou granites are both metaluminous and belong to the shoshonitic series. The Dayang granite exhibits very flat REE patterns, showing the tetrad effect, and the spidergrams show striking negative Ba, Sr, Nb, and Ti anomalies and a positive Ta anomaly. In contrast, the Juzhou granite has sloping REE patterns, but like the Dayang granite it also has striking negative Ba, Sr, Nb, Ta, and Ti anomalies. Petrographic and geochemical evidence indicates that the Dayang granite is a highly fractionated I-type granite and that the Juzhou granite is a typical I-type granite. The tetrad effect in the Dayang granite can be interpreted in terms of melt–rock interactions at a late stage of magma evolution, whereas the main mechanism during the evolution of the Juzhou magma was fractionation of plagioclase, biotite, hornblende, apatite, zircon, and allanite. Nd–Hf isotope data suggest that the Dayang and Juzhou granites were both formed partial melting of Paleoproterozoic basement rock and juvenile material (underplating basalts or Mayuan Group amphibolites), with the Juzhou granite having a greater contribution from juvenile material than the Dayang granite. Our new data, together with existing data, suggest that the tectonic setting of the early Yanshanian (∼143 Ma) highly fractionated I-type Dayang granite was a back-arc that formed in response to the westward subduction of the Paleo-Pacific Plate, and that the late Yanshanian (∼133 Ma) Juzhou granite formed in a continental arc setting in response to rollback of the Paleo-Pacific Plate toward the coastline. The Mo mineralization in the Makeng ore area was probably the result of the exsolution of Mo-bearing fluids from the Dayang granitic magmas due to extensive fractional crystallization.

The large-scale Maoping W&ndash, Sn deposit in the Gannan metallogenic belt of the eastern Nanling Range, South China, spatially associated with the Maoping granite pluton, hosts total ore reserves of 103,000 t WO3 and 50,000 t Sn. Two different types of mineralization developed in this deposit: Upper quartz vein-type mineralization, mostly within the Cambrian metamorphosed sandstone and slate, and underneath greisen-type mineralization within the Maoping granite. Cassiterites from both types of mineralization coexist with wolframite. Here we report for the first time in situ U&ndash, Pb data on cassiterite and zircon of the Maoping deposit obtained by LA-ICP-MS. Cassiterite from quartz vein and greisen yielded weighted average 206Pb/238U ages of 156.8 &plusmn, 1.5 Ma and 156.9 &plusmn, 1.4 Ma, respectively, which indicates that the two types of mineralization formed roughly at the same time. In addition, the two mineralization ages are consistent with the emplacement age of the Maoping granite (159.0 &plusmn, 1.5 Ma) within error, suggesting a close temporal and genetic link between W&ndash, Sn mineralization and granitic magmatism. The two types of mineralization formed at the same magmatic-hydrothermal event. Cassiterite from both types of mineralization shows high Fe, Ta, and Zr contents with a low Zr/Hf ratio, suggesting that the ore-forming fluid should be derived from the highly differentiated Maoping granite pluton. Cassiterite in greisen has higher contents of Nb and Ta but a lower concentration of Ti compared with that in quartz vein, indicating that the formation temperature of greisen-type mineralization is little higher than that of quartz-vein-type mineralization.

The North China Craton is a classic case for the destruction of an ancient craton, in that it records the loss of more than 100 km of ancient refractory lithospheric mantle during the late Mesozoic and early Cenozoic. However, the mechanisms for this lithospheric thinning remain controversial in large part due to the lack of any systematic investigations of the Mesozoic asthenospheric mantle via its derived mafic rocks, which are key to understand the thinning processes. In this paper, we present detailed zircon U–Pb geochronology, elemental geochemistry, and Sr–Nd–Hf isotopic data for lamprophyres and diabase-porphyries of the Jiaodong Peninsula, in the eastern North China Craton in order to place constraints on models for lithospheric thinning. Our results show that the lamprophyres and diabase-porphyries are derived from the convective asthenospheric mantle via different degrees of partial melting, and that this mantle source was previously modified by carbonatitic liquids. Zircon LA-ICP-MS U–Pb dating suggests an emplacement age for these rocks of 123–121 Ma, the earliest evidence for asthenospherically-derived melts in the Jiaodong Peninsula so far. This emplacement age indicates that the thickness of the lithosphere in the Jiaodong Peninsula was relatively thin at that time. Co-occurrence of the asthenospheric and lithospheric mantle-derived mafic rocks as well as high-Mg adakites record a rapid transition from lithospheric to asthenospheric mantle sources, indicating that the lithosphere beneath the Jiaodong Peninsula was rapidly detached just prior to ca. 120 Ma. Lithospheric thinning of the North China Craton may have been initiated from the Jiaodong Peninsula and Bohai Sea and then propagated towards the interior of the craton.

The Xianhualing District at Jinzhai in the northern Dabie Orogen, China, is a significant area for Pb–Zn–Cu–Au polymetallic exploration. The main rocks in the area are mica–quartz schist of the Neoproterozoic Foziling Group, and magmatic rocks which are controlled by two sets of faults striking NNE and NW. Recent drilling has revealed that the orebody occurs mainly in mica–quartz schist in the form of breccia and veinlets. Major ore minerals include pyrite, sphalerite, galena, chalcopyrite, magnetite, gold, silver, and silver sulfosalts, with alteration assemblages of predominantly quartz, sericite, calcite, and chlorite. Three types of fluid inclusions occur in quartz–sulfide vein samples collected from eight drill-holes: two-phase liquid-rich inclusions (type I), two-phase vapor-rich inclusions (type Ⅱ), and halite-bearing inclusions (type III). Microthermometric studies of type I and Ⅱ fluid inclusions indicate homogenization temperatures of 161–378 °C and salinities of 0.5–7.8 wt% NaCl equivalent. Fluid inclusion microthermometric data and mineralization and alteration characteristics indicate an intermediate-sulfidation epithermal environment. Current exploration is focused on the location of potential deep porphyry mineralization associated with epithermal mineralization. In this study, 28 drill-core samples from different levels were selected for fluid inclusion microthermometry to elucidate fluid-evolution pathways and hence to determine the likelihood of porphyry bodies. The consistent fluid inclusion petrography, distribution patterns, and fluid-evolution trends indicate that the deeper part of the Dongchong area may have been the regional thermal center of fluid flow. The estimated mineralization depths of type III fluid inclusions are in the range 0.4–1.5 km, indicating a relatively shallow formation. Fluid chemical compositions obtained from single-inclusion laser-ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) analyses support the occurrence of a single magmatic–hydrothermal fluid source, which has a degree of mixing with meteoric water and a small amount of basinal brines during the migration path, and the fluid evolution pattern agrees well with the fluid inclusion mapping result. Quartz-vein hosted fluid inclusions contain significant amounts of Pb, Zn, and Cu, indicating good exploration prospects for porphyry Cu mineralization at depth.

The Dehua gold orefield is an important epithermal gold metallogenic district closely related to volcanic–subvolcanic rocks in the coastal region of the Cathaysia Block, southeastern China. This paper presents new LA-ICP-MS zircon U–Pb ages, elemental and Hf isotopic data for volcanic and intrusive rocks in the Dehua gold orefield. Our results show that the volcanic rocks were produced during the Middle Jurassic (ca. 169–164 Ma), whereas the intrusive rocks were formed in the Late Jurassic (ca. 163–157 Ma). Geochemically, these rocks are characterized by high-K calc-alkaline series and are commonly enriched in LILEs and LREE, depleted in HFSE with negative Nb, Ta, and Ti anomalies, and have lower Ta, Yb, Y and Rb contents, suggesting an arc magma geochemical affinities. Hence, this study firstly reports the Middle Jurassic high-K continental arc volcanic rocks in SE China, implying that the initial subduction of the paleo-Pacific plate began at least in the Middle Jurassic. Besides, in situ Hf isotopic analyses for dated zircon from the volcanic and intrusive rocks yield eHf(t) values range from −9.03 to +1.46 and the Paleo- to Mesoproterozoic two stage Hf model ages. The partial melting of the mixture of ancient continental crust materials and newly underplated potassic-rich mantle-derived mafic magmas likely explains the genesis of volcanic and intrusive rocks in the Dehua gold orefield. In addition, the exposed areas of the Jurassic volcanic rocks in the coastal region of SE China may have great potential to prospect the epithermal deposits.

The Shuangqishan Au deposit lies in the Dehua–Youxi–Yongtai Au metallogenic belt in central eastern Fujian Province, SE China. The orebodies are hosted mainly in the Neoproterozoic Dalingyan Formation. Based on the characteristics of mineralization, alteration mineral assemblages, fluid inclusions, and H–O–C–S–Pb isotopic data, the deposit is classified as a granitoid-related deposit. The primary metallic minerals are native gold, electrum, pyrite, chalcopyrite, galena, tellurbimuth, and tetradymite; the main gangue minerals are quartz, calcite, sericite, and illite. The main types of wall-rock alteration are silicification, pyritization, carbonatization, and sericitization. Fluid inclusions in quartz from auriferous polymetallic sulfide-bearing quartz veins from the main ore stage were studied. Two-phase liquid-rich (type I), CO2-rich (type II), and pure CO2 (type III) inclusions were identified. Their homogenization temperatures (196 °C–295 °C) and salinities (0.8–5.0 wt% NaCl equivalent) indicate that the ore-forming fluids of the Shuangqishan deposit were of a medium-temperature, low-salinity H2O–CO2–NaCl system. Gold deposition at Shuangqishan was likely caused by immiscibility of fluids. H isotopic compositions (δDH2O = −68.0‰ to −64.8‰) of inclusion water in quartz and O isotopic compositions (δ18OH2O = 3.8‰ to 6.3‰) of fiuid, which was calculated from δ18O of quartz, imply that ore-forming fluids were mainly of magmatic origin. C isotopic compositions (δ18CPDB = −15.7‰ to −5.7‰) of the fluid inclusions indicate that the CO2 in the ore-forming fluids was predominantly magma-derived, but was contaminated by organic carbon from the Neoproterozoic Dalingyan Formation. δ34S values of sulfide minerals have a narrow range of–2.7‰ to −0.9‰, suggesting that S was derived from a homogeneous magmatic source. Pb isotopic ratios of gold-bearing ores are similar to those of late Mesozoic granodiorite porphyry of the Xianyang pluton, indicating that the granodiorite porphyry was the source of Pb for the ores.

In this study, we carried out petrography, zircon U-Pb geochronology and Hf isotopic analyses on a granitic pegmatite dyke in the Xiaoqinling area in southern margin of the North China Craton (NCC). Our study suggests that the pegmatite dyke likely crystallized from a volatile-rich pegmatitic magma. Different from most other pegmatite elsewhere, zircon from this pegmatite dyke does not contain unusually high U and Th concentrations and suffered no evident radioactive damage, therefore we successfully obtained a zircon U-Pb dating using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), which yields an average 207Pb/206Pb age of 1 814±6 Ma, representing the intrusive age of the granitic pegmatite dyke. Zircon ɛ Hf(t) values are between −8.3 and −3.0, corresponding to Hf depleted mantle model ages from 2 649 to 2 991 Ma with an average of 2 881 Ma. These data indicate that this granitic pegmatite dyke may have been derived from partial melting of Meso-Neoarchean metamorphic rocks from the Xiaoqinling basement. Granitic pegmatite magma may have emplaced within the Taihua Group wall rocks during the last stage of the middle to high grade metamorphism. Furthermore, according to the petrographic observation, the 1.81 Ga pegmatite dyke and the 1 800–1 750 Ma Xiong’er Group rocks were not undergone middle to high grade metamorphism, indicating 1.81 Ga as the termination of the latest regional metamorphism in the southern margin of the NCC.

Mesozoic lamprophyres are widely present in gold province in the Jiaodong Peninsula. In this study, we analyzed major and trace elements and Sr–Nd–Pb isotopic compositions of lamprophyres from the Linglong and Penglai Au-ore districts in the Jiaodong Peninsula, in an attempt to better understand Mesozoic lithospheric evolution beneath the eastern North China Craton. These lamprophyre dikes are calc-alkaline in nature, and are characterized by low concentrations of SiO2, TiO2 and total Fe2O3, high concentrations of MgO, Mg# and compatible element, enriched in LREE and LILE but variably depleted in HFSE. They display initial 87Sr/86Sr ratios of 0.709134–0.710314, eNd(t) values of − 13.2 to − 18.3, 206Pb/204Pb of 17.364–17.645, 207Pb/204Pb of 15.513–15.571 and 208Pb/204Pb of 37.995–38.374. Interpretation of elemental and isotopic data suggests that the Linglong and Penglai lamprophyres were derived from partial melting of a phlogopite- and/or amphibole-bearing lherzolite in the spinel–garnet transition zone. The parental magma might have experienced fractionation of olivine and clinopyroxene, and minor crustal materials were incorporated during ascent of these mafic magmas. Before ~ 120 Ma of emplacement of these calc-alkaline lamprophyres, the ancient lithospheric mantle was variably metasomatized by hydrous fluids rather than melts from subducted/foundered continental crust. It is proposed that continuous modification by slab-derived hydrous fluids from the Paleo-Pacific plate converted the old cratonic lithospheric mantle to Mesozoic enriched lithospheric mantle. Geodynamic force for generation of these lamprophyres may be related to large scale lithospheric thinning coupled with upwelling of the asthenosphere beneath the North China Craton. Continental arc-rifting related to the Paleo-Pacific plate subduction is favored as a geodynamic force for the cratonic lithosphere detachment.

Lithospheric thinning and destruction of the North China Craton have been topics of active discussion throughout the last two decades, but the specific processes associated with lithospheric thinning remains controversial. Here we report co-occurrence of low-Ti (TiO 2 2 > 2 wt.%, Ti/Y > 370) types of lamprophyres in the Jiaodong Peninsula, eastern North China Craton in order to address this issue. Low-Ti lamprophyres are depleted in HFSE and enriched in Pb, both typical subduction signatures. We suggest they were derived from partial melting of an ancient and enriched lithospheric mantle, which was previously modified by slab-derived hydrous fluids. In contrast, the high-Ti lamprophyre has trace element patterns similar to many oceanic basalts with depletion of Pb but little or no HFSE depletion. We infer that they originated from partial melting of a convective asthenospheric mantle. Zircon U–Pb dating shows that both types of lamprophyres intruded the eastern North China Craton about 121 Myr ago. Their indistinguishable ages thus appear to record a rapid transition from lithospheric to asthenospheric mantle source, suggesting further that the lithosphere beneath the eastern North China Craton was removed, potentially delaminated ca. 121 Myr ago beneath Jiaodong Peninsula. The detachment of cratonic lithosphere is likely related to continental arc-rifting which resulted from Palaeo-Pacific plate subduction in the Mesozoic.

The Linglong granite is one of the most important Mesozoic plutons in the Shandong Peninsula, eastern China, and its petrogenesis has long been controversial, particularly with regard to the nature of source region and geodynamic setting. Our new precise zircon U–Pb dating results reveal that the Linglong granite was emplaced in the Late Jurassic (157–160 Ma). In addition, abundant inherited zircons are identified in the granite with four groups of age peaked at ~ 208, ~ 750, ~ 1800 and ~ 2450 Ma. Geochemical studies indicate that the Linglong granite is weakly peraluminous I–type granite, and is characterized by high SiO 2 , Sr and La, but low MgO, Y and Yb contents, strongly fractionated REE pattern and high Sr/Y and La/Yb ratios. It also exhibits high initial 87 Sr/ 86 Sr ratios (0.7097 to 0.7125), low e Nd (t) (− 17.7 to − 20.3) and variable zircon e Hf (t) (− 22.2 to − 8.7) values. Calculation of the zircon saturation temperature (T Zr ) reveals that the magma temperatures are 760 ± 20 °C, and the lowest T Zr value of 740 °C may be close to initial magma temperature of this inheritance-rich rock. Interpretation of the elemental and isotopic data suggests that the Linglong granite has some affinities with the adakite, and was most likely derived from partial melting of thickened lower crust without any significant contribution of mantle components. The presence of a large number of inherited zircons and variable Sr–Nd–Hf isotopic compositions reveal that the Linglong granite probably has multiple sources consisting of the lower crust of both South China Block and North China Block, as well as the collision-related alkaline rocks and UHP metamorphic rocks. The continental arc-rifting related to the Izanagi plate subduction was the most likely geodynamic force for formation of the Jurassic Linglong adakatic granite in the Shandong Peninsula.

In the Longwangzhuang area along the southern margin of the North China Craton (NCC), a layer of Cretaceous K-feldspar granites surrounds Paleoproterozoic granites. The Paleoproterozoic granites are enriched in sodic ferrogedrite and show low Al2O3 (12.3–13.0 wt%) and aluminum saturation index (ASI) (0.93–1.09) with high Zr (609–966 ppm), Y (47.2–96.7 ppm) and Nb (58.7–97.7 ppm) concentrations, resembling A-type granites. The Cretaceous K-feldspar granites have relatively high Sr (145–419 ppm), Ba (1252–1660 ppm), Sr/Y (19–127), La/Yb (36–56) ratios, but low Y (4.01–8.88 ppm) and Yb (0.46–0.99 ppm), geochemically resembling adakite-like rocks. However, these Cretaceous adakite-like K-feldspar granites have rather low MgO (0.08–0.26 wt%), Al2O3 (13.6–14.5 wt%), Mg# (11–23), Cr (2.30–4.61 ppm) and high initial 86Sr/87Sr (0.7098–0.7118), as well as abundant K-feldspar minerals, and are different from typical adakite. Zircon LA–ICP–MS geochronology shows that the two types of granites investigated in this study formed at 1616 ± 20 Ma and 140 ± 1 Ma, respectively. However, zircons from both the Paleoproterozoic and Cretaceous granites yield similar two-stage Hf model ages at ca. 2.5–2.6 Ga, suggesting the reworking of Late Archean juvenile crust. The Paleoproterozoic A-type granites show enriched Nd–Hf isotopic features but high whole-rock oxygen isotopes. These rocks may have formed from partial melting of restitic crustal material during lithospheric thinning, along with extension and experienced crystal fractionation of plagioclase, apatite and magnetite. The Cretaceous adakite-like K-feldspar granites were formed by local anatexis of TTG rocks from the Taihua Group, with amphibole as the major residual phase. The local anatexis and accompanying migmatisation suggest crustal compression and possible transpression. Therefore, the lithospheric thinning in the NCC should have taken place after 140 Ma on the southern margin of the NCC. Copyright © 2012 John Wiley & Sons, Ltd.

The Huashan complex granitic batholith, occurred in the core of the Xiaoqinling orogen and gold mineralization belt along the south margin of the North China Craton, consists of amphibole monzogranite and biotite monzogranite in the Wengyu and Fangshanyu valleys, respectively. Zircon LA-ICP-MS U–Pb dating yields ages of 205 ± 2 Ma and 132 ± 1 Ma for the Wengyu and Fangshanyu granites, respectively, which represent the two major episodes of Mesozoic magmatism in the region. These rocks are characterized by metaluminous, high silica and total alkalinity, and have high FeO total /(FeO total + MgO) ratios, high large-ion lithophile elements (LILEs, especially Sr and Ba) and light rare earth elements (LREEs), and low heavy rare earth elements (HREEs) and Y concentrations and insignificant negative Eu anomalies. The Wengyu granites have higher Ba and Sr contents, which can be classified as high Ba–Sr granites, whereas the Fangshanyu granites show much lower Ba and Sr contents and display an adakitic affinity. Elemental and isotopic compositions suggest that the main sources of both the Wengyu and Fangshanyu granites are likely the ancient basement materials of Taihua Group. However, the high Ba and Sr contents of the Wengyu granites require addition of small amounts of enriched lithospheric mantle metasomatised by fluid/melt derived from pelagic sediments-bearing subducted slab in the sources. The Wengyu granites were most likely generated earlier by partial melting of the lowest part of the crust due to the subducted slab break-off under the post-collision extensional stage of the continental collision orogeny. The Fangshanyu granites might be mainly derived later from the partial melting of thickened lower crustal materials, representing by the Taihua Group basement rocks, corresponding to the tectono-magmatism of the post-orogeny to rift extensional environment during the tectonic transition from the PaleoTethys subduction-collision system to the Paleo-Pacific regime.

The Shi-Hang zone is an important NE trending Mesozoic magmatic belt composed of granites with relative high eNd(t) values and young TDM model ages in South China. However, the petrogenesis and the tectonic environment for the Shi-Hang zone magmatic rocks remain controversial. We report here mineral chemistry, geochemical and Sr–Nd–Hf isotopic data for the Cailing and Furong granites and mafic microgranular enclaves (MMEs) from the Qitianling granite batholith in southern Hunan province, South China. The Qitianling granite batholith is a multi-staged composite pluton with three phases (Cailing, Furong, and Huangtangling) according to their ages and petrography. The Cailing (163–160 Ma) and Furong (157–153 Ma) phases are mainly composed of porphyritic amphibole–biotite monzogranite, and they share similar geochemical and isotopic characteristics. Both of them show similar SiO2 contents from 66.50 to 70.28%, and metaluminous A/CNK values of 0.80 to 0.98. The granites are characterized by high contents of large ion lithosphile elements (LILE) such as Rb, Th, U, Pb; high field strength elements (HFSE) such as Nb, Ta, Zr, Hf; and Zr + Nb + Ce + Y contents > 350 ppm, and high 10,000 ∗ Ga/Al ratios > 2.6. Chondrite-normalized REE patterns show relative enrichment of light rare earth elements (LREEs) and significant negative Eu anomalies. Mineralogical and geochemical features suggest that the Cailing and Furong granites are A-type, which can be further classified as A2 subtype. They have relatively lower (87Sr/86Sr)i ratios (0.7091–0.7132), higher eNd(t) values (− 5.5 to − 7.6) and younger Nd isotopic model ages (1.48–1.56 Ga) than those common S-type granites in South China. Zircon eHf(t) values vary from − 8.1 to − 3.7. The MMEs in the Cailing phase show similar trace element and Sr–Nd isotopic characteristics with the host granites. But zircons from the MMEs show different eHf(t) values (− 6.4–+ 2.6) with those from the host granites (− 8.1 to − 3.7). This indicates that the MMEs and host granites were crystallized from different sources of magmas, providing direct evidence for mafic–felsic magma mixing processes. The isotope data indicate that the Cailing and Furong granites from the Qitianling batholith were derived from a hybrid magma consisting of about 80% felsic magma derived from old crust and about 20% mantle-derived mafic magma. The strong magma mixing at about 160–155 Ma caused by intra-arc rifting or back arc extension related to subduction of the Paleo-Pacific plate, is favored to explain the petrogenesis of the Cailing and Furong granites, as well as the Shi-Hang zone.

The Mesozoic granitoids at the southern margin of the North China Craton are of considerable geologic interest, because of their geodynamic context and likely relationship to Mesozoic lithospheric delamination, but also because they are associated with one of the most important gold belts in China. However, their detailed age relations and petrogeneses have not been described by systematic and comprehensive geochemical studies. Here we report a systematical zircon U–Pb dating, petrogeochemistry, and Sr–Nd–Hf isotopic data on two of these granitoids (namely the Wenyu and the Niangniangshan plutons) in the Xiaoqinling gold district, Henan Province, North China. Both plutons are metaluminous to weakly peraluminous, and can be classified as I-type granites with similar zircon U–Pb ages of 131 ± 1 Ma and 134 ± 1 Ma. They are enriched in Si, K, Ba, and Sr, while depleted in Nb, Ta, P, Ti, Mg, Ni, V and Y, and both have Archaean-type tonalite–trondhjemite–granodiorite (TTG) and adakitic affinity, e.g. enrichment in LREE with high Sr/Y and La/Yb ratios and without Eu anomalies. Both the plutons show relatively high initial 87 Sr/ 86 Sr ratios (0.7076–0.7089 for the Wenyu pluton and 0.7074–0.7086 for the Niangniangshan pluton), negative e Nd (t) values (− 15.0 to − 10.1 for the Wenyu pluton and − 18.5 to − 12.2 for the Niangniangshan pluton), and negative e Hf (t) values (− 21.9 to − 10.4 for zircons from the Wenyu pluton and − 30.8 to − 20.8 for zircons from the Niangniangshan pluton). All the isotopic data indicate old crustal sources for the magma. Furthermore, low concentrations of MgO, Ni, and V also indicate little or no mantle materials in the source. The local Neoarchaean to Palaeoproterozoic basement rocks are the most likely sources, but their isotopic compositions do not cover the total isotopic range of the plutons, hence there maybe other sources involved. The occurrence of 1.78 Ga inherited zircon grains on the depleted mantle Hf isotopic evolution line indicates 1.78 Ga underplating mafic rocks to be a possible source. Detailed petrologic and geochemical data indicate that the two plutons derived from partial melting of Neoarchaean to Palaeoproterozoic metamorphic rocks and possibly with minor amounts of 1.78 Ga mafic lower-crustal rocks at a depth of at least 50 km, with eclogite, garnet amphibolite or amphibolite residues. During the magma crystallization stage, amphibole, apatite and titanite fractionation caused the observed variations of the element compositions. Meanwhile, the existence of > 50-km-depth crust indicates that large-scale lithospheric thinning in this part of the south margin of North China Craton did not take place prior to the emplacement of these granitoids 130 Myr ago. However, a fuller understanding of the geological significance of the widespread occurrence of Mesozoic granitic magmatism in the south margin of North China Craton will require similarly detailed studies of other granitoids in the region. In this way it should be possible to constrain their source compositions and the nature of the heat source(s) that led to this lithospheric thinning event.

The Xiaoqinling district, the second largest gold producing district in China, is located on the southern margin of the North China Craton. It consists of three ore belts, namely, the northern ore belt, the middle ore belt and the southern ore belt. Pyrite from the Dahu gold deposit in the northern ore belt and Wenyu and Yinxin gold deposits in the southern ore belt were investigated using a combination of ore microscopy and in-situ laser-ablation inductively-coupled plasma-mass spectrometry (LA-ICP-MS). A range of trace elements was analyzed, including Au, Te, Ag, Pb, Bi, Cu, Co, Ni, Zn, Mo, Hg, As and Si. The results show that there are no systematic differences between the trace element compositions of pyrite in the three deposits from different ore belts. In general, Au concentrations in pyrite are low (from 2 -rich ore fluids; spatial association with large-scale compressional structures of the Qinling orogen; δ 18 O and δD data suggestive of mixing between metamorphic and meteoric waters; δ 34 S and Pb-isotopic data that point to a mixed crustal-mantle source) all point to typical orogenic-type gold deposits. High Ni concentrations (up to 8425 ppm) of pyrite possibly linked to deep-seated mafic/ultramafic metamorphic rocks provide further evidence on the orogenic gold deposit affinity, but against the model of a granitic derivation of the mineralizing fluid as previously suggested by some workers. Generally low Au concentration in pyrite is also consistent with those from worldwide orogenic gold deposits. Therefore, the gold mineralization in the Xiaoqinling district is described as orogenic type, and is probably related to Indosinian collision between the North China Craton and the Yangtze Craton.

article i nfo Article history: The behavior of boron and its isotopes in fluid-dominant processes and hydrothermal alteration of granites is examined using fresh and altered granite samples from the Qitianling granite and associated hydrothermal tin deposits in South China. Boron concentrations are highest in the fresh granite (37 ppm) and depleted as a result of two stages of fluid mobility and fluid-rock interaction within the granite. Constraints provided both by δ 11 B and δ 18 O data suggest that the first stage was related to exsolution of aqueous fluids from the granite magma at a temperature of N450 °C. This was followed by further boron depletion in the granite by hydrothermal circulation of meteoric water at lower temperatures (~350 °C) and low water/rock ratios. The sensitivity of coupled boron and oxygen isotope systematics to these processes suggests that they can provide valuable constraints on of fluid mobility in granite and associated mineralization.

Many studies have addressed the Paleozoic to Triassic collisional processes along the southern margins of the North China Craton (NCC), but little is known about the evolution of this margin during Precambrian time. This paper examines the geochronology and geochemistry of gabbros from the Luanchuan Group, which is located on the southern margin of the NCC. These gabbros are dated at ca 830 Ma by SHRIMP and LA–ICP-MS zircon U–Pb methods. They are characterized by high contents of TiO2 (2.21–4.45 wt%) and light-REEs (rare earth elements) ((La/Yb)N = 9.54–7.71). The gabbros have overall OIB (ocean island basalts)-like trace element patterns, without the positive Pb and Sr anomalies and negative Nb–Ta anomalies. In addition, they have low La/Nb (

The Xiong’er Group is an important geologic unit in the southern margin of the North China Craton. It is dominated by the volcanic rocks, dated at 1763 ± 15 Ma, that have SiO2 contents ranging from 52.10 wt% to 73.51 wt%. These volcanic rocks are sub-alkaline and can be classified into three subgroups: basaltic andesites, andesites and rhyolites. They unexceptionally show enrichment of light rare earth elements (LREE) and share similar trace element patterns. Depletions in Nb, Ta, Sr, P and Ti relative to the adjacent elements are evident for all the samples. The volcanic rocks are evolved with low MgO contents (0.29–5.88 wt%) and accordingly low Mg# values of 11–53. The Nd isotopes are enriched and show a weak variation with ɛNd(t) = −7.12 to −9.63. Zircon Hf isotopes are also enriched with ɛHf(t) = −12.02 ± 0.45. The volcanic rocks of the Xiong’er Group are interpreted to represent fractional crystallization of a common mantle source. The volcanic rocks might have been generated by high-degree partial melting of a lithospheric mantle that was originally modified by the oceanic subduction in the Late Archean. This brings a correlation with the subduction-modified lithospheric mantle in an extensional setting during breakup of the Columbia supercontinent in the late Paleoproterozoic, rather than in an arc setting. The elevated SiO2 contents and evolved radiogenic isotope features indicate the possible incorporation into their source of lower crustal materials that have similar Nd isotopic characteristics to the subcontinental lithospheric mantle. The existence of extensive Xiong’er volcanic rocks (60,000 km2) indicates an early large-scale subduction-related metasomatism in the area and probably suggest a flat subduction model for the plate-margin magmatism in the Late Archean.

High precision zircon U-Pb dating indicates that main intrusive bodies (Tong’an, Niumiao, Huashan, Lisong), and a mafic microgranular enclave in the Huashan-Guposhan complex were formed at 160–163 Ma. The ɛHf(t) values of zircons from the Huashan granite vary from −2.8 to +0.3 and those from the Lisong granite vary from −2.3 to +0.3, which are obviously different with those values (+2.6 to +7.4) of the mafic enclaves from the Lisong granite. These Hf isotopic data indicate that the mafic enclaves and host granites were crystallized from different sources of magmas, providing evidence for mafic-felsic magma mixing processes. The highest ɛHf(t) value of zircons from the mafic enclaves is up to +7.4, indicating that the mafic magma was originated from a relatively depleted mantle source. Studies on regional geology and the contemporaneous mafic and alkaline rocks in this area indicate that the mafic magma was not originated from reworking of basaltic juvenile crust, but from partial melting of the mantle. However, it remains to be resolved whether the mafic magma was derived from partial melting of the asthenosphere or the lithospheric mantle. The Huashan granite and the Lisong granite were formed from hybrid magma of mantle-derived and crust-derived magmas, and the mafic enclaves are considered as remains of mantle-derived magma during mixing processes. The ɛHf(t) values of zircons from the Niumiao diorite vary from −1.1 to +2.1, and those from the Tong’an quartz monzonite vary from −1.7 to +1.7. These values are lower than those from the mafic enclaves, suggesting that the diorite and monzonite were formed from different source-derived magma with the mafic enclaves. The ɛHf(t) values for the Niumiao diorite and the Tong’an monzonite are only slightly higher than those for the Hushan granite and the Lisong granite. Abundant mafic enclaves also occur in the Niumiao diorite and in the Tong’an monzonite. Thus, we suggest that the Niumiao diorite and the Tong’an monzonite were probably also formed from the same hybrid magma as the granites but come through less degree of fractional crystallization and crustal contamination. The strong mantle-derived and crust-derived magma mixing caused by an intense crustal extension and thinning in the Mid-Late Jurassic may be the major mechanism for generating the diorites and granites in southeastern Hunan and northeastern Guangxi belt in South China.

Extensive middle to late Jurassic felsic and mafic magmatism occurred in the southern Hunan province, southeast China. SHRIMP zircon U–Pb dating, mineral chemical, element geochemical and Sr–Nd–Hf isotopic data have been determined for these rocks. The results indicate that the middle Jurassic (178–170 Ma) Changchengling and Ningyuan basaltic rocks belong to tholeiitic series and alkaline series, respectively, and were formed by fractional crystallization of the parent magmas that were derived from partial melting of asthenospheric mantle triggered by the slab-released fluids of the subducted Paleo-Pacific plate. The late Jurassic (152–146 Ma) Daoxian basalts and Guiyang lamprophyre dikes are low-Ti, high-Mg potassic rocks. They were derived directly by partial melting of shallower (60–100 km) lithospheric mantle composed of amphibole- and phlogopite-bearing lherzolite in response to thermal perturbations associated with the rifting of continental arc. The middle Jurassic (164 Ma) Tongshanling granitic rocks belong to calc-alkaline series and are strongly peraluminous. They were formed by partial melting of Palaeoproterozoic metasedimentary basement in the lower-crust plus additional input from coeval basaltic magma. The late Jurassic (156 Ma) Jinjiling and Xishan granitic rocks show A2 subtype affinity. They were generated by partial melting of granulitized Palaeoproterozoic metamorphic basement in the lower crust in response to injection of coeval low-Ti, high-Mg potassic magmas. A moderate degree (56–58%) of fractionation of these pure crustal melts could account for more felsic end-member of granitic rocks. Detailed petrologic and geochemical data for the middle to late Jurassic felsic and mafic rocks from the southern Hunan imply that during the middle Jurassic time SE China on the southeast of the Shi-Hang zone was a continental arc coupled with the subduction of the Palaeo-Pacific plate and since the beginning of late Jurassic time an intra-arc rift has been formed along the Shi-Hang zone as a consequence of slab roll-back.

The Yulong porphyry copper ore belt is the largest belt of porphyry copper deposits in China. Detailed geological and geochemical comparison indicates that ore-bearing and barren porphyries in this belt were derived by progressive partial melting of veins of phlogopite-garnet clinopyroxenite in lherzolitic lithosphere. Ore-bearing porphyry represents the earliest melt derived by partial melting of accessory phases such as apatite, carbonate, and phlogopite, and thus contains high contents of volatiles F, Cl, and H2O. These volatiles promoted copper extraction and enrichment. Barren porphyry is the product of relatively high degrees of partial melting involving clinopyroxene and garnet, and thus is depleted in volatiles, hence barren of copper. This is the essential petrogenetic discrimination between ore-bearing and barren porphyries. Geochemical discrimination includes the following: Cu > 100 ppm, W > 5 ppm, F + Cl > 900 ppm, K2O/Na2O > 1.2, and Sm/Yb > 6.5 for bulk rock of the ore-bearing porphyries, an...

The Huziyan basalts, occurring in the southern Hunan province, contain abundant mafic xenoliths. These xenolith and the basalt samples offer a unique opportunity to investigate the origin and nature of the lower crust beneath the inland area of the South China Block and to shed new light on the study of the early crustal evolution in the region. We carried out combined SHRIMP U–Pb geochronology and Hf isotope analyses on zircons from both the Huziyan mafic xenoliths and the host basalts. We have also carried out mineral chemistry, whole-rock geochemical, and Sr–Nd isotopic analyses on these mafic xenoliths. Our data show that these xenoliths were once seated in the lower crust according to petrographic examination and P–T estimation. We discovered one of the oldest zircon (207Pb/206Pb age = 3.73 Ga, and TDM = 4.08 Ga) in the Cathaysia Block in the Huziyan basalts, which implies the existence of a crustal remnant as old as 3.7 Ga. Three representative xenoliths yield consistent U–Pb ages of about 220 Ma (220 ± 9 Ma for H4-2 determined through two baddeleyites, 230 ± 8 Ma for H4-3 and 233 ± 5 Ma for H4-5-2). Some of the zircons with ages of about 220 Ma display depleted mantle-like Hf isotopic compositions. It is thus deduced that some juvenile crust formed at 220 Ma when the mafic melt, derived from depleted mantle, underplated the lower crust. Such a thermal event in the deep crust might have induced intensive crust–mantle interaction and contributed to the formation of contemporaneous Indosinian granitoids in peripheral areas. Another thermal event leading to crustal growth at about 800 Ma can also be identified both from U–Pb ages (770–850 Ma) of xenocrystic zircons in the basalts and xenoliths, and from upper intercept ages of discordia in two xenoliths (933 ± 65 Ma and 828 ± 80 Ma). Episodic crustal growths might also have taken place at 2.7 Ga and 1.9 Ga. This is implied by Hf isotope model ages of some of the zircons. Large variation in Hf isotopic compositions among zircons of the same age (ɛHf(t) = − 5.4 to 20.8 for 220 Ma zircons, and − 8.3 to 10.9 for 800 Ma zircons) suggests mixing and interaction between DM-derived melt and old crustal components at both of these times. Furthermore, petrographic and geochemical characteristics suggest that these xenoliths were formed through accumulation of pyroxene and plagioclase, and were then metamorphosed in the lower crust. Multiple episodes of juvenile growth, crustal reworking, and mafic underplating resulted in complexity and heterogeneity in the lower crust, as demonstrated by diversities in bulk geochemistry, Sr–Nd isotopic compositions and zircon Hf isotopic composition of these xenoliths.

Four types of tourmaline in the Qitianling granitic batholith, South China, were identified in this study: euhedral disseminated tourmaline (DT type) in the early stage of granite consolidation; typical interstitial nodular tourmaline (NT type) formed late in the crystallization history; radial tourmaline veinlet (RT type) and vein tourmaline (VT type) of hydrothermal origin. We performed major and trace element analysis by in situ electron microprobe and laser ablation inductively coupled plasma mass spectrometry on these four tourmaline types. Compositionally, these tourmalines fall into the alkali group and schorl–dravite solid solution series. There is clear correlation between trace and major elements in VT-type tourmalines, likely related to co-variations of these elements in the hydrothermal fluid from which the tourmaline precipitated. Tourmaline from granites displays low REE abundances and negative LREE trends, positive Eu anomalies, and HREE below or close to their detection limits. The DT-type tourmalines show a positive Eu anomaly, which is probably due to a preferential incorporation of Eu2+ over Eu3+. REE depletion in NT-type tourmalines may reflect co-crystallization of REE-rich minerals. The positive Eu anomaly in NT-type tourmalines is due to late-stage release of Eu2+ caused by tourmaline replacement of early feldspar. Vein tourmalines (RT and VT type) display similar slopes from La to Nd, without an Eu anomaly. The chondrite-normalized REE patterns in tourmalines from veins display a concave upward-shaped, MREE-depleted pattern, with minimum values at Ho increasing steadily to Lu, and may reflect the REE characteristics of the precipitated medium. HREE enrichment in hydrothermal fluid can be attributed to the formation of REE-fluoride complexes during the internal fluid evolution.

SHRIMP zircon U–Pb dating, mineral chemical, element geochemical and Sr–Nd–Pb–Hf isotopic data have been determined for the Yulong monzogranite-porphyry in the eastern Tibet, China. The Yulong porphyry was emplaced into Triassic strata at about 39 Ma. The rocks are weakly peraluminous and show shoshonitic affinity, i.e., alkalis-rich, high K 2 O contents with high K 2 O / Na 2 O ratios, enrichment in LREE and LILE. They also show some affinities with the adakite, e.g., high SiO 2 and Al 2 O 3 , and low MgO contents, depleted in Y and Yb, and enrichment in Sr with high Sr / Y and La / Yb ratios, and no Eu anomalies. The Yulong porphyry has radiogenic 87 Sr / 86 Sr (0.7063–0.7070) and unradiogenic 143 Nd / 144 Nd ( e Nd = − 2.0 to − 3.0) ratios. The Pb isotopic compositions of feldspar phenocrysts separated from the Yulong porphyry show a narrow range of 206 Pb / 204 Pb ratios (18.71–18.82) and unusually radiogenic 207 Pb / 204 Pb (15.65–15.67) and 208 Pb / 204 Pb (38.87–39.00) ratios. In situ Hf isotopic composition of zircons that have been SHRIMP U–Pb dated is characterized by clearly positive initial e Hf values, ranging from + 3.1 to + 5.9, most between + 4 and + 5. Phenocryst clinopyroxene geothermometry of the Yulong porphyry indicates that the primary magmas had anomalously high temperature (> 1200 °C). The source depth for the Yulong porphyry is at least 100 km inferred by the metasomatic volatile phase (phlogopite–carbonate) relations. Detailed geochemical and Sr–Nd–Pb–Hf isotopic compositions not only rule out fractional crystallization or assimilation-fractional crystallization processes, but also deny the possibility of partial melting of subducted oceanic crust or basaltic lower crust. Instead, low degree (1–5%) partial melting of a metasomatized lithosphere (phlogopite–garnet clinopyroxenite) is compatible with the data. This example gives a case study that granite can be derived directly by partial melting of an enriched lithospheric mantle, which is important to understand the source and origin of diverse granites.