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BACKGROUND Gypsum-salt formation affects the oxygen fugacity of ore-forming fluid and changes the fluid composition, and then affects the trace element composition, which plays an important indicator role in the formation of iron ore deposits. Therefore, changes in the elemental composition of magnetite can be used to classify the types of deposits and determine their genesis. Gypsum-salt formation is widely developed in "Pamir-type" iron deposits in Xinjiang and Ningwu iron deposits in the middle and lower part of the Yangtze River. However, the controlling mechanism of gypsum-salt formation is still unclear. OBJECTIVES In order to investigate the metallogenic process and formation environment of the two types of magnetite, and to discuss the role of gypsum-salt formation in the formation of magnetite deposits. METHODS In situ LA-ICP-MS were employed to determine trace elements in magnetite. RESULTS: LA-ICP-MS results showed that magnetite in the Ningwu area were mainly rich in Ti and V, indicating that it was closely related to magmatism, while the contents of Nb, Ta, Zr, Hf and other high field strength elements (HFSE) in magnetite in the Tashkurgan magnetite deposit in Xinjiang were depleted. Combined with the discrimination diagram of magnetite types, it was mainly divided into two genetic types: magmatic hydrothermal magnetite and hydrothermal metasomatic skarn magnetite related to marine volcanic activity. CONCLUSIONS The results show that the gypsum-salt formation changes the oxygen fugacity during the formation of magnetite deposits in the Tashkurgan area, and provides an important source of ore-forming material for mineralization during the formation of porphyrite-type iron ore in the Ningwu area.

[Display omitted] • Two main types of sphalerites were identified and showed significant trace element differences. • The occurrence of trace elements in sphalerite was discussed, and several possible coupled substitutions are discovered. • PCA on trace elements in Sphalerite from the Fankou Pb-Zn deposit suggest the Fankou Pb-Zn deposit belongs to MVT deposit. Sphalerite is one of the most ubiquitous and abundant sulfides in the Fankou Pb-Zn deposit, Guangdong province, South China, which is hosted predominately in Middle-Upper Devonian and Lower Carboniferous carbonate strata. Two main generations of sphalerites were identified during the filed investigation and microscopic observation: Sphalerite I (including Sp Ia and Sp Ib), "brownish-red" in color, coexists with pyrite, galena, pyrrhotite, chalcopyrite and minor arsenopyrite. By contrast, Sphalerite II (including sphalerite IIa and Sp IIb),"yellow" in color, is associated with galena, pyrite, calcite, and dolomite. The EMPA and LA-ICP-MS analyses show that: (1) Sphalerite I contains higher Fe, Ga, Ge, and Ag, but relatively lower Zn, Sn, Sb, and Pb, compared to sphalerite II; (2) Iron, Mn, Cd, Ga, Ge, In and Sn occur in solid substitution with rhythmically banded compositional changes, with Cu, Sb, and Pb likely also present in solid substitution or microscopic inclusions in the Fankou sphalerite; (3) Possible trace element substitution mechanisms are summarized as follows: (1) Zn2+ ↔ (Fe2+, Mn2+, Cd2+), (2) potential coupled substitutions of 2Zn2+ ↔ Cu+ + Ga3+, 3Zn2+ ↔ 2Cu+ + Ge4+ and 3Zn2+ ↔ 2Ag+ + Ge4+. Principal component analysis (PCA) of selected sphalerite from deposits of the Jinding Pb-Zn deposit, MVT, SEDEX, skarn, VMS, and the Fankou Pb-Zn deposit reveal significant differences. Our study suggests that crystallization temperatures and trace and minor element behaviors of sphalerite from the Fankou deposit were similar to those of sphalerite from typical Mississippi-valley-type (MVT) deposits. [ABSTRACT FROM AUTHOR]

[Display omitted] The Xuefeng Uplift Belt (XUB), in the western part of the Jiannan Orogenic Belt (JOB) South China, hosts numerous low-temperature W-Sb-Au deposits, including the Woxi W-Sb-Au deposit, the Zhazixi Sb-W deposit and the Darongxi W deposit. In order to understand the origin of these low-temperature W deposits and the difference from other moderate-high temperature tungsten deposits in the South China Block, Cathodoluminescene (CL) and LA-ICP-MS are employed to investigate the detailed texture of scheelite, and to identify trace element composition and distribution in scheelite, especially rare earth elements (REEs). LA-ICP-MS results show that the most abundant trace elements in scheelite in this study were Sr, Y, Nb, Mo, Zr, Hf, Ta and REEs. Six types of scheelite can be classified according to variations of REEs pattern. Type I and II scheelites from the Zhazixi Sb-W deposit and the Woxi W-Sb-Au deposit have elevated concentration of Sr, low concentrations of Nb, Mo and variable Nb/Ta ratio, reflecting low temperature (<250℃) reducing environments. By contrast, the Type III scheelite from the Darongxi skarn deposit, Type IV scheelite from the Dabaoshan polymetallic deposit, Type V scheelite from the Niutangjie skarn W deposit and Type VI scheelite from the Daping W deposit have relatively higher Nb, Mo and relatively constant Nb/Ta ratios, and lower Sr concentration, consistent with the feature of moderate to high temperature oxidizing environments. Type I scheelite from the Zhazixi Sb-W deposit can be subdivided into Ia, Ib and Ic, which cover a wide range from MREE-rich to MREE-depleted, indicating a complete dynamic evolution process. Type II scheelite from the Woxi W-Sb-Au deposit has uniform patterns with significant depletion of LREE and enrichment of MREE, revealing that the substitutions of MREE into scheelite lattices are dominated by crystallographic factors, especially the Ca-site size in scheelite crystals rather than the REE concentrations and REE complex stability in hydrothermal fluids. Type III scheelite from the Darongxi W deposit shows two distinctive REE patterns, types IIIa and IIIb, which are likely to be two end members, suggesting that successive precipitation results in changes in REE concentrations and Eu anomalies. Type IV scheelite from the Dabaoshan polymetallic deposit inherited the signature of the granitic porphyry. Type IV b and IVc are similar to those Type V scheelites from Niutangjie, both showing the characteristics of skarn type scheelite mineralization. Trace element variations suggest the predominant control factors differ according to temperature. Trace element concentrations and distribution of scheelite formed at low temperature were mainly controlled by crystallographic factors, which contrasted with fluid-controlled feature of the medium–high temperature scheelite mineralization. [ABSTRACT FROM AUTHOR]

The Chuankou tungsten ore field is situated in the central area of the Xuefeng Uplift Belt in South China. The deposit is characterized by two types of tungsten mineralization: quartz-scheelite veins in both the Neoproterozoic Banxi Group and Devonian Yanglin'ao Formation and quartz-wolframite (scheelite) veins in the Chuankou granite. The host rocks of the Chuankou tungsten Deposit of South China are similar to the stratigraphic sequence of Au-Sb-W deposits in the Xuefeng Uplift Belt. It is thus an appropriate location for the study of scheelite mineralization in the belt, especially the relative contributions of surrounding rocks, magma and hydrothermal fluids. Optical Microscope-Cathodoluminescene (OM-CL) and Laser Ablation Inductively Coupled Mass Spectrometers (LA ICPMS) were used to examine scheelite textures and trace element concentrations in the Chuankou deposits. Scheelite in quartz-scheelite veins was formed over three generations. In situ LA-ICPMS trace elemental analyses of scheelite I show light rare earth element (LREE)-rich REE patterns and negative Eu anomalies, suggesting a relatively close fluid system. Significantly positive Eu anomalies of scheelite II and III indicate variable degrees of addition of meteoric water during scheelite precipitation. Therefore, ore-forming fluids of the Chuankou deposit were dominantly magma-derived, with different contributions of recycled meteoric water in the surrounding strata. [ABSTRACT FROM AUTHOR]

The Yiliu tungsten polymetallic deposit, located in the south central portion of the Nanling nonferrous metal metallogenic province in South China, is an area with common Yanshanian tectonothermal events. Early Yanshanian magmatism leads to the emplacement of voluminous tungsten-bearing granite intrusions, such as the Baoshan, Benggangling and Junye plutons, which are considered temporally and spatially associated with W-polymetallic mineralization in the Yiliu region. Here, we investigate the basic geological and petrological characteristics of the Junye granites, and present major and trace element geochemical data and bulk-rock Sr-Nd-Pb-Hf isotopic data to gain insight into the petrogenesis and tectonic setting of granitic intrusions in the region. The Junye granites are high-K calc-alkaline and metaluminous to weakly peraluminous [A/CNK = molar ratios of Al2O3/(CaO + Na2O + K2O) = 0.97–1.02] with enrichment in SiO2 (75.68–76.44 wt.%), relatively high total alkalis (K2O + Na2O = 8.06–8.45 wt.%) with K2O/Na2O ratios ranging from 1.12 to 1.42, and moderate Al2O3 (12.62–13.00 wt.%), but low in P2O5 (<0.01 wt.%), MgO (0.02–0.04 wt.%), CaO (0.78–0.95 wt.%) and Fe2O3T (0.93–1.07 wt.%). They show spectacular tetrad effect REE (rare earth element) patterns with low ΣREE content (53.2–145.3 ppm), negative Eu anomalies (δEu = 0.09–0.17) and slight enrichment of LREEs (light rare earth elements) relative to HREEs (heavy rare earth elements). The granites are enriched in Rb (481–860 ppm), Th (16.2–46.1 ppm) and U (25.4–40.8 ppm) but depleted in Ba (1.0–5.8 ppm), Sr (11.1–23.4 ppm), P (9.5–26.7 ppm) and Ti (241–393 ppm). All geochemical features lead us to interpret the Junye granites as highly fractionated I-type granites. These granites underwent intense interaction between highly evolved magma and volatile-rich hydrothermal fluids during the late stage of formation, and accompanied fractional crystallization of biotite, plagioclase and accessory minerals, such as apatite, monazite and allanite. Additionally, the granites show uniform Nd isotopic ratios with calculated εNd (152 Ma) values of −8.28 to −8.91 and Nd model age (TDM2) of 1645 to 1698 Ma, stable age-corrected initial Pb isotopic compositions with (206Pb/204Pb)i of 18.646–19.010, (207Pb/204Pb)i of 15.767–15.786 and (208Pb/204Pb)i of 39.113–39.159, respectively, and homogeneous Hf isotopic values yielding εHf (152 Ma) values from −6.9 to −9.5 with TDM2 ages of 1680 to 2214 Ma, collectively suggesting that the granitic magma was probably derived from the remelting of ancient infracrustal materials in the basement of the Nanling region. Consequently, we consider that the Junye granites are the products of partial melting of Paleoproterozoic infracrustal medium- to high-K metamorphic basaltic rocks in the Cathaysia Block, which was caused by the underplating of coeval mantle basaltic magmas that provided abundant heat energy for melting in a tectonic setting, with lithospheric extension and thinning during the late Jurassic period. [ABSTRACT FROM AUTHOR]

The article discusses a research of rare earth elements (REE) and trace element characteristics of quartz from Dayingezhuang gold deposit, Jiaodong Peninsular, China. Topics discussed include association of the most of the gold deposit in north China craton to Mesozoic era's crust thining events, a table related to a study that shows the detected limits of element in quartz, and estimation of temperature of quartz from Dayingezhuang gold deposit.

• S and Pb isotopes of sulfides indicate a crust source for the Shiweidong deposit. • Early stage fluids were inherited from the primary magmatic-hydrothermal fluids. • Latter stage fluids were modified by the intense fluid-rock interaction. • REE substitution in scheelite were mainly controlled by the 3Ca2+ = □Ca + 2REE3+. The Shiweidong W–Cu polymetallic deposit, with resources of 300,000 t WO 3 and 200,000 t Cu, is one of the major tungsten polymetallic deposits in the giant Dahutang ore field. This study conducted a series of in-situ analyses on scheelite and sulfides, aiming to provide some new insights into the sources, hydrothermal ore-forming processes, fluid evolution history and genesis of this deposit, which is of importance to understand the formation of the super-large Dahutang ore field. Quartz vein- and veinlet-disseminated-type tungsten ore bodies are mainly hosted in Neoproterozoic granodiorite and/or the Yanshanian porphyritic two-mica granites. Four stages of mineralization from early to late are identified in this deposit: 1) pegmatite stage; 2) silicate-oxide stage; 3) oxide-sulfide stage; and 4) sulfide stage. The δ34S V - CDT values of stage 3 chalcopyrite and pyrite are from −1.73‰ to −1.46‰ and from −1.66‰ to −0.31‰, respectively, indicating a magma-related hydrothermal origin. The 206Pb/204Pb, 2067Pb/204Pb and 208Pb/204Pb ratios of pyrite range from 18.169 to 18.295, 15.650 to 15.679, and 38.496 to 38.525, respectively, revealing a crust origin for the Pb. Trace element compositions of scheelite show that the both stage 2 scheelite (scheelite-II) and stage 3 scheelite (scheelite-III) have high contents of Nb and REEs. The scheelite-II has a narrow range of the Y/Ho ratios (16.2–31.0), obviously negative Eu anomalies (Eu/Eu* = 0.04–0.46) and relatively low 87Sr/86Sr ratios of 0.72640–0.73336, whereas scheelite-III shows variable Y/Ho ratios of 20.6–96.9, positive Eu anomalies (Eu/Eu* = 1.31–7.11) and relatively high 87Sr/86Sr ratios of 0.73496–0.76098. These data indicated that the Eu anomalies and Sr isotopic compositions of scheelite-II were inherited from magmatic-hydrothermal fluids, whereas those of scheelite-III were sourced from modified fluids due to intense fluid-rock interaction and input of meteoric fluids. Our data also reveal that the REEs of scheelite-II and scheelite-III are mainly controlled by the substitution mechanism of 3Ca2+ = □Ca + 2REE3+. The W-rich reduced fluids and intense fluid-rock interactions, which could provide enough W and Ca, are likely the key factors for the formation of scheelite in the Shiweidong tungsten deposit. [ABSTRACT FROM AUTHOR]