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The tectonic evolution of the South Tianshan Orogenic Belt has long been a focus of geological research. As the intermontane basin of the South Tianshan, the Kumishi Basin has recorded important information relating to the evolution of the South Tianshan Orogenic Belt. The provenance and structural evolution of the Kumishi Basin was analyzed by U–Pb dating of late Quaternary detrital zircon to provide an important information record for the evolution of the South Tianshan Orogenic Belt. The zircon U–Pb ages of 62 effective zircons in the samples were measured by LA-ICP-MS. The zircon ages mainly ranged from ~ 461–422 Ma, ~ 416–366 Ma, to ~ 358–251 Ma. The Th/U ratio showed that the zircons in the Kumishi Basin were mainly magmatic. Based on the analysis of the rock properties and age composition of the potential provenance, it was speculated that the detrital zircons aged ~ 461–422 Ma and ~ 416–366 Ma were related to the subduction of the South Tianshan ocean, and the detrital zircons aged ~ 358–251 Ma were controlled by the magmatic tectonic activity around the basin during the Palaeozoic (from the Carboniferous to the Permian). A comparison of these ages with the tectonic events around the basin indicated that the extensive detrital zircon ages recorded the evolution of the South Tianshan orogenic belt. [ABSTRACT FROM AUTHOR]

The Biguo area is in the Jiaodong terrane, east of the North China Craton, which hosts numerous giant gold deposits. However, the genesis of gold deposits is still controversial which slows down the development of further gold exploration and prospecting in this area. This study was designed to investigate the gold potential in the Biguo area by mapping gold mineralization-related geochemical anomalies on a 1:50,000 scale based on stream sediment data. Firstly, compositional robust factor analysis (CoRFA) was used to identify hidden relationships among 16 geochemical variables, followed by extraction of the first five factors that explained 60.7% of the total variance. The results indicate that the negative loadings of the first factor primarily reflect the Pb–Sn-Sb-Au–Ag association, and the positive loadings of the fifth factor (F5) reflect the Au anomaly. Secondly, singularity-quantile (S-Q) analysis was applied to characterize the potential for gold mineralization based on Au geochemical values. The results indicate that the distribution of gold mineralization-related anomalies can be divided into two distinct groups, each either trending along the NNE or NNW direction, which may be a result of Pacific plate subduction during the Mesozoic and the Yangtze craton plate collision during the Paleoarchean. This study established a linkage between sediment data and plate movement and also revealed the NNE anomalies caused by Pacific plate subduction in the Mesozoic, rather than Yangtze craton plate collision in the Paleoarchean, which provided us a new clue for further gold exploration in the Jiaodong terrane. [ABSTRACT FROM AUTHOR]

Neoproterozoic Abu Ghalaga ilmenite-bearing mafic rocks were subjected to geological, petrographical and geochemical studies integrated with mineral chemistry of ilmenite, pyrite and magnetite in order to deduce their petrogenesis. Abu Ghalaga mafic intrusions hosting the largest ilmenite reserve in the Egyptian part of the Arabian-Nubian Shield. Field observations revealed that the intrusions impound ilmenite ore, which occurs as interlayer of massive bands or disseminated within gabbroic rocks. Petrographically, Abu Ghalaga mafic intrusions include different kinds of gabbro; olivine pyroxene gabbro, pyroxene gabbro, pyroxene hornblende gabbro, altered gabbro and Fe-Ti-rich gabbro. They have calc-alkaline to tholeiitic magmas, which are depleted in high field strength elements (e.g., Ta, Nb and Th) relative to low field strength elements (e.g., Ba, Sr and Rb), and exhibit light rare earth elements enrichment relative to heavy rare earth elements with positive Eu anomaly (Eu/Eu*= 0.8-2.4). Variable mineralogical and wide variation of bulk rock geochemistry are ascribed to fractional crystallization and hydrothermal overprinting. Abu Ghalaga gabbroic rocks are derived from fractional crystallization of depleted mantle magmas that were modified by ascending fluids from subducted slab in volcanic arc setting. Fe-Ti oxides required high oxygen fugacity (ƒO2) and water contents by crystal settling of Ti-rich mantle which is applicable with subduction setting. It can be inferred that Abu Ghalaga mafic rocks are neither related to ophiolite nor to Alaskan type but to one of the layered intrusions hosting Fe-Ti oxides. [ABSTRACT FROM AUTHOR]

The Zhob Ophiolite, Balochistan, Pakistan, comprises imbricated thrust sheets of igneous, sedimentary, and metamorphic rocks. The sedimentary units are more widely developed and found around the ophiolitic blocks while ultramafic, mafic, and metamorphic units occur in three imbricated thrust blocks, and are thrust over the sedimentary rock units. The gabbro bodies intrude all three blocks. Petrographically, the gabbro can be divided into hornblende gabbro, pyroxene gabbro, and olivine gabbro. The gabbros are enriched in large ion lithophile elements (LILE) and depleted in high field strength elements (HFSE) relative to N-MORB and have a negative Nb anomaly. Their overall trace element signatures suggest an island arc tectonic setting. Low Mg # (42–56), and low Ni, Co, and Cr contents indicate that the parental magma of the gabbro fractionated in an upper-level magma chamber en route to intrusion. Incompatible trace element ratios show that the parental magma of these rocks was produced by 5–30% partial melting of a slightly depleted-enriched spinel lherzolite mantle source. It is suggested that Zhob Ophiolite was formed in a Late Jurassic-Cretaceous Ceno-Tethyan convergence zone along with several other arcs and back-arc basins including Muslim Bagh, Waziristan, Semail, Zagros, Chagai-Raskoh, and Kohistan-Ladakh. [ABSTRACT FROM AUTHOR]

Systematic geochronology and geochemistry were performed on the volcanic rocks in the Ganhe area, northern Great Xing'an Range, northeastern China. Zircon U–Pb data indicate that there are three periods of volcanism in the Ganhe area, namely the Manketouebo Formation (166.3 ± 2.5 Ma), Manitu Formation (155.2 ± 1.4 Ma), and Baiyingaolao Formation (123.3 ± 1.0 Ma). The rhyolites of Manketouebo Formation and Baiyingaolao Formation exhibit chemical affinities to A-type granites, implying an extensional environment. Their geochemical features indicate that they are the result of the partial melting of the crust. The andesites of Manitu Formation exhibit chemical affinities to the magmatic rocks associated with a subduction zone. Their geochemical features indicate that they were generated by partial melting of a mantle wedge that had been metasomatized by subduction fluids or subducted oceanic slab. According to the geochemical features of coeval igneous rocks from the northern Great Xing'an Range and its adjacent areas, we propose that the Manketouebo Formation was generated in a continental back-arc extensional setting caused by the subduction of the Mongolia-Okhotsk plate, the Manitu Formation was related to the subduction zone metasomatism caused by the southward subduction of Mongolia-Okhotsk plate, and the Baiyingaolao Formation was generated in a continental back-arc extensional setting caused by the westward subduction of Paleo-Pacific slab or a post-collisional extensional setting after the closure of Mongolia-Okhotsk Ocean. [ABSTRACT FROM AUTHOR]

The Guangnan pluton is located on the central of South China and the junction of Hunan and Jiangxi provinces. The zircon U–Pb age dating results show that the pluton formed between 164 and 148 Ma. The pluton composed of biotite granite, two-mica granite, and garnet-bearing granite, which contain higher SiO2 (72.82–76.16wt.%), lower Zr (83.5–118 μg/g), and ASI > 1. These geochemical characteristics are very similar to high-silicon peraluminous light-colored granite or ferroan calc-alkaline high-silica granite, or muscovite-containing peraluminous granite (MPG) type. The zircon εHf(t) value (− 3.94– − 11.67) and those of inherited zircon characteristics indicate that multiple melting of lower crustal materials, which were formed in the Caledonian, Indosinian, and Early Jurassic periods, acted as part of the source rock of the mid-late Jurassic Guangnan high-silica granite in the Zhuguangshan area. This study shows that the high-silica granite in Guangnan area is the production of the post-collision stage of the collision between Western Pacific ancient land and the South China orogenic belt in Early Yanshanian. In the "post-collision" stage during the Middle Jurassic, the magmatic material was formed by partially melting and multiple remelting of the lower crustal metamorphic argillaceous rock and/or metamorphic acidic igneous rock because of the heat from the base-invasion basic magma. [ABSTRACT FROM AUTHOR]

Mineralization of the southern Chah-Palang W (Cu–Au) deposit in the Yazd Block, central Iran are ore-bearing veins and veinlets commonly hosted by Jurassic sandstone and shale rocks of the Shemshak Formation that is intruded by younger dacitic domes. Tungsten and gold are temporally and spatially related to NW-trending, subvertical hydrothermal breccias veins with silicic–chloritic alterations. The deposit formed during granitic magmatism. Three stages of veins–veinlets are recognized: early-stage quartz 1, wolframite, scheelite 1, pyrite 1, chalcopyrite 1, and arsenopyrite1 vein–veinlets; intermediate stage: quartz 2, scheelite 2, gold, pyrite 2, chalcopyrite 2, arsenopyrite 2, pyrrhotite, bornite, native bismuth, niccolite, cobaltite, and sphalerite vein–veinlets; late-stage hematite: quartz and carbonate vein–veinlets. The first two stages are economic significance. The homogenization temperatures (Th) and salinities of fluid inclusion groups from the early stage (milky quartz) range from 260 to 288 °C and 5.1 to 12.7 wt.% NaCl equiv., respectively. In the intermediate stage (white quartz), the fluid temperature and salinity range from 223 to 247 °C and 3.5 to 9.5 wt.% NaCl equiv. The δ34Sfluid values of pyrrhotite and chalcopyrite range between 5.7 and 9.2‰. The southern Chah-Palang mineralization is related to a magmatic geothermal system. δ18Ofluid (8.61 to 3.44‰ values) suggest that the early-stage ore-forming fluids were primarily extracted from magmatic fluid, with the addition of meteoric water in the intermediate stage. Early-stage apatite precipitated mainly from a volatile-rich magmatic fluid. The oxygen isotopic data, fluid inclusions, and mineral chemistry of the apatite samples indicate that the ore-forming fluids of the vein-type southern Chah-Palang deposit were dominated by magmatic-hydrothermal fluids during the early stage and that meteoric water was added during fluid evolution. [ABSTRACT FROM AUTHOR]

Pegmatites (the Wudaogou pegmatite dikes) with minor beryllium mineralization have been discovered recently in the southern East Kunlun Orogen (EKO). This paper reports a study of zircon U–Pb dating, whole-rock geochemistry, and zircon Hf isotope and trace element compositions of the pegmatites and related granodiorite. Analyses of zircon morphology and in situ trace element compositions reveal that zircons from the pegmatite display spongeous texture in cathodoluminescence images, show extremely low Th/U ratios in the range of 0.002–0.013, and are enriched in heavy rare earth elements (REEs), with positive Ce and negative Eu anomalies. These features, as well as data patterns in a (Sm/La)N-La diagram, suggest that zircons from the pegmatite formed during the transition stage between magmatic and hydrothermal zircons. The laser ablation–inductively coupled plasma–mass spectrometry zircon U–Pb age of the pegmatite is 425.8 ± 2.2 Ma (MSWD = 0.17), and that of the granodiorite is 427.7 ± 2.9 Ma (MSWD = 0.082), suggesting that the pegmatite formed simultaneously with or slightly later than the granodiorite. Both the pegmatite and granodiorite samples have high silica contents (SiO2 = 72.31–76.10 wt.%), are peraluminous (A/CNK = 1.04–1.24), and belong to medium-K and shoshonitic series. The pegmatite samples have very low total REE contents (ΣREE = 5.39–8.08 ppm) with LaN/YbN ratios of 3.73–12.01 and strong positive Eu anomalies (Eu/Eu* = 1.47–2.75), whereas the granodiorite samples exhibit REE enrichment (ΣREE = 115.62–194.17 ppm) with (La/Yb)N = 9.35–35.53 and negative Eu anomalies (Eu/Eu* = 0.35–0.49). The REE contents of the pegmatite are markedly lower than those of the granodiorite, which may be related to the crystallization differentiation of accessory minerals, such as apatite, during magmatic evolution. Hf(t) values of the pegmatites range from − 3.89 to − 0.79 (mean = − 2.26), and those of the granodiorite range from − 7.53 to 2.73 (mean = − 2.48), which suggest a consistency of Hf(t) values of granodiorite and pegmatite. These geochemical characteristics imply that pegmatites and granites from the Wudaogou area have a genetic relationship and that the pegmatite being a more highly differentiated product of the same magma from which the granodiorite was formed. Both rock types formed in an extensional tectonic setting after the final closure of the Proto-Tethys Ocean in the EKO. [ABSTRACT FROM AUTHOR]

The Nanmushu lead–zinc deposit is located in the northern margin of Yangtze plate, midwest China. Ore bodies are hosted in Sinian carbonate rocks, which is controlled by the Sinian Dengying Formation. Metal mineral includes sphalerite, galena, pyrite, gangue minerals including dolomite, quartz and small amount of barite and calcite. The ores have breccia, veins, disseminated and geode structure. Three stages of hydrothermal mineralization are: an early stage of bitumen (B1) (Stage I), a middle stage of sphalerite–galena (Stage II) and a late stage of bitumen (B2) (Stage III) based on the ore structure, textures, crosscutting relationship and mineral assemblages. The reflectivity and total organic carbon content (TOC) values of natural bitumen, combining crosscutting relationships between the bitumen and various minerals, clarify that the B1 (early-stage bitumen) is closely related to mineralization; the Cambrian Guojiaba Formation provides abundant organic matter for natural bitumen in the Dengying Formation. Four types of FIs were identified: liquid-rich (L0-type), vapor-rich (V-type), single-phase, aqueous (ML-type) and single-phase, pure-gas FIs (MV-type). The ore-forming fluids were characterized by medium-to-low temperature (100–280 °C), medium salinity (2–16 wt% NaCl eq.), a medium density (0.91–1.07 g/cm3), contained CH4 and small amounts of bitumen, H2S. The petrography and microthermometric data indicate that the small scale of fluid boiling is inferred to take place in sphalerite–galena stage. The δD (-113.0% to -41.6%) and δ18OH2O (2.69% to 12.73%) data from stage I to stage III indicate that the ore-forming fluids were derived from basin fluids and in the late stage of hydrothermal mineralization mixed with organic water or meteoric water. The δ13CPDB and δ18OSMOW values of hydrothermal calcite range from –3.1 to –1.6 ‰ and from 15.6 to 18.3 ‰, respectively, and are plotted near the dissolution line of carbonate rock and marine carbonate rock, indicating that the carbon in the ore-forming fluids may have been derived from the dissolution of marine carbonates in the sedimentary rocks. The δ34S values (δ34SPy, δ34SSp and δ34SGa) have a narrow range, inferring a single sulfur source. The δ34SCDT values of sphalerite, galena, and pyrite from hydrothermal ore-forming stage 2 range from 13.7 to 19.4 ‰, average 17.09 ‰, 12 to 16.8 ‰, average 14.61 ‰, 18.6 to 18.8 ‰, average 18.7 ‰, respectively. The barite has obviously different δ34SCDT values, ranging from 31.3 to 33‰, average 32.2 ‰. It is concluded that thermochemical sulfate reduction (TSR) is the main formation mechanism of reduced sulfur in ore-forming fluids by comprehensive analysis. [ABSTRACT FROM AUTHOR]

This contribution focuses on new geological and geochemical investigations of Wadi Ibib (WI)-Wadi Suwawrib (WS) metasediments and pyrite-bearing quartzites to deduce the paleoweathering, paleoclimatology processes, sources, and provenances of their old sediments. Variable weathering indexes such as the chemical alteration index (CIA) and chemical index of weathering (CIW) as well as the plagioclase alteration index (PIA) reflect a mild-medium chemical-weathering effect. Furthermore, variation in climate increases the opportunity for chemical weathering. The studied metasediments are enriched in major (with expectation of SiO2), trace, and rare earth elements (REEs) relative to quartzite. The steep slope of LREEs is clear in the studied metasediments and quartzite (La/Sm av. = 1.8, 3.07, respectively) and weakly fractionated of HREEs for both (Gd/Yb av. = 1.3, 0.28, respectively). A strong negative Eu anomaly (Eu/Eu* = 0.1–0.4; 0.26 in average) was obviously recorded in the examined quartzite and shallower in metasediments (Eu/Eu*= 0.2–0.9; 0.53). The latter contain Eu/Eu* values akin to Egyptian metasediments, Proterozoic greywackes, Post-Archean Australian shale (PAAs), and upper continental crust (UCC). The SiO2/Al2O3 ratio ranges from 7.73 to 9.32 (av. 8.5) for quartzite, suggesting sedimentary maturation, while metasediments (3.28–4.59) are immature. Variable discrimination diagrams reveal that the WI-WS metasediments deposited in continental arc setting may be back-arc comparable with Egyptian metasediments, whereas the examined quartzite was developed in passive margin. [ABSTRACT FROM AUTHOR]

The Lianhuashan Au deposit, located in the northern margin of North China Craton, is hosted in the metamorphic rocks of Neoarchean Wulashanyan Group along NNW- to N-trending faults, with pyrite as the predominant ore mineral. The mineralization process can be divided into four stages, involving stage I quartz-pyrite, stage II quartz-magnetite-chalcopyrite, stage III quartz-marcasite-pyrite, and stage IV quartz-calcite. Three types of fluid inclusions (FIs) have been identified, namely, pure carbonic inclusions (PC-type), aqueous-carbonic inclusions (AC-type), and aqueous inclusions (A-type). Stage I auriferous quartz veins host all three types of FIs, inclusions from stage II quartz are AC- and A-type, and only A-type FIs are recognized in stage III quartz and stage IV calcite veins. The FIs of stages I to IV were homogenized at temperatures of 300–360 °C, 275–326 °C, 252–289 °C, and 220–264 °C, with salinities of 4.0–11.7 wt%, 3.4–9.3 wt%, 2.1–7.0 wt%, and 1.4–3.1 wt% NaCl eqv., respectively. The ore-forming fluids belong to a medium-temperature, low-salinity H2O–NaCl–CO2 system. Gold deposition was likely caused by fluid immiscibility. The δDH2O and δ18OH2O values of ore fluids vary from −121.1 to −112.4‰ and from 2.8 to 6.2‰, respectively, within the range of enriched mantle-derived fluids in the North China Craton. The carbon isotope compositions of calcite (δ13CPDB = −2.87 to −2.38‰) show the features of mantle carbon. S-Pb isotope compositions of pyrite (δ34S = 2.58-3.96, 206Pb/204Pb = 16.077-16.119, 207Pb/204Pb = 15.329-15.332, and 208Pb/204Pb = 37.305-37.338) reveal that the ore-forming materials may have originated from crustal rocks. Based on the geological and geochemical observations, we suggest that the Lianhuashan deposit can be classified as an orogenic gold deposit. [ABSTRACT FROM AUTHOR]

The Jinya Au deposit is a typical Carlin-type deposit in the Golden Triangle of Yunnan, Guizhou, and Guangxi provinces, China. The ore bodies occur in the Middle Triassic Baifeng Formation, which are turbidites deposited on the edge of a carbonate platform. The main Au-bearing minerals are arsenopyrite and pyrite, and previous studies have found that pyrite can be divided into three types: pre-, syn-, and post-mineralization. In this study, electron microscopy, laser ablation inductively coupled plasma mass spectrometry, and secondary ion mass spectrometry were used to determine the in situ elemental and S isotopic composition of pre-mineralization pyrite in the Jinya Au deposit. The pre-mineralization pyrite can be divided into syn-sedimentary (Py I) and diagenetic pyrite (Py II). Pyrite Co/Ni ratios are < 1, with an obvious sedimentary origin. Pyrite Co/Ni and Se/Tl ratios indicate that the formation temperature of Py II was higher than that of Py I. δ34S values of Py I range from –8.61 to –2.63‰, with an average of –3.68‰, which are similar to the δ34S values of sulfides formed in Permian–Triassic oceans. δ34S values of Py II range from + 10.13 to + 13.30‰, with an average of + 12.13‰, and are typical of thermochemical sulfate reduction formation of pyrite. This study shows that the syn-sedimentary pyrite (Py I) precipitated from an undersaturated solution of Fe and S at low temperatures and that Cu, Pb, Zn, As, Se, Ag, Sb, and Au in the detrital material resulted in strong cataclastic dissolution and regrowth of syn-sedimentary pyrite during diagenesis. In the later stages of diagenesis, strong thermochemical sulfate reduction in the sediments reduced the range of δ34S values, and Py II began to precipitate, resulting in pre-enrichment of Au and other elements. [ABSTRACT FROM AUTHOR]

The lower Cambrian black rock series in eastern Yunnan province is a high-quality shale gas reservoir with great prospect for oil-gas exploration. However, the depositional conditions and mechanisms of organic matter enrichment are not well understood. In this study, geochemical characteristics of total organic carbon (TOC) and major and trace elements of fourteen black rock series samples from Dahai outcrop in eastern Yunnan province are systematically investigated to analyze the paleoenvironment and their effects on organic matter enrichment and established the accumulation model of organic matter. Results show that TOC contents of the four lithologic units of Qiongzhusi Formation black rock series are 0.70, 0.34, 1.77, and 0.27, respectively, which suggests that TOC content is generally low (mean = 0.51%). The main elements show that P2O5, CaO, and MgO are relatively rich, whereas other elements depleted. The enrichment factors (EFs) of trace elements showed that Pb and Zn are highly enriched in all samples, and Cu, Sr, Ba, U, Mo, V, Be, and Mo are also enriched in different lithofacies units. The elemental anomalies may be related to hydrothermal activities, which may lead to the distortion of some paleoenvironmental indicators to some extent. The Rb/Sr and Sr/Cu values show that the palaeoclimate gradually changed from dry to humid. Al concentrations indicate a gradual increase in terrigenous detritus supply. The hydrodynamic conditions and sedimentation rates implied by Zr/Al and Ti/Al values correspond well with lithology and grain size. Based on the comprehensive analysis of B/Ga and Sr/Ba ratios, it is considered that the black rock series in Qiongzhusi Formation was mainly formed in brachial water. Multiple paleoredox indicators (e.g., Ni/Co, V/Cr, U/Th, and V/(V+Ni) ratios) suggest that the sedimentary environment is mainly oxidized, which is usually considered unfavorable for organic matter preservation, and it also forms carbonaceous shale (unit 3) in a dysoxic environment. The Mo/TOC ratios suggest that the sedimentation during Qiongzhusi Formation period was under restricted conditions. The paleoproductivity indicated by P/Ti, Ni/Al and Babio values decreased gradually from medium level to low level. In summary, relatively high paleoproductivity is a prerequisite for organic matter accumulation and less terrigenous debris supply, and relatively arid climate and reductive conditions are favorable for the preservation of organic matter. [ABSTRACT FROM AUTHOR]

The newly discovered large-scale skarn deposit of Youmapo tungsten-molybdenum deposit is located in the Bobai-Cenxi metallogenic belt of the southeastern Guangxi, south China. The stratiform, lentoid, and vein ore-bodies occur along the contact zone between the Devonian calcareous-argillaceous siltstone and Youmapo granitic complex pluton. The Youmapo granitic complex pluton consists of main granodiorite (109.7 ± 1.1 Ma) and complementary muscovite granite (100.7 ± 0.5 Ma). Up to now, WO3 reserves were estimated at more than 80 thousand tons, with grades 0.191~1.284% WO3 and 0.001~0.019% Mo. Among them, No. I ore-body accounts for 84% of the total reserve. Four types of fluid inclusions are recorded in the Youmapo deposit (NaCl-H2O, NaCl-CO2-H2O, pure CO2, and monophase H2O) and characterized by medium-high temperature (190~340 °C) and low salinity (3~10 wt%NaCleq). According to the S, H, and O isotopic characteristics, the ore-forming fluid is mainly post-magmatic fluid. The complementary muscovite granite geochemically represents high evolution granite that derived the ore-forming fluid. Six molybdenite samples from No. I ore-body yield an 187Re-187Os isochron age of 100.1 ± 3.3 Ma and a consistent weighted average model age of 100.37 ± 0.62 Ma, suggesting the Cretaceous period for the tungsten-molybdenum mineralization and their spatio-temporal relation to the muscovite granite. [ABSTRACT FROM AUTHOR]

In conventional geochemical exploration work, the samples of the same particle size range are used to eliminate the interference of foreign substances. However, the influence of topography on element migration is not considered in the anomaly delineation, and only a unified anomaly lower limit is used to delineate anomalies, which may result in false anomaly or hide some weak mining-induced anomaly information. This research proposes to introduce elevation elements into the processing of geochemical data, divides elevation data groups at equal intervals according to the relative elevation differences, and analyzes the vertical migration characteristics of elements under different landscape conditions. The present study has shown that summarizing the superficial vertical migration of elements can finely divide the geochemical background area, shield the influence of high background values on weak and small anomalies, and have a greater reality in screening, identifying weak and false anomaly information, and guiding actual fieldwork significance. [ABSTRACT FROM AUTHOR]

Oceanic plagiogranites are directly or indirectly related to ophiolites. A small plagiogranite vein has been discovered in the No. III mafic–ultramafic complex of the Xiarihamu ophiolite from the eastern margin of Qiman Tagh, East Kunlun Orogen, northwest China. This plagiogranite yielded a weighted mean zircon U–Pb age of 435.7 ± 4.3 Ma (MSWD = 0.073) and is characterized by high SiO2 (73.08–76.24 wt.%) and Na2O (6.42–8.34 wt.%) contents and high Na2O/K2O ratios (3.06–12.36) with metaluminous and calc-alkaline affinity. It is enriched in Th and U, depleted in Nb, Sr, Ti, and Ba, and has low ΣREE contents (7.64–11.35 ppm), negative Eu anomalies (δEu = 0.31–0.71), and light REE enrichment. These features are typical of oceanic plagiogranites. Whole-rock Sr–Nd isotopic data for the plagiogranite show obvious EMII mantle characteristics. The petrographic, geochemical, and Sr–Nd isotopic characteristics suggest the plagiogranite is part of an ophiolite formed by partial melting of oceanic crust in the presence of hydrothermal fluids. Given this, other parts of the Xiarihamu ophiolite and other ophiolites in Qiman Tagh area, we propose the plagiogranite formed in a back-arc basin setting in the early Silurian, probably the youngest known intrusion related to the Proto-Tethys Ocean. [ABSTRACT FROM AUTHOR]

The Dasuji Mo deposit lies on the northern margin of the North China Craton. Based on vein crosscutting relationships, mineral assemblages, and alteration characteristics, the formation of the deposit can be divided into four stages: K-feldspathization with minor Mo mineralization (stage 1), the main stage of Mo mineralization (stage 2), Pb–Zn mineralization (stage 3), and post-mineralization (stage 4). This paper presents new He–Ar–S isotopic data to constrain the origin of this deposit. Pyrite-hosted fluid inclusions yield 3He/4He ratios of 0.21–3.48 Ra (average = 0.96 Ra; Ra = 1.4 × 10−6) and 40Ar/36Ar ratios of 464.9–832.1 (average = 624.6), which indicate the ore-forming fluids were predominantly crust-derived with minor mantle-derived components. Molybdenite within the deposit contains 0.06–29 ppm Re, indicative of derivation from a crustal source. δ34S values of sulfide samples range from + 3.14 to + 6.84‰, with corresponding H2S δ34S values of stage 2 fluids of + 2.8‰ to + 3.1‰ and stage 3 fluids of + 4.9‰ to + 5.9‰. The δ34Sfluid values of stages 2 and 3 are + 3.1‰ to + 4.0‰ and around + 6‰, respectively. The escape of H2S during stage 2 was a key factor in increasing δ34Sfluid values, and contributed to the precipitation of sulfides. [ABSTRACT FROM AUTHOR]

Geochemical data and their various approaches are useful to evaluate the climatic control on the depositional environments. This study aims to evaluate the paleoweathering and plaeoclimate condition that have controls on the depositional environments of the Miocene to Pliocene siliciclastic sequence at Al-Rehaili area, north of Jeddah. To achieve this aim, selected sandstone samples were geochemically (major and trace elements analysis) and petrographically examined. The results of these analyses reveal that the examined sandstones were deposited in non-marine (fluvial/alluvial-lacustrine) environments and suffered from weak to intermediate chemical weathering and intense physical induration under semi-arid to semi-humid climatic conditions. [ABSTRACT FROM AUTHOR]

The Longsheng mafic-ultramafic suite consists of more than 100 mafic and ultramafic intrusions and are extensively distributed within the Neoproterozoic Danzhou Group along the Jiangnan Orogenic Belt in northern Guangxi, China. The suite has been a hotly debated subject in the context of emplacement age, source of magmas, and tectonic setting for several decades. In this article, we present newly obtained LA-ICP-MS zircon U-Pb age data, whole-rock major and trace elemental data, and Sr-Nd and zircon Lu-Hf isotopic data. These data support a middle Neoproterozoic intrusive emplacement mechanism as a result of asthenospheric underplating and subsequent lithospheric thinning, extension, and rifting. This integrated process might well correspond to the early stage of the Rodinia breakup. For example, five mafic-ultramafic rock samples yielded an emplacement age of 774 ± 2 Ma. The samples contain a large number of inherited zircon xenocrysts dated at 821 ± 3 Ma, 1.4–2.1 Ga, and 2.3–2.8 Ga, indicative of crustal contamination. The mafic-ultramafic rocks are characterized by calc-alkaline to shoshonitic associations; their Zr/Nb, Th/Yb, La/Nb, Ba/La ratios, trace, and REE patterns show an OIB affinity. Their initial 87Sr/86Sr values range from 0.697721 to 0.708579 with an average of 0.702352. They have relatively low initial 143Nd/144Nd values of 0.511530–0.511859 with an average of 0.511661. Sixteen magmatic zircon grains from diabase samples show 176Hf/177Hf values of 0.281326–0.282638, εHf(t) values of − 34.48–11.89, and TDM2 of 925–3819 Ma. Their Nb/U and Th/Ta ratios support crustal contamination as well. It is concluded that the Longsheng mafic-ultramafic suite was originated from partial melting of the enriched upper mantle (EM-I type) due to asthenospheric underplating and lithospheric extension during the incipient Rodinia breakup, and that the magmas were contaminated with crustal material during ascent. [ABSTRACT FROM AUTHOR]

Magmatic Ni–Cu–platinum group element (PGE) sulfide deposits form as the result of segregation of immiscible sulfide liquid from mafic–ultramafic magma. Sulfide ores formed in this process commonly take their places in the lower part of mafic–ultramafic intrusion, and many researchers attribute this phenomenon to gravity settling of dense sulfide droplets within lighter silicate magma. Some laboratory experiments, however, suggest that not all the sulfide droplets can migrate downward through crystal mush, especially those forming disseminated ores. On the basis of geochemical analysis, we employ a multivariate statistical method to investigate whether downward motion of sulfide droplets can happen during formation of disseminated ores. Two typical magmatic Ni–Cu–PGE sulfide deposits, namely the Hongqiling and Kalatongke deposits, were selected, and the relationship between sulfide composition (bulk-rock Cu, Ni, S, and PGE contents) and silicate composition (bulk-rock SiO2, Al2O3, K2O, Na2O, CaO, and MgO contents) was investigated by canonical correlation analysis (CCA). The result shows that there is a strong relationship between the sulfide and silicate compositions in the disseminated ores, which indicates that the sulfide droplets may have formed from the local crystal mushes, and furthermore that they have not migrated away from the crystal mushes. Hence, we conclude that sulfide droplets that form disseminated ores may tend not to migrate downward for long distances after segregating from mafic–ultramafic magma. [ABSTRACT FROM AUTHOR]

The In Allarene mafic-ultramafic complex is located at the southern part of the In Ouzzal terrane and was known as the unique Pan-African mafic-ultramafic intrusion in this terrane. The complex shows a ring-shaped intrusion of about 20 km2 and concentric structures. Petrological observations and mineralogical analyses show that the core of the intrusion is composed of harzburgites and dunites surrounded by lherzolites, whereas the outer part consists of fine- to coarse-grained gabbros that are crosscut by dolerite dykes. The mineralogy and geochemistry of these rocks show that they are mainly cumulates, but some gabbros and dolerites have characteristics indicating that they correspond to magmatic liquids or they have trapped a variable amount of magmatic liquid. They correspond to the least magnesian and the most alkaline-rich gabbros and dolerites. The geochemistry of the gabbros and dolerites is very similar to the mafic-ultramafic complexes linked to arc zones and they exhibit all the features of the subduction zones magmatism as showing in the N-MORB normalization, with LILE enrichment relatively to HFSE, and Nb-Ta and Ti negative anomalies. The chemical compositions of clinopyroxene and spinel support this hypothesis. This is also the case for all geodynamic setting discrimination diagrams, both those using major elements and trace elements. Several of these diagrams also show that the studied rocks can be distinguished from intracontinental plate tholeiites, which can be very close geochemically to continental arc tholeiites. These results support the hypothesis of the existence of an arc-type metasomatized mantle under the In Ouzzal terrane during Pan-African orogeny. [ABSTRACT FROM AUTHOR]

As a carbonate-hosted deposit, the Huamuqing Pb–Zn deposit is situated in the western margin of the Yangtze Block. The strata-bound, irregular or vein-type Pb–Zn orebodies of the Huamuqing Pb–Zn deposit are mainly hosted by carbonate rocks of the Sinian Dengying Formation or Cambrian Meishucun Formation. Ores metallic minerals include mainly sphalerite, galena, and pyrite, whereas non-metallic minerals include mainly quartz and calcite. The alteration/mineralization can be divided into three stages: (I) the pyrite-quartz stage, (II) the polymetallic sulfide-quartz stage, and (III) the pyrite-calcite stage. The C–O isotopes of stage III hydrothermal calcite and multi-isotopes (S, Pb, Rb, Sr) of stage II sulfides were analyzed to constrain the ore-forming material source and mineralization timing at Huamuqing. The ranges of δ13CPDB and δ18OSMOW values for the stage III calcites are from − 0.641 to + 0.180‰ and + 17.542 to + 18.443‰, respectively. This suggests that the carbon of stage III was mainly derived from the Sinian dolostone, and the O isotope signatures of stage III were probably in connection with water/rock (W/R) interactions between the δ18O-depleted fluids and δ18O-enriched Sinian dolostone. The stage II sulfide δ34SCDT values vary from + 13.037 to +20.696‰, indicating that the reduced sulfur was originated mainly from Sinian to Triassic evaporites. The stage II sulfide 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ranges are from 18.184 to 18.393, 15.575 to 15.691, and 38.325 to 38.436, respectively. This demonstrates multiple Pb sources, which may have included sedimentary rocks, basement rocks, and basalts. Initial 87Sr/86Sr ratios of eight sphalerite samples range from 0.70815 to 0.71399, indicating that the ore fluids most probably came from or percolated through basement rocks, basalts, and sedimentary rocks. The mineralization timing was sphalerite Rb–Sr dated to be Late Triassic (204 ± 2 Ma), reflecting the Huamuqing deposit formed during late Indosinian. Hence, the Huamuqing deposit is a carbonate-hosted, thrust fault–controlled epigenetic Pb-Zn deposit that has a mixed source of ore-forming metals and ore-forming fluids. [ABSTRACT FROM AUTHOR]

The Tuwu deposit is one of the largest porphyry copper deposits in Eastern Tianshan, NW China. The widespread hydrothermal alteration is associated with porphyries and their wall-rocks in the porphyry deposit can be divided into potassic, chlorite–sericite, phyllic, and propylitic zones. In this study, we conducted a detailed study on the mineralogy of hydrothermal magnetite, mica, and epidote. Magnetite is closely related to the potassic alteration, and evolves from earlier disseminated magnetite (Mt-I) to the later magnetite–quartz ± biotite ± pyrite ± bornite ± chalcopyrite veins (Mt-II). The significant decrease in the Cr2O3 and V2O3 contents of magnetite from early to late period indicates the gradual increase of oxygen fugacity. The crystallization of magnetite supplies enough reduced sulfur that promotes the sulfide precipitation. The dominance of muscovite (Mc-I) in the early phyllic stage and the increasing of phengite muscovite (Mc-II) in the late phyllic stage suggest the evolution of hydrothermal fluid from a high-temperature and acidic environment to a low-temperature and less acidic environment. This process also results in the decrease of sulfide mineral deposition in the late phyllic stage. Epidote from propylitic zones at Tuwu has similar characteristic with the overprinting epidote in the Yandong porphyry Cu systems. Propylitic Ep-I have higher FeO content than Ep-II. The interaction of Fe-rich propylitic epidote with hydrothermal fluid enhanced both Ca2+ activity and pH value, and favored the precipitation of sulfides (e.g., chalcopyrite). In addition, the Fe-rich and less acidic fluids, which derived from the propylitic zones and flow though the sericitic rocks in the phyllic zones, also promote the deposition of Cu mineralization. Our results, combined with previous research on fluid inclusion, isotopes, and mass transfer, suggest that the changes in temperature, oxygen fugacity, and pH caused by the fluid–rock interaction played a critical role for the Cu mineralization at Tuwu. [ABSTRACT FROM AUTHOR]

The Middle Triassic Laojiagou porphyry Mo deposit is located in the Xilamulun metallogenic belt, along the northern margin of the North China Craton (NCC). Molybdenum mineralization is associated with a monzogranite porphyry and occurs primarily in quartz veins and veinlets hosted in wall rocks affected by potassic, silicic, sericitic, and propylitic alteration. The ore-forming process is divided into three stages, characterized by veinlets comprising molybdenite + pyrite + quartz (stage I), pyrite + chalcopyrite + molybdenite + quartz (stage II), and pyrite + quartz (sulfide-poor) (stage III). We identify three fluid inclusion types in quartz grains: carbonic (C-type), liquid-rich two-phase (L-type), and rare vapor-rich two-phase (V-type) inclusions. Microthermometric results indicate that an initial high-temperature (> 350 °C) and low-salinity (< 10 wt% NaCl equiv.) CO2-rich fluid evolved to a low-temperature (< 280 °C) and CO2-poor fluid, comprising dominantly of meteoric water. Hydrogen and oxygen isotopes indicate that initial ore-forming fluids were magmatic and became progressively mixed with meteoric water (stage I δ18OH2O = 4.4–4.8‰ and δDH2O = − 105.8 to − 101.5‰). Zircon U–Pb dating indicates that the monzogranite porphyry formed at 232.2 ± 3.6 Ma (MSWD = 0.88). The porphyry has high SiO2, K2O, and Al2O3 and low MgO and CaO concentrations and is classified as high-K calc-alkaline and weakly peraluminous. All samples are enriched in light rare earth and large-ion lithophile elements and depleted in high-field-strength elements. Our results indicate that the Laojiagou porphyry Mo deposit formed in the Middle Triassic, associated with post-orogenic extension following closure of the Palaeo-Asian Ocean. [ABSTRACT FROM AUTHOR]

The Early Paleozoic Bianjiadayuan complex of monzodiorite and biotite-bearing monzogranite is located in the southern part of the Huanggangliang-Ganzhuermiao metallogenic belt, southern Greater Khingan, China. The Pb/U ages of zircons from the monzodiorite and biotite-bearing monzogranite are 129.67 ± 0.4 and 143.20 ± 1.2 Ma, respectively. The total REE contents of the rocks are very high, especially LREEs, suggesting obvious LREE and HREE fractionation; the monzodiorite has weak negative Eu anomalies, the biotite-bearing monzogranite highly negative anomalies. These rocks are all rich in large ion lithophile elements (Rb and U) and relatively depleted in high-field-strength elements (Nb and Ta). The monzodiorites and biotite-bearing monzogranites have ε ( t) values of 1.39-5.69 and 0.86-2.46 and t ages of 0.82-1.09 and 1.04-1.24 Ga, respectively. In the ε ( t)- t diagram, the data plot between the chondrite and depleted mantle lines of Hf isotopic evolution, showing the rocks were derived mainly from new crustal material that had been derived by the differentiation of the mantle. We conclude that this area underwent an important episode of crustal growth in the Meso-Neoproterozoic. The relationship between the intrusive complex and the orebody was related to faulting; we infer that the Bianjiadayuan Pb-Zn polymetallic deposit is mainly related to Late Jurassic-Early Cretaceous (144-129 Ma) magmatic activity, and it represents large-scale mineralisation in the context of Paleo-Pacific plate subduction and regional extension. [ABSTRACT FROM AUTHOR]

The Cu-Au deposit of the Talat n'Imjjad occurrence, southwestern Azegour mine, western High Atlas of Morocco, is situated in a NW trending quartz vein along a shear zone in quartz diorite host rocks. The recently discovered shear zone, ~200-m long, NW-SE trending, so-called Talat n'Imjjad vein system of Cu-Au-Bi-Te-Se mineralization that crosscuts the Al Medinet quartz diorite, represents a landmark in regional metallogeny. This region has long been known for its polymetallic ore deposits, with the historical Mo-Cu-W mine of Azegour and Pb-Zn-Ag mine of Erdouz. The economic sulfide enrichment is often hosted by breccias and quartz veins in the ductile shear zone. Samples from the field surface and boreholes show macro- and microscopic evidence of shearing such as S-C fabrics and microshear planes. The quartz diorite was deformed and mylonitized, then the igneous texture was modified. On the basis of textures, mineral assemblages, and hydrothermal alteration, four stages were documented and could be distinguished: (1) quartz I-sericite-chlorite-epidote pre-ore stage; (2) chlorite-quartz II-calcite-pyrite ore stage; (3) native bismuth-bismuthinite-emplectite-wittichenite-(tsumoite-laitakarite)-chalcopyrite-sphalerite-native gold-calcite ore stage II; and (4) bismuthite-hematite-malachite-covellite post-ore stage. Bi-chalcogenides are considered as pathfinders for gold in Au-quartz veins. The association of gold with Bi-minerals is linked to the role of Bi as scavenger for gold. Tellurides and selenides are also the best indicators of the magmatic signature. The alteration types of the wall rocks include seritization, silicification, chloritization, carbonatization, and propylitization. The auriferous shear zone of Talat n'Imjjad represents a newly discovered occurrence in the western High Atlas characterized by its mineralogy, paragenetic sequence, hydrothermal alteration, and magmatic and structural control of the deposit of sulfide minerals. [ABSTRACT FROM AUTHOR]

LA-ICP-MS U-Pb dating has been performed on detrital zircons from the Nanyinger Group in the eastern section of the north Qilian orogenic belt in Jingyuan County, Gansu Province. The results show five major age groups: 3.1-2.0, 1.8-1.4, 1.4-0.8, 0.6-0.4, and ~0.26 Ga. Archean to Neoproterozoic zircons were derived from the central Qilian belt. The early Paleozoic grains are considered to have been derived from the magmatic arc related to ocean closure. The youngest age may be derived from the recycling of sediments prior to the Nanyinger Group. The youngest detrital zircon age (262 ± 5 Ma) is close to the depositional age of the strata, suggesting rapid uplift of the Qilian Mountains. In the early Indosinian, the palaeo-Qilian Mountains uplifted rapidly and provided the main source for the Hexi Corridor basins. The North Qilian Belt is the southern boundary of the Hexi Corridor basins. From the Ordovician to the Triassic, the depocenter gradually moved to the Qilian Mountains and was very close to the Qilian Mountains in the Late Triassic. By comparing with previous research, we infer that the Hexi Corridor basin may not connect with the Ordos Basin in the Triassic. [ABSTRACT FROM AUTHOR]

Natural particles have always been abundantly present since the Earth's origin. Over the years, researchers have focused on natural particles coming from the Earth's surface. However, in this paper, we establish, via transmission electron microscopy (TEM), that many nano- or near-nanoparticles also can be produced in a concealed deposit. Particles collected from the oxidation zone in the Dabaoshan polymetallic concealed deposit were 50–700 nm in size and contained elements among the most abundant in the Earth's crust, such as O, Mg, K, Ca, Si, Al, Ti, Fe and P, and concealed ore body-related elements. Nearly all particles were found to have O and S, indicating that these nano- or near-nanoparticles were formed via oxidation of primary minerals in the concealed deposit. According to their crystal form and chemical compositions, these particles were grouped into three main categories: (i) particle with low O content (O < 10 wt.%), (ii) particle with moderate O content (30 wt.% > O > 10 wt.%) and (iii) particle with high O content (O > 30 wt.%). The crystal form and chemical compositions of particles can represent the degree of oxidation of primary minerals in the concealed deposit. Combining the close relationship with orebodies, nano- or near-nanoparticles can be used to be a useful prospecting method for deep-seated orebodies. Additionally, strong acids are also formed during the oxidation process that can destroy the ecosystem of the oxidation zone in the concealed deposit. [ABSTRACT FROM AUTHOR]

The Haobugao Pb–Zn deposit located in the southern Great Xing'an Range (SGXR) is one of the most important deposits within the Huanggangliang–Ganzhuermiao polymetallic metallogenic belt. Xiaohanshan quartz monzonite porphyry and Wulandaba granodiorite are present in the ore area and are assumed to be closely related to the mineralization. In this study, a new isotopic dating technique, zircon U–Pb laser ablation inductively coupled plasma mass spectrometer analysis, was applied to the granites; the analyses indicate that the Xiaohanshan quartz monzonite porphyry and Wulandaba granodiorite were emplaced at 143.9 ± 1.1 Ma and 151.3 ± 1.4 Ma, respectively. Geochemically, these A-type granites are characterized by relatively high SiO2 and K2O contents, low Al2O3 content, and negative Eu anomalies. Additionally, both granites display strong Rb, Th, U, and Ce enrichment and Ba, K, Sr, and Ti depletion. Their relatively high εHf (t) values (with averages of 7.13 and 7.87, respectively) and young two-stage Nd and Hf model ages indicate that the two granites may have predominantly derived from the partial melting of a juvenile lower crust, followed by fractional crystallization during magma ascent. The geological, elemental, and isotopic evidence shows that the Xiaohanshan quartz monzonite porphyry and Wulandaba granodiorite formed due to the upwelling of mantle-derived alkaline magma and partial melting of the crust, with a certain degree of mixed dyeing, under a tectonic background of asthenosphere upwelling and lithosphere extension via the subduction of the ancient Pacific plate. [ABSTRACT FROM AUTHOR]

The Linghu Au deposit is located within the northeastern part of the Xiaoqinling region in the southern margin of the North China Craton. Field investigations, cross-cutting relationships, and mineral paragenetic associations have identified three stages of hydrothermal activity. To determine the origin and evolution of ore-forming fluids, and better understand genesis of the Linghu Au deposit, we have undertaken a series of studies including fluid inclusion and He–Ar–H–O–S–Pb isotope systematics. Fluid inclusion study indicates that the early stage of gold mineralization was characterized by a high-temperature and low-salinity H2O–CO2–NaCl hydrothermal fluids that have δD values of – 82.0 to – 78.6‰ and δ18OH2O values of 5.3 to 6.4‰. The intermediate stage of gold mineralization involved moderate temperature H2O–CO2–NaCl hydrothermal fluids with δD and δ18OH2O values of – 92.7‰ to – 87.9‰ and – 1.4‰ to 0‰, respectively. Pyrite samples from this mineralization stage have 3He/4He and 40Ar/36Ar ratios of 0.26–0.31 Ra and 2834.7–4300.6, respectively. The last mineralization stage involved (low-temperature and low-salinity NaCl–H2O system of hydrothermal fluids with relatively lower δD values of – 93.1 to – 92.3‰ and δ18OH2O values of – 5.7 to – 5.2‰. Moreover, sulfides in ores yielded δ34S values of – 3.6 to 5.9‰, with an average of 2.65‰. The sulfides have 206Pb/204Pb ratios of 17.101–17.804, 207Pb/204Pb ratios of 15.438–15.554, and 208Pb/204Pb ratios of 37.438–38.654. The results of fluid inclusions and H–O, S–Pb, and He–Ar isotopes indicate that hydrothermal fluids associated with the early stage of mineralization originated from magmatic fluids, with sulfur and lead being derived from both units of the Taihua Group and a Late Triassic magmatic–hydrothermal system. All of these data indicate that the Linghu gold deposit formed as a result of magmatic–hydrothermal mineralizing processes. [ABSTRACT FROM AUTHOR]

This study explores the spatial relationship between the spatial distribution features and the fracture distribution of deposits in northeastern Yunnan based on spatial point pattern statistics and the Fry analysis method. The K(r) function value of the spatial point pattern analysis shows that the spatial distribution of lead-zinc deposits displays cluster features. Fry analysis shows that the spatial distribution of lead-zinc deposits can be divided into three distinct scales: the 5-km deposit scale, 20-km ore belt scale, and 100-km regional scale. With a change in the measured scale, the dominant direction in the spatial distribution of the lead-zinc deposits changes from northwest at a scale of 5 km to east-northeast and approximately northeast at a scale of 20 km to nearly north-south at a scale of 100 km. At the deposit and ore belt scales, northwest-southeast-striking faults may control lead-zinc mineralization. At the regional scale, north-south-striking faults affect the spatial distribution of lead-zinc deposits. The seven main orebodies in the Xiaohe lead-zinc deposit in Qiaojia County are used to analyze the features of the Xiaohe lead-zinc orebody. The orebodies at the deposit scale are distributed along a northwest-southeast direction, which seems to confirm the relationship between the northwest-southeast-striking faults and the lead-zinc deposits at the mining area scale, which is also consistent with the Fry analysis results. [ABSTRACT FROM AUTHOR]

The Qozlou Fe skarn deposit is located at the Abhar–Mahneshan belt of the Central Iranian Zone. It is associated with Upper Eocene porphyritic granite that intruded into the Upper Cretaceous impure carbonaceous rocks. The Qozlou granite has high-K calc-alkaline affinity and is classified as subduction-related metaluminous I-type granitoids. Skarn aureole in the Qozlou is composed of endoskarn and exoskarn zones, with the exoskarn zone being the main skarn and mineralized zone. It includes garnet skarn, garnet-pyroxene skarn, pyroxene skarn, epidote skarn, and pyroxene-bearing marble sub-zones. The Qozlou Fe deposit is 300 m long and 5–30 m wide. Magnetite is the main ore mineral associated to pyrite, chalcopyrite, and pyrrhotite. Garnet, clinopyroxene, actinolite, epidote, calcite, and quartz occur as gangue minerals. Covellite, hematite, and goethite were formed during the supergene processes. The ore and gangue minerals have massive, banded, disseminated, brecciated, vein–veinlets, replacement, and relict textures. EPMA data indicate that garnets have andradite–grossularite compositions (Ad39.97–100–Gr0–49.62) and clinopyroxenes have diopsidic composition (En29.43–42.5–Fs14.31–20.99–Wo43.08–50.17). Based on mineralogical and textural criteria, skarnification processes in the Qozlou skarn can be categorized into three discrete stages: (1) isochemical (metamorphic–bimetasomatic), (2) metasomatic prograde, and (3) metasomatic retrograde. Anhydrous calc-silicate minerals (garnet and clinopyroxene) were formed during the prograde metasomatic stage, while ore minerals and hydrous calc-silicate minerals were formed during the retrograde ore-forming sub-stage. Temperature and ƒO2 conditions range between 430 and 550 °C and 10−26 and 10−23, respectively, for the metasomatic prograde stage. The retrograde metasomatizing fluids had likely ƒS2 = 10−6.5 and temperatures < 430 °C at the beginning of the ore-forming sub-stage. [ABSTRACT FROM AUTHOR]

The Pingshun skarn iron deposit is located in the southern Handan–Xingtai iron district of the southern Taihang Mountains, North China Craton. Skarns and ore bodies occur as lamina, lenses, and veins along the contact between a dioritic pluton and carbonates of the Middle Ordovician Majiagou Formation. The paragenetic sequence is albite followed by diopside, then garnet, magnetite, and finally calcite. Diorite and olivine-bearing hornblende gabbro in the Pingshun area contain zircon grains with SHRIMP U–Pb ages of 123.4 ± 1.7 and 125.5 ± 2.3 Ma, respectively. Based on the close spatial association between diorite and mineralization, we suggest that both magma activities and iron mineralization in the Pingshun area took place at 125–123 Ma. Three types of fluid inclusions identified in minerals from the Pingshun deposit include three-phase (type 1), two-phase (type 2), and pure liquid (type 3) inclusions. The ore-forming fluid evolved from high temperature (515–679 °C) with high salinity (39.8–77.6 wt% NaCl equiv.) in diopside, to medium–high temperature (365–496 °C) with moderate–low salinity (11.8–17.6 wt% NaCl equiv.) in garnet, and to low temperature (162–295 °C) with moderate–low salinity (6.7–35.5 wt% NaCl equiv.) in calcite. The presence of hematite, halite, and gypsum daughter minerals in type 1 fluid inclusions and the occurrence of andradite in skarns indicate that the pre-ore–forming fluid was oxidized. The δ34S values of pyrite separated from ores vary from 12.5 to 17.4‰, with 206Pb/204Pb = 17.26–19.03, 207Pb/204Pb = 15.42–15.69, and 208Pb/204Pb = 37.29–39.76, suggesting the ore-forming fluid was originated from a magmatic source and with additional crustal material during the mineralization process. This is consistent with H–O isotope data (δ18Odiopside-H2O = 10.8‰, δ18Ogarnet-H2O = 9.5–10.8‰, δ18Omagnetite-H2O = 9.8–13.4 ‰, δDgarnet varying from − 106 to − 86‰, δDdiopside = − 90‰). The microthermometry of fluid inclusions and isotope data reveal that the addition of gypsolyte and salt-bearing marlstone into the ore-forming fluid increases Na, Ca, and Cl and that it significantly increases the ability to transport Fe and enhances the capacity of Fe in the ore-forming fluid. Fluid boiling and additional meteoric water involved are two major key factors controlling the ore precipitation. Mantle materials involved in magma and high oxygen fugacity are considered to be crucial roles in the formation of numerous iron deposits in the Handan–Xingtai iron district. [ABSTRACT FROM AUTHOR]

The Dacaoping and Sadaigoumen Mo deposits were recently discovered along the northern margin of the North China Craton. In this paper, we present new zircon U–Pb ages, Hf isotope data, and whole-rock major and trace element data for the monzogranite and granodiorite in the Dacaoping Mo deposit and the monzogranite in the Sabagaogoumen Mo deposit, and we use these data to constrain the metallogenic epoch and the tectonic background in the area. Combined with previous data, we suggest four phases of mineralization in the Dacaoping and Sabagaogoumen Mo deposits; these phases are 248 Ma, 236 Ma, 147 Ma, and 140 Ma. The Early Triassic monzogranite and Early Cretaceous granodiorite in the Dacaoping Mo deposit and the Middle Triassic monzogranite in the Sabagaogoumen Mo deposit are I-type granite with similar geochemical characteristics. The Triassic granites formed in a collisional–post-collisional setting between the North China plate and the Siberian plate, and the Cretaceous granodiorite formed from the rapid thinning of the lithosphere. Their source rock should mainly originate from the partial melting of ancient crustal material. Compared with other Mo deposits in the region, we can further divide these Mo deposits into three phases, namely (1) Triassic (ca. 248–223 Ma), (2) Early–Middle Jurassic (ca. 187–165 Ma), and (3) Late Jurassic–Early Cretaceous (ca. 155–130 Ma), which are consistent with the times of magmatic activity. These activities occurred during the collision and post-collision between the North China plate and the Siberian plate after the Paleo-Asian Ocean's closure, intracontinental orogeny, and rapid thinning of the lithosphere, respectively. [ABSTRACT FROM AUTHOR]

Multiple geoscience databases as big data can be interpreted and understood by geologists using mineral system, including geological setting, metallogenic progress, and ore-bearing geological objects (e.g., porphyry, skarn, fault, fold, and stratum), and they can be used to extract exploration criteria based on GIS technology, weights of evidence (WofE), and concentration-area (C-A) methods for potential targets. In this paper, Luanchuan polymetallic district as a case study, the methodology and mineral system analysis based on the multiple datasets (geology, geophysics, geochemistry, remote sensing, and exploration engineering) were summarized as follows: (1) the databases' construction using multiple geosciences involving the 1:25,000 scale gravity and magnetic dataset, 1:10,000 scale geologic map, and tens 1:5000 geological, geochemical, and geophysical cross-sections, more than 400 borehole datasets with 8000 assay; (2) Pb-Zn polymetallic deposit datasets involving magma-hydrothermal metallogenic model, ore-forming and rock-forming chronology, geochemistry and geophysics of stratum, and intrusion rocks; (3) GIS spatial analysis technology, 3D visualization technology, WofE, and C-A fractal methods were used to derive exploration criteria at different levels (the near surface (0 m), − 400 m, − 800 m); (4) potential target identification in vertical direction are compared and interactive interpreted to decease the uncertainty of the potential targets in the study area. The results show that the multiple geoscience datasets can be used to extract exploration criteria from surface to depth, the exploration criteria can be validated in the 3D geological model additional metallogenic model/genesis understanding (knowledge) and known polymetallic deposits of mineral system. The methodology can be used in the other mineral exploration districts or camps in the world. [ABSTRACT FROM AUTHOR]

The Angeer Yinwula Pb-Zn deposit of Inner Mongolia, China, is located in the Erlianhot-Dongwuqi metallogenic belt, which is considered to be the eastern part of the Central Asian Orogenic Belt. We used the ore geology, fluid inclusion, isotopes, and zircon U-Pb geochronology to elucidate the genesis and tectonic setting of the deposit. The deposit belongs to the moderate-temperature hydrothermal-vein type, and most of the ore bodies occurred in the quartz diorite intrusions and silty slate country rocks of the Devonian Angeer Yinwula Group. Fluid inclusion petrography and microthermometry results show that the inclusions that developed in the different mineralization stages changed from the LV type (vapor-rich two-phase) + S type (daughter-mineral-bearing three-phase) + VL type (liquid-rich two-phase) to the VL type + LV type and eventually evolved into the VL type, and the ore-forming fluids changed from a moderate-temperature and moderate- to high-salinity, boiling fluid system to a low-temperature and low-salinity H2O-NaCl system. The isotope (C, H, O, S) characteristics suggest that the ore-forming fluids were derived from a magmatic source, and the lead was derived from a deep-seated mantle-derived magma and also included some crustal material. The LA-ICP-MS zircon U-Pb age of the quartz diorite is 152.0 ± 1.5 Ma, which is the best estimate for the age of mineralization of the deposit. Overall, we suggest that the deposit formed in a Late Jurassic Paleo-Pacific Plate subduction setting, although this hypothesis needs to be further tested by conducting computational simulations in the field of emerging computational geosciences. [ABSTRACT FROM AUTHOR]

Statistical analysis of the mineralization intensity in the No. І ore body of the Xincheng gold deposit in Jiaodong Peninsula, China, including grade and linear productivity, was used to study the mineralization characteristics of the hydrothermal gold deposit based on a lognormal distribution pattern and exponential fluctuations. The results show that the mineralization intensity of the hydrothermal gold deposit follows a lognormal distribution pattern. The grade and linear productivity in terms of the strike, dip, and thickness aspects are not linear, while the mineralization intensity fluctuations in exponential function were introduced between the peaks and valleys. This means the gold deposition mineralization process in the hydrothermal gold deposit takes place in accord with the mass action law of the first-order chemical reaction. The logarithmic averaging method is proposed to calculate the average grade and linear productivity of hypothermal gold deposits in accordance with the law of mineral fluctuations that are expressed as exponential functions. These research results have both academic and practical significance for further studies on hydrothermal gold mineralization, extra high-grade processing, improving traditional methods of estimation, and ultimately utilization of gold mineral reserves. [ABSTRACT FROM AUTHOR]