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The large Bilugangan porphyry Mo deposit is one of the oldest Mo deposit in eastern part of the Central Asian Orogen in Inner Mongolia. The orogen is currently regarded as the most important Phanerozoic region with widespread crustal growth between the Siberian Craton to the north, and North China Block to the south. The Bilugangan Mo mineralisation is hosted by a porphyritic monzogranite and along the contact with the Late Permian Linxi Formation. The mineralisation is disseminated in places and includes various types of hydrothermal veins. The mineralising stages of the deposit includes the pre-ore quartz–K-feldspar(–biotite) pegmatite succeeded by quartz–K-feldspar–molybdenite–muscovite–sericite(–pyrite) veins, quartz–molybdenite–chalcopyrite–perthite–muscovite–sericite(–pyrite–sphalerite), and post-ore quartz–fluorite–calcite (–sericite–muscovite–) veins. Seven molybdenite samples from the mineralisation yield a Re-Os Mo weighted mean date of 238 ± 1 Ma, which is the same, within error, as the Re-Os isochron age of 238 ± 2 Ma, and the ca. 240 Ma age of the porphyritic monzogranite. This is the oldest porphyry Mo – type deposit in the eastern part of the orogen, and the only large –sized Mo deposit in the region, which shows that the east CAO is prospective for Triassic mineralisation. Thirty-three samples of sulfide from the deposit have a narrow δ34SVCDT(‰) range of 1.5 to 4.3‰, indicating that the sulfur the sulfur has primarily a magmatic source. The sulfides from the Mo-bearing veins have relatively concentrated Pb isotopic compositions with 206Pb/204Pb ratios between 18.295 and 19.576, 207Pb/204Pb ratios between 15.535 and 15.662, and 208Pb/204Pb ratios between 38.066 and 38.653. These values are consistent with those of the initial Pb isotope ratios for whole rock samples from the porphyritic monzogranite and hornfels. Fifteen gangue quartz samples from various veins define a range of δ18Ofluid values from 0.5 to 5.2‰ with δDfluid values ranging from −115 to −60‰, indicating that the onset of the mineralising fluid was generated from in-situ degassing of a magmatic source, followed by an input of meteoric water during the late ore-forming stage. It is proposed that the deposit is a collision-related Dabie-type deposit, which is related to the closure of the Paleo-Asian Ocean between the North China Block and Siberian Craton.

The Xiaoshuijing Syenogranite is the host of Mo mineralisation recently discovered in the Tengchong Terrane of southwestern China. Here, we present new zircon U-Pb ages and molybdenite Re-Os ages, whole-rock geochemical data, and zircon Hf isotopic data for the Xiaoshuijing Syenogranite hosting disseminated Mo mineralisation. The syenogranite’s mineralogical and geochemical characteristics indicate it is a high-K, alkaline, and peraluminous granite. LA-ICP-MS analysis of zircon yields an age of 65 ± 1 Ma (n = 14, MSWD = 2.1), and yields negative zircon eHf(t) values ranging from −18.23 to −12.92, interpreted to have a crustal source. The Re-Os Mo age of 64 ± 2 Ma (n = 4, MSWD = 2.2) for the mineralisation is the same as the syenogranite’s age, within error. The geochemistry also indicates that the syenogranite is related to a thickened crust resulting from the eastward subduction of the Neo-Tethyan oceanic lithosphere shortly before the collision of the Indian and Eurasian continental crusts.

Research on history of the Earth’s continents and the genesis of mineral deposits has been one of the hotspots in geology. But only limited studies have been completed on iron deposits hosted by banded iron-formations (BIFs), such as the large Hanwang iron deposit located in the eastern North China Craton (NCC). In this contribution, we present the petrology, zircon U–Pb geochronology, Lu–Hf isotopes and whole-rock geochemistry on Hanwang iron deposit hosted by the metamorphosed Neoarchean to early Paleoproterozoic Taishan Group and orthogneiss derived from tonalite–trondhjemite–granodiorite (TTGs). Magnetite-bearing amphibolite, magnetite-bearing quartz amphibolite, and gneiss host the Hanwang iron deposit, which is characterised by subhedral to euhedral magnetite, pyrite with minor galena and BIF laminations. Gangue minerals include hornblende, plagioclase and quartz with minor amounts of biotite, chlorite, epidote and microcline. This mineral assemblage is indicative of amphibolite-facies metamorphism with regression to greenschist-facies. The deposit is located in a transition zone between metamorphosed mafic to felsic volcanic rocks. The age of the Hanwang BIF-hosted iron deposit is late Neoarchean. Lu–Hf isotope systematics indicate that the protolith for the biotite amphibolite is derived from a Neoarchean mantle contaminated by the crust, and orthogneiss is derived from the Neoarchean crust. The biotite amphibolite is characterised by high Na, Fe and low K assays, enrichment in light rare earth elements (LREE), and relatively depletion in heavy REEs (HREE) without an obvious Ce anomaly. The geochemistry of the orthogneiss is characteristic of a volcanic–arc granite, although this must be accepted with caution given that the orthogneiss is metamorphosed and deformed at amphibolite-facies. It is proposed that Hanwang iron deposit was deposited in a marine volcanic–arc environment and derived from hydrothermally leached volcanic units, and similar to the Algoma-type iron deposit. Most BIFs occurring in Neoarchean granite-greenstone succession of the eastern NCC belong to the Algoma-type iron deposits. Globally, this sequence appears to be coeval with the Yilgarn Craton in Western Australia.

The Yinachang Fe-Cu-Au-U-REE deposit is located in the Kangdian region at the southwestern margin of the Yangtze Block. This contribution presents petrological, geochronological, whole rock geochemical, and Rare Earth Elements (REE) geochemistry of zircons of gabbro and diorite dykes associated with the Yinachang Fe-Cu-Au-U-REE deposit, aiming to constrain the age of the mineralisation and help refine our understanding of the tectonic setting of the region. Zircons from diorite have a Palaeoproterozoic U-Pb age of 2014 ± 30 Ma, and zircons from the gabbro could not be dated because they are metamict, having a high concentration of uranium. The ca. 2014 Ma age of the zircons in the diorite indicates that the southwestern part of the Yangtze Block is partly synchronous with the Columbia Supercontinent. Geochemically, the diorite and gabbro are enriched in large-ion lithophile elements (LILEs) such as Rb and U, and depleted in high-field-strength elements (HFSEs) such as Nb, P, Ti, Ba, and Sr. The diorite is enriched in light REEs (LREEs) and has a slight to negligible Eu anomaly, which are characteristic of ocean-island basalts containing mantle-derived high potassic calc-alkaline rocks. In contrast, the gabbro is weakly enriched in LREEs and has a slightly negative Eu anomaly similar to those of potassic calc-alkaline enriched mid-ocean-ridge basalt. The average combined REE content of zircons from the gabbro is 19401 ppm and is significantly higher than that of the zircons from the diorite averaging 1020 ppm. This indicates that the gabbro is closely related with the REE mineralisation at the deposit. The geochemistry of the diorite indicates that it formed at the continental margin of a volcanic-arc. It also indicates that the magmatic rocks in the region have a possible mantle plume origin contaminated by crustal material and located at a transitional zone between a rift and an ocean-continent tectonic setting.

Jurassic and Late Cretaceous granites are spatially and temporally associated with mineralisation in the Paleozoic Dayaoshan Terrane in South China (also known as South China Block). The porphyritic Baoshan Monzogranite of Late Cretaceous is an example that is petrographically studied in this contribution. Sensitive High-Resolution Ion-Microprobe (SHRIMP) zircon U-Pb ages, in-situ zircon O-Hf isotopic analyses, and whole-rock geochemistry are here used to better constrain the genesis of the monzogranite, which is porphyritic, and located in the Baoshan Cu mining area. SHRIMP zircon dating yields a weighted mean 206Pb/238U age of 89 ± 1 Ma, interpreted to be the crystallisation age of the porphyritic monzogranite. Its geochemical data indicates it is derived from partial melting of the lower to crust, followed by fractionation, and emplacement in secondary faults related to the major Bobai-Cenxi Fault. The monzogranite has a Paleo- to Mesoproterozoic source in the crust, which was metasomatised during Neoproterozoic subduction. The rotation of Izanagi Plate’s subduction from NW to NE resulted into the reactivation of NW and NE-trending thrust faults as transpressional or extensional ones. It was during this period that Late Cretaceous intrusions such as the Baoshan porphyritic monzogranite were emplaced in the terrane near the NW-trending faults and other intrusions at the edges of basins such as Yangchun, Luoding and Bobai basins near NE-trending faults.

The Baiganhu W-Sn ore field in the northwestern area of the East Kunlun Orogen, NW China, contains three economically important W-Sn deposits, namely Kekekaerde, Baiganhu and Bashierxi. Timing of the W-Sn mineralization remains under debates due to lack of precise isotope dating directly conducted on ore minerals. We herewith report LA-MC-ICP-MS (laser ablation (multi-collector) inductively coupled plasma mass spectrometry) and ID-TIMS (isotope dilution thermal ionization mass spectrometry) cassiterite U−Pb ages for the Kekekaerde W-Sn deposit in the Baiganhu W-Sn ore field. The ID-TIMS cassiterite 206 Pb/ 238 U results yield a weighted mean age of 416 ± 1 Ma (95% confidence, MSWD = 0.8), and the LA-MC-ICP-MS analytical data give a 206 Pb/ 207 Pb– 238 U/ 207 Pb isochron age of 426 ± 13 Ma (95% confidence, MSWD = 0.1). These two ages are same within errors, suggesting that the mineralization in the Baiganhu W-Sn ore field occurred at ca. 416 Ma. These new ages and understandings are consistent with the previously reported zircon U−Pb ages of 430–420 Ma for the ore-bearing granites in the ore-field, and with the 40 Ar/ 39 Ar plateau ages of ca. 412 Ma for the hydrothermal muscovite from ore-bearing quartz veins and greinsenized granite. It shows that the granite magmatism and its associated hydrothermal mineralization resulted from the Caledonian Orogeny that accommodated the closure of the Proto-Tethys, followed by the continental collision between the Central Kunlun, Northern Kunlun terranes and the Qaidam Block.

Knowledge of the history of the Earth’s continents and the genesis of mineral deposits is poorly understood on a crustal-scale. This contribution combines geological and zircon Hf-isotopic data collected from igneous rocks associated with mineralisation to gain a better understanding of the nature of the growth of, and mineral genesis in the North China Craton. The new zircon U–Pb dates reported here are 2587 ± 62 Ma for syenogranite at Zanhuang in the northeast part of craton, 2552 ± 24 Ma for trondhjemitic gneiss and 2554 ± 29 Ma for metadiorite at Dengfeng in the eastern and central part of, and 2820 ± 6 and 2821 ± 32 Ma for tonalite at Lushan in the southeast part of the craton. Lu-Hf isotopic data collected from granitic rocks for this study yield eHf(t) values and Hf crustal model ages (TDMc) of 3–5.8 and 2580–2600 Ma for the syenogranite at Zanhuang, 1.9–7.4 and 2550–2580 Ma for trondhjemitic gneiss and metadiorite at Dengfeng, and 0.5–5.2 and 3120–2840 Ma for tonalite at Lushan. Six major magmatic events have been recognised throughout the region. The crustal growth and reworking of the craton includes Eo- to Mesoarchean, early Neoarchean, and Paleoproterozoic events. The consistency in the evolution of Neoarchean magmatism coupled with zircon Hf isotope systematics indicate that similar crustal growth and reworking were in action in the Eastern, Trans-North China, and Western blocks. The crust architecture indicated by Hf isotopic mapping of the North China Craton constrains the distribution of mineral deposits. The BIF-hosted Fe deposits are spatially related to juvenile or reworked crustal domains, with groups of deposits located internal to and at the margins of Archean terranes, and orogenic Au deposits are spatially associated with juvenile crustal domains.

The duration (or time scales) of multistage combined magmatic and hydrothermal events provides key information constraining the metallogenic history of porphyry deposits, but the duration (time scale) of the mineralising hydrothermal process remains uncertain. Here, we report zircon U–Pb isotopic age, fluorite Sm–Nd isochron ages, and Ti-in-quartz diffusion chronometry for the giant Chalukou porphyry Mo deposit with reserves of 2.46 Mt @ 0.087 wt% Mo in NE China. The deposit is genetically related to hydrothermal fluids associated with a Late Jurassic (148–147 Ma) porphyritic magmatic event coincident with our new fluorite Sm–Nd isochron age of 148 Ma. Porphyry Mo mineralisation is characterised by the superposition of multiple generations of crosscutting quartz-bearing veins including: quartz veins with minor magnetite and hematite associated with K-silicate alteration (A-veins), quartz-molybdenite veins with K-feldspar alteration halos that host the bulk of the Mo mineralisation (B-veins), and late base-metal mineralisation with phyllic alteration (D-veins), as well as post-mineralisation veins with argillic alteration. Hydrothermal veins from the Chalukou porphyry Mo deposit contain multiple generations of quartz that are distinct in their Ti concentrations and scanning electron microscope-cathodoluminescence images. The A-veins preserve subhedral to euhedral characteristics with alternating CL bright and dark growth zoning. The A-veins probably formed at a near-lithostatic pressure of ∼1.35 kbar and contain CL-bright quartz assaying 31–71 ppm Ti with Ti-in-quartz temperatures averaging 603 ± 30°C, and CL-dark quartz assaying 6–25 ppm Ti with Ti-in-quartz temperatures averaging 496 ± 36°C. The mineralised B-veins also CL-dark quartz, although they display less growth zoning with lower Ti assays of 0.4–27.9 ppm. These veins have near 0.7 kbar pressure and Titanium-in-quartz temperature averaging 390 ± 79°C. The D-veins are dominated by CL-dark quartz and systematically lower Ti concentrations of 0.4–8 ppm, being lower than the relatively latter vein generations, formed at a temperature of 348 ± 58°C and pressure of 0.4 kbars. The Ti diffusion in quartz has become a successful method constraining time scales and duration of magmatic and hydrothermal processes. Ti diffusion modelling indicates that the A-veins were deposited and cooled in a period between 2500 and 50,000 years. This shows that the earliest magma-related hydrothermal fluids activities formed within tens of thousands of years.

The Zhaibei Granite in Jiangxi Province, southern China, hosts an ion-adsorption light rare earth element (LREE) deposit. Recently, heavy REE (HREE) ores have also been reported from weathered crusts of the granitic rocks. In this study, petrological, geochemical, and mineralogical characteristics of the Zhaibei pluton were analysed to establish the genesis of this REE deposit. The pluton contains coarse-grained biotite syenogranite and minor hornblende–biotite–quartz monzonite in its central zone, medium-grained biotite syenogranite in its transitional zone, and fine-grained muscovitic alkali-feldspar granite and porphyritic muscovitic biotite–alkali-feldspar granite together with monzogranite porphyry intrusions in its marginal zone. The REE minerals include titanite, allanite, monazite, bastnasite, and thorite-(Y) in the central zone, allanite, monazite, xenotime, bastnasite, and thorite-(Y) in the transitional zone, and synchysite-(Y), thorite-(Y), and xenotime in the marginal zone. The SiO2 content increases from 62 to 77 wt% from the centre to the margin, whereas the Al2O3, TiO2, MgO, FeO, and CaO contents decrease. In addition, the size of the negative Eu anomaly and HREE content increase, accompanied by decreases in Co, Zr, Hf, Sr, and Ba and increases in Rb, Cs, Nb, and Sn. These observations indicate that the Zhaibei Granite might have been formed by crystallisation differentiation of magma. The granitic pluton was also influenced by reactions with late-magmatic F-, CO2–, and REE-rich fluids that altered magmatic minerals and crystallised as REE-fluorocarbonates and thorite. The hydrothermal REE minerals constitute ∼ 40% of the total REEs in the bedrock and are the major supplier of ion-exchangeable REEs in the ores of the Zhaibei deposit. LREE-rich ores may have been derived from the LREE-rich granitic rocks, which contain bastnasite, titanite, and allanite, whereas HREE-rich ores were sourced mainly from the HREE-rich granites, which contain synchysite-(Y) and thorite-(Y). Furthermore, REE ores with enrichment in both HREEs and LREEs were probably sourced from the monzogranite porphyry bedrock, which contains bastnasite-(Y), bastnasite, allanite, and thorite-(Y).

Accurate determination of the time scales of multiple magmatic-hydrothermal pulses is a critical and difficult problem, which can provide information needed to better constrain the genesis of porphyry deposits. Here, we take advantage of zircon U-Pb dating and improvements in the field of diffusion chronology to determine time scales of multistage magma-related hydrothermal events at the giant Yulong porphyry Cu-Mo deposit in eastern Tibet. New LA-ICP-MS zircon U-Pb data showing that the mineralised Yulong porphyry crystallised at ca. 41 Ma, with the emplacement of the subeconomic Ganlongla intrusion at ca. 41 Ma, indicating a contemporaneous magmatism and mineralisation. Quartz from porphyry and hydrothermal veins exhibits cathodoluminescence (CL) images with a variety of brightness and textures, whereas trace element analyses show that the CL intensity is strongly related to the Ti contents of quartz. The Ti-in-quartz analyses of quartz precipitated in equilibrium conditions yield TitaniQ temperatures that agree with the temperatures calculated using independent thermometers. The sharpness of the Ti gradients observed in the CL images coupled with Ti diffusion modelling for different quartz generations indicate that the bulk of the mineralisation at Yulong formed in a short period of between 880,000 and 16,000 years. These data, together with available isotopic dating data, suggest that the mineralisation is coeval with the emplacement of the porphyries. Complex multi-stage hydrothermal stockwork veins and shorter time scales reveal that the individual magma and fluid pulses at Yulong formed rapidly within tens of thousands of years.

The Bilugangan porphyry Mo deposit is located in the southern Great Xing'an Range, and the Bilugangan area near the Hegenshan-Heihe Fault in the eastern part of the Central Asian Orogen (CAO). The deposit is hosted by a NE-trending, partly concealed, composite granite consisting of highly altered porphyritic granite (G1), porphyritic monzogranite (G2), fine- to medium-grained monzogranite (G3), medium -grained monzogranite (G4), and monzogranitic porphyry dykes (G5). The Mo mineralisation forms hydrothermal stockworks or disseminated sulphides in the G2 and G3 phases and the adjoining hornfels. Magmatic zircons from the intrusions yield 206Pb/238U weighted mean ages of 295 ± 2 Ma for G1, 240 ± 1 Ma for G2, 235 ± 2 Ma for G3, 230 ± 1 Ma for G4, and 100 ± 2 Ma for G5,indicating that multiple magmatic events have been active during the Early Permian to Early Cretaceous emplacement of the Bilugangan Granite. The age of the Mo is constrained between the Middle and Late Triassic and the magma-related hydrothermal activity proceeded in at least two pulses over a period of around 5 Ma. The first pulse has a molybdenite Re-Os weighted mean age of 238 ± 2 Ma, and the second dates at 236 ± 1 Ma. These dates are coeval with those of G2 and G3, indicating a genetic association between them and the mineralisation. The Sr-Nd-Hf isotopic systematics shows that the Bilugangan Granite was probably formed by partial melting of at least two sources. The first source is a dominant Late Mesoproterozoic to Early Carboniferous juvenile lower crust indicated by the whole rock eNd(t) values of −1.9 to 5.1 and zircon eHf(t) values of 3.5 to 14.3 with two-stage depleted mantle Nd (TDM2) and Hf (tDM2) model ages of ca. 1086 to 350 Ma, which is possibly related to the evolution of the Palaeo-Asian Ocean. The second source includes Neoarchaean to Palaeoproterozoic crustal components and a subordinate Mesoproterozoic crustal component. The Neoarchaean to Palaeoproterozoic component is indicated by the presence of ca. 2700 to 2600 Ma xenocrystic zircons, negative eHf(t) values of −16.4 to −10.1 with tDM2 ages of ca. 2300 to 1900 Ma. The Mesoproterozoic component yields eHf(t) values of −4.5 to 1.1 and tDM2 ages of ca. 1600 to 1200 Ma. These data show that pre- Mesoproterozoic substrate is present beneath the southern Great Xing'an Range. Although the post-mineralisation G4 and G5 phases have comparable positive eHf(t) values with the earlier granitic phases, the G2 and G3 phases have a more complex source with distinctly negative eHf(t) values of −16.4 to –1.3, indicating that the older crustal components in the magma’s source are also probable sources for the Mo mineralisation.

Magmatism was widespread in the Proterozoic to Early Paleozoic Altyn-Tagh Orogen of NW China. Rare metal deposits hosted by ca. 472 Ma pegmatite dykes with a monzogranitic geochemistry have recently been discovered in the orogen, including the Tugeman Li-Be deposit. The pegmatites contain spodumene – beryl (– columbite – tantalite – cassiterite), and are coeval with the ca. 482 Ma biotite monzogranite as a late-stage phase of the monzogranite, and both the monzogranite and pegmatite intrude orthogneiss and gneissic syenogranite. Two samples of biotite monzogranite yield weighted mean Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) U–Pb zircon dates of 482 ± 5 and 475 ± 5 Ma, and columbite-tantalite dates of 472 ± 8 Ma for the pegmatite, and minimum dates of 438–412 Ma for hosts of the columbite-tantalite. The gneissic syenogranite and orthogneiss in the deposit’s wallrocks have zircon U–Pb ages of ca. 900 Ma. The geochemistry and Hf-Lu isotopic systematics indicated that the protoliths for the gneissic syenogranite and orthogneiss have a mantle source with a contribution from the Proterozoic crust, and the biotite monzogranite has a Proterozoic crustal source. The Tugeman Li-Be deposit, therefore, has a Precambrian crustal source and was deposited during the Ordovician, which we propose was a post-collision extensional event and a previously unknown mineralising event in China.

Polyhalite is a special potash fertilizer resource, which is widely distributed in the Triassic evaporite strata in the Sichuan Basin, but its genetic mechanism has always been controversial. This contribution presents new petrological, geochemistry , electron probe analyses, and Ca-S isotope systematics on Triassic polyhalite minerals for the first time from the Sichuan Basin aiming to better understand their origin. We present petrological observations of long columnar and granular polyhalites co-existing with halites (rock salt) and anhydrites that are not metasomatic in origin. Metasomatic polyhalites have also been studied, which have a fibrous and radial habit interwoven with anhydrite. The primary (sedimentary) polyhalite is solely formed from the evaporation of seawater, and the formation of metasomatic polyhalite involved impure meteoric water . The Ca and S isotopic values show that the sulphur and calcium in diamond-drillholes ZK001 and ZK601 are derived from seawater, whereas the sulphur and calcium in Well YS01 are derived from meteoric water. The sulphur and calcium in Well ZK02 are derived weathered terrigenous gypsum . This study demonstrates that the combined sulphur (δ 34S) and calcium (δ44/40Ca) isotopes can be used to reveal the genesis of polyhalite.

Liancheng is an important Cu–Mo deposit hosted by red-beds in the Mesozoic to Cenozoic Lanping Basin located in the Sanjiang Tethyan Orogen of SW China. The deposit is fault controlled where it has been affected and enriched by four hydrothermal events indicated by four distinct sets of veins and their cross-cutting relationships. A detailed Cu–S–H–O isotopic study is reported here on the mineralization focusing on the source of the metals and fluid, and on the mineralizing processes. The first two hydrothermal events are characterised by CO2 and fluid-rich inclusions with homogenisation temperatures of 124–446 °C and salinities ranging from 0.4 to 24.6 wt% NaCl equiv. The next two hydrothermal events are characterised by liquid–rich fluid inclusions that homogenise at 145–256 °C, with salinities ranging from 1.4 to 22.9 wt% NaCl equiv. The H–O isotope values obtain from the fluid inclusions indicate that the first three hydrothermal events relate to mineralizing fluids derived from a metamorphic source, but the last event includes a mixed metamorphic and meteoric source. Chalcopyrite, tennantite, and bornite from the deposit have δ34S values between −11.5 and 3‰. The δ65Cu values for quartz-Cu sulfide mineralization associated with the second hydrothermal event range from −0.31 to 0.2‰, but carbonate-Cu sulfide mineralization associated with the third hydrothermal event ranges from −1.01 to −1.08‰. The combination of the Cu and S isotopic values and field observations indicate that the controlling factors include structures, the temperature of regional metamorphism, and the pH of the mineralizing fluid. The zation is, therefore, characteristic of an orogenic-type deposit.

The Matou Mo(-Cu) deposit, located in the Yangtze Valley Metallogenic Belt of central-eastern China, is a typical porphyry-type Mo deposit. The orebodies at the deposit are hosted by Matou porphyritic granodiorite, which is the largest intrusive in the area. Quartz vein-type and disseminated sulfide mineralization are well developed in the porphyry and near its contact with Silurian sandstone. Crosscutting relationships indicate that porphyritic granodiorite is the oldest phase in the pluton, which is crosscut by a porphyritic diorite containing traces of chalcopyrite, and later dolerite dykes. These phases have U-Pb zircon dates of 147 ± 3, 140 ± 1 and 135 ± 1 Ma, which confirms the cross-cutting relationships observed in the field. A Re-Os molybdenite isochron age of 147 ± 4 Ma indicates that the porphyritic granodiorite is the source of the oldest Mo mineralization in the metallogenic belt and was formed during a change of the tectonic setting in the area, from an intracontinental orogeny to extensional tectonics. From 147 to 135 Ma, crust-mantle interaction played an important role in the formation of magmatic rocks at Matou. Systematic petrological and geochemistry investigations reveal that the three phases have a crust source with minor input from the mantle. Investigation of ore-forming fluid, H-O isotopes, S isotopes, and the Re content of molybdenite indicate that the ore-forming fluid and metals were derived from the lower crust. During the evolution of fluid from initial magmatic fluids (stage I) to ore-forming fluids (stage II), fluid boiling accompanied by the input of relatively cooler meteoric water led to the deposition of the Mo mineralization.

Graphite is one of the most essential non-metallic minerals with a wide variety of uses, and is an important commodity used in the emerging industry of China. Graphite is sourced from 170 mine areas in China from 25 provinces. This contribution is on a study of 15 regions in China with known graphite resources based on the spatial and temporal analyses of the regional metamorphic, contact metamorphic, and hydrothermal types of graphite. The knowledge gained on the metallogenesis of graphite in China is used to develop a model for choosing prospective regions for graphite, and to target areas for detailed exploration. It outlined 28 prediction areas with predicted graphite resources of about 1.63 billion tonnes to a maximum depth of 500 m in the Heilongjiang, Jilin, Liaoning, Shandong, Inner Mongolia and Hunan provinces. And of these, the predicted flake graphite resources in the Heilongjiang Province has been totalling almost a billion tonnes representing almost 60% of China’s graphite resource. As a result of this study, it is concluded that graphite has been formed during restricted periods of time, with the regional metamorphic type being the main style present in China.

The assessment of the mineral resources by the China National Mineral Assessment Initiative was completed between 2007 and 2013. The initiative’s aim is to compile mineral prospectivity maps and estimate the total (known and unknown) resources available and mineral types for 25 of the most perspective strategic minerals located in China. The project includes the construction of deposit models applied to various types of mineralisation, such as supergene, sedimentary, and hydrothermal mineralisation. The “Integrated information assessment” methods based on the “deposit model” approach was developed and is introduced in this contribution. Eighty mineral deposit models have been developed, documented, and included in a geographic information system (GIS). The models are applied to at least 1000 known deposits in China, and are used to calculate the geological parameters for and statistics of multiply spatial datasets for mineral deposits at a regional scale of 1:200,000. The initiative will be expanded in the future to an assessment of China’s mineral potential to a minimum depth of

The estimation of undiscovered mineral resources is an important part in the potential value of a mineral field and its long-term use. This manuscript documents six procedures for estimating the volume of potential mineral resources in an area that is based on integrated geological information forming part of a metallogenic model. The technique for this methodology includes: (1) the development a metallogenic model or models for mineral deposits in the study area; (2) the integration of the characteristics of known mineral anomalies with geology, geochemistry and geophysics to establish a predictive model for mineralization; (3) the definition of possible mineral resources incorporating predictive models with characteristic analyses, the knowledge-driven Delphi method, and magnetic anomalies; (4) calculate the parameters for the quantitative prediction, areas of known mineral deposits and their estimated dip extension, ore‐bearing coefficients, and their similarity coefficients based on explored ore-deposits in the area studied; (5) complete quantitative predictions using an synthetic volumetric equation; and (6) assess zones that are considered prospective for mineral resources. The procedure is tested for magmatic Ti-V-Fe resources in a known mineralized zone in the Sichuan Province of China.

This paper demonstrates a partial least-squares regression (PLS) method for geochemical modelling, and then uses the models and geological favourable features to obtain mineral potential maps. The PLS is one of multivariate analysis technologies, which can identify variations in associations and correlations among geochemical elements and mineralisation. The method is here used to calculate principal components as well as to identify correlations between Pb–Zn (mineralization) and 25 stream sediment elements for constructing geochemical models in the Huayuan-Fenghuang district of northwestern Hunan Province, China. The models showing the distribution of geochemical anomaly are useful in interpreting the distribution of faults and the Cambrian Qingxudong Formation (ore-bearing formation), and to better define the architecture on mineralisation in the study area. In addition, the models and other favourable features (proxies) are easily integrated into single possibility map by Boost Weights-of-Evidence (Boost WofE) approach for targets.

The Jinding Zn–Pb deposit located in the Mesozoic-Cenozoic Lanping Basin of southwest China has ore reserves of ∼ 220 Mt with an average grade of 6.1% Zn and 1.3% Pb. The mineralization is hosted by sandstone in the Early Cretaceous Jingxing Formation and limestone breccia in the Paleocene Yunlong Formation. Mineralization in both types of host rocks is characterized by a paragenetic sequence beginning with marcasite–sphalerite (Stage 1) followed by pyrite–marcasite–sphalerite–galena (Stage 2), and then galena–sphalerite–pyrite–sulfate–carbonate (Stage 3). Pyrite from these stages have different δ 33 S compositions with pyrite from Stage 1 averaging − 9.6‰, Stage 2 averaging − 8.9‰, and Stage 3 averaging + 0.3‰. Sphalerite hosted by the sandstone has similar δ 66 Zn values ranging from 0.10 to 0.30‰ in all stages of the mineralization, but sphalerite samples from the limestone breccia-hosted ore show variable δ 66 Zn values between − 0.03 and 0.20‰. Our data on sphalerite precipitated during the earlier stages of mineralization has a constant δ 66 Zn value and cogenetic pyrite displays a very light sulfur isotope signature, which we believe to reflect a sulfur source that formed during bacterial sulfate reduction (BSR). The Stage 3 sphalerite and pyrite precipitated from a late influx of metal-rich basinal brine, which had a relatively constant variable δ 66 Zn isotopic composition due to open system isotope fractionation, and a near zero δ 33 S composition due to the influence of abiotic thermochemical sulfate reduction from observed sulfates in the host rock.

The Chalukou deposit is located in the North Great Xing’an Range of the Xing’an-Mongolia Orogen bordering and to the northeast of the North China Craton. The deposit is a high-F-type porphyry Mo deposit hosted by the Chalukou composite igneous body containing small intrusive bodies genetically related to Mo mineralization. The composite igneous body includes pre-mineralization dolerite, monzogranite and syenogranite, syn-mineralization rhyolitic porphyry, granitic porphyry and fine-grained monzogranite, and post-mineralization rhyolitic porphyry, quartz porphyry, dioritic porphyry and andesitic porphyry. Detailed laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb zircon dating of the igneous components of the composite igneous body was carried out to determine the temporal framework for magmatism in the Chalukou region. The new LA-ICP-MS U-Pb ages constraint documented here, together with the published ages, indicate that there was a protracted porphyry Mo ore-forming event of approximately 7 million years between ca. 152 when the ore related rhyolitic porphyry was emplaced and ca.145 Ma when molybdenite ceased being deposited. The dating reveals that the mineralization is a part of relatively long-lived magmatic cycle involving the emplacement of small doleritic stocks at ca. 165 Ma that progressively evolved into extensive granitic intrusions at ca. 164 Ma, and then diminished with the emplacement of mineralization-related porphyries to ca. 152 Ma. The emplacement of barren Early Cretaceous magmatism, represented by volcanic units in the ca. 136 Ma Guanghua Formation and porphyries, followed the mineralized magmatism. The syn-mineralization porphyry units associated with Mo contain zircons assaying ∼15 times higher in U and Th than the pre-mineralization magmatic phases. This indicates that there was a significant enrichment of Mo, U and Th in the magma, and directly associated with ore fluid exsolution. The return to their normal levels in the three elements in the post-mineralization magmatic phases indicates that they were exhausted from the magma chamber in the later phases. A genetic model is proposed for the enormous introduction of ore metals and enrichment at the Chalukou deposit. The protracted and multiphase igneous activity during the long-lived magmatism reflects a multistage enrichment of metal, and may play a crucial role in the formation of a volatile-enriched, fertile and large-volume magma chamber beneath the Chalukou deposit. Such a chamber is envisaged to be required for the formation of porphyry Mo deposits in general.

The Longmala deposit is a representative of the skarn Pb-Zn-Cu deposits found in the Nyainqentanglha area of Tibet, China. The mineralization is hosted by skarn and marble of the Permian Wululong Formation intruded by an early Eocene biotite monzogranite, which is associated with the Pb-Zn-Cu mineralization. The genesis of the deposit is related to a four-stage progression involving: Stage I involves the development of prograde skarn; Stage II is a pre-ore retrograde skarn; Stage III is the emplacement of quartz-sulfides ore; and Stage IV is the emplacement of post-ore carbonate. The biotite monzogranite is a high-K calc-alkaline highly fractionated I-type granite characterized by its elevated SiO2 (68.38–72.62 wt%), FeT (4.09–6.19 wt%), and K2O + Na2O (7.82–8.33 wt%) contents. Its aluminum saturation index of 0.97–0.99 and a high differentiation index of 79–86 are indicative of a last-stage fractionation of the magma. The monzogranite is relatively enriched in light rare-earth elements, Th, U, and Rb, depleted in Sr, Ba, K, Nb, P, and Ti, and has a negative Eu anomaly. The eHf(t) values (−6.2 to +1.5), two-stage Hf model ages (average TDM2 = 1224 Ma) for zircons, and whole rock Pb isotopic compositions (206Pb/204Pb = 18.806–18.938, 207Pb/204Pb = 15.676–15.697, and 208Pb/204Pb = 39.234–39.376) indicate that the source of the magma is the crust of Lhasa Terrane. The study of fluid inclusions from each of the four stages mentioned above show that garnet and diopside from the prograde skarn (Stage I) are characterized by high temperatures and high oxygen fugacity indicative of magmatic fluids. The succeeding mineralization (Stage III) is characterized by moderate to high temperature and a reducing fluid, and final carbonate veining (Stage IV) with a decreased fluid temperature and salinity. The δ18Ow values range from 1.3 to 10.8‰, and the δDw values are −123.5 to −93.4‰, indicating that the ore-forming fluids were derived from mixture magmatic and meteoric fluids, and the δ34S values of sulfides have a relatively narrow range of 0.3–3.6‰, suggestive of a magmatic source. The 206Pb/204Pb (18.571–18.722), 207Pb/204Pb (15.707–15.796), and 208Pb/204Pb (39.116–39.448) values of sulfides show that ore-forming metals were derived from the crust in the Lhasa Terrane. Major and trace elements characteristics of the ore-associated biotite monzogranite, combined with the dating results, suggest that the Longmala deposit were formed within the India-Asia continental-collision tectonic setting.

The Haobugao Zn–Fe deposit is a typical skarn deposit located in the southern part of the Great Xing’an Range that hosts polymetallic mineralization over a large region. The main ore minerals at the deposit include sphalerite, magnetite, galena, chalcopyrite and pyrite, and the main gangue minerals include andradite, grossular garnet, hedenbergite, diopside, ilvaite, calcite and quartz. There are broadly two mineralizing periods represented by the relatively older skarn and younger quartz–sulfide veins. In detail, there are five metallogenic stages consisting of an early skarn, late skarn, oxide, early quartz–sulfide, and late quartz–sulfide–calcite stages. Electron microprobe analyses show that the garnet at the deposit varies in composition from And97.95Gro0.41Pyr1.64 to And30.69Gro66.69Pyr2.63, and pyroxene is compositionally in the diopside–hedenbergite range (i.e. Di90.63Hd8.00Jo1.37–Hd88.98Di4.53Jo6.49). Petrographic observations and electron microprobe analyses indicate that the sphalerite has three generations ([Zn0.93Fe0.08]S–[Zn0.75Fe0.24]S). The Zn associated with the first generation sphalerite replaced Cu and Fe of early xenomorphic granular chalcopyrite (i.e. [Cu1.01Fe1.03]S2–[Cu0.99Fe0.99]S2), and part of the first generation sphalerite is coeval with late chalcopyrite (i.e. [Cu0.96Fe0.99Zn0.03]S2–[Cu1.00Fe1.03Zn0.01]S2). Magnetite has a noticeable negative Ce anomaly (δCe = ∼0.17 to 0.54), which might be a result of the oxidized ore-fluid. Thirty δ34SV-PDB analyses of sulfides from the ore range from −2.3 to −0.1‰ in value, which are indicative of a magmatic source. The δ13C‰ and δ18O‰ values for calcite from the ore formed at quartz–sulfide–calcite stage vary from −9.9 to −5.5‰ and from −4.2 to 1.1‰, respectively, contrasting with δ13C‰ (2.9–4.8‰) and δ18O‰ (9.8–13.9‰) values for calcite from marble. It is suggested that the ore-forming fluid associated with late stage of mineralization was predominantly magmatic in origin with some input of local meteoric water. Molybdenite from the Haobugao deposit defines an isochron age of 142 ± 1 Ma, which is interpreted as the mineralization age being synchronous, within error, with the zircon U–Pb ages of 140 ± 1, 141 ± 2, and 141 ± 1 Ma for granite at the deposit. These data and characteristics of lithology and mineralization further show that the Zn–Fe mineralization is temporally and spatially related to the emplacement of granite in an extensional tectonic setting during the Mesozoic.

Isotope dilution thermal ionization mass spectrometry (ID-TIMS) and laser ablation inductively coupled plasma mass spectrometry (LA–ICP-MS) are two popular analytical methods used to constrain the age of minerals, including cassiterite. Compared to ID-TIMS, the LA–ICP-MS analytical method is often favoured due to its simple analytical procedure and sample preparation, although the methodology constantly needs modification. Our recent paper on dating cassiterite from the Baiganhu W-Sn ore field in NW China based on LA–MC-ICP-MS and ID-TIMS methods has received a response from Dr. Leonid A. Neymark (2017). Definitely, Neymark is appreciated, and his suggestions are helpful to improve the methodology of cassiterite U–Pb geochronology. Based on a discussion on the cassiterite U–Pb dating method, we re-confirm the validity of the cassiterite U-Pb ages for the Baiganhu W-Sn ore field. The initial non-radiogenic 204Pb used in the U-Pb isochron approach can be replaced by the non-radiogenic 207Pb, because the radiogenic 207Pb decayed from 235U can be ignored in cassiterite with a high Pb content. Therefore, the cassiterite U-Pb isochron yields an age similar to that obtained from T-W concordia for the same sample, testifying the validity of the cassiterite 238U/207Pb–206Pb/207Pb isochron method.

The Sidingheishan porphyry Cu–Mo deposit is located in the northeastern margin of the Kanggur–Huangshan Shear Zone of the Eastern Tianshan Terrane (ETT) in the Xinjiang Province of northwestern China. Laser Ablation–Inductively Coupled Plasma–Mass Spectrometry (LA–ICP–MS) zircon U–Pb dating of rocks in the area yielded an emplacement age of 427 ± 3 Ma for the ore-bearing granodiorite, which is intruded by 406 ± 3 to 397 ± 4 Ma gabbro, and a 382 ± 4 Ma monzogranite. These rocks have a tholeiitic to calc–alkaline and metaluminous geochemical affinities, with A/CNK values ranging from 0.65 to 1.14. The Silurian granodiorite and Carboniferous monzogranite are enriched in LREEs and LILEs (i.e. K, Ba, Pb and Sr), depleted in HREEs and HFSEs (i.e. Nb, Ta and Ti), and slightly positive Eu anomalies (Eu/Eu* = 0.94–1.39) indicative of crystal fractionation. The granodiorite and monzogranite have elevated MgO assays (0.36–1.85 wt%) and Mg# values (34–52), low (87Sr/86Sr)i ratios of 0.70320–0.70435, high eNd(t) values (5.9–6.9), TDM2 Nd model ages between 687 and 568 Ma, and eHf(t) values between + 8.37 and + 17.44. The geochemistry of the Early Devonian gabbro is characterised by its low SiO2 assays of 47.69–51.34 wt% and high Al2O3 assays of 18.07–22.91 wt% and MgO assays of 2.29–7.09 wt% (with Mg# values of 38–64), eNd(t) values of 4.7–6.9, eHf(t) of 8.04–17.97, and (87Sr/86Sr)i values of 0.70371–0.70420. The gabbro samples are enriched in LILEs, depleted in HFSEs, and have positive Eu anomalies. Combined with the regional geological history and above mentioned data, we suggest that the Sidingheishan granodiorite and monzogranite were formed during partial melting of subducted oceanic crust interacting with the lithospheric mantle. We also proposed that the Devonian gabbro developed during an extensional tectonic setting involving subduction–related magmatism in a continental arc margin rather than during mantle plume activity in the post–collisional extensional tectonic setting. The Sidingheishan granodiorite and associated porphyry Cu–Mo mineralisation were generated in an arc setting, associated with the N-dipping subduction of the Palaeo–Tianshan oceanic plate beneath the Dananhu–Tousuquan island arc.

The Daganshan region in the western part of the Guangdong Province is an important mineralised area containing W, Sn, and Ag–Pb–Zn occurrences. Although vein-type Ag-Pb-Zn deposits are usually spatially related to W-Sn and Sn deposits, the genetic links between them are still not understood. The newly discovered Gaocheng deposit is a typical vein-type Ag-Pb-Zn deposit in this region, which is hosted predominantly by a Silurian biotite monzogranite and to a lesser extent by a Late Cretaceous quartz porphyry . Here, we present new Rb-Sr dating of sphalerite, fluid inclusion microthermometry, and H-O-S isotopic geochemistry of the deposit, and whole-rock major and trace elements geochemistry of the mineralised quartz porphyry. The aim is to better understand the genesis of the Ag-Pb-Zn mineralisation and its link with W, and Sn deposits in the region. The sphalerite Rb-Sr age is 90 ± 6 Ma, indicating that mineralisation is Late Cretaceous similar to that of the quartz porphyry. Three vein sets have been recognised around the quartz porphyry comprising early arsenopyrite–pyrite–quartz veins crossed by sulphides–quartz–Ag veins and late (non-mineralised) calcite–quartz–fluorite veins. The fluid inclusions have homogenisation temperatures of 360–300 °C with salinities of 8.2–6.4% NaCl equivalent for the first vein set, 320–240 °C with salinities of 6.5–4% NaCl equivalent for the second vein set, and 220–160 °C with a corresponding salinity of 4.2–3.4% NaCl equivalent for the late vein set. This indicates a gradual decrease of temperature and salinity of the mineralising fluids. The composition of the vapour accompanying the saline fluid in the inclusions is H 2O with minor amounts of CO2 and CH4, which indicates that the mineralising fluid included H2O–NaCl(–CO2–CH4). The fluid inclusions in the early vein set assays +6.52 - +6.13‰ δ18OH2O and –91 - –85‰ δDH2O, and the fluid inclusions in the mineralised second vein set contains +5.72 to +2.41‰, δ18OH2O and −72 to −42‰ δDH2O. These data indicate that the mineralised fluids represented by the stage I and II vein sets included magmatic fluids that were gradually contaminated by meteoric fluids. The magmatic source of the mineralising fluid is also indicated by the narrow range of δ34 S values between −2.2 and −2.4‰. The whole-rock analyses show that the Late Cretaceous quartz porphyry is a highly fractional peraluminous granite , similar to the W- and Sn-related granites in the Daganshan region. The Gaocheng vein-type Ag-Pb-Zn deposit is therefore genetically related to the Late Cretaceous quartz porphyry and shares similar geochemical characteristics at Sn-bearing granites in the Daganshan region and is also prospective for Sn mineralisation.

The recently discovered Weilasituo Sn-polymetal deposit is located in the southern part of the Great Xing'an Range of Inner Mongolia, NE China, which is belonged to the eastern part of the Central Asian Orogenic Belt (CAOB). Sn-polymetal mineralization is closely related to the emplacement of the Early Cretaceous fine- to medium-grained quartz porphyry. Three types of mineralization have been recognized at Weilasituo with the disseminated and stockwork Sn-polymetal mineralization mainly hosted by the quartz porphyry, the vein-type Sn-polymetal mineralization hosted by NE-trending and WE-trending fractures and faults in the upper and outer part of the porphyry, and breccia mineralization occurred within a steep cryptoexplosive breccia pipe. The ore-related alteration typically consists of Na-Ca-Sr alteration and greisen. In order to understand the petrogenetic link between the Sn-polymetal mineralization and the host quartz porphyry, this paper presents new whole-rock geochemistry for the quartz porphyry, EPMA analysis of ore and gangue minerals, and in situ U-Pb dating of cassiterite. The Laser Abrasion Multiple Collector Inductively Coupled Plasma Mass Spectrometer (LA-MCICP-MS) cassiterite U-Pb dating yields two well-defined isochron ages of 138 ± 6 Ma for disseminated ore and 135 ± 6 Ma for the vein-type ore, which could be regarded as the ore-forming age. The cassiterite U-Pb ages (ca. 138–135 Ma) determined in this study, together with previous data, reveals the close temporal and genetic relationship between the mineralization event and the emplacement of the quartz porphyry. The quartz porphyry is characterized by high SiO2, Na2O, and A/CNK values (1.09–1.21). REE tetrad effect combined with extremely high Rb/Sr, K/Ba ratios and low K/Rb, Zr/Hf, La/Nb, La/Ta and Eu/Eu* ratios indicate that the quartz porphyry is a highly fractionated peraluminous I-type granite that is hydrothermally altered. Low eNd(t) values of 4.27–0.28 and the two-stage depleted mantle Nd model ages (T2DM = ca. 1279–908 Ma) for the quartz porphyry, are similar to granites in Precambrian microcontinents of the eastern part of the Central Asian Orogen (CAOB). This suggests that the quartz porphyry was derived from the remelting of juvenile crust and Precambrian rocks in an extensional setting. Therefore, the highly fractional crystallization and magmatic-hydrothermal interactions of the quartz porphyry have contributed to the formation of the Weilasituo Sn-polymetal deposit.

Zijinshan is the largest high-sulfidation epithermal Cu–Au deposit on mainland China. The primary mineralization at the deposit is characterized by pyrite, digenite and covellite. Although some Rb Sr isochron ages of the fluid inclusions in quartz and the apparent K-Ar age of the Cu-bearing alunite alteration zone have been previously interpreted as the ore-forming age, the Rb-Sr and K-Ar dating systems are usually readily reset due to their closure temperature, and thus document the latest thermal event. In order to precisely determine the age of the Cu mineralization, eight-pyrite separates were Re-Os dated, and seven yielded an isochron age of 103 ± 4 Ma with an initial 187 Os/ 188 Os ratio of 0.45 ± 0.14. This date is interpreted as the age of Cu mineralization, which is in agreement with geochronological data from molybdenite and the porphyritic granodiorite that hosts Cu-Mo mineralization at Luoboling (located 2 km NE of Zijinshan), suggesting that these two deposits were formed during the same metallogenic event. The relatively low initial 187 Os/ 188 Os ratio indicates that the source of the Cu at Zijinshan is predominantly the crust with input from the mantle.

Isotopes (Rb Sr, C, O, S, and Pb) were investigated from the Zhenzigou Pb Zn deposit in the Qingchengzi mineral field (QMF) of the North China Craton as an aid to determine the genesis of stratiform Pb Zn deposits in the Liao-Ji Rift. A step-dissolution Rb Sr age of 1798 ± 8 Ma with 206Pb/204Pb ratios of 17.7477–17.8527 were obtained from sphalerite. Sulfur isotopic ratios for pyrite (5–14.4‰), sphalerite (2.4–8.6‰), and galena (− 0.3–8.6‰) from Zhenzigou have a narrower range than those from the host Paleoproterozoic Dashiqiao Formation, and granite in the area. Calcite and limestone from ore and wallrocks at the deposit have similar C and O isotope compositions, with δ13CPDB ranging from − 6.0 to − 2.3‰ and δ18OSMOW from 9.8 to 13.7‰, which are similar to those of carbonatite and the mantle. Comprehensive analysis of the Pb isotopic composition of the sulfide from the Zhenzigou deposit and Pb Zn deposits in adjacent area show that the Pb originated from the upper crust and mixed with Pb from the mantle. Sulfur isotopes from Zhenzigou deposit indicate that the mineralization has a volcanic eruption source. The δ13CPDB and δ18OSMOW values indicate that the CO2 originated from a mixed mantle, marine carbonate and organic source. Combined with the study of regional metallogenic background, this paper proposes that deposition of stratiform Pb Zn mineralization in the QMF began ca. 2052 Ma during development of the Liaoji Rift. The mineralization extended to ca. 1798 Ma prior to deformation associated with the Lvliang Movement, which dismembered the stratiform Pb Zn mineralization. The veined mineralization in the region cross-cuts the stratiform deposits and represents remobilized and redeposited deposits associated with the emplacement of Triassic plutons such as the Xinling and Shuangdinggou granites.

The Dayana W-Mo deposit in eastern Ujumchin of Inner Mongolia is a quartz-vein type deposit in the mid-western part of the Central Asian Orogenic Belt (CAOB). Biotite monzogranite, quartz porphyry and hornfels host W-Mo in quartz veins. Based on spatial relationships, molybdenite was deposited first followed by wolframite. This contribution presents precise laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) U–Pb zircon dating and geochemical analysis of the biotite monzogranite. The U–Pb dating shows that the monzogranite is 134 ± 1 Ma. Major and trace element geochemistry shows that the monzogranite is characterized by high SiO 2 and K 2 O contents, a “Right-inclined” shape of the chondrite normalized REE patterns, enrichment of large ion lithophile elements (LILEs), and depletion of high field strength elements (HFSEs) such as Nb, P, Ba. The monzogranite is high-K calc-alkaline, has a strong negative Eu anomaly (Eu/Eu* = 0.04–0.45), low P 2 O 5 content, high A/CNK of > 1.2, enriched in large-ion lithophile elements (LILEs; such as Rb, Th, U, Nd, and Hf), and notably depleted in Ba, Sr, P, Ti, and Nb. These characteristics define the Dayana monzogranite as a highly fractionated peraluminous granite. Re–Os isotopic analysis of seven molybdenite samples from the deposit yield an isochron age of 133 ± 3 Ma (MSWD = 2.2), which indicates that the monzogranite and ore have the same age within error, are probably genetically related, and related to a major Early Cretaceous mineralizing event in China known as the Yanshanian.

Buffer zones in bo\th two-dimensional (2D) and three-dimensional (3D) spaces are commonly used in prospectivity mapping. The method completes a modelling that starts with a real example and progresses to the development of a virtual model. This includes the consideration of lithological or structural contacts at depth, which is a theoretical concept based on extrapolation of data collected in the field, rather than an empirical observation of the feature based on physical samples. This contribution documents an improved buffer analysis method for the study of 3D-space that is implicit (rapid), precise (smooth) and based on triangulated characteristics, which can be used to construct influence domains of geological models. As traditional 2D GIS-based mineral potential mapping is gradually becoming limited with time, mineral potential mapping in three dimensions (3D) is increasingly becoming an important tool in finding concealed economic mineralization. This contribution documents an improved methodology of buffer analysis for prospectivity mapping processing mineralized favourable models rather than describing an advance in the geometry of surface rendering of “geological complexity”. Measures used in this buffer analysis include the: (1) voxelization of geological objects (i.e. assigning numerical values of features on a regular cube in 3D-space); (2) revision of the 3D Euclidean distance transform and the calculation of signed distance field; (3) extracting surfaces from the field; and (4) construction of a buffer-surface based on a “discrete smooth interpolation” (DSI) algorithm. Furthermore, this contribution constructs 3D models using a buffer analysis algorithm and prospectivity mapping introduced here, which is based on real data from the Jiama Cu-polymetallic deposit in Tibet and Daye Fe deposit in the Hubei Province, China. This contribution also presents a comparison between voxel and irregular triangle models, which illustrate that irregular triangle mesh buffer analysis (ITB) can improve modelling techniques for GIS-based 3D mineral potential mapping. The outcome is an increase in the accuracy of prospectivity mapping.

The Anjiayingzi gold deposit is hosted by the Jiguanzi Quartz Monzonite in the footwall of the Kalaqin Metamorphic Core Complex (MCC) at Chifeng in the northern part of the North China Craton (NCC). An earlier (ca. 135–125 Ma) top-to-the-NE ductile–brittle shear and a later (ca. 121 Ma) top-to-the-NW and SE brittle detachment normal faulting are recognized around the Kalaqin MCC. The Jiguanzi Quartz Monzonite intruded the footwall of the Kalaqin MCC at ca. 133 ± 1 Ma with crystallization temperatures of 640–691 °C, pressures of 167–271 MPa and an average depth of 8.6 km. Gold veins in the Anjiayingzi gold deposit are hosted by the monzonite and controlled by the NE-trending brittle–ductile and brittle fault zones. These ore-bearing faults are products of a regional sinistral shearing event coinciding with the earlier top-to-the-NE ductile–brittle shear at the Kalaqin MCC. The ore of the Anjiayingzi deposit is characterised by its low Au/Ag ratio ( 2 O–CO 2 –NaCl fluid system with salinities of 1.3–15.6 wt.% NaCl equiv. Trapping pressures of ore fluids were 50–110 MPa, corresponding to an average depth of ~ 2.5 km under a lithostatic load and ~ 7.5 km under a hydrostatic load. Fluid mixing and immiscibility are potential causes for the rapid precipitation of sulphides carrying Au. The stable isotope δ D (− 80.3 to − 96.5‰) and δ 18 O H 2 O (3.7 to 5.5‰) of the ore fluids, the consistent Pb isotope compositions between the ore-bearing sulphides and K-feldspar from the Jiguanzi Quartz Monzonite, and a > 2 billion year time gap between the gold mineralization and metamorphism of the basement all indicate that the mineralizing fluids and metals are derived from a concealed intrusion near the major eastern Louzidian Fault in the Kalaqin MCC. This proposal is supported by the presence of mafic magmatic enclaves and rhyolite dykes in the Jiguanzi Quartz Monzonite, and higher average Th total (322 °C) and δ 34 S (2.4‰) of Eastern veins than those of Western veins (with a Th total of 287 °C and δ 34 S value of 0.3‰). The ca. 133–126 Ma gold mineralization at Anjiayingzi was formed during rapid cooling of ca. 133–126 Ma Jiguanzi Quartz Monzonite at a cooling rate of 42–71 °C/Ma, and fast exhumation and cooling of the Kalaqin MCC between ca. 135 and 121 Ma at a cooling rate of 30 °C/Ma. This process was accompanied by fluid immiscibility and mixing within the structural transition from ductile–brittle to brittle deformation with resultant fluid-pressure fluctuations between the supra-hydrostatic and hydrostatic regimes.

The Jinchangyu Au deposits contained an original resource of 50 t of gold and is located close to the northeastern margin of the North China Craton (NCC). The orebodies are controlled by structures in the amphibolite units of the Archaean Zunhua Group. Mineralization is generally associated with albite and hematite which is indicative of Na–Al–Si–Fe alteration. The most common styles of mineralization are subdivided based on the cross-cutting relationships of mineral assemblages as follows: (i) quartz–albite–hematite; (ii) quartz–albite–polymetallic sulfides with gold and molybdenite; (iii) quartz–pyrite; and (iv) quartz–carbonate. Quartz samples from the second (Stage II) and third (Stage III) assemblages contain two-phase fluid inclusion types; these are: (i) CO2–H2O fluid inclusions, and (ii) daughter mineral-bearing inclusions, which have homogenization temperatures of 270°–350 °C (for assemblage Stage II) and 180°–240 °C (for Stage III), and salinities of ≤ 13 wt.% NaCl equiv. A few S-type fluid inclusions suggesting salinities of 27.6–28.3 wt.% NaCl equiv. The S isotope composition of pyrite and molybdenite from Stage II (δ34S = –4.4 to 1.9‰) indicates that the mineralizing fluid originated predominantly from a magmatic source. The H–O isotope signatures from Stage II indicate a magmatic-dominated source for the mineralizing fluid with some addition of meteoric fluids. Previously published Pb and C isotope data indicate that ore and magma in the eastern part of the Hebei Province of China interacted with Precambrian country rocks, and so the fluids moved from the lower crust to shallower level during mineralization. The red quartz–albite–hematite veins from Jinchangyu were generated under strongly oxidizing alkaline conditions that were favorable for the incorporation of gold into the fluid and the crystallization of albite during the early stage of gold deposition. Seven molybdenite samples from Jinchangyu yield Re–Os model ages of ca. 233 to 219 Ma with a weighted mean age of 225 ± 4 Ma and an isochron age of 223 ± 5 Ma. This indicates that at least some of the gold associated with molybdenite is Late Triassic in age, and could be associated with buried intrusions that are part of the Late Triassic Dushan granites in the eastern portion of the NCC. This mineralization was formed after the closure of the Paleo-Asian Ocean. These results indicate that the intrusion-related Jinchangyu deposit is the far-field structural product of the collision of the NCC with the Siberian Craton to the north along the northern margin of the NCC.

The Haoyaoerhudong gold deposit is located in the Urad Middle Banner area of Inner Mongolia in China, and is hosted by black schist of the Bilute Formation in the Mesoproterozoic Bayan Obo Group. The gold mineralization is within a 4500 m long and 100 m wide zone associated with sulphide(–quartz) veins following the schistosity and crosscutting fractures in the host-rocks; locally as disseminated sulphide in altered black schist. The sulphide mineral assemblage is pyrrhotite–pyrite(–arsenopyrite–chalcopyrite–sphalerite) and is associated with a weak hydrothermal alteration characterized by a silica halo with variable amounts of biotite, sericite and carbonate. The Bilute Formation was intruded by multi-stage dykes; these include metamorphosed porphyritic diorite that pre-dates mineralization, unmetamorphosed amphibole olivine gabbro that pre-dates mineralization, and tourmaline-bearing pegmatite that post-dates mineralization. In order to constrain the timing of the gold mineralization and host rocks, zircons from the porphyritic diorite, amphibole olivine gabbro and tourmaline-bearing pegmatite were extracted for U–Pb dating. Gold-bearing pyrite samples were analysed for δ 34 S to help determine the possible source of S in the mineral zones. A weighted mean 206 Pb/ 238 U age date of 288 ± 3 Ma (MSWD = 2.4) was obtained for the porphyritic diorite, a weighted mean 206 Pb/ 238 U age date of 282 ± 1 Ma (MSWD = 0.58) was obtained from the amphibole olivine gabbro, and a weighted mean 206 Pb/ 238 U age date of 182 ± 1 Ma (MSWD = 1.04) was obtained from the tourmaline-bearing pegmatite. These dates constrain the timing of gold mineralization to between 282 ± 1 and 182 ± 1 Ma, and are consistent with the hydrothermal alteration ages of ca. 267–246 Ma reported from the literature. These new zircon dates indicate that the regional metamorphism of the Bayan Obo Group ceased by the time the Haoyaoerhudong gold mineralization was deposited and the genesis of mineralization is not related to the regional metamorphic event. The gold-bearing pyrites gave positive δ 34 S V-CDT values between 6.8 and 13.4‰, and are different from the δ 34 S widely distributed values for the typical black rocks, indicating that the sulphur is not derived from the black Bilute Formation, but sourced from some other relatively uniform reservoir. Widespread contemporaneous granitic magmatism is developed in the Haoyaoerhudong area and we suggest that the sulphur forming the gold-bearing sulphides is probably sourced from a carbonate-contaminated granitic magma reservoir. The new zircon dates for the dykes and the δ 34 S data for gold-bearing sulphides indicate that the gold mineralization did not form from metamorphosed black schist in the Bayan Obo Group, but is associated with magmatic–hydrothermal activity.

The large Yu'erya gold deposit (65 t of contained gold averaging 2.3 g/t Au) in the eastern part of the Hebei Province of China is spatially associated with the Yu'erya Granite, and a group of NE- and NNE-trending faults. The alteration associated with mineralization is characterized by the assemblage pyrite, quartz, sericite, albite, and carbonate. Four stages of mineralization, in chronological order, are (1) quartz and medium- to coarse-grained pyrite; (2) quartz, fine-grained pyrite, and gold; (3) quartz, polymetallic sulfide, tellurobismuthite, and gold; and (4) quartz, pyrite, and carbonate. Most of the gold was deposited during the second and third stages of alteration from mesothermal fluids. These fluids were relatively rich in H 2 O, CO 2 , K + , Ca 2 + , Cl, and S, and low salinity. The H–O and sulfur isotope ratios determined for the mineralized samples indicate a magmatic source, and the Pb isotope data indicate that the Au mineralization originated from the mantle and lower crustal materials. Geochronological data indicate that the gold mineralization event was restricted to 200–163 Ma whereas the associated magmatism occurred between 200 and 150 Ma. This Mesozoic gold mineralization is related to the subduction of the Mongolia–Okhotsk and Paleo-Pacific oceans along the edges of the North China Craton.

This volume of Ore Geology Reviews is dedicated to Dr Feng-Jun Nie and credits his significant contribution to understanding the ore deposits of China. In recent years, he has dedicated his life to the study of mineralization in the North China Craton and Central Asian Orogen to the north, and that is the focus of this volume. 谨将本《矿床地质论评》专辑献给聂凤军博士，以表彰他对中国矿床地质研究所做出的杰出贡献。聂凤军博士近年来一直致力于华北克拉通及其北部中亚造山带的成矿规律研究，这也是本专辑的焦点。

The newly discovered and large ca. 99 Ma Gaosongshan gold deposit is located in the Lesser Hinggan (or Xinggan) Range to the west of the Jiamusi Massif. The deposit is located at the border of the Great Hinggan Range–Mongolian Orogen with the Circum-Pacific tectonic belt and has a resource of ~ 22 t @ 6.3 g/t Au. Gaosongshan is classified as an adularia–sericite epithermal deposit associated with the large tensional Shaqihe Fault and has a low-sulfide content with a high concentration of gold hosted by pure chalcedonic quartz, which makes the deposit both unique and economically important in the area. Early Cretaceous volcanic rocks host the deposit as well as other gold deposits in the region. The mineralization at Gaosongshan includes Au, Ag, Mo, Sb, As, Pb and Hg. Stable isotope studies of fluid inclusions associated with the mineralization suggest that the mineralizing fluid had a meteoric origin (D V-SMOW : − 129 to − 111‰; 18 O fluid : 7.9 to 13.8‰). Fluid inclusion thermography indicates that the mineralized fluid was between 150° and 310 °C and had a low salinity (0.7–3.71 wt.% NaCl), low density (0.48–0.94 g/cm 3 ), shallow metallogenic depth (430–1270 m), and a large amount of reducing gaseous components (CH 4 , C 2 H 6 , CO, N 2 , and CO 2 ). The presence of large quantities of flaky quartz, adularia, gas-rich fluid inclusions, low-sulfide minerals and pure gold-bearing chalcedonic quartz suggests that fluid boiling was the principal mechanism for the gold precipitation. Sulfur isotopic data (δ 34 S: ~ − 2.4 to 2.9‰) indicate a deep magmatic origin for the mineralization, and the Pb isotopes ( 206 Pb/ 204 Pb: 18.14–18.46; 207 Pb/ 204 Pb: 15.51–15.57; 208 Pb/ 204 Pb: 38.01–38.40) also indicate that the metallogenic source of the deposit contained a significant mantle component. The mineralizing fluid interacted with a Late Paleozoic (ca. 260–253 Ma) substrate and ca. 141–91 Ma volcanic host rocks. The geological and geochemical characteristics of the deposit, and the Tuanjiegou, Dongan, Sandaowanzi and other large gold deposits represent an Early Cretaceous (114–80 Ma) epithermal mineralizing events in the Lesser Hinggan Range. The belt is controlled by the volcanic Sunwu–Jiayin Basin formed in a back-arc extensional setting along an active continental margin in East China, and the gold deposits in the belt have the same genesis as porphyritic Au(–Cu) deposits along the continental margin in eastern Jilin and Heilongjiang provinces. It is here proposed that the mineralization in both regions is related to the subduction of the Paleo-Pacific plate.

The Langxi vein-type Ba-F deposit, located in the southeast of the Sichuan Basin in the central part of Yangtze Block, South China, is hosted by Ordovician limestone. The paragenesis of the deposit’s veins is subdivided into pre-, syn- and post-ore stages. The syn-ore stage includes two fluorite generations with the first (Fl-1) deposited at ~140° to 200° C and the second (Fl-2) at ~140° to 180 °C. The syn-ore barite mineralisation was deposited with the temperature range of 110°–160 °C, and the syn-ore calcite records a temperature range of 90° to 140 °C. These temperature ranges show that the mineralising fluids were low- to moderate in temperature and decreased with the initial deposition of fluorite followed by barite and then calcite. The types of fluid inclusions in the veins are classified as monophase liquid (L-type, type I), biphase liquid + vapour (L + V type, type II) and polyphase (L + V + S type, type III) brine inclusions. The salinity of the mineralising fluid for the three types of inclusions during the deposition of F-Ba-Ca is 0.35–21.7% NaCl eqv., indicating that the ore-forming fluid varied greatly during the mineralising process. There are no obvious differences in the fluid inclusion density in the different minerals with the average densities being 0.98 g/cm3 for Fl-1, 0.99 g/cm3 for Fl-2, 1.00 g/cm3 for barite, and 1.01 g/cm3 for calcite. This shows that the density of the F–Ba–Ca mineralising fluid belong to a moderate- low density. The deposition of the minerals took place with a change from a reducing to an oxidising environment. The liquid phase initially included Na+ and Cl−, and evolved containing Ca2+, SO42−, K+, and Mg2+. LA-ICP-MS analyses reveal that the L-V type fluid inclusions associated with Fl-1 assays 46,600 ppm Na, 3470 ppm K (with a mean Na/K ratio of ~24), ~28,200 ppm for Cl, and 1060 ppm Br (with a mean Cl/Br mass ratio of ~27). The second-generation fluorite L-V type fluid inclusions average around 47,000 ppm Na and 12,000 ppm K, corresponding to and a Na/K mass ratio of 7. The halogen content of Fl-2 averages 26,200 ppm Cl and 950 ppm Br, corresponding to a Cl/Br mass ratio of 28. These analyses indicate that the mineralising fluid was rich in NaCl, assuming the fluid inclusions represent samples of the mineralising fluid. It is proposed that Ba-F concentrated in the mineralising fluid were derived from basinal fluids mixed with meteoric water circulating through faults at increased temperature gradients. The driving force was Late Cretaceous tectonic activity related to the subduction of the Paleo-Pacific Oceanic Plate. This model is consistent with the geodynamic setting of other barite-fluorite-rich districts in the Yangtze Block of South China.

The Yinachang Fe-Cu-Au-U-REE deposit is hosted by the lower part of the Paleoproterozoic Kunyang Group in the central Yunnan Province of SW China in an area known to contain iron-oxide Cu-Au mineralisation. The deposit includes: (i) the sulphide assemblage chalcopyrite – pyrite – magnetite – cobaltite – molybdenite – cassiterite; (ii) Rare Earth Element assemblage bastnaesite – parasite – fergusonite – xenotime – monazite; (iii) the uranyl hydroxide mineral vandendriesscheite; (iv) gold commonly hosted by ankerite; and (v) the gangue mineral assemblage apatite – biotite – fluorspar – quartz – calcite. The ore is commonly massive, disseminated, banded, or in calcite veins. The banded mineralisation contains high concentration of Au, Co, Mo, U, Fe, Cu and REE, and the vein-type mineralisation has abundant REE minerals of bastnaesite, parisite, fergusonite and xenotime. Monazite exists as inclusions in apatite or as discrete grains on the surface of magnetite, and the uranium is associated with chalcopyrite. The mineralising process can be divided into an initial Na-alteration followed by the ore-forming assemblages of Fe-REE and Cu-Au-U-REE mineralisation. The average δ18OH2O values in the quartz and calcite change are between 3.5 and 10.7‰, with δDV-SMOW values ranging between −98.2 and −47.7‰. The calcite, siderite and ankerite have δ13C isotope composition ranges from –14 to +1‰ and δ18O compositions of +6.9 to +22‰. The H–O–C isotope systematics indicate that the mineralising fluids have mixed magmatic and metamorphic sources, whereas the carbon is sourced from marine carbonate, and the low temperature alternation of polyphase mantle material. In situ δ34S sulphide value ranges between 1.1 and 11.9‰, and the bulk δ34S value ranges between −4.7 and 10.5‰. In situ Pb isotopes of sulphide samples have 206Pb/204Pb values of 18.58–18.76, 207Pb/204Pb values of 15.51–15.66 and 208Pb/204Pb values of 37.47–38.06. These values plot in the upper crust Pb-evolution curve, indicative of a complex source of Pb in the deposit. The Pb is interpreted to have a deep-seated magmatic source with a contribution from the crust. It is also proposed that the REE-mineralised fluids are derived from a late stage of alkaline magma differentiation. The 40Ar-39Ar biotite date indicates that the Precambrian rocks in the Kangdian region were regionally metamorphosed at ca. 900 Ma. The Yinachang Fe-Cu-Au-U-REE deposit is interpreted as an IOCG deposit based on geological and isotopic studies. The banded ore and vein type ore are the main exploration targets for uranium, gold and REE. This study helps us better understand IOCG deposits in China.

The Tugurige gold deposit, in the northeastern margin of the North China Craton (NCC) and western part of the Xing'an–Mongolia Orogenic Belt (XMOB), is a large tonnage quartz-vein type deposit with a resource of ~ 24 t at about 4 g/t Au. Gold mineralization is hosted by porphyritic syenogranite and controlled by NW-trending faults. Our study provides the first precise age for the Tugurige gold mineralization and host porphyritic syenogranite. The U–Pb age of zircons from the syenogranite is 276 ± 2 Ma, and Re–Os dating of six pyrite separates from the deposit yields an isochron age of 268 ± 15 Ma. The results show that the ages of syenogranite and gold mineralization are the same within error. Furthermore, geological and geochronological evidence indicate that the syenogranite and gold mineralization have very close genetic relationships and that they are products of Permian magmatism related to post-collisional extension of the Central Asian Orogenic Belt (CAOB). The initial Os isotopic compositions (187Os/188Os = 1.26 ± 0.69) of pyrite indicate that the source of Os, and by inference other ore-related materials, are derived from the crust. The Late Paleozoic is an important period in which economic gold mineralization was deposited in the CAOB.

Post-mineralisation exhumation is pivotal because of its strong effects on the preservation of ore deposit. The Jiguanzi quartz monzonite hosts the Anjiayingzi Au deposit at the centre of the Kalaqin Antiform (or Kalaqin metamorphic core complex) in the northern North China Block (NCB). We can link the exhumation of the deposit with regionally geodynamic events and evaluate its exploration implications using low-temperature thermochronology from the quartz monzonite host. Sericite 40Ar/39Ar dating of auriferous quartz-sulphide veins indicates that gold mineralisation timing is 130 ± 1 Ma. Zircon fission track ages of fresh samples from the host quartz monzonite vary from 118 ± 6 to 99 ± 4 Ma, and apatite fission track ages vary from 99 ± 6 to 66 ± 5 Ma. A four-stage post-mineralisation exhumation history is revealed by combining the binomial peak fitting of single-grain ages and low-temperature thermal history inverse modelling. The first exhumation event is dated at ca. 130–100 Ma, and characterised by the most rapid exhumation rate of 167 m/Ma and ca. 5 km rise. This movement is related to the top-to-NW and a SE ductile-brittle extensional deformation of the Kalaqin Antiform. Regionally, it is also contemporaneous with the formation of extensional metamorphic core complexes, development of basins, and increasing heat flow and decreasing thermal lithospheric thickness in the eastern NCB. All of these synchronous events can be linked to the back-arc setting of the subducting Izanagi Oceanic Plate and resulted geodynamic changes beneath the NCB. The relatively slow stage 2 exhumation, dated at ca. 100–65 Ma with an exhumation rate of 20 m/Ma, was triggered by the collision between the Izanagi Oceanic Plate and eastern China at ca. 100 Ma and following change in the drift direction of the Izanagi Oceanic Plate. Sedimentation of basins in the NCB was continuous during this period. Resumed stage 3 exhumation (ca. 65–45 Ma, 27 m/Ma) and synchronous sedimentary inversion are products of regional compression event related to the collision between India and the Eurasian plates. Change of the Pacific Oceanic Plate drifting direction at ca. 50 Ma finally induced the monotonic cooling and exhumation of stage 4 (19 m/Ma). The estimated post-mineralisation exhumation is ~7.1 km, and the ore-forming depth of the Anjiayingzi Au deposit is between 5.1 and 10.1 km. In combination with previously published data, the differential exhumation history, exhumation degree and preservation potential of major gold provinces in NCB are confirmed, which further indicate that their gold prospectivity must be assessed individually.

Manganese is, an important industrial mineral used in the manufacture of various products, including in the refinement of iron ore and as an alloy in steel. China has rich resources of manganese (Mn), with the majority of deposits located in southern China. The common types of Mn deposits are sedimentary, hydrothermally modified, and supergene. Exploring a suitable method to quantitatively assess the Mn mineral resources at the craton-scale is, therefore, an open challenge for the geologist. The purpose of this contribution is to present a framework for the region-scale assessment of manganese based on mineral-system analysis and the model-based synthetic volume method. The framework involves: (1) summarising the status of Mn resources in regions of southern China considered to be prospective for the metal; (2) constructing datasets based on mineral exploration; (3) completion of mineral-system analysis of Mn deposits in each prospective area; (4) establishing a prediction model based on mineral-system analysis; (5) construction of geographic information system (GIS) layers to represent the mineralisation processes; (6) using a mathematical model to conduct a spatial analysis of areas considered to be prospective; (7) estimation of mineral resources based on the synthetic volume method; and (8) delineation of “minimum potential area” (MPA) and the calculation of the total predicted resources. The innovations of this research are the translation of the ore-forming processes into mappable features in the geosciences datasets by applying the concept of mineral system, and quantitative assessment of the Mn mineral resources based on the assumption that the larger the volume of a trap, the more resources it probably holds. This framework was used for China’s “National Mineral Resources Assessment Initiative” in recent years, and help to assess the Mn mineral resources at the craton-scale, and determine the critical characteristic of the Mn deposits that can be used for the construction of model-based prospectivity mapping, especially in southern China, which can be used for manganese exploration.

The Tumen molybdenite–fluorite vein system is hosted by carbonate rocks of the Neoproterozoic Luanchuan Group, located on the southern margin of the North China Craton (NCC) in central China. Previous studies divided the mineralization into four stages according to the crosscutting relationships between veinlets and their mineral assemblages. In this contribution, two distinctive types of fluorite mineralization are recognized: 1) the first type (Type 1) includes colourless, white or green fluorite grains present in Stage 1 veins; and 2) the second type includes Type 2a purple fluorite present in Stage 2 veins and does not coexist with sulfides, and Type 2b purple fluorite crystals associated with sulfides in Stage 2 veins. The rare earth element (REE) content in the fluorite ranges between 13.8 and 27.9 ppm in Type 1, 16.9 and 27.2 ppm in Type 2a, and 42.5 and 75.1 ppm in Type 2b, which suggests that the fluorite was precipitated from acidic fluids (given that REEs are mobile in saline HCl-bearing fluids at high temperature (~ 400 °C)). Comparing the REE chemistry of the Stage 1 against Stage 2 fluorite, the LREE/HREE ratios decrease from 9.8 to 4.0, La/Yb ratios decrease from 16.0 to 6.9 and La/Ho ratios decrease from 10.2 to 3.0, indicating that the hydrothermal process was at high-T and low-pH conditions. The Eu/Eu* ratios in the fluorite decrease from 1.11 ± 0.35 for Type 1 through 0.89 ± 0.19 for Type 2a to 0.75 ± 0.17 for Type 2b, suggesting a gradual increase in oxygen fugacity ( f O 2 ) and pH of the mineralising fluid. The Tb/Ca, Tb/La and Y/Ho ratios of the fluorite types indicate that they were formed from the interaction between magmatic fluids and carbonate wallrocks. The fluorite samples show similar REE + Y (REY) patterns to those of dolostone units in the Luanchuan Group and the nearby Neoproterozoic syenite, suggesting that the REY in the fluorite was mainly sourced from the host-rocks, although the syenite could be an additional minor source.

Zijinshan is a large porphyry–epithermal Cu–Au–Mo–Ag ore system located in the Zijinshan mineral field (ZMF) of southwestern Fujian Province, China. Although it is commonly accepted that the early Cretaceous magmatism and the metallogenesis of the mineral field are closely related, the tectonic setting for the ore-forming event(s) has been controversial and regarded as either extensional or subduction-related. New U–Pb zircon geochronology, Sr–Nd–Pb isotopic systematics, and geochemical data presented here from granites and volcanic rocks in the mineral field help to clarify this uncertainty. LA–MC–ICP-MS U–Pb zircon analyses yield weighted mean ages of between ca. 165 and 157 for the monzogranite, ca. 112 Ma for granodiorite, and between ca. 111 and 102 Ma for nine samples of volcanic units in the study area. These dates, integrated with previous geochronological data, indicate that there were two magmatic events in the area during the Middle to Late Jurassic and the Early Cretaceous. Major and trace element geochemistry indicates that these rocks are high-K, calc-alkaline granites, are enriched in LREE and Th, U, Ta, Nd, Sm and Yb, and depleted in Ba, K, Sr, P, Ti and Y. These features are characteristic of volcanic-arc granites or active-continental margin granites. The Middle to Late Jurassic monzogranitic plutons in the region have initial 87 Sr/ 86 Sr ratios of 0.7096 to 0.7173, eNd T values of − 10.1 to − 7.6, 206 Pb/ 204 Pb isotope ratios of 18.51–18.86, 207 Pb/ 204 Pb isotope ratios of 15.64–15.73, and 208 Pb/ 204 Pb isotope ratios of 38.76–39.18. The Early Cretaceous granodiorite and volcanic rocks are distinctly different with initial 87 Sr/ 86 Sr ratios of 0.7055–0.7116, eNd T values of − 8 to 0.5, 206 Pb/ 204 Pb ratios ranging between 18.49 and 19.77, 207 Pb/ 204 Pb ratios of 15.63–15.71, and 208 Pb/ 204 Pb ratios of 38.71–40.62. These characteristics suggest that the source for the Middle to Late Jurassic monzogranitic plutons is a partially melted Mesoproterozoic substrate, with a minor component from Paleozoic material, whereas the Early Cretaceous granodiorite and volcanic rocks may represent mixing of crustal and mantle-derived melts. It is therefore suggested that the Middle to Late Jurassic monzogranitic plutons, and the Early Cretaceous granodiorite and volcanic rocks in the ZMF are the result of an active continental-margin setting related to the subduction of the Paleo-Pacific Plate beneath the Eurasian continent. Given that the mineralization and the early Cretaceous granodiorite and volcanic rocks in the area are genetically related, the Zijinshan porphyry–epithermal ore system formed in the subduction-related tectonic setting.

Aeromagnetic data is important for the exploration of gold and other hydrothermal deposits because geologically favourable environments are associated with changes in rock magnetism. For example, Archean orogenic gold mineralisation is known to be present in areas of structural complexity near major shear-zones that form conduits for mineralising fluids. Potential fluid pathways such as shear zones and faults are often associated with magnetite destructive alteration resulting in linear negative anomalies in magnetic data. Here, we present a new image analysis method that identifies geological structural complexity using lineaments automatically mapped within magnetic data. This quantitative analysis is efficient and self consistent in dealing with large volumes of data, and is suitable as a first-pass ground selection tool for orogenic gold exploration in greenfield terrains. Using regional aeromagnetic data, our method firstly identifies lineaments as a reliable indicator of geological structures, exploiting a combination of texture analysis and contrast invariant ridge detection to find laterally continuous textural ridges. Using the detected lineaments, two scenarios of local structural complexity are explored: feature intersection density based on the number of faults intersections and splays; and feature orientation diversity representing deviations of strike of lower order faults and ductile shear zones. The local structural complexity is visualised using heat maps that highlight the regions of structural complexity. The method has been tested using aeromagnetic data from the Archean Eastern Goldfields Superterrane of the Yilgarn Craton in Western Australia and a region from the Archean Abitibi greenstone belt in the Superior Craton, Ontario, Canada. Both cratons are mature exploration areas where granite–greenstone terrains host numerous orogenic gold deposits. The regions selected by the proposed system as most structurally complex, and hence prospective, correlate with the known gold deposits in these areas.

The Palaeoproterozoic Killi Killi Formation is a succession of turbiditic sedimentary rocks in the Granites–Tanami Orogen of Western Australia and the Northern Territory. SHRIMP U–Pb data from zircons in the Killi Killi Formation in Western Australia indicate that these rocks could be as old as ca. 1864 Ma and about 30 million years older than the previously proposed ages for the formation. A petrological and geochemical study shows that these rocks: 1) have an igneous source; and 2) based on comparisons with modern analogues, were deposited in an active continental margin. These findings also confirm that the Coyote deposit in the Western Australian portion of the Granites–Tanami Orogen is a typical orogenic gold deposit of Palaeoproterozoic association. Basin deposition culminated by ca. 1850 Ma, followed by inversion and collisional tectonics at ca. 1800 Ma, giving rise to widespread formation of orogenic lode-gold deposits throughout the Granites–Tanami Orogen at the time that the Granite–Tanami Orogen collided with the Arunta Orogen to the south.