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The research on the source of marine sediments has a vital impact on identifying material sources, transport mechanism, and the evolution of sedimentary environments. Previous studies have shown many outstanding achievements on the source analysis of the South China Sea, but there are still some controversies over the complex source and transport mechanisms of the Zhongjiannan Basin. In this study, we took a gravity core (583cm) from the Zhongjiannan Basin and analyzed the particle size, rare earth elements, and Sr-Nd isotopes of the core sediments to further reveal the source and transport mechanism. The surface sediments in the Zhongjiannan Basinwere relatively stable, with an average particle size ranging from 5.66 to 17.74 mm. The normalized standard curve of chondrite exhibited the depletion of Eu, with LREE dominated in REE. As the depth increased, 87Sr/86Sr ratios showed a gradually increasing trend, while dNd change was relatively complex. On the whole, 87Sr/86Sr ratios (from 0.721537 to 0.725322) and dNd (from -11.561617 to -12.289374) were in a relatively narrow range. Based on the particle size characteristics, we found the geochemical characteristics of sediment largely resulted fromdifferent sediment sources. By comparing rare earth elements and Sr-Nd isotopes, we concluded the sediment of the Zhongjiannan Basin was from mainly terrigenous contribution. In addition, taking into account factors such as terrain, migration distance, and river drainage system, we conclude the sediment were mainly from the Mekong River, the Red River, Taiwan Island, and Hainan Island. The surface current along the northeast direction was the main transportation route for the sediments of the Mekong River. The Guangdong coastal current and the southwest surface current transported sediment from the Red River and Hainan Island to the Zhongjiannan Basin. The surface current and deep-water current in the southwest direction carried sediment from Taiwan Island to the study area, while the Kuroshio also had some impacts on the sediment transportation of Taiwan Island. This study has reinforced the research on provenance in the South China Sea Basin and has an important significance on evolution of sedimentary environments, evolution of ancient oceans. [ABSTRACT FROM AUTHOR]

The Baoshan Cu-Pb-Zn deposit is situated at the intersection of the Qin-Hang Cu polymetallic and Nanling W-Sn polymetallic metallogenic belts. The age, lithology, petrogenesis, and tectonic setting of granodiorite porphyry within the deposit remain subjects of debate. Additionally, there is a lack of comparative studies with the W-Sn-related granites in the region. This study conducted whole-rock major and trace element analysis, Sr-Nd isotope analysis, and zircon U-Pb dating on the Baoshan granodiorite porphyry. The zircon U-Pb age of the granodiorite porphyry is 162 ± 1 Ma. The whole-rock SiO2 and K2O contents range from 65.87 to 68.21 wt.% and 3.42 to 5.62 wt.%, respectively, indicating that the granodiorite porphyry belongs to high-potassium calc-alkaline I-type granite. The granodiorite porphyry is characterized by enrichment in LREE and depletion in HREE (LREE/HREE ratio = 6.2–21.2). The samples of granodiorite porphyry generally exhibit weak negative Eu anomalies or no Eu anomalies (δEu = 0.62–1.04, mean = 0.82). The (87Sr/86Sr)i and εNd(t) values are 0.707717–0.709506 and −7.54 to −4.87, respectively. The whole-rock geochemical composition and Sr-Nd isotopic values indicate that the magma originated from the partial melting of the Mesoproterozoic ancient crust and Neoproterozoic mafic juvenile lower crust, with the addition of high oxygen fugacity and water-rich lithospheric mantle melts. The source of the granodiorite porphyry in the Baoshan deposit is significantly different from the crust-derived metapelite source of the W-Sn-related granite in the area, indicating that different magma sources might be the main reason for the co-spatial and nearly contemporaneous development of Cu-Pb-Zn and W-Sn mineralization in the southern Hunan region. [ABSTRACT FROM AUTHOR]

The petrogenesis and geodynamic implications of the Early Paleozoic adakitic rocks in the east of Inner Mongolia remain topics of debate. This study presents new petrology data through zircon U-Pb age and Lu-Hf isotopic composition, whole-rock major-trace element geochemistry, and Sr-Nd isotopes from adakitic rocks. The zircon U-Pb dating results demonstrate that the formation age is 242.8 ± 1.0 Ma, which is the product of Early Triassic magmatism. Petrology and geochemical study have shown that the granodiorite have high SiO2 (66.93~69.40%), Al2O3 (15.37~15.43%), and MgO (1.35~1.55%), with LREE enrichment and HREE deficit, and they have high Sr, low Y, and high Sr/Y ratios, showing typical signatures of adakitic rocks. The εHf(t) values of zircon vary between +11.3 and +13.8, with low whole-rock (87Sr/86Sr)i (0.703382) and positive εNd(t) values, and the average Mg# of the rock is 56.14, suggesting that adakite derived from partial melting of MORB materials and magma interaction with the mantle. Comprehensive analysis suggests that during the Late Permian to Early Triassic, the subducted slab of the Paleo-Asian Ocean broke off, and the residual oceanic slab preserved in the mantle beneath the subduction zone underwent partial melting, generating adakitic magma. [ABSTRACT FROM AUTHOR]

The relative contributions of asthenospheric mantle, lithospheric mantle, and continental crust in the genesis of the Siberian Traps Large Igneous Province (ST-LIP) remain poorly constrained. Most models invoke partial melting of asthenospheric mantle within a mantle plume with an inventory of recycled crustal material, with or without melting of subcontinental lithospheric mantle, and crustal contamination during ascend through the continental lithosphere. A greater understanding of this topic is of fundamental importance because the ST-LIP basalts are associated with the large Permian-Triassic extinction and the world's largest magmatic Ni-Cu-platinum group element sulfide resources (Ni-Cu-PGE), the Norilsk-Talnakh mining camp. The ∼250 ± 2 Ma Siberian Traps at Norilsk contain a classic sequence of basaltic rocks that provide a spatial and stratigraphic context for changing chemistry of the eruptive products. We present a detailed geochemical and Sr-Nd-Hf-Mo isotopic investigation of ST-LIP volcanic rocks and associated sedimentary rocks, including coal and anhydrite, from the Norilsk area. The 98Mo/95Mo isotope ratios (reported as δ98Mo ratio relative to NIST SRM 3134) vary significantly from −0.62 to 0.07 ‰ for the older basalt formations and −0.41 to 0.03 ‰ for the younger basalt formations. The range of δ98Mo and its correlation with the other geochemical tracers cannot be explained by post-magmatic alteration, magmatic differentiation, or sulfide fractionation as Mo behaves as a lithophile element under these magmatic conditions. We suggest that the δ98Mo range can be explained by interaction of the plume with subcontinental lithospheric mantle modified by subduction processes. This is particularly prominent in the earlier Ivakinsky to Gudchikhinsky formations where light δ98Mo values coupled with low Mo/Ce can be explained by contributions from a dehydrated eclogitic component, whereas more rare heavy δ98Mo values and high Mo/Ce likely require contributions from a fluid metasomatized mantle source. Later magmas of the Nadezhdinsky formation show clear evidence of crustal contamination in their combined Mo-Sr-Nd-Hf isotope and trace element systematics, while the later more voluminous Morongovsky type magmas are shallower, large degree melts with limited crustal interaction. Our data shows the usefulness of Mo isotopes in deciphering magma sources of large igneous provinces eruptions. [ABSTRACT FROM AUTHOR]

High‐resolution Sr and Nd isotope compositions along with major and trace element abundances have been analyzed in silicate fraction of sediments core, SSD004‐GC03, from the Equatorial Indian Ocean (7.2°N and 77.9°E) at 1,540 m water depth with a depositional history of ∼38 ka to determine source variabilities and their controlling factors. 87Sr/86Sr (0.71978–0.72491), ƐNd (−14.8 to −21.9), and a couple of source diagnostic elements display profound variability over the depositional time scale and point toward major sediment contribution from the Peninsular Gneissic Complex (PGC) and the Deccan Basalts along with aeolian dust flux, their relative proportions being determined by climate variability. The cold/arid periods are characterized by an enhanced proportion of aeolian dust and the Deccan Basalts, whereas the sediment contribution from the PGC is augmented during the warm/humid periods. The sediment provenance variations at the Equatorial Indian Ocean coincide very well with known cold/arid (Heinrich Stadial events: HS 1–4, LGM, Younger Dryas, 8.2 ka, 5.2 ka, and 1.1 ka) and warm/humid (Early Deglacial, Holocene Intensified Monsoon) climatic events reported in the tropical region and sea‐level change which are strongly captured by the Sr‐Nd isotope and elemental composition of sediments. The present investigation underscores the significant role of climate, mainly the aridity, in modulating the dust fluxes and erosion intensity and the strong coupling between Indian monsoon and North Atlantic climatic oscillations and further demonstrates minimal time delay between the production and transport of sediment from source to sink. Key Points: High‐resolution 87Sr/86Sr, ƐNd and a few diagnostic elements track temporal variation of sediment sources in the Equatorial Indian OceanThe cold periods are characterized by enhanced proportions of aeolian dust and the Deccan Basalts, whereas the PGC dominates warm periodsNorth Atlantic climatic oscillations modulate Indian monsoon thereby controlling dust and erosional fluxes in the Equatorial Indian Ocean [ABSTRACT FROM AUTHOR]

The Baoshan Cu-Pb-Zn deposit is situated at the intersection of the Qin-Hang Cu polymetallic and Nanling W-Sn polymetallic metallogenic belts. The age, lithology, petrogenesis, and tectonic setting of granodiorite porphyry within the deposit remain subjects of debate. Additionally, there is a lack of comparative studies with the W-Sn-related granites in the region. This study conducted whole-rock major and trace element analysis, Sr-Nd isotope analysis, and zircon U-Pb dating on the Baoshan granodiorite porphyry. The zircon U-Pb age of the granodiorite porphyry is 162 ± 1 Ma. The whole-rock SiO2 and K2O contents range from 65.87 to 68.21 wt.% and 3.42 to 5.62 wt.%, respectively, indicating that the granodiorite porphyry belongs to high-potassium calc-alkaline I-type granite. The granodiorite porphyry is characterized by enrichment in LREE and depletion in HREE (LREE/HREE ratio = 6.2–21.2). The samples of granodiorite porphyry generally exhibit weak negative Eu anomalies or no Eu anomalies (δEu = 0.62–1.04, mean = 0.82). The (87Sr/86Sr)i and εNd(t) values are 0.707717–0.709506 and −7.54 to −4.87, respectively. The whole-rock geochemical composition and Sr-Nd isotopic values indicate that the magma originated from the partial melting of the Mesoproterozoic ancient crust and Neoproterozoic mafic juvenile lower crust, with the addition of high oxygen fugacity and water-rich lithospheric mantle melts. The source of the granodiorite porphyry in the Baoshan deposit is significantly different from the crust-derived metapelite source of the W-Sn-related granite in the area, indicating that different magma sources might be the main reason for the co-spatial and nearly contemporaneous development of Cu-Pb-Zn and W-Sn mineralization in the southern Hunan region.

The petrogenesis and geodynamic implications of the Early Paleozoic adakitic rocks in the east of Inner Mongolia remain topics of debate. This study presents new petrology data through zircon U-Pb age and Lu-Hf isotopic composition, whole-rock major-trace element geochemistry, and Sr-Nd isotopes from adakitic rocks. The zircon U-Pb dating results demonstrate that the formation age is 242.8 ± 1.0 Ma, which is the product of Early Triassic magmatism. Petrology and geochemical study have shown that the granodiorite have high SiO2 (66.93~69.40%), Al2O3 (15.37~15.43%), and MgO (1.35~1.55%), with LREE enrichment and HREE deficit, and they have high Sr, low Y, and high Sr/Y ratios, showing typical signatures of adakitic rocks. The εHf(t) values of zircon vary between +11.3 and +13.8, with low whole-rock (87Sr/86Sr)i (0.703382) and positive εNd(t) values, and the average Mg# of the rock is 56.14, suggesting that adakite derived from partial melting of MORB materials and magma interaction with the mantle. Comprehensive analysis suggests that during the Late Permian to Early Triassic, the subducted slab of the Paleo-Asian Ocean broke off, and the residual oceanic slab preserved in the mantle beneath the subduction zone underwent partial melting, generating adakitic magma.

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The Gacun deposit is a typical Volcanic Hosted Massive Sulfide (VHMS) associated with Late Triassic seafloor calc-alkaline felsic volcanics. Studies of zircon ages, petrology, major and trace element geochemistry, and Sr-Nd-Hf isotope geochemistry of volcanic rocks from the Northern Yidun arc were undertaken in this paper. We reshaped the Gacun magmatic system activity time, defined the origin of magma evolution, and proposed a metallogenic model of the deposit. Whole-rock major element compositions of the magmatic rocks in the Northern Yidun island arc indicate that they are a complete basalt–andesite–dacite–rhyolite assemblage, showing three obvious stages of composition evolution. They are enriched in large-ion lithophile and light rare earth elements, but depleted in high field-strength and heavy rare earth elements, with weak-to-negligible Eu anomalies (obvious in rhyolite). These geochemical features indicate that the Northern Yidun island arc is a magmatic arc based on ancient continental crust. The Ganzi–Litang oceanic subduction induced mantle melting and produced calc-alkaline basaltic magma, while the MASH processes at the bottom of the crust produced andesitic magma. Part of the andesite magma erupted to form andesite lava. The remaining part was mixed with magma produced via anatexis of ancient crust (approximately 20%–40% of the ancient crustal component), forming the ore-bearing rhyolite. Zircon U-Pb age data defines Gacun magmatic–hydrothermal mineralization sequence of events: At 238 Ma, arc magmatism led to the formation of andesite in the eastern part of the deposit. At 233 Ma, in the arc zone (the western part of Gacun deposit), a large-scale bimodal magmatism formed the main ore-bearing rock series of Gacun deposit, rhyolitic volcanic rocks. At 221 Ma, volcanic eruptions tended to end and sub-volcanic intrusion occurred, forming a lava dome, which was located under the ore-bearing rhyolitic volcanic rocks. The lava dome acted as a thermal engine and promoted hydrothermal circulation. The hydrothermal activity reached a peak at 217 ± 1 Ma, and the Gacun VHMS deposit was formed. [ABSTRACT FROM AUTHOR]

Cretaceous‐Miocene sedimentary rocks in the Nepalese Lesser Himalaya provide an opportunity to decipher the timing of India‐Asia collision and unroofing history of the Himalayan orogen, which are significant for understanding the growth processes of the Himalayan‐Tibetan orogen. Our new data indicate that detrital zircon ages and whole‐rock Sr‐Nd isotopes in Cretaceous‐Miocene Lesser Himalayan sedimentary rocks underwent two significant changes. First, from the Upper Cretaceous‐Palaeocene Amile Formation to the Eocene Bhainskati Formation, the proportion of late Proterozoic‐early Palaeozoic zircons (quantified by an index of 500–1200 Ma/1600–2800 Ma) increased from nearly 0 to 0.7–1.4, and the percentage of Mesozoic zircons decreased from ca. 14% to 5–12%. The whole‐rock 87Sr/86Sr and εNd(t = 0) values changed markedly from 0.732139 and −17.2 for the Amile Formation to 0.718106 and −11.4 for the Bhainskati Formation. Second, from the Bhainskati Formation to the lower‐middle Miocene Dumri Formation, the index of 500–1200 Ma/1600–2800 Ma increased to 2.2–3.7 and the percentage of Mesozoic zircons abruptly decreased to nearly 0. The whole‐rock 87Sr/86Sr and εNd(t = 0) values changed significantly to 0.750124 and −15.8 for the Dumri Formation. The εHf(t) values of Early Cretaceous zircons in the Taltung Formation and Amile Formation plot in the U‐Pb‐εHf(t) field of Indian derivation, whereas εHf(t) values of Triassic‐Palaeocene zircons in the Bhainskati Formation demonstrate the arrival of Asian‐derived detritus in the Himalayan foreland basin in the Eocene based on available datasets. Our data indicate that (1) the timing of terminal India‐Asia collision was no later than the early‐middle Eocene in the central Himalaya, and (2) the Greater Himalaya served as a source for the Himalayan foreland basin by the early Miocene. When coupled with previous Palaeocene‐early Eocene provenance records of the Tethyan Himalaya, our new data challenge dual‐stage India‐Asia collision models, such as the Greater India Basin hypothesis and its variants and the arc–continent collision model. [ABSTRACT FROM AUTHOR]

The Yamaat Uul mafic complex with Cu-Ni mineralization is located in the Khangai Mountains of Western Mongolia. We have received new unique data for mafic rocks of the complex: U-Pb dating (SHRIMP II), mineralogy (WDS) and geochemistry (XRF, ICP-MS), Sm-Nd and Rb-Sr isotope data and sulphur isotopes. The Yamaat Uul mafic complex consists of two intrusions: Intrusion 1 is represented by rocks of plagioclase cumulates and olivine–pyroxene cumulates; Intrusion 2 consists of monzogabbro. Intrusions 1 and 2 are different in composition of minerals such as olivine, plagioclase and biotite. The monzogabbro has higher contents of incompatible elements (REE, K, Ti, P) than rocks of Intrusion 1. Zircon U-Pb dating of the anorthosite and Bt-Am-Ol gabbronorite shows a Late Permian age (255.8 ± 2.9 Ma and 262.6 ± 3.1 Ma, respectively) for the Yamaat Uul mafic complex. All of the rocks of the complex are derived from a unified parental melt due to different amounts of trapped melts in plagioclase and olivine–pyroxene cumulates and without crustal contamination. The Cu-Ni mineralization of the complex has a low degree of evolution of the sulphide melt, similar to PGE-Cu-Ni mafic–ultramafic intrusions of the Khangai Mountains (Nomgon and Oortsog Uul). The Yamaat Uul mafic complex together with other mafic–ultramafic intrusions of the Khangai Mountains is related to the Khangai LIP and can be considered as potential for the PGE-Cu-Ni. The new geological, petrological, geochemical and isotope–geochronological data can later be used to reconstruct the geotectonics of the Khangai Mountains and the Central Asian orogenic belt as a whole. [ABSTRACT FROM AUTHOR]

The Eastern Pontides orogenic belt (EPOB) represents a significant segment of the Alpine-Himalayan orogenic belt that evolved from the Paleozoic to Cenozoic periods. Here we report new zircon U-Pb ages, together with Lu-Hf isotopes, and whole-rock geochemical and Sr-Nd isotopic analyses of plutonic rocks from EPOB, northeastern Turkey. Our aim is to interpret magmatic evolution in which the granitoids formed. Zircon U-Pb dating of six samples yielded crystallization ages of ∼134, ∼82, ∼39 Ma, respectively. They show a wide range of 87Sr/86Sr(i) (0.703 9–0.710 9), and εNd(t) values varying from −9 to +4.6, yielding model ages (TDM) from 520 to 1 623 Ma, suggesting a heterogeneous magma source. Dated zircons show exlusively positive εHf(t) values (+12.4 to +1.4), yielding model ages (TDM) from 352 to 1 059 Ma, implying that they are most likely derived from a juvenile lower crust rather than the mature continental crust. In this study, we suggested that the northward subduction of the Neo-Tethyan oceanic slab began from the Early Cretaceous and resulted in the Late Cretaceous magmatism. Moreover, the Middle Eocene magmatism in the EPOB was related to the collision of the Anatolide Taurid Platform (ATP) with the Pontides. [ABSTRACT FROM AUTHOR]

The Ninety-east Ridge (NER) is located in the southern Bay of Bengal in the northeast Indian Ocean and is composed of pelagic and hemipelagic sediments. In addition to contributions from marine biomass, the ridge also contains terrestrially sourced sedimentary material. However, considerable disagreement remains regarding the origin of these terrestrial materials and transport pathways. This paper discusses the collection of seafloor surface sediments and three sediment cores recovered from the northern region of the NER, as well as the analysis of clay minerals, Sr-Nd isotopes, and sediment grain size. The ages of the three core sediments are constrained by AMS 14C dating to better establish the source and transport pathways of the terrestrial materials within NER sediments over the past 35000 years. The research results show that the Qinghai-Tibet Plateau is the predominate source of terrigenous sedimentary material in the NER. In the plateau, the crustal materials were weathered and stripped and then transported to the Andaman Sea via the Irrawaddy River. From there, the material was transported westward by monsoon-driven circulation to the northernmost part of the NER before being transported to the south for final deposition. This transport mode has changed little over the past 35000 years. However, during the rapidly changing climate of the Younger Dryas (12.9~11.5 ka BP), there were some variations in the input amount, grain size, and Sr-Nd isotope value of the source material. The above conclusions are significant for re-evaluating the source of terrigenous sediments, the temporal and spatial changes in transport modes, and the sensitivity of the NER to climatic shifts.

The paper presents data on the U–Pb chronology of detrital zircon grains and radiogenic isotopic composition (87Sr/86Sr, ɛNd) from the Proterozoic clastic successions of the Garhwal‐Kumaon Lesser Himalaya representing the extended northern Indian cratonic margin, NW India. The Proterozoic Lesser Himalayan Basin in Garhwal‐Kumaon Himalaya is divided into two sectors, namely, Inner Lesser Himalaya (ILH) and Outer Lesser Himalaya (OLH) by a tectonic boundary, namely the Tons Thrust (TT). Age distribution from inner and outer sectors of the Lesser Himalaya shows that the U–Pb chronology of most of these zircons provides Palaeoproterozoic (between 1.6 and 1.8 Ga) to Neoproterozoic (800 Ma) ages. The age data suggest sedimentation of the Rautgara Formation (Damtha Group) of ILH continued till the Neoproterozoic (~850 Ma), which was earlier regarded as ≤1.6 Ga. Tracking the detrital U–Pb zircon ages in the near adjacent cratonic parts point towards Aravalli Orogen as the major source region. Whole‐rock ƐNd(0) values for ILH rocks range from −37.6 to −14.6 and for OLH it ranges from −19.6 to −6.7. More negative ƐNd values along with dominance of Neoarchean‐Palaeoproterozoic ages in ILH indicates supply from more evolved protolith or recycled sources and less negative ƐNd values with major Neoproterozic zircon ages from OLH supports for less evolved source rock. The change from more negative ƐNd to less negative ƐNd values progressively upward the stratigraphy can be due to a shift in source with time. Both U–Pb zircon and ƐNd supports for a continuous sedimentation model, rule out the presence of ~500 Ma unconformity within the LH and argues for separate evolution of the Lesser Himalayan Basin on the trailing edge of the extended north Indian craton in "Columbia" configuration. [ABSTRACT FROM AUTHOR]

The tectonic setting of Jiangda-Weixi magmatic belt is still controversy. Two different interpretations include the eastward subduction of Longmucuo-Shuanghu-Changning-Menglian Paleo-Tethys main ocean basin, and the westward subduction and subsequent collision of Jinshajiang Paleo-Tethys main ocean basin. These controversies concern different models for tectonic evolution of Paleo-Tethys. A new set of intrusive complex has been discovered in Pantiange area, the southern part of Jiangda-Weixi magmatic belt. The main components include dioritic, granodioritic and granitic rocks, which have been mylonitized. The zircons from granitic rocks have U-Pb mean age of (243.0±4.8) Ma. The age is considered as crystallization age of granitic rocks. Dioritic rocks have high contents of Na2O and Al2O3, and moderate content of K2O, suggesting they belong to metaluminous and calc-alkaline series. Granodioritic rocks has high contents of K2O and Al2O3, but low content of Na2O, suggesting they belong to peraluminous and shoshonite, high potassium calc-alkaline series. Granitic rocks have moderate content of Na2O and low content of K2O, and belong to metaluminous-peraluminous and low-potassium series. All three types of rocks are enriched in LILEs (such as Rb, Th, U), depleted in HFSEs (such as Nb, Ta, P, Ti) and LILEs (such as Ba, Sr), with high values of LREE/HREE ratio. The dioritic rocks have no obvious Eu anomaly, whereas granodioritic and granitic rocks show weak negative Eu anomaly. The granitic rocks have zircon εHf(t) values of-11.92--8.54, whole rocks initial 87Sr/86Sr ratio of 0.717 229-0.725 994, and εNd(t) values of-14.2--7.8. These characteristics show that dioritic magmatism is formed by partial melting of Paleoproterozoic basaltic lower crust; granodioritic magmatism is formed by partial melting of metamorphic mudstones of Paleoproterozoic upper crust with the addition of mantle material; granitic magmatism originates from partial melting of metamorphic graywacke in Paleoproterozoic upper crust, and then underground crystallization fractionation with the addition of mantle material. Combined with regional tectonic setting and petrogeochemical characteristics, it is proposed that Jiangda-Weixi magmatic belt is formed by the eastwards subduction of Paleo-Tethys. [ABSTRACT FROM AUTHOR]

Fluorite is a widespread mineral in porphyry and hydrothermal vein Mo-polymetallic deposits. Here, fluorite is utilised as a probe to trace the fluid source and reveal the fluid evolution process in the Chalukou giant Mo (Pb–Zn) deposit, Northeast China, which is characterised as early porphyry Mo and later vein-style Zn–Pb mineralisation. A detailed rare earth element (REE) and Sr–Nd isotope study of fluorite combined with Sr isotopes of sphalerite is conducted for the Chalukou deposit. The chondrite-normalised REE patterns of fluorites from molybdenite veins show light REE (LREE)-enriched patterns, with negative Eu anomalies (δEu = 0.60) and weakly negative Y anomalies (Y/Y* = 0.72). The fluorites associated with sphalerite veins exhibit rare earth element (REE)-flat patterns with negative Eu anomalies (δEu = 0.65 to 0.99) and positive Y anomalies (Y/Y* = 1.37 to 3.08). In addition, during the progression from Mo to Zn–Pb mineralisation, the total concentration of REEs decreases from 839 ppm to 53.7 ppm, and Y/Ho ratios increase from 22.1 to 92.5. These features may be explained by the different mobilities of REE complexes during fluid migration. The Eu anomalies are considered to be inherited from source fluids. All the initial 87Sr/86Sr ratios of fluorite and sphalerite are between those of ore-forming porphyries and wall rocks (rhyolite), with fluorite ratios ranging from 0.706942 to 0.707386 and sphalerite ratios varying from 0.705221 to 0.710417. The majority of εNd(t) values of fluorite varying from −6.4 to −3.6 are also located between the ratios exhibited by ore-forming porphyries and rhyolite, whereas three εNd(t) values of fluorites ranging from −0.26 to 0.36 are close to those of ore-forming porphyries. All the isotopic features indicate that the Sr-Nd isotope ratios of hydrothermal fluid are derived from porphyries and disturbed by fluid–rock reactions. Together with a two-stage Sr–Nd isotope mixing model, we suggest that different sources and fluid–rock interactions (syn-ore intrusions and strata) finally influence the Sr–Nd isotopes of the ore-forming fluids, which are recorded by the majority of fluorite and sphalerite. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Kunshan complex pluton can be divided into three stage granitoids. • The three stage melts were derived from same crust-mantle mixed source gradually strengthen FC degrees. • The latest granodiorite is the ore-forming granitoid. The Xuancheng mineralization district (XMD) is an important part of the Middle-Lower Yangtze River Metallogenic Belt, and hosts a number of porphyry-skarn Cu poly-metal discoveries in recent years. The Kunshan pluton is located in the northeastern sector of the Xuancheng district, and is composed of fine-grained pyroxene diorite, coarse-grained pyroxene diorite and granodiorite. This study reports zircon LA-ICP-MS U-Pb chronology, whole-rock geochemistry and Sr-Nd isotope analysis of the Kunshan Complex pluton. The intrusions young from the fine-grained pyroxene diorite (137.2 ± 2.0 Ma), through the coarse-grained pyroxene diorite (136.1 ± 2.1 Ma) to the granodiorite (134.8 ± 2.2 Ma). All three stages of magmatic samples are high-potassium calc-alkaline to potassium dolerite series, they are enriched in light rare earth elements (LREE) and large ion lithophile elements such as Rb, Sr, and (Ba), but depleted in heavy rare earths elements (HREE), and high field strength elements such as Nb, Ta, Ti, and P. Their (87Sr/86Sr) i and (143Nd/144Nd) i values range from 0.706703 to 0.707618 and 0.512023 to 0.512064 respectively. The samples from the Kunshan complex pluton are consistently plotted the zone between the mantle evolution trending line and MLYB crust, which indicating the three-stage melt are derived from the crust-mantle mixed source, with closer to lithosphere mantle. All phases of the pluton were derived from the same magmatic source, likely the crust-mantle mixed zone between the lower Yangtze crust and enriched lithospheric mantle. The 3 stage melts formed Kunshan complex pluton gradually strengthen fractional crystallization (FC) during their emplacement process, while the late granodiorite melt with highest FC degree was the ore-forming intrusion, which is characterized with oxidized melt with low temperature, and high H 2 O content. After Compared with the mineralized granitoid intrusive rocks in the Middle-Lower Yangtze River Metallogenic Belt, it suggests that the late highly differentiated granitoids, like Kunshan granodiorite, are probably favorable metallogenic indications. [ABSTRACT FROM AUTHOR]

The Gacun deposit is a typical Volcanic Hosted Massive Sulfide (VHMS) associated with Late Triassic seafloor calc-alkaline felsic volcanics. Studies of zircon ages, petrology, major and trace element geochemistry, and Sr-Nd-Hf isotope geochemistry of volcanic rocks from the Northern Yidun arc were undertaken in this paper. We reshaped the Gacun magmatic system activity time, defined the origin of magma evolution, and proposed a metallogenic model of the deposit. Whole-rock major element compositions of the magmatic rocks in the Northern Yidun island arc indicate that they are a complete basalt–andesite–dacite–rhyolite assemblage, showing three obvious stages of composition evolution. They are enriched in large-ion lithophile and light rare earth elements, but depleted in high field-strength and heavy rare earth elements, with weak-to-negligible Eu anomalies (obvious in rhyolite). These geochemical features indicate that the Northern Yidun island arc is a magmatic arc based on ancient continental crust. The Ganzi–Litang oceanic subduction induced mantle melting and produced calc-alkaline basaltic magma, while the MASH processes at the bottom of the crust produced andesitic magma. Part of the andesite magma erupted to form andesite lava. The remaining part was mixed with magma produced via anatexis of ancient crust (approximately 20%–40% of the ancient crustal component), forming the ore-bearing rhyolite. Zircon U-Pb age data defines Gacun magmatic–hydrothermal mineralization sequence of events: At 238 Ma, arc magmatism led to the formation of andesite in the eastern part of the deposit. At 233 Ma, in the arc zone (the western part of Gacun deposit), a large-scale bimodal magmatism formed the main ore-bearing rock series of Gacun deposit, rhyolitic volcanic rocks. At 221 Ma, volcanic eruptions tended to end and sub-volcanic intrusion occurred, forming a lava dome, which was located under the ore-bearing rhyolitic volcanic rocks. The lava dome acted as a thermal engine and promoted hydrothermal circulation. The hydrothermal activity reached a peak at 217 ± 1 Ma, and the Gacun VHMS deposit was formed.

The Yamaat Uul mafic complex with Cu-Ni mineralization is located in the Khangai Mountains of Western Mongolia. We have received new unique data for mafic rocks of the complex: U-Pb dating (SHRIMP II), mineralogy (WDS) and geochemistry (XRF, ICP-MS), Sm-Nd and Rb-Sr isotope data and sulphur isotopes. The Yamaat Uul mafic complex consists of two intrusions: Intrusion 1 is represented by rocks of plagioclase cumulates and olivine–pyroxene cumulates; Intrusion 2 consists of monzogabbro. Intrusions 1 and 2 are different in composition of minerals such as olivine, plagioclase and biotite. The monzogabbro has higher contents of incompatible elements (REE, K, Ti, P) than rocks of Intrusion 1. Zircon U-Pb dating of the anorthosite and Bt-Am-Ol gabbronorite shows a Late Permian age (255.8 ± 2.9 Ma and 262.6 ± 3.1 Ma, respectively) for the Yamaat Uul mafic complex. All of the rocks of the complex are derived from a unified parental melt due to different amounts of trapped melts in plagioclase and olivine–pyroxene cumulates and without crustal contamination. The Cu-Ni mineralization of the complex has a low degree of evolution of the sulphide melt, similar to PGE-Cu-Ni mafic–ultramafic intrusions of the Khangai Mountains (Nomgon and Oortsog Uul). The Yamaat Uul mafic complex together with other mafic–ultramafic intrusions of the Khangai Mountains is related to the Khangai LIP and can be considered as potential for the PGE-Cu-Ni. The new geological, petrological, geochemical and isotope–geochronological data can later be used to reconstruct the geotectonics of the Khangai Mountains and the Central Asian orogenic belt as a whole.

The Jiaodong Peninsula is the most important gold mineralization area in China, and the formation of gold deposits is closely related to granitoids. The isotopic ages of the Early Cretaceous granodiorites in the northwestern Jiaodong Peninsula are concentrated in the range of 111~123 Ma, and are coeval with the formation of the gold deposits in the area. However, the studies on the geotectonic settings of the granodiorites, especially their petrogenesis and relationship with gold deposits in the northwestern Jiaodong Peninsula, are scarce. Based on field and petrographic observations, geochemistry, EPMA analysis, zircon U-Pb chronology, and Sr-Nd isotopes of the Early Cretaceous Zhouguan granodiorite in the Jiaodong area, the formation age of Zhouguan granodiorite is determined as 115 Ma ± 0.77 Ma; the analysis of EPMA shows that biotite is mainly composed of Fe-biotite and Mg-biotite, with its MgO content ranging from 9.797% to 11.635%. The crystallization temperature of biotite is in the range of 500 °C~625 °C and the emplacement depth of the rock mass is 3.98~8.71 km. The amphibole in the mass mainly includes magnesiohornblende, pargasite, and magnesiosadanagaite; among them, the former two are of crustal origin, while magnesiosadanagaite is of mantle origin. The crystallization pressure and depth of the former two are in the range of 0.75~3.02 kbar and 2.81~11.4 km, respectively, while the crystallization pressure and depth for the latter is 4.64 kbar and 17.53 km, respectively. The (87Sr/86Sr) values range from 0.710424 to 0.711074 and the (143Nd/144Nd) values range from 0.511530 to 0.511808. The parental magma of the Zhouguan granodiorite is highly oxidized with high-water content that is favorable for Au enrichment. Combined with the Nb-Y and Yb-Ta diagrams, a model describing the formation of Zhouguan granodiorite is proposed. [ABSTRACT FROM AUTHOR]

The Fanchang volcanic basin is located between the ore-cluster districts of Tongling and Ningwu，the Middle-Lower Yangtze Metallogenic Belt (MLYMB), regionally. This study extends a set of methods，i.e., petrographic observations, chemical compositions of intrusive rocks and LA-ICP-MS analysis of magmatic zircons, zircon LA-ICP-MS U-Pb geochronology and whole-rock Sr-Nd isotope analysis, on several intrusive rocks, such as Baimashan, Xiangxingdi, Zhuhouling, Chichong, Suishan, Puyingshan and Zishanling. In detail, in this area, monzonite, quartz diorite, granite and syenite are characterized by a series of high-K calc-alkaline and shoshonite, with a positive anomaly in Rb, Th, U, Ce, Pb, Nd, Sm, Gd and a negative anomaly in Ba, Nb, Ta, Sr, P, Ti, plus LREE enrichments and a flattened right-dip of HREE. Moreover, the diagenesis ages of these intrusions mainly overlap the 128–121 Ma time, all but two exceptions, including Baimashan quartz dioritic porphyrite (138.5 ± 4.9 Ma) and Puyingshan diorite (132.1 ± 3.8 Ma). Interestingly, the inherited zircon ages in the Baimashan intrusion are polyphased, primarily in three intervals, 2211.1–2675.9 Ma, 1862.0–2057.1 Ma and 661.1–990.7 Ma, respectively, indicating diachronic magmatic sources and possible existence of the late-Archean and Proterozoic basements. In addition, crystallization temperatures of these intrusive rocks in the Fanchang volcanic basin significantly increase from 802 °C to 931 °C, while the values of (Ce4+/Ce3+)zircon decrease from 192.34 to 24.84, throughout the period from 132 Ma to 125 Ma, probably due to the enhanced magma assimilation process with the reductive carbonaceous wall rocks. Furthermore, A-type granites in this area, as defined in this paper, would have been derived from the partial melting of the residues of the early I-type granite source area. Values of (S7Sr/86Sr)i array between 0.70718 and 0.72642 (a.v. 0.70970) and εNd(t) between −14.0 and 2.2 (a.v. −7.1). In brief, the intrusive rocks in Fanchang volcanic basin is considered to have characteristics of both enriched mantle and lower crust and a strong assimilation process had occurred.

This geochemical study reports the concentrations, spatial distributions, and sources of heavy metals in soil samples from southern Konya. The investigation focused on topsoil (0–20 cm; n = 65), two soil profile (20–100 cm; n = 5), bedrock (n = 12) and stream sediment (n = 4) samples. A total of 70 soil samples were collected and in some samples determined to be enriched in Cd (5.38 ppm), Co (86.4 ppm), Cr (342 ppm), Cu (647 ppm), Fe (6.82%), Ni (755 ppm), Mn (2850 ppm), Zn (529 ppm) and As (89.8 ppm) relative to maximum allowable heavy metal concentrations in Turkey's soil. The heavy metals accumulated and enriched in stream sediments are mainly Cr, Ni, Co. The samples of soil profiles collected from different depths show commonly geogenic and partially anthropogenic effects. According to calculated geoaccumulation index (Igeo), enrichment factor (EF), and contamination factor (Cf) to evaluate possible metal enrichment in soil, the enrichment of heavy metals in the study area shows in the decreasing order of As > Ni > Cd > Co > Cr > Cu > Mn. The topsoil samples have CIA (Chemical Index of Alteration; 4.34–68.27) and CIW (Chemical Index of Weathering; 4.36–74.37) values ranged indicative of low–medium weathering. The 87Sr/86Sr and εNd values ranged from 0.705341 to 0.707491 and − 0.62 to − 4.95 in topsoil samples suggesting their bedrock sources. Lead isotopic data (207Pb/206Pb = 0.816–0.852; 208Pb/206Pb = 2.000–2.242) of the topsoil and profile soil samples show mostly geogenic (natural), partially anthropogenic sources. Ni, Cr, Co, and Cu enrichments in soils and stream sediments are related extremely with weathering of ophiolitic rocks and partially with traffic and agricultural activities (fertilization, irrigation, etc.), while As and Cd enrichments in soils are related commonly with weathering of volcanic rocks and partially with similar human activities. The geochemical results of heavy metals, Pb and Sr–Nd isotope analyses indicate that the most important source of high amounts of As, Cd, Co, Cr, Ni, Cu, Mn in some of soils in southern Konya is dominantly geological materials (natural resources) and rarely human activities (anthropogenic). [ABSTRACT FROM AUTHOR]

The study area is located in Ardabil province in the northeast of Meshkinshahr city. More than 200 small and large Eocene-age dykes form outcrops in this area. Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) U–Pb zircon analyses yield a consistent age of 44.3 ± 1.8 Ma for the dyke swarms. These dykes include tephritic, andesitic and basaltic compositions, and show enrichment in LREEs (relative to HREEs) and are characterized by enrichment in LILEs and depletion in HFSEs. Petrological observations, along with major, rare earth and trace elements geochemistry, suggest that the dykes have a shoshonitic signature. All the rocks are highly enriched in incompatible trace elements and have variable Sr–Nd isotopes. Enrichment in incompatible elements and other geochemical features for the dyke swarm rocks suggest that a metasomatized subcontinental lithospheric mantle is the magma source. The negative Nb–Ta–Ti anomalies in the rocks are comparable with the features of subduction-related magmatism and contamination with ancient crustal components. The radiogenic 87Sr/86Sr isotopic values of the rocks imply the involvement of slab terrigenous sediments and/or a continental lithosphere. Isotopically, the volcanic rocks exhibit a binary trend, representing 1–5% mixing between the primary mantle and sediment melts. Our melting models suggest that there are residual garnet + spinel in the source, which are incompatible with the partial melting of amphibole- and/or phlogopite-bearing lherzolites. The geochronological, geochemical and isotopic data for the northeast Meshkinshahr dyke swarms suggest that these Late Eocene magmas were derived from a small degree of partial melting of a subduction-metasomatized lithospheric mantle source in a post-collisional setting. [ABSTRACT FROM AUTHOR]

The Neoproterozoic banded iron formations (BIFs) were closely associated with the "Snowball Earth" during the breakup of the Rodinia, thus they played an important role in our understanding of the atmospheric and oceanic oxygen levels during this period. In this contribution, the Neoproterozoic (ca. 737 Ma) Baijianshan BIF at Southeast Tarim, northwestern China was identified. Magnetite is the dominated iron‐species, which occurs as the lamina interbedded with chert. The BIF contains low concentrations of trace elements, and is depleted in light rare earth elements (LREEs) based on comparison with the Post‐Archean Australian Shale (PAAS). In addition, the BIF exhibits slightly positive La‐Eu anomalies, negligible Ce anomalies, insignificant Y anomalies, chondritic Y/Ho ratios (23–32), and slightly chondritic initial ∊Nd (t = 737 Ma) values (–0.45 to 1.46, averaging 0.37). All these features indicate that the precipitation of Baijianshan BIF was closely related to the submarine low‐T hydrothermal fluids with little detrital contribution. Moreover, the Baijianshan BIF is characterized by the significant enrichment of heavy Fe isotopes, with δ57FeIRMM‐014 values ranging from 1.78‰ to 3.05‰, revealing the partial oxidation of Fe2+ into Fe3+ during the precipitation of this BIF. Our data suggest that the formation of Baijianshan BIF was closely associated with a significantly reducing ocean, which most likely was isolated from the oxidized atmosphere by a local ice sheet. This Neoproterozoic Baijianshan ocean has the initial oxygen levels as low as, or even lower than that of Archean and Paleoproterozoic oceans. [ABSTRACT FROM AUTHOR]

Fluorite is a widespread mineral in porphyry and hydrothermal vein Mo-polymetallic deposits. Here, fluorite is utilised as a probe to trace the fluid source and reveal the fluid evolution process in the Chalukou giant Mo (Pb–Zn) deposit, Northeast China, which is characterised as early porphyry Mo and later vein-style Zn–Pb mineralisation. A detailed rare earth element (REE) and Sr–Nd isotope study of fluorite combined with Sr isotopes of sphalerite is conducted for the Chalukou deposit. The chondrite-normalised REE patterns of fluorites from molybdenite veins show light REE (LREE)-enriched patterns, with negative Eu anomalies (δEu = 0.60) and weakly negative Y anomalies (Y/Y* = 0.72). The fluorites associated with sphalerite veins exhibit rare earth element (REE)-flat patterns with negative Eu anomalies (δEu = 0.65 to 0.99) and positive Y anomalies (Y/Y* = 1.37 to 3.08). In addition, during the progression from Mo to Zn–Pb mineralisation, the total concentration of REEs decreases from 839 ppm to 53.7 ppm, and Y/Ho ratios increase from 22.1 to 92.5. These features may be explained by the different mobilities of REE complexes during fluid migration. The Eu anomalies are considered to be inherited from source fluids. All the initial 87Sr/86Sr ratios of fluorite and sphalerite are between those of ore-forming porphyries and wall rocks (rhyolite), with fluorite ratios ranging from 0.706942 to 0.707386 and sphalerite ratios varying from 0.705221 to 0.710417. The majority of εNd(t) values of fluorite varying from −6.4 to −3.6 are also located between the ratios exhibited by ore-forming porphyries and rhyolite, whereas three εNd(t) values of fluorites ranging from −0.26 to 0.36 are close to those of ore-forming porphyries. All the isotopic features indicate that the Sr-Nd isotope ratios of hydrothermal fluid are derived from porphyries and disturbed by fluid–rock reactions. Together with a two-stage Sr–Nd isotope mixing model, we suggest that different sources and fluid–rock interactions (syn-ore intrusions and strata) finally influence the Sr–Nd isotopes of the ore-forming fluids, which are recorded by the majority of fluorite and sphalerite.

Gejiu area in Yunnan is located at a faulted depression basin in the southwestern of Youjiang continental margin rift basin, which is the transitional zone between Yangtze platform and South China Caledonian geosyncline, and the tectonic location is in the southwestern South China. The geology, geochemistry of Late Ladinian-Norian meta-basalt in Tabai area of Gejiu, Yunnan indicate that these basalts have undergone strong metamorphism because of regional dynamic tectonics. The meta-basalts are characterized by low contents of silica, calcium, magnesium, and enrichment of incompatible elements(Ti, P, K, etc.). They can be classified as high-Ti alkaline basalts. The trace elements are characterized by extremely low contents of Rb and Ba, severely depletion in Sr and enrichment in Ta, Ti, Zr, Hf, Th, which is similar to the weak crustal contamination of the Emeishan high-Ti basalt. The chondrite-normalized REE pattern shows LREE enrichment and weak positive Eu anomaly. The Sr-Nd isotopes suggest that meta-basalts in Tabai area of Gejiu are mainly from the primitive mantle and fall in the oceanic island basalts(OIB), which are of the same origin as Emeishan high-Ti basalts. Emeishan mantle plume activity has ended in Late Permian. Therefore, the stretching of Yangtze massif in Triassic and the subduction of Simao massif to Yangtze massif induce Emeishan mantle plume stigma to a low degree of partial melting. Because the influence of mantle plume activity lasts for a long time, the energy of mantle plume activity is low in some areas, the basaltic magma does not erupt to the surface and forms magma chamber. Meta-basalts in Tabai area of Gejiu are formed in the relatively weak stage of the center of mantle plume magma activity, especially in the edge zone of mantle plume activity center, the relatively thick lithosphere, and low melting degree. The magma chamber activity in Late Triassic re-erupts and forms basalt. [ABSTRACT FROM AUTHOR]

Introduction The Urumieh-Dokhtar Magmatic Assemblage (UDMA) forms a distinct NW-SE linear intrusive–extrusive complex Magmatism of the UDMA that occurred from Eocene to Quaternary, although the maximum activity was in the middle Eocene (Berberian and King, 1981; Ghasemi and Talbot, 2006). Collision of Arabian and Iranian plates led to termination of Neo-Tethys crust subduction and magmatism activity was abated in the UDMA, although there is no common agreement on collision timing. The Takht magmatic complex is located in the north of the Hamedan province (west Iran), and it belongs to ‎the UDMA. The assemblage of volcano-plutonic rocks is present in the study area. The volcanic rocks include dacite, rhyodacite and trachyandesite with some tuff and agglomerated and the plutonic rocks are mostly occupied by granodiorite and diorite (containing mafic micro-granular enclaves) with some gabbro. These bodies are mostly intruded in Jurassic schists and are in contact with Cretaceous limestone leading to the formation of a skarn iron-ore deposit. The detailed geochemical and isotopic data is lacking and the age of the Takht granodiorite has not been determined. In the present study, the authors mainly have focused on the geochemistry and Sr-Nd isotopic ratios of the Takht magmatic complex to clarify questions regarding pterogenesis and its geodynamic evolution. We also reported U–Pb zircon ages for Takht granodiorite to study the relationship between its genesis and geological evolution history of the UDMA. Materials and methods A total of about 80 samples from the Takht plutonic-volcanic rocks were collected. 16 plutonic-volcanic samples were selected for whole-rock chemical analysis. Major element oxides were analyzed by the X-ray fluorescence spectrometry (XRF) method using an Optima 7300DV XRF instrument in the Lab West laboratory, Australia. Trace elements were also analyzed in this laboratory with the inductively-coupled plasma mass spectrometry (ICP-MS) method using a NeXION 300 ICPMS instrument. Three chip samples with equal weight (4.5 kg) were collected from the Takht granodiorite. Then upon mixing, average samples were obtained for U–Pb dating of zircon. Hand-picked zircon crystals were supplied to the ALC (Arizona Laser Chron Center) in Arizona University. The 14 selected samples for Nd-Sm and Rb-Sr isotope analysis were crushed to less than 60µm. All isotope analyses were performed on a Nu Instruments Nu Plasma HR in the MC-‎ICP-MS facility, in the University ‎of Cape Town, Rondebosch, South Africa. Results The plutonic rocks have metaluminous nature and are of calc-alkaline affinity. The Sr/Nd, Nb/La and Th/U ratios of the granodiorite show that its magma was formed mainly by melting of continental crust, and that its enclaves were formed from a mantle derived mafic magma. The samples have negative anomalies in Nb, Sr, Ti, P and Eu and positive anomalies in Th, K, Zr, Yb and Rb thus indicating contribution of mantle and crustal materials in their generation. The Takht granodiorite has geochemical features of I and A-type granites and also shows properties of both volcanic arc and within plate magmatism association granitoids (high levels of LILEs and HFSEs). In order to obtain better results, all the data were plotted on a common 206Pb/238U versus 207Pb/235U diagram. The results show an age of 16.8 ± 0.24 Ma (Middle Miocene) for the Takht granodiorite. Based on the results, the Takht granodiorite was generated in Miocene. In the Takht magmatic complex initial 87Sr/86Sr range from 0.70678 to 0.70778 and εNd also changes from -0.79398 to -5.83370. Nd-Sm isotopic contents and trace element ratios indicate that the Takht magmatic complex has originated from oceanic slab break-off with continental crust mingling in the post-collision stage. The εNd (16.8 Ma) vs. initial 87Sr/86Sr ratios diagram reveals, the role of continental crust materials in the generation of the granodiorite samples, while where the enclaves lie are plotted in the mantle evolution array field. Discussion The Takht magmatic complex has geochemical properties of arc related igneous rocks such as Ba, Nb, Sr, P, Ti and Y negative anomalies and for Rb, Th, U, K, Nd and Zr positive anomalies. Most of the Takht area samples are plotted in the triple junction of volcanic arc granites (VAG), within plate granites (WPG) and syn-collision (syn-COLG) on Y versus Nb and the Y+Nb versus Rb diagrams (Pearce et al., 1984). These data suggest post-collisional tectonic setting for the Takht magmatic complex. Field, microscopic and geochemical evidences indicate that simple fractional crystallization of a mafic magma was not the only processes involved in the generation of the studied rocks. On this basis, continental crust material had extensive contribution in the generation of the granodiorites whereas the enclaves are from mantle derived magmas. Relatively high fractionated REE patterns of the granodiorite samples with high LREE/HREE indicate an amphibole-bearing, garnet-free source for the samples while small to moderate negative Eu anomalies require residual plagioclase in the source. The granodiorite samples basically have geochemical properties of I-type granites and it is confirmed by their Nd and Sr isotopic ratios. However, relatively high HFSE contents make them similar to A-type granites. Melting of a former continental arc crust and contamination with mantle derived magmas led to both volcanic arc and within plate geochemical properties of the granodiorites that make them similar to I-type and A-type granitoids. The age of 16.8 ± 0.24 Ma (Middle Miocene) of the Takht granodiorite is consistent with the other post-collisional igneous rocks of the area and regarding its post-collisional geochemical properties the age of collision and related orogeny must be considered at least before Miocene. References Berberian, M. and King, G.C.P., 1981. Towards a paleogeography and tectonic evolution of Iran. Canadian Journal of Earth Science, 18(2): 210–265. Ghasemi, A. and Talbot, C.J., 2006. A new tectonic scenario for the Sanandaj–Sirjan Zone (Iran). Journal of Asian Earth Sciences, 26(6): 683–693. Pearce, J.A., Harris, N.B.W. and Tindle, A.G., 1984. Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of Petrology, 25(4): 956–983.

The Tannurjeh porphyry Au-Cu prospect area is located in the northeastern Kashmar, the Khorasan Razavi province, and central of the Khaf-Kashmar-Bardaskan magmatic belt. Geologically, the area is dominated by the Tertiary rhyolitic-rhyodacitic volcanic rocks, which are intruded by monzonitic to dioritic subvolcanic intrusive rocks. The texture in the most of the study igneous rocks is porphyry with fine groundmass and the main minerals are plagioclase, alkali feldspar, quartz, biotite, hornblende and magnetite. The monzonitic intrusions are the source of widespred mineralization and alteration, whereas the diorite is the later phase, which is devoid of mineralization. Using zircon U-Pb method, the age of monzonitic intrusive was determined at 39.8 Ma (Middle Eocene), geochemically as well as mineralogically, the igneous rocks of the area are calc-alkaline granitoids belonging to magnetite series (I-type) which were developed in subduction tectonic setting. The LREE enrichment relative to HREE and enrichment in K, Rb, Cs, Th, and U in comparison to Ti and Nb elements are observed in all of the samples studied. Eu negative anomalies and low Sr/Y ratios can be attributed to the presence of residual plagioclase in the source. (87Sr/86Sr)i (0.705673 and 0.705158), (143Nd/144Nd)i (0.512524 and 0.512570), and εNdi (-1.22 and -0.32) values indicate magma is derived from mantle wedge above subducted slab, which is assimilated with upper crust. Finally, the Eocene is an important metallogenic episode, particuarly for Au and Cu, in NE of Iran.

Granitoids of the Ekecikdağ Igneous Association (Central Anatolia/Turkey) are products of collisional–post-collisional magmatism in the Ekecikdağ area. These granitoids are granodiorite, microgranite and leucogranite. Field relations of granodiorites with microgranites is obscured, but leucogranites intrude both rock types. Mean zircon laser ablation (LA)-ICP-MS 206Pb-238U ages of granodiorites and microgranites are 84.52 ± 0.93 Ma and 80.7 ± 1.6 Ma, respectively, and age of leucogranites is suggested as 80 Ma, based on field relations combined with 206Pb/238U and Rb-Sr ages. Crystallisation temperatures of granodiorites, microgranites and leucogranites are 728°C-848°C, 797°C-880°C, 704°C-809°C, respectively. Geochemical characteristics including Sr-Nd isotopic evidences infer a non-cogenetic character, as there is a high crustal contribution in I-type granodiorite sources, a crustal source with insignificant and significant mantle inputs in S-type microgranites and leucogranites, respectively. LA-ICP-MS Lu-Hf isotope data from zircons reveal their crustal nature (εHf(t): −1.3 ± 0.5 to −8.8 ± 0.5). Crustal melting linked to the Alpine thickening during the Late Cretaceous led to formation of heterogeneous sourced granitoids with crustal dominated sources in the Ekecikdağ area. Understanding of the nature and evolution of collisional Ekecikdağ granitoids is not only important to put contribution in the geodynamic evolution of Central Anatolia and surrounding Alpine area, but also to better understand systematics of collisional magmatic systems.

The Jiaodong Peninsula is the most important gold mineralization area in China, and the formation of gold deposits is closely related to granitoids. The isotopic ages of the Early Cretaceous granodiorites in the northwestern Jiaodong Peninsula are concentrated in the range of 111~123 Ma, and are coeval with the formation of the gold deposits in the area. However, the studies on the geotectonic settings of the granodiorites, especially their petrogenesis and relationship with gold deposits in the northwestern Jiaodong Peninsula, are scarce. Based on field and petrographic observations, geochemistry, EPMA analysis, zircon U-Pb chronology, and Sr-Nd isotopes of the Early Cretaceous Zhouguan granodiorite in the Jiaodong area, the formation age of Zhouguan granodiorite is determined as 115 Ma ± 0.77 Ma; the analysis of EPMA shows that biotite is mainly composed of Fe-biotite and Mg-biotite, with its MgO content ranging from 9.797% to 11.635%. The crystallization temperature of biotite is in the range of 500 °C~625 °C and the emplacement depth of the rock mass is 3.98~8.71 km. The amphibole in the mass mainly includes magnesiohornblende, pargasite, and magnesiosadanagaite; among them, the former two are of crustal origin, while magnesiosadanagaite is of mantle origin. The crystallization pressure and depth of the former two are in the range of 0.75~3.02 kbar and 2.81~11.4 km, respectively, while the crystallization pressure and depth for the latter is 4.64 kbar and 17.53 km, respectively. The (87Sr/86Sr) values range from 0.710424 to 0.711074 and the (143Nd/144Nd) values range from 0.511530 to 0.511808. The parental magma of the Zhouguan granodiorite is highly oxidized with high-water content that is favorable for Au enrichment. Combined with the Nb-Y and Yb-Ta diagrams, a model describing the formation of Zhouguan granodiorite is proposed.

The study area is located in Ardabil province in the northeast of Meshkinshahr city. More than 200 small and large Eocene-age dykes form outcrops in this area. Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) U–Pb zircon analyses yield a consistent age of 44.3 ± 1.8 Ma for the dyke swarms. These dykes include tephritic, andesitic and basaltic compositions, and show enrichment in LREEs (relative to HREEs) and are characterized by enrichment in LILEs and depletion in HFSEs. Petrological observations, along with major, rare earth and trace elements geochemistry, suggest that the dykes have a shoshonitic signature. All the rocks are highly enriched in incompatible trace elements and have variable Sr–Nd isotopes. Enrichment in incompatible elements and other geochemical features for the dyke swarm rocks suggest that a metasomatized subcontinental lithospheric mantle is the magma source. The negative Nb–Ta–Ti anomalies in the rocks are comparable with the features of subduction-related magmatism and contamination with ancient crustal components. The radiogenic 87Sr/86Sr isotopic values of the rocks imply the involvement of slab terrigenous sediments and/or a continental lithosphere. Isotopically, the volcanic rocks exhibit a binary trend, representing 1–5% mixing between the primary mantle and sediment melts. Our melting models suggest that there are residual garnet + spinel in the source, which are incompatible with the partial melting of amphibole- and/or phlogopite-bearing lherzolites. The geochronological, geochemical and isotopic data for the northeast Meshkinshahr dyke swarms suggest that these Late Eocene magmas were derived from a small degree of partial melting of a subduction-metasomatized lithospheric mantle source in a post-collisional setting.

Gubaoquan dolerite dykes are predominantly intruded into Ordovician-Devonian granodiorites, and a few are interspersed in Early Paleozoic strata. The dykes are divided into two different rock types, including dolerite and sillite. The mainly minerals are plagioclase and pyroxene, with minor am phi bole, biotite and some accessory minerals. The results of zircon UPb dating yield an age of (285. 0 ± 4. 7) Ma, indicating the emplacement time of dolerite dykes, which is coeval to the formation age of dolerite dykes in other places of Beishan area. The εNd (t) of Gubaoquan dolerite varies from 6. 39 to 6. 78, indicating that the parental magma is derived from a depleted mantle source. The whole rock Sr-Nd isotopic simulation suggests that the magma undergoes a 10 %-15 % of contamination by upper crust materials during emplacement process. The LREE/HREE ratio of dolerite varies from 1. 72 to 2. 17, and the chondrite normalized REE pattern displays a flat pattern. The primitive mantle-normalized trace element spider diagram shows obvious negative anomalies of Nb-Ta. The characteristics of rare earth and trace elements are different from Bachu dolerite associated with mantle plume activities in Tarim block, but are similar with Yin'aoxia (east part) and Podong (west part) dolerites in Beishan area. Integrated with the existing research results, it is suggested that Gubaoquan dolerite dykes are formed after the closure of Paleo-Asian ocean, as the result of basaltic magmatism caused by the decompression and partial melting of asthenosphere due to lithosphere delamination and break-off in an extensional environment. [ABSTRACT FROM AUTHOR]

During orogenic extension, partial melting of the continental crust usually produces post‐collisional granitoids, and the characteristics of their petrogenesis can provide crucial constraints on the geodynamics of tectonic regimes and post‐collisional lithospheric processes. A case study for this issue is the high‐silicon adakitic granites from the Jingtieshan area, North Qilian orogenic belt. In this study, we present a range of evidences on petrology, zircon U‐Pb dating, zircon Lu‐Hf isotopic composition, whole‐rock geochemistry, and Sr‐Nd isotopes from the studied high‐silicon adakitic granites to better understand the geodynamic processes of the North Qilian orogenic belt. The adakitic rocks consisted of plagioclase (55–60 %), K‐feldspar (5–10 %), quartz (20–25 %), and a small amount of biotite and accessory minerals. Zircon grains from the studied sample yielded a weighted mean 206Pb/238U age of 430 ± 2 Ma (MSWD = 0.96) with positive εHf(t) values (−1.4 to +6.3, with an average of +4.2). Geochemical results suggested that the adakitic rocks were enriched in LREE without evident Eu anomalies (except for one sample; δEu = 0.32–0.41), and these samples exhibited high Sr/Y ratios with negative εNd(t) values (−4.9 to −3.1). A combined study of petrology and geochemical arguments lead us to propose that the high‐silicon adakitic granites from the Jingtieshan area within the North Qilian orogenic belt were generated by partial melting of the thickened crust in a post‐collisional tectonic setting and that the adakitic melts were derived from the partial melting of the metabasite that was emplaced into the crust during the late Proterozoic‐early Neoproterozoic. [ABSTRACT FROM AUTHOR]

The eastern part of Asia between the North China and Siberian cratons contains orogenic belts formed by the Paleo-Asian and Pacific subduction and older continental blocks. A fundamental question regarding these and all mobile belts is the fate of the continental lithospheric mantle (CLM) during their formation, i.e. whether, or to what extent the CLM may be formed, replaced or affected during orogeny. Insights into these processes can be obtained from mantle xenoliths hosted by Cenozoic basalts in the Proterozoic Khanka block in the far eastern Russia between NE China and the Pacific coast of Asia. We report petrographic, chemical, and Os-Sr-Nd isotope data for spinel peridotite xenoliths at two Khanka sites: Sviyagin and Podgelban. The modal abundances and chemical compositions suggest that the peridotites are residues of low to moderate degrees of melt extraction from fertile mantle. They show an 187Os/188Os vs. 187Re/188Os correlation with an apparent 1.9 Ga age; the 187Os/188Os ratios are positively correlated with Al 2 O 3 and other melt extraction indices. These results provide the first robust CLM age constraints for the eastern Central Asian Orogenic Belt (CAOB). The ages suggest that the ancient CLM of the Khanka block may be roughly coeval with reworked CLM at Hannuoba (North China craton), and that it persisted through the Phanerozoic orogenies. Moreover, despite the proximity to Phanerozoic subduction zones, the Khanka CLM shows little post-melting enrichment, e.g. the clinopyroxenes are typically LREE-depleted and have Sr-Nd isotope ratios typical of the MORB mantle. We posit that the metasomatism of the CLM, earlier proposed for North China xenolith suites and ascribed to the effects of Pacific or older subduction and related mantle upwelling, may not be widespread in the CAOB. In general, Proterozoic blocks composed of residual peridotites may be more common in the CLM of the SE Siberia and northern China, and possibly other orogenic belts, than previously thought. [ABSTRACT FROM AUTHOR]

Granitoids of the Ekecikdağ Igneous Association (Central Anatolia/Turkey) are products of collisional–post-collisional magmatism in the Ekecikdağ area. These granitoids are granodiorite, microgranite and leucogranite. Field relations of granodiorites with microgranites is obscured, but leucogranites intrude both rock types. Mean zircon laser ablation (LA)-ICP-MS 206Pb-238U ages of granodiorites and microgranites are 84.52 ± 0.93 Ma and 80.7 ± 1.6 Ma, respectively, and age of leucogranites is suggested as 80 Ma, based on field relations combined with 206Pb/238U and Rb-Sr ages. Crystallisation temperatures of granodiorites, microgranites and leucogranites are 728°C-848°C, 797°C-880°C, 704°C-809°C, respectively. Geochemical characteristics including Sr-Nd isotopic evidences infer a non-cogenetic character, as there is a high crustal contribution in I-type granodiorite sources, a crustal source with insignificant and significant mantle inputs in S-type microgranites and leucogranites, respectively. LA-ICP-MS Lu-Hf isotope data from zircons reveal their crustal nature (εHf(t): −1.3 ± 0.5 to −8.8 ± 0.5). Crustal melting linked to the Alpine thickening during the Late Cretaceous led to formation of heterogeneous sourced granitoids with crustal dominated sources in the Ekecikdağ area. Understanding of the nature and evolution of collisional Ekecikdağ granitoids is not only important to put contribution in the geodynamic evolution of Central Anatolia and surrounding Alpine area, but also to better understand systematics of collisional magmatic systems. [ABSTRACT FROM AUTHOR]

Abstract Extreme hydrologic events such as floods have caused catastrophic losses to modern human society, especially in highly developed coastal areas. However, high-resolution reconstructions of extreme flood events are scarce due to a paucity of suitable proxies in marginal seas. Here we present a high-resolution record of extreme flood events in the Changjiang River catchment during the last 110 years using samples from the subaqueous delta of Changjiang River estuary. We used a multi-proxy approach including Sr-Nd isotopes, Zr/Rb ratio and biomarkers (branched GDGTs, i.e. brGDGTs, and crenarchaeol, and the ratio of the two as calculated by the BIT index) as proxies for the evolution of extreme floods in the Changjiang River catchment. Rapid shifts in these proxies agreed with the timing of floods on the Changjiang River. We also tested the reliability of biomarker indices to reconstruct paleoflood events in this area. The results indicated that the abundances of GDGTs fluctuated in concert with historical floods. Cross-spectral analyses revealed that historical floods in the Changjiang River catchment were consistent with ENSO variance. Highlights • Sr-Nd isotopes and BIT were applied as Paleoflood multiproxy indices. • Zr/Rb ratio records of historical floods in core sediments had been compiled. • BIT and brGDGTs distributions co-varied with palaeoflood record in subaqueous delta. • Profiles of Sr-Nd isotopes responded to climate change coherently. [ABSTRACT FROM AUTHOR]

This study presents zircon U–Pb ages and geochemical and Sr–Nd isotopic data for acid granites from the Uliastai continental margin, which is located in the Ulaan Tolgoi area of the south‐eastern Central Asian Orogenic Belt (CAOB). Although most samples have similar calc‐alkaline (K2O/Na2O = 0.55–1.70, average of 1.35) and peraluminous (A/CNK = 1.02–1.20 and A/NK = 1.09–1.87) characteristics, the granodiorites, monzogranites, and alkali feldspar granites exhibit distinct light rare earth element (LREE)/heavy REE (HREE) anomalies, including negative Nb, P, Ti, Sr, and Ba anomalies and negative εNd(t) values. These characteristics indicate that this complex massif comprises lower Early Carboniferous subduction‐related calc‐alkaline granodiorites (348 ± 1 Ma); an upper Early Carboniferous syn‐collisional segment characterized by S‐type, high‐K, calc‐alkaline, and peraluminous monzonitic granites (334 ± 1 Ma); and Late Carboniferous post‐orogenic extensional A2‐type peraluminous alkali feldspar granites (317 ± 1 Ma). Previous studies performed on coeval volcanic rocks and Early Palaeozoic granites in the same area have demonstrated that the Early Carboniferous granodiorites have the same geochemical characteristics as volcanic arc granites (VAGs), thus indicating that the northward subduction of the Hegenshan Ocean may have continued through the Early Carboniferous. The monzogranite and alkali feldspar granites, in conjunction with the Late Carboniferous lagged arc volcanic rocks observed in this area, suggest a syn‐collisional to post‐collisional setting. The new data presented in this study provide constraints on the timing of the transition from island‐arc magmatism to post‐collisional extension‐related magmatism in this region during the later stage of the Early Carboniferous. [ABSTRACT FROM AUTHOR]

Subduction zones are important for understanding of the global carbon cycle from the surface to deep part of the mantle. The processes involved the metamorphism of carbonate-bearing rocks largely control the fate of carbon and contribute to local carbon isotopic heterogeneities of the mantle. In this study, we present petrological and geochemical results for marbles and carbonated eclogites in the Southwestern Tianshan UHP belt, NW China. Marbles are interlayered with coesite-bearing pelitic schists, and have Sr-Nd isotopic values (εNd (T=320Ma)  = −3.7 to −8.9, 87 Sr/ 86 Sr (i)  = 0.7084–0.7089), typical of marine carbonates. The marbles have dispersed low δ 18 O VSMOW values (ranging from 14 to 29‰) and unaffected carbon isotope (δ 13 C VPDB  = −0.2–3.6‰), possibly due to infiltration of external H 2 O-rich fluids. Recycling of these marbles into mantle may play a key role in the carbon budget and contributed to the mantle carbon isotope heterogeneity. The carbonated eclogites have high Sr isotopic compositions ( 87 Sr/ 86 Sr (i)  = 0.7077–0.7082) and positive εNd (T = 320 Ma) values (from 7.6 to 8.2), indicative of strong seafloor alteration of their protolith. The carbonates in the carbonated eclogites are mainly dolomite (Fe #  = 12–43, Fe #  = Fe 2+ /(Fe 2+  + Mg)) that were added into oceanic basalts during seafloor alteration and experienced calcite – dolomite – magnesite transformation during the subduction metamorphic process. The uniformly low δ 18 O values (∼11.44‰) of carbonates in the carbontaed eclogites can be explained by closed-system equilibrium between carbonate and silicate minerals. The low δ 13 C values (from −3.3 to −7.7‰) of the carbonated eclogites most likely reflect contribution from organic carbon. Recycling of these carbonated eclogites with C isotope similar to typical mantle reservoirs into mantle may have little effect on the mantle carbon isotope heterogeneity. [ABSTRACT FROM AUTHOR]

The Tannurjeh porphyry Au-Cu prospect area is located in the northeastern Kashmar, the Khorasan Razavi province, and central of the Khaf-Kashmar-Bardaskan magmatic belt. Geologically, the area is dominated by the Tertiary rhyolitic-rhyodacitic volcanic rocks, which are intruded by monzonitic to dioritic subvolcanic intrusive rocks. The texture in the most of the study igneous rocks is porphyry with fine groundmass and the main minerals are plagioclase, alkali feldspar, quartz, biotite, hornblende and magnetite. The monzonitic intrusions are the source of widespred mineralization and alteration, whereas the diorite is the later phase, which is devoid of mineralization. Using zircon UPb method, the age of monzonitic intrusive was determined at 39.8 Ma (Middle Eocene), geochemically as well as mineralogically, the igneous rocks of the area are calc-alkaline granitoids belonging to magnetite series (I-type) which were developed in subduction tectonic setting. The LREE enrichment relative to HREE and enrichment in K, Rb, Cs, Th, and U in comparison to Ti and Nb elements are observed in all of the samples studied. Eu negative anomalies and low Sr/Y ratios can be attributed to the presence of residual plagioclase in the source. ( 87Sr/86Sr)i (0.705673 and 0.705158), ( 143Nd/144Nd)i (0.512524 and 0.512570), and εNdi (-1.22 and -0.32) values indicate magma is derived from mantle wedge above subducted slab, which is assimilated with upper crust. Finally, the Eocene is an important metallogenic episode, particuarly for Au and Cu, in NE of Iran. [ABSTRACT FROM AUTHOR]

Whole-rock geochemical and Sr- Nd isotopic data are presented for late Miocene volcanic rocks associated with the Chah Zard epithermal Au- Ag deposit in the Urumieh- Dokhtar Magmatic Arc ( UDMA), Iran, to investigate the magma source, petrogenesis and the geodynamic evolution of the study area. The Chah Zard andesitic to rhyolitic volcanic rocks are characterized by significant Large Ion Lithophile Element ( LILE) and Light Rare Earth Element ( LREE) enrichment coupled with High Field Strength Element ( HFSE) depletion. Our geochemical data indicate an adakitic-like signature for the volcanic rocks (e.g. SiO2 > 62 wt%, Al2 O3 > 15 wt%, MgO < 1.5 wt%, Sr/ Y > 70, La/ Yb > 35, Yb < 1 ppm, and Y < 18 ppm, and no significant Eu anomalies), distinguishing them from the other volcanic rocks of the UDMA. The Chah Zard volcanic rocks have similar Sr and Nd isotopic compositions; the 87 Sr/86 Sr(i) ratios range from 0.704 902 to 0.705 093 and the εNd(i) values are from +2.33 to +2.70. However, the rhyolite porphyry represents the final stage of magmatism in the area and has a relatively high 87 Sr/86 Sr ratio (0.705 811). Our data suggest that the andesitic magmas are from a heterogeneous source and likely to result from partial melting of a metasomatized mantle wedge associated with a mixture of subducted oceanic crust and sediment. These melts subsequently underwent fractional crystallization along with minor amounts of crustal assimilation. Our study is consistent with the model that the volcanic host rocks to epithermal gold mineralization in the UDMA are genetically related to late Miocene Neo- Tethyan slab break-off beneath Central Iran. [ABSTRACT FROM AUTHOR]

• A Neoproterozoic orogenic gold province has been recognized in South China. • Two metallogenic episodes of gold mineralization occurred in the Huangling region. • Apatite Sr-Nd isotopic data suggest magmatic sources for the ore-forming fluids. • The mineralized time of Huangling gold province was at the transition period. • This transition period was from convergent to extensional post-collision tectonics. Gold mineralization types were rarely exposed in the Neoproterozoic accretionary-to-collisional orogen, particularly in China, throughout Earth's history. The Huangling region in South China contains more than 70 gold deposits/occurrences hosted in Archean-Paleoproterozoic metamorphic rocks and Neoproterozoic granitic complexes. However, the absolute age of hydrothermal mineralization, genesis, and their relationship with regional-scale processes, such as tectonism, magmatism, and metamorphism, remains unclear. Therefore, in this study, we investigated three gold deposits (Shuiyuesi, Hongwucun, and Guaizigou) hosted in different lithological units from the northern, central, and southern regions of Huangling, respectively. We conducted detailed fieldwork and analyzed the hydrothermal apatite and monazite geochronology and Sr-Nd isotopic composition of these deposits. The gold mineralization is mainly hosted within sulfide-quartz veinlets, and it is structurally controlled by second-order NW- or NNW-striking faults of the first-order NW trending main fault zone. Gold is present in various forms, such as native gold, electrum, and petzite or in fine-grained pyrite as invisible gold co-precipitated with alteration mineral assemblages that include sericite, quartz, and hydrothermal apatite, and monazite. LA-ICP-MS U-Pb dating of the hydrothermal monazite and apatite for the Shuiyuesi deposit yielded two ages: 831 ± 2 Ma and 830 ± 23 Ma. These ages are consistent with the weighted mean 206Pb/238U age of 834 ± 3 Ma for apatite, obtained from the southern Guaizigou deposit within margin of error. Monazite and apatite dating of the Hongwucun gold deposit yielded younger ages of 810 ± 3 Ma and 800 ± 10 Ma, respectively. The new dates suggest that the gold deposits in the Huangling region underwent two distinct metallogenic episodes of gold mineralization during the Neoproterozoic, coeval with the temporal post-collisional mafic dykes, which postdated the regional metamorphism by ∼100 m.y, as indicated in the Huangling region after the peak period of collisional orogeny and in response to an extensional setting, possibly due to asthenosphere wedging. The Sr-Nd isotope of apatite and monazite (87Sr/86Sr: 0.69555–0.76244, ε Nd (t): −22.1–−2.9) and collective geochemical data indicate that ore-forming fluids are mainly consistent with magmatic sources with significant contribution from mantle materials. The results of the study suggest that the Huangling gold mineralization province is genetically related to Neoproterozoic post-collisional magmatism. Additionally, the region shares many characteristics of large orogenic gold provinces around the world, including alteration types, element associations, occurrence states of gold, and the evolution of orogenic belts, offering valuable new insights into the gold metallogeny of the early Neoproterozoic period, which is generally not known for its abundance of Au deposits. [ABSTRACT FROM AUTHOR]

The Sikhote-Alin Orogenic Belt in Russian Far East is an important Late Mesozoic to Early Cenozoic accretionary orogen related to the subduction of the Paleo-Pacific Plate. This belt was generated by successive accretion of terranes made of accretionary prisms, turbidite basins and island arcs to the continental margin of northeastern Asia (represented by the Bureya-Jiamusi-Khanka Block) from Jurassic to Late Cretaceous. In order to study the tectonic and crustal evolution of this orogenic belt, we carried out zircon U-Pb dating, and whole-rock elemental and Sr-Nd isotopic analyses on granites and volcanic rocks from the Primorye region of southern Sikhote-Alin. Zircon dating revealed three episodes of granitoid emplacement: Permian, Early Cretaceous and Late Cretaceous to Early Paleogene. Felsic volcanic rocks (mainly rhyolite, dacite and ignimbrite) that overlay all tectonostratigraphic terranes were erupted during 80–57 Ma, postdating the accretionary process in the Sikhote-Alin belt. The Cretaceous-Paleogene magmatism represents the most intense tectonothermal event in the Sikhote-Alin belt. Whole-rock major and trace elemental data show arc-like affinity for granitoids and volcanic rocks, indicating that they were likely generated in a supra-subduction setting. Their initial 87 Sr/ 86 Sr ratios range from 0.7048 to 0.7114, and ε Nd (t) values vary from +1.7 to −3.8 (mostly < 0). Thus, the elemental and Sr-Nd isotopic data suggest that the felsic magmas were generated by partial melting of source rocks comprising mantle-derived juvenile component and recycled crustal component. In addition to the occurrence in the Sikhote-Alin orogenic belt, Cretaceous to Early Paleogene magmatic rocks are also widespread in NE China, southern Korean peninsula, Japanese islands and other areas of Russian Far East, particularly along the coastal regions of the Okhotsk and Bering Seas. These rocks constitute an extended magmatic belt along the continental margin of NE Asia. The generation of this belt was ascribed to subduction of the Paleo-Pacific Plate. [ABSTRACT FROM AUTHOR]

Laocheng pluton exposed in Ningshan area of South Qinling, together with Wulong pluton. consist of an important part of Early Mesozoic granitoid magmatism in central South Qinling. Abundant mafic enclaves can be found in different units of Laocheng pluton. Analysis results of zircon U-Pb ages show that the host rock from Laocheng pluton is emplaced in 213-219 Ma, and its mafic enclaves are crystallized in 211 Ma, which are more or less simultaneous with the formation of Wulong pluton. Geochemical data show that the host rock from Laocheng pluton is granodiorite and quartz monzonite in composition with the characteristics of low Si. rich alkali, weak peraluminous and high Mg# (52-67), and belongs to high-K calc-alkaline I-type series; mafic enclaves are mainly dioritic, having the characteristics of low Si02 (52. 6%-62. 4%), rich alkali and high Mg# (63-72), belonging to shoshonite series. Compared with the host rock, the mafic enclaves have lower initial N(87 Sr)/N(86 Sr) (0.704 66-0.705 82), high ɛNd(t) (-4.3- -1.6) and higher Mg# , suggesting that the primary magma of the enclaves might have originated from a basaltic magma. Sr-Nd isotope geochemistry suggests that the host rock and mafic enclaves have exchanged prior to the formation of Laocheng pluton, and an equilibrium has been reached. Compared with Sr-Nd isotope ratio of basement rocks exposed in South Qinling, it is suggested that the magma of Laocheng granite originates from Neoproterozoic mafic crustal material. Relationship between host rock and mafic enclaves indicates that a magma mixing between the crystallizing acid magma and the basic magma slightly later injects into the magma chamber; these two magmas are not completely miscible during the mixing process. [ABSTRACT FROM AUTHOR]

Newly-discovered Suyunhe Mo deposit (0.57 Mt Mo metal), located in the Barluk Mountains of the West Junggar terrain, Xinjiang, NW China, is the largest porphyry Mo deposit discovered in Xinjiang so far. The Suyunhe Mo deposit is associated with the Suyunhe intrusive complex which was emplaced into the volcano-sedimentary sequences of the Middle Devonian Barluk Group. The Suyunhe complex consists of the deep granite intrusion and the shallow granite porphyry, granodiorite porphyry, monzonitic granite porphyry, and tonalite porphyry stocks which are cut by the felsic dikes. Dominant Mo mineralization is hosted in the Barluk Group volcano-sedimentary rocks but is minor in the granite, granite porphyry, granodiorite porphyry, and monzonitic granite porphyry of the Suyunhe complex. We report in situ zircon U–Pb ages, whole rock geochemistry, Sr–Nd isotopic and zircon Lu–Hf isotopic data for the ore-bearing intrusive rocks from the Suyunhe deposit. Secondary ion mass spectrometry (SIMS) zircon U–Pb dating indicates that the deep granite emplaced at 298.4 ± 1.9 Ma–295.3 ± 3 Ma and the shallow granodiorite porphyry intruded during 294.7 ± 2.1 Ma–293.7 ± 2.3 Ma. The Suyunhe granite intrusion, including fine- and medium-grained granite, belongs to the high-K calc-alkaline series. Most of them have low Zr + Nb + Y + Ce (< 350 ppm) and 10,000 Ga/Al (< 2.7) values, showing a geochemical affinity to I-type granite. These granites are enriched in light rare earth elements (LREE) and depleted in heavy rare earth elements (HREE) and Eu, Ba, Sr, Nb, P and Ti, indicating that they have experienced advanced fractional crystallization. They have low initial 87 Sr/ 86 Sr ratios (0.70318–0.70380), high whole-rock εNd(t) values (+ 4.4 to + 6.0), high zircon εHf(t) values (+ 10.8 to + 14.6), and young whole-rock Nd and zircon Hf model ages. They also show low Mg# (< 0.35). These features demonstrate that the ore-bearing granite formed by partial melting of the juvenile lower crust and experienced advanced fractional crystallization. The Suyunhe granite porphyry and monzonitic granite porphyry are compositionally similar to the granite, indicating that they share a common magma source and process with the granite. The Suyunhe granodiorite porphyries belong to slightly high-K calc-alkaline series and have LREE enrichment and HREE, Nb and Ti depletion. They have low ( 87 Sr/ 86 Sr) i ratios (0.70421–0.70444), high εNd(t) values (+ 4.9 to + 6.2), high zircon εHf(t) values (+ 9.6 to + 15.2), and young whole-rock Nd and zircon Hf model ages. They also show low Mg# (< 0.39) with one reception of 0.48. These features indicate that the granodiorite porphyries have a relatively deeper magma source region of the lower crust and have not experienced as much fractional crystallization. The Suyunhe barren tonalite porphyries show enrichment of LREE and depletion of HREE, Nb and Ti depletion, and have chemical composition (e.g., Mg# = 0.41–0.48) different from the Suyunhe granodiorite porphyries, though isotopically they are indistinguishable. This suggests that the parental magma of the barren tonalite porphyries originated from melting of a lithospheric mantle. Therefore, the Suyunhe ore-bearing magmas derived from the juvenile lower crust which has a high potential to bear porphyry Mo deposit and result in the formation of the Suyunhe large porphyry Mo deposit. [ABSTRACT FROM AUTHOR]

Apatite is a common accessory mineral, having a high Sr-Nd content and a low Rb content. The precise determination of micro-area Sr-Nd isotopic composition for apatite will provide important geochemical information for discussing the details of the geological process. Laser Ablation Multi-collector Inductively Coupled Plasma-Mass Spectrometry (LA-MC-ICPMS) technique has the characteristics of rapid analysis, high analytical precision and high spatial resolution, and is particularly suitable for Sr-Nd isotopic analysis of a large quantity of fine-grained apatite samples. The precise deduction of isotopic interference and calibration of instrument mass bias are crucial for in-situ analysis to obtain Sr-Nd isotopic ratio. In this article a method is described, which adopts LA-MC-ICPMS and combines with the newly published method for deduction of interferences, like Kr, Rb, divalent ions of REEs and calcium-containing polymer for Sr isotopes, Sm for Nd isotopes. The calibration of instrument mass bias is carried out, and the in-situ Sr-Nd isotopic analysis approach for apatite is established. The test results of Durango apatite standard, Apatite 1 and PE show that Sr-Nd isotopic composition of apatite sample with high Sr-Nd content can be accurately determined. The specific results are consistent with literature or the measured values by Thermal Ionization Mass Spectrometry (TIMS) within error. The measurement precision of Sr isotopes is < 0.015% (2SD), and that of Nd isotopes is < 0.005% (2SD). The established method is applied for Sr-Nd isotopic analysis of Durango apatite standard, Apatite 1 and PE (laboratory standard), respectively. The analysis results indicate that the Sr-Nd isotopic compositions of the three apatite samples are basically consistent, and can serve as ideal reference samples for in-situ Sr-Nd isotopic analysis.