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... However, the genesis of these Makeng-type Fe polymetallic deposits remains unclear, particularly regarding the timing and nature of the different stages of mineralization within the SFDB, and the links between metallogenesis and ore-related magmatism (Zhang et al., 2012a(Zhang et al., , 2012b(Zhang et al., , 2012cZhang and Zuo, 2013, 2014Zhao et al., 2020). Previous studies reporting molybdenite Re-Os and zircon U-Pb ages have regarded $130 Ma as the formation time of the Fe polymetallic mineralization in SFDB (e.g., Wang et al., 2010Wang et al., , 2015bZhang et al., 2012aZhang et al., , 2012bZhang et al., , 2012cLai et al., 2014;Yuan et al., 2014;Zhao et al., 2016). In this study, our systematic geological survey and geochronological results have established that the Pb-Zn-Cu, Fe, and Mo mineralization in the Dapai deposit formed at $175, $147, and $131 Ma,. ...
... Skarn-type Fe mineralization occurrences of the Makeng-type Fe polymetallic deposits in the SFDB generally share the following Mao et al., 2003Mao et al., , 2006Luo et al., 2009;Wang et al., 2010Wang et al., , 2015bWang et al., , 2015cZhang et al., 2010bZhang et al., , 2012aZhang et al., , 2012bZhang et al., , 2012cZhang et al., , 2018Lai et al., 2014;Lv, 2014;Yuan et al., 2014Yuan et al., , 2019Ding, 2015;Zhao et al., 2016;Yang et al., 2017a;Zhao et al., 2018;Yuan, 2020). ...
... Mo mineralization is common in the Makeng-type Fe polymetallic deposits in the SFDB, and molybdenite Re-Os dating analyses suggest that the Mo orebodies formed at 135-130 Ma, including those of the Dapai, Makeng, Luoyang, Cuntou, Yangshan, and Pantian deposits (Figs. 2 and 14;Wang et al., 2010Wang et al., , 2020Zhang et al., 2012bZhang et al., , 2012cLai et al., 2014;Yuan et al., 2014;Zhao et al., 2016Zhao et al., , 2018Yuan, 2020). Similar to the case of the Dapai deposit as discussed above (Figs. ...
The southwestern Fujian depression belt (SFDB) is an economically important Mesozoic Fe metallogenic belt in South China and is renowned for its Makeng-type Fe deposits, in which stratified skarn Fe orebodies generally occur in or near the contact zone between late Paleozoic carbonate sequences and Mesozoic granites. However, the genesis and geodynamic setting of these deposits remain unclear because the characteristics of the widely distributed Pb–Zn–Cu and Mo orebodies in these deposits and the temporal, spatial, and genetic relationships between magmatism and mineralization are poorly defined. The Dapai Fe polymetallic deposit in the SFDB is a typical example of Makeng-type Fe deposits but also has regional significance, whereby the stratified skarn Fe orebodies have overprinted the stratabound Pb–Zn–Cu mineralization followed by final fissure-filling by vein-disseminated Mo mineralization. A detailed geological investigation suggests that episodic magmatic–hydrothermal events were involved in the formation process of the Dapai Fe polymetallic deposit.
Pyrite and sphalerite from the Pb–Zn–Cu orebodies yield an Rb–Sr isochron age of 175.5 ± 3.3 Ma, which is regarded as the timing of Pb–Zn–Cu mineralization. Zircon grains from Fe-mineralized granodiorite porphyry and Mo-mineralized monzogranite yield weighted-mean 206Pb/238U ages of 146.3 ± 0.9 Ma and 131.7 ±0.4 Ma, interpreted as the timings of Fe and Mo mineralization, respectively. Six zircons from granodiorite also yield a 206Pb/238U model age cluster of ~184 Ma, which coincides reasonably with the timing of Pb–Zn–Cu mineralization and implies the existence of an unidentified ore-related intrusion in the Dapai deposit. Five further zircons from the porphyritic granodiorite yield an age cluster of ~150 Ma, consistent with the timing of Fe mineralization. Galena, pyrite, and sphalerite from the Dapai and Makeng deposits have similar S–Pb isotopic compositions and suggest a magmatic source. Combining our results with published isotopic data for the SFDB, we suggest that the Pb–Zn–Cu mineralization in this area was derived from crustal magmas that mixed with mantle-derived magma prior to emplacement. The δ56Fe and δ57Fe values of magnetite from Dapai and Makeng are both slightly lower than those of the ore-related granites, suggesting that Fe in the initial fluid in both deposits was derived mainly from coeval granitic rocks. The Fe isotopic variation between intrusions and skarn Fe orebodies is interpreted as resulting from mass fractionation that occurred during fluid exsolution from melt. Contents of Re in molybdenite from published data for the SFDB indicate crust–mantle mixed sources of Mo and Re. The Makeng-type Fe polymetallic deposits formed as a result of three magmatic–hydrothermal episodes, generating Pb–Zn–Cu mineralization at 185–160 Ma, Fe–Mo mineralization at 150–140 Ma, and Mo–Fe mineralization at 135–130 Ma. The different metal associations formed during multiple stages of magmatism caused by ongoing subduction and rollback and/or retreat of the paleo-Pacific Plate.
... The U-Pb isotope system of the Wol-2 wolframite in the two deposits may be disturbed by the later hydrothermal process (after ~153 Ma), which cause their younger U-Pb ages relative to Wol-1. The late hydrothermal process (~134 Ma) was confirmed by U-Pb dating of hydrothermal zircon and by Rb-Sr dating of fluid inclusions hosted in quartz ( Wang et al., 2010;Wang and Ren, 2018). Considering the position of Wol-1 on the regression line defined by the uncorrected 207 Pb/ 206 Pb and 238 U/ 206 Pb data (Fig. 5), it is impossible that similar proportions of U and Pb were reset by hydrothermal alteration in the different wolframite grains from the two deposits. ...
... However, previous age determination suggested that the latest hydrothermal W mineralization occurred at ca. 134 Ma for both deposits (Fig. 7a). This event is constrained by Rb-Sr isochron dating of fluid inclusions hosted in quartz (133.7 ± 5.4 Ma; Wang et al., 2010) and hydrothermal zircon U-Pb dating (133.7 ± 1.3 Ma; Wang and Ren, 2018). Quartz from the mineralized veins commonly contains abundant secondary fluid inclusions (Cao et al., 2009;Ni et al., 2015;Legros et al., 2019), implying that the Rb-Sr isochron age likely dates a post-mineralization hydrothermal event. ...
... The previous W mineralization ages for the Yaogangxian and Piaotang vary from 170 ± 5 Ma to 153 ± 7 Ma and 160.7 ± 4.2 Ma Dong et al., 2014;Zhang et al., 2017;Wang and Ren, 2018) and hydrothermal W mineralization ( Peng et al., 2006;Mao et al., 2007;Liu et al., 2008;Wang et al., 2008;Wang et al., 2009;Wang et al., 2010;Bai et al., 2013;Zhang et al., 2017;Wang and Ren, 2018) from the Yaogangxian and Piaotang deposits. Probability density plots generated by the previously published ages of hydrothermal W mineralization (b) and granite emplacement (c) in the Nanling region (data from ages reviewed by Zhao et al., 2017;Zhao et al., 2018;Legros, 2017). ...
The wolframite series may contain relatively high U and low common Pb contents, and thus has been used for direct U-Pb dating of hydrothermal W mineralization. In this paper, we present in-situ laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) analysis of U–Pb isotopes and trace elements of wolframite crystals from the giant Yaogangxian and Piaotang W deposits in the extensive Nanling metallogenic belt, South China. The objective of this work is to directly constrain the timing of hydrothermal W mineralization in these two deposits. Wolframite crystals from both deposits show textural evidence for two generations. Early wolframite (Wol-1) has higher Fe and lower Mn contents relative to those in the late wolframite (Wol-2). Uranium is correlated positively with Nb ⁵⁺ , tetravalent (Ti, Sn, Zr, Hf), and trivalent (Sc, V, Y, REEs) cations in all wolframite samples, suggesting that the incorporation of U into wolframite is controlled by the coupled substitution mechanisms. The early and late wolframite domains from the Yaogangxian deposit yielded U–Pb ages of 159.1 ± 2.0 Ma (2σ; MSWD = 0.7) and 153.7 ± 0.7 Ma (2σ; MSWD = 0.5), respectively. Similarly, two wolframite generations from the Piaotang deposits yielded U–Pb ages of 159.5 ± 1.3 Ma (2σ; MSWD = 0.3) and 152.1 ± 0.9 Ma (2σ; MSWD = 0.5). The obtained U–Pb ages confirm two successive episodes of hydrothermal W mineralization at ~159 Ma and ~153 Ma in the Yaogangxian and Piaotang deposits. This study demonstrates the potential of U–Pb dating of wolframite by LA-ICPMS and highlights its importance for directly dating hydrothermal ore-forming processes.
... These ore deposits host more than 90% of China's W resources; over 56% of global W resources [1 -3]. Extensive research has been carried out around Yanshanian W mineralization and related igneous rocks using high-precision geochronological data [2,[6][7][8][9][10][11][12][13][14][15][16]. In contrast, the Indosinian igneous rocks and W deposits have been not widely concerned since they are small in size and bear minimal U, Nb, and Ta deposits [17][18][19]. ...
... HNCK10-9 and 10-10 are fine-grained granite (G-3) from the Nanwan deposit, and HNCK10-14 and 14-1 are biotite monzogranites (G-1) from the Manwan deposit. Four out of thirteen samples were selected carefully for LA-ICP-MS zircon U-Pb analysis (HNCK2, 10-8, 10-10, [10][11][12][13][14], and 6 out of 13 samples were selected for whole-rock Rb-Sr and Sm-Nd isotopic composition analysis (HNCK1, 2, 3, 10-5, 10-9, and 10-14). ...
Chuankou tungsten (W) ore field, with an estimated WO3 reserve exceeding 300,000 tonnes, is so far the largest Indosinian (Triassic) granite-related W ore field in South China. However, the precise emplacement ages, sources of granitoids, and their relationship with W mineralization are still not well understood. In this research, four main magmatic stages (G-1 to G-4) have been identified in the Chuankou ore field, including G-1 (phase I, biotite monzogranite), G-2 (phase II, two-mica monzogranite), G-3 (phase III, fine-grained granite), and G-4 (phase IV, granite porphyry). LA-ICP-MS U-Pb dating of zircon grains from granitoids of the Chuankou W ore field yields emplacement ages of 230.8 ± 1.6 Ma, 222.1 ± 0.56 Ma, 203.1 ± 1.6 Ma, and 135.5 ± 2.4 Ma, respectively. Granitoids from the Chuankou ore field contain a large amount of peraluminous minerals such as biotite, musvite, garnet and tourmaline. Geochemically, the granitoids have high Si and Al (A/CNK > 1.1) content but low alkali, Fe, Mg, Mn, and Ca content. Moreover, there is enrichment of Rb, Zr, Hf, Th, and U, but depletions of Ba, Sr, P, and Ti. The granitoids have especially low Zr + Nb + Ce + Y and high Rb/Ba ratios, further indicating a highly fractionated S-type granite affinity with a significant crystal fractionation process in regard to K-feldspar, plagioclase, biotite, Ti-bearing minerals (except rutile), zircon, apatite, allanite, and monazite. Whole-rock εNd(t) and TDM2 values are −10.77 and 2090 Ma for G-1, −9.09 to −7.47 and 1764–1684 Ma for G-2, −10.07 to −6.53 and 1669–1471 Ma for G-3, respectively, indicating that the Chuankou granitoids were derived from two episodes of partial melting of the Paleoproterozoic to Mesoproterozoic metamorphic basement. Trace elements within the zircons and whole-rock geochemistry yielded evidence of the close relationship between W mineralization and G-1 and G-2 granitoids of the Chuankou ore field. The batholith of the Chuankou ore field was formed 20–10 Ma later than the peak age of the collisions orogeny and formed in a post-collisional setting.
... Previous radiometric dating by different isotopic systems gave a broad age range from 133 to 162 Ma, including U–Pb age on zircon (158.0–161.8 Ma), a K–Ar age on muscovite (155.7 Ma) for granites (He et al., 2010; Mu and Lu, 1988; Zhang et al., 2009), and muscovite K–Ar and 40 Ar– 39 Ar ages (152–160 Ma, Bai et al., 2013; Chen et al., 2009; Mu and Lu, 1988; Zhang et al., 2009), a Rb–Sr isochron age of fluid inclusions in quartz (133–150 Ma, Chen et al., 2009; Li et al., 1993 ), and 40 Ar– 39 Ar ages of fluid inclusions in cassiterite and wolframite (154–159 Ma, Bai et al., 2013) for the hydrothermal system. The published ages are not consistent with each other, which led to confusion with respect to granite magmatism and W–Sn mineralization in the Piaotang deposit. ...
... Previous radiometric dating by different isotopic systems gave a broad age range from 133 to 162 Ma, including U–Pb age on zircon (158.0–161.8 Ma), a K–Ar age on muscovite (155.7 Ma) for granites (He et al., 2010; Mu and Lu, 1988; Zhang et al., 2009), and muscovite K–Ar and 40 Ar– 39 Ar ages (152–160 Ma, Bai et al., 2013; Chen et al., 2009; Mu and Lu, 1988; Zhang et al., 2009), a Rb–Sr isochron age of fluid inclusions in quartz (133–150 Ma, Chen et al., 2009; Li et al., 1993 ), and 40 Ar– 39 Ar ages of fluid inclusions in cassiterite and wolframite (154–159 Ma, Bai et al., 2013) for the hydrothermal system. The published ages are not consistent with each other, which led to confusion with respect to granite magmatism and W–Sn mineralization in the Piaotang deposit. ...
The large low-grade Piaotang W–Sn deposit in the southern Jiangxi tungsten district of the eastern Nanling Range, South China, is related to a hidden granite pluton of Jurassic age. The magmatic-hydrothermal system displays a zonation from an inner greisen zone to quartz veins and to peripheral veinlets/stringers (“Five-floor zonation model”). Most mineralization is in quartz veins with wolframite > cassiterite. The hidden granite pluton in underground exposures comprises three intrusive units, i.e. biotite granite, two-mica granite and muscovite granite. The latter unit is spatially associated with the W–Sn deposit.
Combined LA-MC-ICP-MS U–Pb dating of igneous zircon and LA-ICP-MS U–Pb dating of hydrothermal cassiterite are used to constrain the timing of granitic magmatism and hydrothermal mineralization. Zircon from the three granite units has a weighted average 206Pb/238U age of 159.8 ± 0.3 Ma (2σ, MSWD = 0.3). The cathodoluminescence (CL) textures indicate that some of the cassiterite crystals from the wolframite-cassiterite quartz vein system have growth zonations, i.e. zone I in the core and zone II in the rim. Dating on cassiterite (zone II) yields a weighted average 206Pb/238U age of 159.5 ± 1.5 Ma (2σ, MSWD = 0.4), i.e. the magmatic and hydrothermal systems are synchronous. This confirms the classical model of granite-related tin–tungsten mineralization, and is against the view of a broader time gap of >6 Myr between granite magmatism and W–Sn mineralization which has been previously proposed for the southern Jiangxi tungsten district. The elevated trace element concentrations of Zr, U, Nb, Ta, W and Ti suggest that cassiterite (zone II) formed in a high-temperature quartz vein system related to the Piaotang granite pluton.
... 135-130 Ma, Zhang et al., 2018a;Zhang et al., 2013;Zhang et al., 2018a). However, other scholars put forward different opinions on the mineralization age according to the relationship between the magnetite orebodies and other wall rocks, and provided chronological evidences of 160-150 Ma (Wang et al., 2010;Yan, 2013;Zhang et al., 2015;Wang et al., 2017a). Especially in the last few years, zircon U-Pb ages of 160-150 Ma for granites from these Makeng-style deposits were reported, such as 154.9 ± 0.9 Ma for Makeng deposit (Yan, 2013), 152.7 ± 1.4 Ma for the Luoyang deposit (Yu, 2017), and 150.2 ± 0.5 Ma for Dapai deposit (Yuan et al., 2020). ...
To reveal the genesis of Makeng-style iron polymetallic deposits from SE China in the paleo-Pacific tectonic domain, a new analytical method of LA-ICPMS garnet U-Pb dating and rare Earth element analysis was conducted for the Makeng, Luoyang, Dapai and Pantian deposits. The U-Pb dating results of nine garnet skarn samples from these deposits suggested that the Makeng-style iron polymetallic deposits mainly formed during 137–130 Ma, which is consistent with the zircon U-Pb and molybdenite Re-Os ages. This study provides more direct evidence of the mineralization age and the relationship between mineralization and granite, compared with previous studies on the zircon U-Pb dating for granites in the ore fields. Rare Earth element (REE) analysis results and REE patterns of four representative garnet samples from the Makeng, Luoyang, Dapai and Pantian deposits show that they are similar to typical skarn deposits, but obvious differences in the REE distribution types indicate that the ore-forming process may be distinct due to different mineralizing fluid for these Makeng-style deposits. Our new garnet U-Pb dating and rare Earth element analysis result not only provides new evidence for the mineralization age and genesis of the Makeng-style deposits but is also of great significance to promote the application of U-Pb dating methods to research skarn type deposits.
... The Zuluhong polymetallic deposit is also a W-Cu ore deposit and has some features that differ from those of the deposits in the Jiangnan orogenic belt. Firstly, the magma source rocks of the W-Cu deposits in the Jiangnan orogenic belt are crustal sediments and the granites are S-type granites with limited mantle input [69,70]. However, the Zuluhong monzogranite has high SiO 2 , high alkalis, high FeO/MgO ratios (average = 4.2), high Rb/Sr ratios (average = 1.68), negative Ce anomalies, and contains accessory fluorite and tourmaline. ...
The Zuluhong quartz-vein-type polymetallic deposit, located in the Alatau area of Western Tianshan, China, is a particular and typical tungsten deposit associated with copper. This paper presents major and trace element analyses of magmatic and altered (i.e, chloritized) biotite from the deposit, in order to identify the source of the magmas and characterize the mineralization physical-chemical condition. Magmatic biotite is Fe-rich and has high Rb/Ba ratios (0.27–9.14), indicative of extensive differentiation of granite. Moreover, magmatic biotite has total rare earth element (∑REE) contents that are 5–10% of the whole-rock contents, shows slight light REE depletion, and negative Ce anomalies. Magmatic biotite is enriched in some large-ion lithophile elements (LILE; e.g., Rb and K) and depleted in some high-field-strength elements (HFSE; e.g., Th and Nb). These geochemical features, coupled with geological evidence, indicate that the Zuluhong intrusion is a highly fractionated I-type granite derived from lower crustal melting. During ore formation, magmatic biotite was partially to totally altered to chlorite due to interaction with ore-forming fluids. The temperature and oxygen fugacity decreased during alteration. The mineralization in the Zuluhong polymetallic deposit can be divided into at least two stages. In the early stage, quartz-vein-type wolframite mineralization formed from Si- and volatile-rich fluids that were derived from fractionated granitic magma. In the later stage, W–Cu ores formed as metal sulfides were dominated by chalcopyrite. The later ore-forming fluids experienced a decrease in temperature and oxygen fugacity as they reacted (i.e, chloritization and lesser silicification) with reducing wall rocks around the contact zone of the intrusion.
... The Nanling W-Sn belt, a world-class W and Sn province within the South China block (Fig. 1), extends across the southern Hunan, southern Jiangxi, northeastern Guangxi and northern Guangdong provinces (Mao et al., 2007. Granitic intrusions, mainly Middle to Late Jurassic granites with distributed late Silurian, Late Triassic, and Cretaceous granite plutons, are widely exposed in this area and coeval with most W-Sn polymetallic deposits (Xu et al., 1983;Hua et al, 2005;Mao et al. 2007Mao et al. , 2011Mao et al. , 2013Mao et al. , 2019Yuan et al., 2019;Wang et al., 2010, Wang et al., 2014a. W deposits with diverse metal associations (Sn, Mo, Bi, Cu, Ag, Sb, Hg, and rare earth elements) are densely distributed in southern Jiangxi Province, and many mineralization ages have been obtained by molybdenite Re-Os, muscovite Ar-Ar and cassiterite U-Pb dating (Table 1). ...
In situ LA-ICP-MS provide high-resolution spatial analysis of wolframite grains. In this paper, wolframite U-Pb isotope dating is presented to directly constrain the timing of W mineralization in five granite-related vein-type W-polymetallic deposits from different ore-concentrated areas in southern Jiangxi Province, South China. In the Jinzhuping, Changkeng, Keshuling, Taoxikeng, and Bikeng deposits, wolframite is the dominant ore mineral, occurring as coarse, euhedral grains that are associated with gangue minerals such as cassiterite, scheelite, molybdenite, sphalerite, (±) galena, (±) marmatite, pyrite, quartz, (±) chlorite, (±) fluorite, and calcite. Wolframite U-Pb dating yielded 206Pb/238U ages of 154.2±4.1 Ma for the Jinzhuping deposit, 157.8±9.4 Ma for the Changkeng deposit, 150.3±1.8 Ma for the Keshuling deposit, 153.8±4.0 Ma for the Taoxikeng deposit, and 152.3±5.6 Ma for the Bikeng deposit, respectively. By comparing the published minerlizing ages of the W-Sn polymetallic deposits in the Nanling region, we suggest that three stages of W mineralization occurred from the Triassic to the Lower Cretaceous.
... In a δD VSMOW -δ 18 O diagram of fluid inclusions trapped in hydrothermal quartz and calcite, most samples from representative Sb deposits plot within the transition field of meteoric water and magmatic/metamorphic water (Fig. 8), indicating a mixing origin of ore-forming fluids, i.e., admixture of magmatic or metamorphic water and meteoric water. However, because the latest metamorphic event documented in this district (460-400 Ma;Faure et al., 2009;Wang et al., 2010) occurred many hundred millions of years ago before the timing of Sb mineralisation in the GSMB, metamorphic fluids thus are unlikely to be candidates as one end-member of oreforming fluids. In addition, the majority of large Sb deposits is primarily hosted in Neoproterozoic epimetamorphic clastic rocks or Devonian-Carboniferous sedimentary rocks, with no obvious direct spatial relationship to magmatic activity, indicating that magmatic fluids seem unlikely to be the major component of ore-forming fluids for these Sb deposits. ...
The giant Sb metallogenic belt in South China (GSMB) has been proved to provide approximately half the world’s reserves and Sb production. This metallogenic belt is tectonically located along the transition zone between the Yangtze and Cathaysia blocks, covering an area of ∼1900 km long and ∼200 km wide, with a set of large or giant Sb deposits such as the Xikuangshan, Banxi, Woxi, Qinglong, and Banpo-Banian. The Sb deposits have the following features in common: localisation in sedimentary rocks or counterpart metamorphic rocks as veins or strata, structural-tectonic control of mineralisation along the regional NE-trending faults, and the presence of intermediate-mafic dyke rocks in the belt whose relationship with Sb mineralisation is not obvious. Fluid inclusion data show that the Sb mineralisation in this belt generally occurred under low-temperature and low-salinity conditions (140–250 °C, 0.2%–10% NaClequiv.). Abundant isotope data suggest that the Sb deposits in this belt were dominantly generated by crustal fluids from the Proterozoic basement sequences and fresh meteoric water or their mixture with various proportions, whereas the magmatic contribution to Sb mineralisation in this region is a preferential heat source rather than a material supplier (i.e., fluids and metals). The reported geochronological data of representative Sb deposits suggest an age distribution trend of Sb mineralisation, from 120–130 Ma in the Xikuangshan, Banxi, Woxi, Banpo and Banian Sb deposits in the northern and central parts of the GSMB, to 140–165 Ma in the Qinglong, Muli and Maxiong Sb deposits in the southern part of this belt. This age trend of the GSMB is largely comparable to that of Mesozoic igneous rocks in the Cathaysia Block, indicating both of them are the products of the west-northwestward flat-slab subduction and post-subduction of the paleo-Pacific Plate during the Late Mesozoic. In combination of the geological, geochemical, and reported geochronological data, we proposed that the Sb deposits in GSMB in South China probably have been mainly generated by low-temperature and low-salinity crustal fluids which leached Sb and S from basement sequences under an extensional setting during Late Mesozoic.
... garnet) if they formed at depth. Furthermore, the host rocks and enclaves should generally have distinctly different zircon U-Pb ages and whole-rock Sr-Nd isotopic ratios (Li et al., 2010;Zheng et al., 2014). Based on our field and petrological observations, the MMEs in Shaocunwu granodiorite intrusion lack hornfels reaction rims or residual high-pressure mineral residues. ...
Magmatic microgranular enclaves (MMEs) are widely developed in the Shaocunwu granodiorite at the northeast margin of the eastern Jiangnan orogenic belt. Field geology showed that the MMEs occur as irregular ellipsoids near the edge of the intrusion, and consist of diorite, dominantly composed of amphibole, biotite, and plagioclase grains, with minor acicular apatite. Zircon U‐Pb dating showed the ages of the host granodiorites and MMEs are 145.9±1.1Ma and 145.6±2.5Ma, respectively, indicating both originated during coeval late Jurassic magmatism. Whole‐rock geochemical results show that the host granodiorite and MMEs have similar rare earth and trace element partition curves in spider grams, and similar 87Sr/86Sr, and 147Nd /144Nd isotope ratios, and their zircon 177Hf/176Hf isotopic ratios are similar. Geochemical studies indicate that both the host granodiorite and MMEs formed by mixing of coeval magma. Zircon Ti thermometers and oxygen fugacity of the host granodiorite and the MMEs show high oxygen fugacity, similar to that of W‐Cu (Mo) mineralized granitoids in the eastern Jiangnan orogenic belt. A similar magma mixing process was probably one of the mechanisms that generated the W‐Cu (Mo) fertile melts.
... Lamporphry + Granite porphyry + Olivine basalt + Devonite Meng et al., 2012;Wang et al., 2003Wang et al., , 2010Xie et al., 2002;Zhao et al., 1998 Coastal Quartz porphyry + Granite porphyry + Biotite granite + Syenogranite + alkali feldspar granite + Alkaline granite + Grandiorite + Quartz diorite + Basaltic andesite + Proterobase porphyrite + rhyolite + Tuff + Trachybasalt Huang & Sun, 1986;Qiu & Wang, ;Shen, Ling, Li, Huang, & Wang, ;Shu et al., 2004;Sun, 2006;Wang, 2004;Wang & Shu, 2007;Wang et al., 2003Wang et al., , 2005Zhou, 2007;Zhou et al., 2006 F (Dalrymple & Jackson, 1973;Morgan, 1972;Tarduno, 2007). Likewise, the typical polymetallic mineralization of mantle origin becomes older eastward (150-120 Ma) also suggests that this composite model of mantle plume and rollback subduction of Palaeo-Pacific Plate (Wang, 1998). ...
During the Late Cretaceous period, massive magmatism occurred in South China. Eastern Hunan Province is situated in the inland part of South China. Comparing with the coastal area, the inland of South China is characterized by the absence of intermediate‐acid intrusive rocks, but the occurrence of multiple mafic rocks. To date, the emplacement and triggering mechanism of magmatism of inland South China is still very puzzling. In this article, we address this question by concentrating on the basalt exposed in eastern Hunan Province. Geochronologically, three stages of zircon grains, which include xenocrysts and authigenic crystals (rare), are recognized, and the last stage of zircon grains with a concordant age of 79.93 ± 0.47 Ma (MSWD = 1.9) represents the actual crystallization age of basaltic magma. Geochemically, the basalt in eastern Hunan Province has low TiO2 and K2O contents (1.11–2.63 and 0.28–2.88 wt%) but high alkali contents (3.75–6.58 wt%) and K2O/Na2O ratios (0.05–0.56). The basalts from eastern Hunan Province are enriched in large‐ion lithophile elements and light rare earth elements and obviously depleted in heavy rare earth elements with weak negative Eu anomalies (Eu/Eu* = 0.87–1.26); they lack significant Ti, Nb, Ta, etc., depletions. These features are much different from those of coastal basalt with strong arc‐related signatures. The incompatible element ratios and Sr–Nd–Pb isotope compositions commonly imply significant EMII‐type OIB‐like source region and within‐plate basalt characteristics. The basalt may have suffered from earlier partial melting of garnet‐spinel peridotite and later rapid fractional crystallization of mafic minerals (olivine and pyroxene). Significant geochemical and petrological discrepancies between inland basalt and coastal basalt suggest a subduction‐absent within‐plate setting for inland basalt but a strong subduction‐related signature for coastal basalt. The magmatic age of mafic rocks from inland South China hold a significant tendency to become younger to the west. The spatial and temporal distribution and variation of components of basalt in South China indicated a mantle plume model which is derived from the 670 km thermal boundary layer (670 TBL) between the lower and upper mantle. The trigger mechanism of this model could be attributed to the westward steep rollback subduction of the Palaeo‐Pacific Plate in the Late Cretaceous. a, The spatial and temporal distribution of alkaline basalts of inland South China presents a tendency becoming younger toward the east; b, The steep rollback subduction causes the imbalance of 670TBL, and induce the intrusion of small blobs (mantle plume); c, The dynamic tectonic mechanism of South China in late Mesozoic is characterized by the deep rollback subduction and mantle plume. The effect is similar to the Hawaiian‐Emperor track, where the relative motion between the mantle plume and the upper plate along a north‐south axis caused the formation of the Hawaii volcanic chain from 80 to 47 Ma
... Magmatic intrusions in the Caixiashan deposit area consist of an exposed diorite-quartz diorite stock and a number of dykes of various compositions including diorite, quartz diorite and diabase (Cao et al., 2012). The stock was emplaced in the Mesoproterozoic Xingxingxia and Kawabulake groups in the northern mining area and has a whole rock Rb-Sr isochron age of 323 Ma ( Fig. 2; Gao et al., 2006;Wang et al., 2010). Hornfels and hydrothermal alterations of tremolite, chlorite, silica, carbonate and actinolite were observed in the contact zones between the stock and the Kawabulake Group ( Fig. 2; Cao et al., 2012Cao et al., , 2013. ...
... Most Mesozoic W-Sn deposits in the Nanling range formed between 160 Ma and 150 Ma, based on U-Pb ages of cassiterite and wolframite, Ar-Ar ages on mica and Re-Os ages on molybdenite (e.g., Bai et al., 2011;Feng et al., 2011;Zhang et al., 2015Zhang et al., , 2017Deng et al., 2019). However, younger ages have also been reported, ranging from 160 to 130 Ma, according to mica Ar-Ar dating from several W-Sn deposits in the Nanling Range (e.g., Liu et al., 2008;Chen et al., 2009;Zhang et al., 2009;Wang et al., 2010a;Bai et al., 2013). Five deposits yielded ca. ...
The W-Sn Maoping deposit and related W-Sn deposits from the world-class Nanling Range in Southeast China formed at ca. 160 Ma and experienced several phases of metal addition and metal redistribution between 160 and 130 Ma. Isotopic dating of ore mineral (wolframite) of Maoping demonstrates that W was deposited first, during a hydrothermal event at ca. 160 Ma. Successive fluid episodes, at ca. 156 Ma (Mo and Sn-rich fluid) and 152 Ma (REE-rich fluid), resulted in the formation of REE- and Fe-Cu-Zn-sulfide minerals. A last fluid event occurring at ca. 130 Ma was responsible for the deposition of Zr-REE-Nb-Ta minerals that are attributed to magmatic fluids derived from unexposed magmatic bodies. The three episodes of fluid circulation post-dating W deposition resulted in partial to complete resetting of the isotopic systems (mica, wolframite, xenotime), which are conventionally used for dating such deposits. We show that W and Sn mineralization in the Nanling Range formed during a unique fluid event at ca. 160 Ma. Later fluid episodes redistributed the previously deposited metals and sequentially introduced additional metals, including Mo-Sn, Fe-Cu-Zn, and Zr-REE-Nb-Ta. Direct dating of paragenetically well-constrained minerals is therefore critical for determining the age and the duration of mineralizing processes and for characterizing the fluid evolution of magmatic-hydrothermal systems, as exemplified in the Nanling Range.
... The quartz monzonite porphyry, which is associated with the mineralization, shows a single-grain zircon U-Pb age of 139.2 ± 0.5 Ma (Qin et al., 1996). The Rb-Sr isochron age of quartz in the Pb-Zn ore constrained as 140.0 ± 11.0 Ma (Wang et al., 2010) and the Rb-Sr isochron age from sphalerite and pyrite at 142.7 ± 1.3 Ma (Li et al., 2014b) mark the Early Cretaceous mineralization event. ...
Located in the eastern section of the Central Asian Orogenic Belt, the Jiawula Ag-Pb-Zn deposit is classified as a volcanic to subvolcanic related vein-type ore deposit. New U-Pb zircon geochronology, whole-rock geochemistry, mineral chemistry, and Sr-Nd isotope data are presented for the intrusions in the Jiawula deposit in order to evaluate the timing, petrogenetic type of the granitoid rocks, origin and evolution of magmatism, geodynamics, and to establish its relationship with lead-zinc mineralization. Zircon SHRIMP U-Pb analyses yield weighted mean ages of 150.1 ± 1.8 Ma for quartz porphyry, 148.8 ± 2.2 Ma for syenite porphyry, and 145.3 ± 1.9 Ma for monzonite porphyry, indicating a Late Jurassic (Yanshanian) magmatic event. An earlier magmatic event (Indosinian) occurred during the Late Permian to Early Triassic from ca. 254 Ma to ca. 247 Ma and is represented by granodiorite (254 ± 2 Ma), dacite porphyry (252.9 ± 4.8 Ma), and diorite porphyry (278 ± 4.1 Ma). Both the Indosinian and Yanshanian igneous rocks are classified as I-type granitoids. The late Jurassic intrusions are highly fractionated and characterized by negative anomalies of Eu, Sr, P, and Ti. The hypabyssal intrusions have initial ⁸⁷Sr/⁸⁶Sr values between 0.70458 and 0.70522, and εNd(t) values of −3.4 to −0.2, indicating relatively older crust in Jiawula among more juvenile crust in this area. Magma generation in Jiawula is linked to juvenile lower crustal and slightly enriched mantle sources. The ∼250 Ma magmatic episode in Jiawula might be related to the subduction of the Mongol-Okhotsk oceanic plate towards the south beneath the Erguna massif. The ∼150 Ma magmatic event occurred after the closure of the Mongol-Okhotsk Ocean followed by the change in subduction direction of the Paleo-Pacific plate. Varying temperature, stronger fractionation and higher oxygen fugacity related to the magmatic-hydrothermal transition caused Pb-Zn mineralization.
... exhumation thickness and exhumation rate) (Meyer, 1985; Zhai et al., 2002; Zhai and Wang, 2011; Groves et al., 2005; Kesler and Wilkinson, 2006; Wang J P et al., 2008 ). The Tianshan orogen is one of the most important polymetallic deposits in Northwest China and the mineralization mostly occurred in the late Paleozoic ( Wang et al., 2006; Chen et al., 2007; Wang, 2008; Zhang et al., 2009; Wang et al., 2010; Xue et al., 2011; Zhang Z H et al., 2012; Sun et al., 2012; Zhang X et al., 2012). Thus, it is very important to reveal the exhumation history by multi-methods thermochronology , which would be helpful to understanding the regularity of ore formation, metallogenic prediction and exploration. ...
The uplift and exhumation process in the Tianshan orogen since the late Paleozoic were likely related to the preservation of ore deposits. This study involved reconstructing the whole tectonic thermal history of the Ouxidaban pluton in central South Tianshan Mountains based on hornblende/plagioclase Ar-Ar and zircon/apatite (U-Th)/He methods. The thermal history and uplift process of central South Tianshan Mountains since the late Paleozoic were analyzed according to the results of previous works and cooling/exhumation rate features. The hornblende yields a plateau age of 382.6±3.6 Ma, and the plagioclase yields a weighted mean age of 265.8±4.9 Ma. The Ouxidaban pluton yields weighted mean zircon (U-Th)/He age of 185.8±4.3 Ma and apatite (U-Th)/He age of 31.1±2.9 Ma, respectively. Five stages of tectonic thermal history of South Tianshan Mountains since the late Paleozoic could be discriminated by the cooling curve and modeling simulation: (1) from the latest Silurian to Late Devonian, the average cooling rate of the Ouxidaban pluton was 7.84°C/Ma; (2) from the Late Devonian to the latest Middle Permian, the average cooling rate was about 2.07°C/Ma; (3) from the latest Middle Permian to the middle Eocene, the cooling rate decreased to about 0.68°C/Ma, suggesting that the tectonic activity was gentle at this time; (4) a sudden increase of the cooling rate (5.00°C/Ma) and the exhumation rate (0.17 mm/a), and crustal exhumation of ~1.83 km indicated that the Ouxidaban pluton would suffer a rapid uplift event during the Eocene (~46-35 Ma); (5) since the middle Eocene, the rapid uplift was sustained, and the average cooling rate since then has been 1.14°C/Ma with an exhumation rate of about 0.04 mm/a and an exhumation thickness of 1.33 km. The strong uplift since the Cenozoic would be related to a far-field effect from the Indian and Eurasian plates’ collision. However, it was hysteretic that the remote effect was observed in the Tianshan orogenic belt.
... A single-grain zircon U-Pb age of the quartz monzonite porphyry intrusion shows an age of 139.2 ± 0.5 Ma, whereas K-Ar dating of sericite from the central part of the mineralization associated with vein copper mineralization yielded 121 ± 0.5 Ma (Qin et al., 1996). The Rb-Sr age of quartz in the Pb-Zn ores is constrained as 140.0 ± 11.0 Ma (Wang et al., 2010), whereas the Rb-Sr isochron age from sphalerite and pyrite is 142.7 ± 1.3 Ma marking Early Cretaceous mineralization . ...
The Jiawula Ag-Pb-Zn deposit is located in the northern part of the Da Hinggan Mountains metallogenic belt in the eastern section of the Central Asian Orogenic Belt. Sphalerite, galena, pyrite, chalcopyrite, and arsenopyrite are the major sulfide minerals occurring in this deposit. Here we report results from electron probe micro-analysis (EPMA), thermoelectricity, and sulfur isotope studies of the constituent silver minerals and sulfide phases of the Jiawula deposit. Petrographic observations and EPMA study reveal abundant silver mineralization in the ore, especially within sphalerite and galena. Discrete grains of silver minerals (including argentite, pyrargyrite, and canfieldite) and isomorphism in silver-bearing sulfides are identified. Silver and tellurium contents in galena are relatively high and show interrelationship. Significant substitution of S by Te in the galena lattice facilitates silver entering the galena structure, which might have been promoted by relatively low lgfS2. The thermoelectric coefficient of pyrite shows a marked gradient from N-type to P-type from pre- to post-metallogenic stages. Pyrites in Jiawula are enriched in Co and As and in the absence of Ni, displaying features typical of epithermal deposits. The isotopic data present a close relationship between the sulfur source and magmatism.
... "Makeng type"iron deposits has been controversial with regards to its genesis so far. Isotopic chronology studies on metallogenic epoch and related magmatism time have significantly progressed. The Re-Os isochron ages of the associated molybdenite in Makeng are (130.50±0.92)Ma (Wang. et al, 2010) and (133.0±1.9)-(134.0±4.2)Ma (Zhang. et al, 2012) respectively which are similar to the age of Juzhou pluton from zircon U-Pb isotopic dating (Mao. et al, 2006;). The Re-Os isotope model age of molybdenite of Luoyan iron deposit in Zhangping is (133.0±1.9)-(134.0±4.2) Ma and the crystallizing ages of granite-porphyry and porphyritic f ...
The Dapai iron polymetallic ore deposit in Yongding country of Fujian province is located in the southern margin of the Southwestern Fujian depression belt, where unique tectonic environments have produced favorable ore-forming geological conditions. It is formed by a set of carbonate rocks and coal-bearing clastic rock sediments of late Paleozoic hosting iron, lead and zinc polymetallic ore deposits and a large number of intrusive granite magma of late Mesozoic. The Makeng type iron deposits mainly occurred in the middle and upper carboniferous to lower permian carbonate formation, around where we can also see the late Mesozoic granite rock bodies. The genesis of Makeng type iron deposits has long been disputed, which include the submarine volcanic eruption (exhalation) of late Paleozoic-superimposed reformation and the strata bound skarn which are related to the Mesozoic granitic magmatic and carbonate rocks. To explore the genesis of the Makeng type iron deposits, It is necessary to do a comparative study of the metallogenic epoch and the relevant magmatism age. The Dapai iron polymetallic ore deposit is newly discovered, it has the characteristics of the Makeng type iron deposits (Xu et al, 2008). Generally, the ore body is strata bound and it is associated with some intermediate-acid intrusive rocks. Therefore this paper selects the molybdenites from the iron ore body in the Dapai polymetallic ore deposits to develop the study of Re-Os isotope geochronology in order to discuss the relationship between the Mesozoic magmatism and iron polymetallic ore deposits mineralization.
The Baishi W-Cu deposit is located in the Nanling metallogenic belt, which is famous for its numerous W deposits and reserves. The formation age of this deposit remains unclear. In order to further infer the formation age of the deposit, this study conducted detailed LA-ICP-MS U-Pb isotopic analyses of zircon and monazite selected from ore-related Baishi granite. The LA-ICP-MS zircon U-Pb weighted average ages of Baishi granite were determined to be 223 ± 2 Ma and 226 ± 1 Ma, and the LA-ICP-MS U-Pb weighted average ages of monazite were determined to be 224 ± 2 Ma and 223 ± 1 Ma. The BSE image of monazite was homogeneous, and the pattern of rare earth elements had an obvious negative Eu anomaly, indicating that monazite was of magmatic origin. Combining the ages of zircon and monazite, this study inferred that Baishi granite and the Baishi W-Cu deposit formed in the Triassic. The determination of the ore-forming event of the Baishi W-Cu deposit provides new data regarding the important Indosinian (Triassic) mineralization events in the Nanling metallogenic belt and suggests that geologists should strengthen the prospecting work of Indosinian tungsten deposits in the Nanling area. In terms of tectonic setting, it was inferred that the Triassic Baishi W-Cu deposit was formed in the extensional environment after intracontinental orogeny.
South China is a well-known grand felsic igneous rocks province. However, it is still controversial and not well understood whether the Mesozoic tectono-magmatic pattern is dominated by the subduction of the paleo-Pacific oceanic plate. In this study, we address this question by concentrating on the long-term evolutionary Guandimiao batholith, which has complex lithofacies with different formation ages and can be a superb record of the Mesozoic tectonic evolution in South China. Geochronologically, four stages of magmatism can be identified combined with previous reports: granodiorite (G1, 239 Ma), biotite monzogranite (G2-1) and two-mica monzogranite (G2-2) (230-203 Ma), granite porphyry (G3, 211-190 Ma), and lamprophyre (L4, 121 Ma). G1 and G2-1 have an affinity with I-type granite and were derived from metabasaltic to metatonalitic sources, whereas G2 and G3 show S-type granite characteristics and were derived from the para-metamorphic basement of the Cathaysia block. The L4 was derived from partial melting of garnet and spinel lherzolite and underwent mixing between Mesoproterozoic pelagic and/ or terrigenous sediments and the subcontinental lithosphere mantle (SCLM) of South China. The granitoids of the Guandimiao batholith underwent intensely fractional crystallization of feldspar, Ti-bearing minerals, allanite and monazite. The zircon U-Pb dating of L4 in the Guandimiao batholith completely records the six stages of pre-Mesozoic tectonic events in the SCB. During the Mesozoic, the main body of the Guandimiao batholith (G1, G2-1 and G2-2) recorded the closure of the paleo-Tethys Ocean in the Triassic and the subsequent regional extension of the postcollision. G-3 and L4 of the Guandimiao batholith documented the transition of tectonic and dynamic regimes in the early Yanshanian and the rollback and steep subduction of the paleo-Pacific Ocean in the late Yanshanian.
China has the largest antimony (Sb) resources, products and consumption in the world, which plays an important role in the global antimony trade. Chinese Sb deposits are characterized by large resources, concentrated distributions, primary deposits dominating, and associating with numerous valuable elements and minerals. In China, most of Sb deposits are located at the edges of various geotectonic units and are constrained by plate suture zones or large deep fault belts. There are 5 Sb metallogenic belts were distinguished in this paper including the Tianshan-Xingmeng Sb ore belt, Qin-Qi-Kun Sb ore belt, Qiangtang-Sanjiang Sb ore belt, South China Sb ore belt and South Tibet Sb ore belt. Sb deposits are hosted in Mesoproterozoic to Quaternary formations, but most of them were occurred in Precambrian, Devonian and Triassic strata. The ages of mineralization of Sb deposits in China are mainly concentrated in the Indosinian, Yanshanian and Himalayan, while the large-scale mineralization is restricted within the Jurassic to Cretaceous of the Yanshanian. Antimony deposits have multiple sources of ore-forming metals and fluids, of which Precambrian basement strata may be one of the most important. The magmatic activity caused by asthenosphere upwelling may be the main evocator for driving the circulation of groundwater to extract mineralized elements. According to the results of China National Mineral Resources Potential Assessment Project (NMRP), China delineated 94 Sb prospect areas, in which, 15.43 million tons of unproven Sb metal were predicted within 2 km below the surface. Among the 5 Sb ore belts, the South China Sb Ore Belt has the largest number of deposits, identified resources and resources potential, showing strongest mineralization intensity. The Qiangtang-Sanjiang Sb Ore Belt followed, where may become the future antimony resource-base of China.
Granites generated in massive volume during an orogeny frequently concentrate abundant trace metals over the requirement of commercial mining. Tungsten mineralization usually develops in massive granite generated during orogenic activities. However, there is no general metallogenic model capable of explaining metal enrichment. In specific, the source of the metals and criteria to distinguish barren from mineralized granites have yet to be clearly identified. In this paper, we present that the muscovite alkali-feldspar granites, as the parental rocks to the tungsten mineralization in the Nanling Range (South China), may result from extremely fractionated granitic magma from the deep-seated magma chamber. Further, the geochemical and geochronological evidence on hydrothermal rims and magmatic cores of zircon grains from these granites reveals two stages of magmatic activities, i.e. the syn-orogenic biotite monzogranites at 155.0 ± 1.0 Ma and the post-orogenic muscovite alkali-feldspar granites at 133.4 ± 1.0 Ma respectively. Since the two granites with the similar zircon εHf(t) values and in the same location should develop from the same magma chamber during the Yanshanian movement, we interpreted that the deep-seated magma chamber survived longer than 20 Myr, within which a continuously fractional crystallization led to unusual concentration of incompatible elements (tungsten, volatile, and aqueous fluid) in the residual magma. When the regional tectonic environment entered the extensional regime at ~133 Ma, the highly fractionated residual magma ascended rapidly from the magma chamber, generated the muscovite alkali-feldspar granite, and developed the accompanying giant tungsten deposit. Our thermal modeling supports the possibility of an ultra-long magma residence time at deep-seated chamber.
The Nanling Range is one of the rare large granite provinces in China, and many of the exposed Mesozoic granites are closely related to tungsten-tin polymetallic mineralization in time, space and genesis. Southern Jiangxi Province, characterized by densely distributed tungsten deposits and multiple associated resources (Sn, Mo, Bi, Cu, Ag, Sb, Hg, and rare earth elements), is an important part of the Nanling region. Keshuling, Baxiannao and Bikeng in southern Jiangxi are exocontact-zone quartz vein subtype tungsten deposits, while Jinzhuping is a endocontact-zone quartz vein subtype tungsten-tin deposit. In this study, we present four cassiterite U-Pb ages and five molybdenite Re-Os ages from samples of the above four deposits to define the metallogenic era. The cassiterite U-Pb ages for Keshuling, Baxiannao and Bikeng are 157.5±4.1 Ma, 158.8±2.9 Ma and 159.0±2.0 Ma within the 2σ error, while the cassiterite U-Pb and molybdenite Re-Os ages of the endocontact-zone quartz vein subtype ores in Jinzhuping are 156.6±3.8 Ma and 157.9±4.2 Ma, respectively. Comparison of these ages of ore minerals with the genetically related granitic rocks shows that there was no resolvable time difference between the granite emplacement and hydrothermal mineralisation, both of which were products of early tectono-magmatic activity in the Yanshanian period in Nanling. The ore-forming ages of the different types of ore bodies generally become younger from the granitic bodies outward. We present a genetic model in which ore forming fluids migrated outward from the granitic source and formed ore bodies in tungsten-tin deposits of southern Jiangxi Province.
The Changkeng quartz vein tungsten deposit is located in the eastern part of the Helong ore field, Nanling region, South China. It has a proven WO3 reserves of 9680 tons WO3, and an average grade of 2.98%. It contains 28 ore-bearing quartz veins, and the mineralization stages are divided as follows: (I) quartz-wolframite-cassiterite-scheelite stage; (II) quartz-wolframite-scheelite-molybdenite-pyrite-sphalerite-galena-flourite stage; (III) quartz-calcite-flourite stage. The intrusion within the deposit is concealed, and comprising medium- and coarse-grained biotite monzogranite. Zircon grains from the Changkeng pluton have a U-Pb age of 156.7 ±0.54 Ma (MSWD = 2.9). Cassiterite grains from stage I yield a weighted mean ²⁰⁶Pb/²³⁸U age of 156.1±3.4 Ma (MSWD = 3.4). Molybdenite separates from stage II have a well-defined ¹⁸⁷Re/¹⁸⁷Os isochron age of 156.9±2.0 Ma (MSWD=0.77), with model ages ranging from 155.6±2.5 to 157.5 ± 2.2 Ma. The zircon εHf(t) values range from -14.1 to -11.1, and the Hf two-stage model ages range from 1.87 to 2.06 Ga, indicating a primary reworking of the Paleoproterozoic crust. The low rhenium contents (0.3238 to 8.763 μg/g) in molybdenite suggest that the ore-forming materials was derived from a crustal source. The age consistence between the intrusion and mineralization, together with the Hf and Re isotope signature, all indicate a close genetic link between magmatism and mineralization. The Changkeng deposit is an example of a Jurassic regional-scale tungsten-tin ore-forming event between 160 and 150 Ma in the Nanling region, South China.
The Luoyang Fe polymetallic deposit is a well‐known Makeng‐type ore deposit in a late Paleozoic basin in southwest Fujian, southeast China. To investigate the generation of Makeng‐type Fe deposits, we conducted an integrated study of geochronology and S–Pb–O–H isotope compositions of the Luoyang Fe deposit. The LA–ICP–MS zircon U–Pb ages of the granite and Re–Os ages of the molybdenite suggest that the emplacement of the granite was coeval with the mineralization of the Luoyang deposit at 133–131 Ma. The H–O and S–Pb isotope compositions indicate that the metallogenic material of the Luoyang deposit had a magmatic hydrothermal source, and was derived mainly from the upper crust with a low degree of contamination of mantle material. The Pb isotope analyses of the ore minerals show that the Luoyang Fe deposit formed in an orogenic setting. We documented a set of new zircon U–Pb and molybdenite Re–Os geochronological and S‐Pb–H–O isotope data to reveal the ore genesis of the Luoyang Fe deposit in SE China. Through isotopic analyses of the ore minerals, we discussed the metallotectonic background and built up a metallogenic model of Makeng type deposit in the southwest Fujian.
The genesis of the Makeng Fe deposit, located in Fujian Province in southeastern China, has been the focus of numerous studies. Recent studies have revealed that the mineralization and alteration of the deposit may have occurred during the intrusion of granitic magma. In this study, we focus on the magmatic activity that has occurred in the region, as well as the geological context of the Makeng and similar deposits. We have divided the magmatic activity that occurred in the Makeng and adjacent areas into four main stages: the first occurred during the early Yanshanian at ~195 Ma, the second occurred from 150 to 170 Ma (related to Cu–Au–Fe mineralization), the third occurred from 140 to 120 Ma (related to FeMo mineralization and producing the Makeng and Longfengchang plutons), and the fourth occurred from 90 to 110 Ma (related to Ag–Cu–Mo mineralization). We propose that the formation of the Makeng Fe deposit was both spatially and temporally related to local granitic magmatism, and that the granitic magma transported Fe during the formation of the deposit. The Juzhou and Dayang plutons also played important roles in the transport and enrichment of other metals during the formation of the Makeng Fe deposit. The Makeng Fe deposit is a concealed or semi-concealed type of granite mineralization, and its ore genesis was due to multiple coupling, critical transformation, and boundary mineralization processes. The contact areas between the granite and the surrounding rocks, as well as the interfaces between the host rock carbonates and silica-rich sediments, are important targets for future prospecting.
The Nanling region gains its reputation for abundant mineral resources, especially W, Sn, Sb, Bi, Pb, Zn, Li, Be, Ta, Nb and ion-adsorption REE within weathering crust as well as uranium. These dominant mineral resources are mainly formed in the Yanshanian period with intimate genetic relationship to Yanshanian granitoids. Spatially, tungsten and tin deposits separately occurred in the eastern and western parts of Nanling region respectively. The complicated genetic relationships between tungsten-tin polymetallic deposits and Nanling granitoids demonstrate a regularity for mineralization (we named this “metallogenic specialization”), reflected in the aspects of specialized metallogenic compositions, age, spatiality, alteration and its geological background. The metallogenic specialization (regional metallogeny) is important to discover mineralization lay the foundation. A new exploration model (named “Five Levels + Basement”) was proposed in this paper. Now, it became a prospecting guidance in Nanling region. Recently, the ongoing prospecting of large tungsten deposits in Nanling and its adjacent region using this model indicates a northward expanding for tungsten deposits in the south part of study area and westward expanding for that in the eastern part. In practice, the model also can be used in deep prospecting (e.g., deep-seated bedded or bed-like orebodies) as well as, not limited to tungsten deposits, other mineral deposits.
Magmatic activity is of great significance to mineralization not only for heat and fluid it provides, but also for parts of material source it brings. Due to the cover of soil and vegetation and its spatial nonuniformity detected signals from the ground's surface may be weak and of spatial variability, and this brings serious challenges to mineral exploration in these areas. Two models based on spatially weighted technology, i.e., local singularity analysis (LSA) and spatially weighted logistic regression (SWLR) are applied in this study to deal with this challenge. Coverage cannot block the migration of geochemical elements, it is possible that the geochemical features of soil above concealed rocks can be different from surrounding environment, although this kind of differences are weak; coverage may also weaken the surface expression of geophysical fields. LSA is sensitive to weak changes in density or energy, which makes it effective to map the distribution of concealed igneous rock based on geochemical and geophysical properties. Data integration can produce better classification results than any single data analysis, but spatial variability of spatial variables caused by non-stationary coverage can greatly affect the results since sometimes it is hard to establish a global model. In this paper, SWLR is used to integrate all spatial layers extracted from both geochemical and geophysical data, and the iron polymetallic metallogenic belt in south-west of Fujian Province is used as s study case. It is found that LSA technique effectively extracts different sources of geologic anomalies; and the spatial distribution of intermediate and felsic igneous rocks delineated by SWLR shows higher accuracy compared with the result obtained via global logistic regression model.
Zhangdongkeng tungsten deposit has a special mineralization model, which is a quartz vein type mineralization in the upper portion while an altered granite type mineralization in the lower part. It also shows that tungsten was enriched in the upper part while molybdenum enriched in the lower. Molybdenites in fine-grained granite and quartz vein were separately used for Re-Os dating to test the temporal relation of the two types of mineralization. The isochron age of three molybdenite samples in fine-grained granite is 155.4±2.1 Ma (MSWD=1.12), with model ages of them between 154.9±2.6 Ma and 156.5±2.6 Ma, and the weighted average age 155.5±1.4 Ma (MSWD=0.44). Five molybdenite samples in quartz vein yield a Re-Os isochron age of 154.6±1.7 Ma (MSWD=0.030), with model ages 154.2±2.3 Ma to 154.7±2.7 Ma, and the weighted mean age is 154.29±0.98 Ma (MSWD=0.045). The results show that the ages of altered granite type mineralization and quartz vein type mineralization are basically almost same, which well indicates that molybdenites in both mineralization types are products of the same magmatic-hydrothermal event.
Mesozoic molybdenum deposits are distributed widely in Fujian, and associated with a certain amount of rhenium. This study explores Mesozoic molybdenum deposits in Fujian. It is found by analysis of characteristics of ore petrology and mineralogy of molybdenite of typical molybnum deposits (Pingdi, Shangxikeng, Luobuling, Makeng, etc.) in Fujian Province, five types of the molybdenum deposits have been determined, including the porphyry type, the magmatic hydrothermal type, the volcanic hydrothermal type, the tectonic breccia type and a few skarn type. Our systematic field investigation and petrography study finds that the ores mainly have coarse-medium fine grain, platy texture, small amount of thick tabular texture; the ore mineral(only molybdenite) is of leaden color, obvious polychroism, 2H polymorph (a small amount of 2H+3R, 3R), low contents of impurities including Re((N-N×100)×10-6, most(N-N×10)×10-6), which indicates the ores formed in moderate-high temperature condition and the ore originates from crust-mantle mixed source (most crust source); Mesozoic molybdenum mineralization is of universality in Fujian province; and as a kind of accompanying elements, Re is of some comprehensive utilization value.
In this paper, through a comparative study of the geological and geochemical features of the typical ore concentration areas, the authors summarized the evolution of the crust and regional metallogenic regularities in the western, middle and eastern regions of the Nanling metallogenic belt. In the western region, magmas intruded into the late Paleozoic and early Mesozoic crust in a short time with an explosive type Sn mineralization in late Yanshanian epoch; in the middle region, magmas intruded into the late Paleozoic crust for a long time accompanied by polymetallic and multi-stage mineralization; in the eastern region, magmas intruded into early Paleozoic crust with the W mineralization peak in Yanshanian epoch, indicating that W mineralization might have occurred in the early Paleozoic crust of the western Nanling region. Correspondingly, the concealed granite, the Shizhuyuan-type deposit under Huangshaping type deposit, and the "basement" under the "five-storey" type W deposit should be the deep exploration targets in the western, middle and eastern Nanling regions, respectively. In addition, the deep exploration across the Qitianling intrusion in southern Hunan Province shows the existence of an upwelling pathway for mantle material indicated by artificial earthquake test at the center of the intrusion, where the later fine-grained granite contained more mantle material than the early coarse-grained granite in the light of Os isotope. In addition, the Sn-rich rhyolite subvolcanic rock vein that intruded into the early coarse grained granite in the Bailashui Sn deposit is a indicator of a later magmatism characterized by enrichment of mantle materiald in the depth of Qitianling intrusion. These metallogenic regularities in Nanling have indicating significance for W-Sn exploration in Tibet, i.e., to explore W-Sn mineralization in the depth of epi-mesothermal deposits in low erosion areas, and to explore the meso-hypothermal W-Sn deposits in the high erosion areas.
LA-ICP-MS zircon U-Pb dating and elements geochemical analysis has been carried out for mafic-ultramafic rock from Pingchuan to discuss the petrology characteristics and the time series of diagenesis-mineralization in Pingchuan region and further improve the geochronological framework of diagenesis-mineralization of the Panxi area. The test results show that Huangcaoping gabbro formed in 259.7±1.2 Ma and its capture zircon's crystallization age is 269.8±2.4 Ma, and the subvolcanic's reference diagenetic age is 248± Ma and its metamorphic zircon age is 67± Ma. The results indicate that mafic-ultramafic rock in Pingchuan region is a set of homologous phase sodium-rich tholeiitic rock series, conduciving to the formation of iron-mineralization, outputting in the continental rift environment, magma source coming from the upper mantle spinel lherzolite. The magmatic activity started no later than 269.8±2.4 Ma, and the large-scale magmatic activity occurred at 259.7±1.2 Ma, which constrained the mineralization time of magmatic profiled and volcanic eruptions (underflow) sedimentary, and the subvolcanic diagenetic age limited the upper mineralization time of sub-volcanic hydrothermal, and the metamorphic zircon U-Pb age recorded that Pingchuan region experienced Himalayan intracontinental orogeny. The tectonic-magmatic activity of Pingchuan region is featured with being explosive, phased and metallogenic; the formation of mafic-ultramafic rock in Pingchuan region is probably related to the large-scaled lithospheric thinning; diagenesis-mineralization in Hercynian-Indosinian in Panxi area is the comagmatic product of different phases evolution, controlled by regional uniform deep geodynamics.
As one of special mineral species deposits in China, molybdenum deposits have got considerable prospecting breakthrough in recent years. Molybdenite, widely distributed in a variety of endogenous Mo deposits, is a molybdenum-bearing mineral with the most significant econonic significance. In this study, the authors chose molybdenite from 57 molybdenum deposits for ICP-MS REE dating. The results show that the total REE values in molybdenum deposits are between 10.99 and 3374 μ g/g (concentrated between 10.99 and 600 μ g/g). The high REE amounts in molybdenite were formed in Yanshanian period (concentrated in the Middle Jurassic - Early Cretaceous), North China has higher REE than South China, and independent Mo deposits or Mo polymetallic deposits have higher REE than other deposits characterized by associated Mo mineral assemblages. REE distribution patterns of molybdenites show diversity, but the patterns are not controlled by metallogenic ages, types and mineral assemblages in different ore concentration areas. Molybdenites are significandy enriched in LREE, and have strong negative Eu anomalies (δ 5 Eu= 0.01-0.80), negative Ce anomalies (6 Ce=0.241.06, Most are less than 1) and positive Sm anomalies (δ5 Sm = 1.29∼79.42). According to these characteristics and distribution patterns of REE in molybdenite, 6 categories of molybdenite can be identified, reflecting the different geneses of molybdenite or different natures of ore-forming fluids captured in the process of molybdenite crystallization. Based on the experimental results of melt/fluid, the authors infer that molybdenumforming fluids are usually enriched in CO2, Cl- (may be also rich in F-) and some reducing gas compositions, indicating a reducing environment. The quartz vein-type deposits, however, were formed in more oxidative environment than porphyry deposits.
The Makeng Fe-Mo deposit is a large deposit hosted in the interlayer fracture zone between carbonates of Huanglong Formation (C2h) and clastic rocks of Lindi Formation (C1l) at the exo-contact zone of the Juzhou-Dayang granite. The iron ore are closely coexisting with skarns. However, the ore genesis here has still been controversial. In this paper, we studied the mineralogical characteristics of skarns in Makeng Fe-Mo deposit with electron microprobe analysis, which showed that the mineral assemblages of skarns in this deposit mainly consisted of pyroxene, garnet and bustamite. The retrograde altered minerals were comprised of chlorite, epidote, amphibole and quartz. The mineral composition of clinopyroxene are diopside, hedenbergite, and a small amount of johannsenite. Pyroxenoids are mainly composed by bustamite and rhodonite. The end member of garnet is dominated by andradite, with minor grossularite. The amphibole in this deposit can be classified into calcic amphibole. All the mineralogical characters of skarns showed that they were mainly formed under relative oxidizing conditions. The skarns in Makeng Fe-Mo deposit resulted from the metasomatism formed by thermal fluid flowing along the interlayer fracture zones between limestone and clastic rocks, most iron ore hosted in the skarns, usually the magnetites formed later than the skarns and constituted a metasomatic texture, not only replaced skarns widely, but also direct alternated limestone, sandstone in the wall rock; the footwall of main orebody often appeared thick quartzite, furthermore the metasomatic also appeared obvious in clastic rocks. The skarn zonations were widespread in the deposit, consistent with typical skarn-type ore deposits. Combining the geological features with mineralogical characteristics of skarns in the Makeng Fe deposit, it shows that the deposit is a strata-bound skarn-type deposit.
China is rich in tin resources, and contains many types of tin deposits. Among the tin deposit types, the cassiterite-sulfide type, skarn type and quartz vein type occupy a large proportion of tin resources and reserves. From the aspect of exploitation and utilization, the most important types are cassiterite-sulfide type and quartz vein type. The cassiterite-sulfide type tin deposits are mainly located in Northern Guangxi and Eastern Yunnan, skarn type deposits are mainly distributed in the ore-concentration areas of South Hunan in Middle Nanling, and the quartz vein type tin deposits are mainly distributed in South China, such as Western Fujian, Middle Jiangxi, Northern Guangzhou and Southern Hunan. The most important metallogenic epoch for tin deposits is the Mesozoic era. The metallogenic geotectonic background is mainly continental environments after orogeny process, with strong tectonic changes, interlaced deep fracture and frequent magmatism. And the most distinctive feature is the well developed Mesozoic granites, which have a close relationship with tin mineralization. Based on the detailed study of the data from 873 tin deposits in China, this paper summarized the metallogenic regularity of tin deposits, classified 20 important metallogenic series of tin or tin-associated deposits, and inferred that the cassiterite-sulfide type, skarn type, quartz vein type and greisen type are the main prediction types of tin resources. Forty-four tin-mineralization belts were divided, among which, 19 belts are the most important. In addition, a series of maps about tin metallogenic belts and tin metallogenic regularity were compiled, aiming to provide theoretical basis for potential estimation and prediction of tin mineral resources.
The Qinzhou Bay-Hangzhou Bay suture zone is an important porphyry copper metallogenic belt in southern China. Previous studies suggest that the ages of regional diagenesis and mineralization are mainly concentrated in the Late-Middle Jurassic (180-155 Ma), and the ore-bearing granite porphyry shows distinctly crust-mantle contamination. The Baoshan copper deposit is a porphyry-type Cu deposit newly discovered in the Dayaoshan region in the southwestern of the Qinhang metallogenic belt in recent years. The granite porphyry is dominated as small stock into Sheshan granodiorite, including two outcropped and one concealed magmatic emplacement. And the copper ore body is all hosted in the Baoshan concealed granite porphyry. In this paper, laser ablation (MC)-ICPMS U-Pb dating and Hf isotopic compositions of zircons from three granite porphyry samples in the Baoshan copper deposit are presented. Highly precise U-Pb results indicate that zircons from one concealed and two outcropped granite porphyries give weighted mean 206Pb/238U age of 91.1±0.6 Ma (1σ), 91.3±0.8 Ma (1σ) and 90.1±1.0 Ma (1σ), respectively. And the zircons crystallized in the late Yanshannian granites give εHf (91 Ma) values ranging from -8.74 to -5.13 and Hf model ages (TDM2) of 1 210-1 394 Ma. U-Pb and Hf isotopic data can be interpreted as the crystallization time of these granites and the mineralization age, indicating it was formed in the ~91 Ma and may be developed by reworking of Mesoproterozoic crust closely related to partial melting. Together with other published geochronological data, it is proposed that the late Yanshannian magmatite and related Cu (Au)-W-Mo deposit are widely developed in the Dayaoshan and its adjacent areas. Moreover, two epochs of porphyry copper mineralization are confirmed in this study, including the Middle-Late Jurassic and the Late Cretaceous, in the Qinhang metallogenic belt, and it is concluded that Late Cretaceous mineralization possibly resulted from the post-collisional crustal extension setting in the continental margin of the South China.
The Makeng Fe (-Mo) deposit is the largest iron deposit in the Southwestern Fujian metallogenic belt of southeast China. This deposit's genesis has been disputed since the 1950s, with the primary view being that of the skarn type. Detailed geological investigations of the deposit were conducted to elucidate the ore-forming processes at work, as well as its localization. The investigations were based on computational geodynamic models that were, in turn, constructed by simulating the syn-extensional cooling of the ore-related intrusion. We have developed a FISH program to transform the MIDAS/GTS geometric solid model into the FLAC3D geodynamic discrete model. The occurrence of the granite xenoliths in ores and the sharp boundary of the ore body suggest that the ore body was formed at the tensile fracture spaces of the host rocks. The results of the numerical simulation show that most ore bodies are located in the weak zones of the limestone strata with dilation zones that are well-developed. Thus, the fluids from different sources can be easily focused due to the coupled mechano-thermo-hydrological (MTH) processes. The ore forming processes are closely related to the mechanical properties of sedimentary strata, especially regarding its competence and the contact relationship with different rock units. The computational model shows the same depth found through deep geological drilling, which also identified significant ore bodies. The simulation model will facilitate the selection of targets for further exploration of concealed deposits.
The Pangushan tungsten deposit is a well-known old and large ore deposit which has attracted many researchers and exploration geologists both in China and abroad. In order to determine the ages of magmatism and mineralization in the deposit and thus to gain insights into the relationship between magmatic process and tungsten mineralization, the association of endocontact mineralization with exocontact mineralization as well as their geodynamic setting, the authors conducted LA-ICP-MS zircon U-Pb and ICP-MS molybdenite Re-Os isotopic measurement of Pangushan concealed granite and its endocontact-mineralized quartz veins discovered by 2000 m Nanling Scientific Drilling (SP-NLSD-2). The results indicate that the weighted average ages of zircon 206Pb/238U ages for Pangushan granite and of molybdenite Re-Os isotopic model ages for the quartz veins are (161.7±1.6) Ma and (155.3±2.8) Ma, respectively, both subordinate to Mid-late Jurassic. The determinations, together with previous data, suggest that the mineralized quartz veins were produced by terminal magma evolution, which is supported by the fact that the ages of mineralization and magmatism were basically in accordance, the mineralization all occurred spatially at the inner- and outer-contacts of the granite, and the gradient relationship of granite→feldspar quartz vein→quartz vein was detected in the deposit. Endocontact and exocontact ore-bearing quartz veins were both produced by the same mineralization. Geodynamically, the Pangushan tungsten deposit is one of many important tungsten-polymetallic deposits formed from 165 Ma to 150 Ma associated with large-scale lithospheric extension in South China.
Tungsten ore resources are abundant in China with relatively complete types of deposits. Skarn type and quartz vein type deposits are dominated in the tungsten resources, whereas quartz vein type wolframite deposits are most important in terms of exploitation and utilization. Skarn type tungsten deposits are concentratedly distributed in the central Nanling region, such as South Hunan, South Anhui and the eastern Qinling region, while quartz vein type tungsten deposits occur mainly in South China, such as West Fujian, South Jiangxi, North Guangdong and South Hunan. The most important metallogenic epoch of tungsten is the Mesozoic, while the metallogenic tectonic setting is featured by an intracontinental environment after orogeny with sever tectonic movements, deep-seated faults and frequent magmatic activities, especially Mesozoic granitoids closely related to tungsten-tin mineralization. 22 metallogenic series of ore deposits characterized by or significantly related to tungsten were defined based on precise statistic information of 1199 tungsten mining areas and thorough the summary of metallogenic regularities. Based on studies of the metallogenic regularity of tungsten deposits, skarn type (or greisen type), quartz vein type and massif-type of tungsten deposits are thought to be the key prediction types. 65 tungsten-forming belts and 22 key ore concentration areas were ascertained and a distribution map of tungsten-forming belts of China was compiled, which provided a theoretical basis for evaluation and prediction of potential tungsten resources.
Lead and zinc resources are abundant in China, with the reserves of 100 million tons ranking only second in the world. There are more than 3000 lead-zinc mine areas nationwide. The classification of lead-zinc (Pb-Zn) deposits has been a highly controversial issue. From the standpoint of evaluating the potential of mineral resources, we construct a Pb-Zn deposit predictive type of classification scheme, and propose a Pb-Zn deposit comprehensive classification scheme (including 5 classes and 13 sub-types) that regards mineralization as the primary factor and the ore rock as secondary. According to the temporal and spatial distribution of Pb-Zn deposits, we conclude that a multi-period, multi-cycle orogenic environment is the most favorable for lead-zinc deposit growth, that the Proterozoic is the major eon for the growth of igneous-type deposits, the Paleozoic is an important development era for sedimentary Pb-Zn deposits, and the Mesozoic and Cenozoic are the heyday eras of magmatic type lead-zinc deposits. On this basis, we analyse the relationship between tectonic evolution and Pb-Zn metallogenic, and propose that the key factors determining geological mineralization are the metallogenic epoch of mineralization and tectonic environment, which determine the temporal and spatial distribution.
The Lakange porphyry Cu-Mo deposit in the Gangdise metallogenic belt of central and southern East Lhasa block within the Tethys tectonic domain is one of the key deposits in the Tibet Plateau geological survey project evaluation in recent years. Reus isotopie dating technique was applied for determination of mineralization events, and eight molybdenite samples were analyzed for Re-Os isotopie compositions, with the model ages obtained ranging from (13.20±0.20) Ma to (13.64±0.21) Ma, and the isochron age being(13.12±0.44)Ma which represents the metallogenic age of the Lakange porphyry Cu-Mo deposit, indicating Miocene. The Re content of the molybdenite is 343.6 × 10-6-835.7 × 10-6, with an average of 557.8 × 10-6, suggesting that the metallogenic material originated from a source with mantle components. The Lakange porphyry Cu-Mo deposit was formed in a stretching background of India-Asia continental collision orogenic collision, the age (17-12 Ma) is identical with ages of numerous porphyry-skarn mineralization systems in the eastern of Gangdise metallogenic belt, and is 2-3 Ma younger than ages of the porphyry-skarn copper polymetallic deposits in the same ore concentration area, such as Jiama, Qulong and Bangpu, with the formation controlled by the same metallogenic geodynamics setting.
The Yanqian tungsten deposit is located in east section of Nanling region, the conjunction of the E-W striking Nanling tectonic belt and the NNE Circum Pacific Ocean tectonic belt. The primary mineralization types include skarn type scheelite deposit and wolframite-quartz vein deposit. The orebodies occur in the inner and the outer contact zone of the Early Yanshanian granite. Based on the studies of regional geology and deposit geology, the LA-ICP-MS zircon U-Pb and molybdenite Re-Os isochron dating have been carried out to accurately determine the ages of the granite pluton and the mineralized quartz vein within the pluton. The zircon U-Pb age of mineralized pluton is (160.6±0.72) Ma. The Re-Os isotopic age of molybdenite within mineralized quartz vein is (159.2±2.3) Ma. The isotopic dating results show that petrogenic age of the granite is similar with that of the mineralized quartz vein, which means that the magmatism and mineralization occurred in the same period. According to the previous research data, it was considered that the magmatism and mineralization during 160~150 Ma in the Nanling region primarily developed within the mid-east section, and might be caused by the large-scale lithosphere extension. The Yanqian tungsten deposit belongs to the same sub-metallogenic series as some famous deposits in the eastern Nanling region, such as Pangushan, Huameiao and Shizhuyuan, with great exploration potential in the depth. The exploration targets in Yanqian area should primarily be aimed at skarn type and quartz vein type tungsten-polymetallic deposits in the inner contact.
Through the study of petrology and geochemistry, the volcanic rocks of Tamulangou Formation in Erentaolegai silver deposit have the characteristics of high SiO2 ( >57%), Al2O3, ( >16%), alkali especially K2O ( >3%) and belong to HKCA series. The content of REE is medium (187 x 10(-6) similar to 240 x 10(-6)), ( La/Yb)(N) ratio is from 18.6 to 27. 9, Yb values are less than 1.90 x 10(-6), Y values are less than 18. 0 x 10(-6), and delta Eu is from 0. 85 to 0. 96. REE fractionation is strong, apparently loss of heavy rare earth and No or slightly negative Eu anomaly. Trace element is relative enrichment of LILE such as Rb, Ba, Th, U, K, loss of HFSE such as Nb, Ta, Ti, HREE, and similar to the characteristics of active continental margin. The characteristics of andesitic volcanic rocks in Tamulangou Formation indicate the andesitic magma comes from the base of the thickened crust ( >50km); the residues are garnet, clinopyroxene and amphibole, partial melting and later evolution process of magma are not equilibrium with :plagioclase. Andesitic volcanic rocks in Tamulangou Formation are the partial melting of CA or HKCA metamorphic Okhotsk Ocean. SHRIMP zircon U-Pb age of quartz porphyry, which was considered close with Erentaolegai silver deposit, is 138. 6 +/- 2. 3Ma and is the digenetic age. So further restrict Erentaolegai silver deposit formed at early stage of Early Cretaceous. Through the comparison between quartz porphyry and Tamulangou volcanic rocks from forming age and the study of characteristics of deposit, the silver deposit type is magmatic hydrothermal.
The Pangushan-Tieshanlong tungsten ore field, located in the center of southern Jiangxi Province, eastern Nanling region, contains many granitic plutons, both exposed and concealed, and hosts numerous tungsten-polymetallic ore deposits. Despite many previous geological studies, the deep geology and structure of the field are poorly known because few geophysical measurements have been undertaken. In this study, we carried out a variety of geophysical measurements, including gravity, magnetic field detection, magnetotelluric sounding (MT) and high-resolution seismic reflection to better outline the nature of the ore field and to aid in site selection for the 2000-m Nanling Scientific Drilling Project (SP-NLSD-2), to be carried out by the Chinese SinoProbe Program. Four granitic intrusives, the Tangcun, Pangushan, Huangsha and Bai’e plutons, crop out independently at the surface but were found to be parts of a large batholith at depth. The Tangcun composite pluton, which at the surface consists chiefly of Caledonian granite and minor Early Yanshanian intrusive material, was found to be chiefly Early Yanshanian granite concealed beneath the lower part of the Caledonian granite. The Bai’e pluton initially decreases in size with depth and then expands as it merges with the major batholith. The Pangushan and Huangsha plutons are domes on the inferred batholith. Four granitic magma channels and a considerable number of faults have been identified. Due to its favorable geological conditions, the top of the Pangushan pluton is predicted to be the best candidate for ore prospecting. It is basically a granite cupola with many cross-cutting and parallel faults. In addition, it is characterized by a high gravity anomaly, a high magnetic anomaly and locally a low electrical resistivity anomaly.
Copper resources in China are rich, but imported copper products are still required. Researches on metallogenic regularity of major types of copper deposits by geologists have involved in worldwide classification, significant copper belts, representative copper deposits, etc. Studies on metallogenic regularity of copper deposits in China also have made achievements with a long-term work. Combined with latest exploration advances obtained in recent ten years, this review aims to conclude the achievements of researches on copper metallogenic regularity in China. Based on data of 814 copper deposits and other ore (mineralized) occurrences, ten prediction types of copper deposits have been suggested. Porphyry and skarn copper ores are taken as the key targets. Porphyry copper deposits are the most important one which concentrate in Gangdese, Changdu-Sanjiang, Dexing and East Tianshan. The Cenozoic and Mesozoic are the major metallogenic epochs. Four main metallogenic epochs are been studied based on the copper ore geochronological data including Precambrian Era (Archean and Proterozoic), Paleozoic Era, Mesozoic Era and Cenozoic Era. Based on the study of metallogenic series of ore deposits in China, twenty-seven metallogenic series of copper deposits are proposed. This is suggested to deepen the study of metallogenic regularity of copper ore and provide the theory guide for copper resources prediction in China.
In a sister paper (Paper I), emphasis was on method comparison between Principal Component Analysis (PCA) and independent component analysis (ICA), suggesting that the main components generated by PCA usually represent dominant populations of samples such as large geological bodies with extensive coverage, whereas the main components of ICA may represent the directions along which there is more divergence of populations of samples. This Paper II contains further demonstration of the differences and similarities between ICA and PCA in applications to a regional stream sediment geochemical data set for geological object identification in the Pinghe district, Fujian Province, China. Considering the input elements have log-normal-like distributions that may significantly influence the results of ICA, the raw data were log-transformed and standardized prior to ICA and PCA analysis. The results show that the second and fourth principal components (PC) obtained by PCA may indicate five geo-objects. Similarly, the second, fifth, sixth, eighth and tenth independent components (IC) obtained by ICA may indicate eleven geo-objects. The first several PCs are most likely to represent geo-objects, and the ICs with low order in kurtosis rank are more likely to reflect some geo-objects. An unsupervised classification method (ISODATA clustering algorithm) applied to scores of the PCs and ICs shows that classification of geo-objects based on the results obtained by ICs is relatively more accurate than that obtained by PCs. The 3D scatterplots for three components show that the samples belonging to the same rock unit have more clear structure in the space of ICs than in the space of PCs. Moreover, IC results show geochemical element patterns depicting different associations between hydrothermal system of Zhongteng plutonic complex and hydrothermal mineralization in the northwestern and southeastern parts of the study area. The loadings of PC indicate hydrothermal systems at different temperatures occurred in the Nanyuan Group and the intrusions. In general, ICA is more effective than PCA for characterizing geo-objects in the study area.
Granitic pegmatites are commonly thought to form by fractional crystallization or by liquid immiscibility of granitic magma; however, these proposals are based mainly on analyses of fluid and melt inclusions. Here, we use the Jiajika pegmatite deposit, the largest spodumene deposit in Asia, as a case study to investigate ore forming processes using isotope dating. Daring of a single granite sample from the Jiajika deposit using multiple methods gave a zircon U–Pb SHRIMP age of 208.4 ± 3.9 Ma, an 40Ar/39Ar age for muscovite of 182.9 ± 1.7 Ma, and an 40Ar/39Ar age for biotite of 169.9 ± 1.6 Ma. Based on these dating results and the 40Ar/39Ar age of muscovite from the Jiajika pegmatite, a temperature–time cooling track for the Jiajika granite was constructed using closure temperatures of the different isotope systems. This track indicates that the granite cooled over ∼40 m. y., with segregation of the pegmatite fluid from the granitic magma at a temperature of ∼700°C. This result suggests that the Jiajika pegmatite formed not by fractional crystallization, but by segregation of an immiscible liquid from the granitic magma. When compared with fractional crystallization, the relatively early timing of segregation of an immiscible liquid from a granitic magma can prevent the precipitation of ore‐forming elements during crystallization, and suggests that liquid immiscibility could be an important ore‐forming process for rare metal pegmatities. We also conclude that isotope dating is a method that can potentially be used to determine the dominant ore‐forming processes that occurred during the formation of granite‐related ore deposits, and suggest that this method can be employed to determine the formation history of the W–Sn ore deposits found elsewhere within the Nanling Metallogenic Belt.
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