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Crustal magma oxidation state and endowments in porphyry copper deposits

Science China Earth Sciences 2025年第1期 226-236页

作者： Yumin AI Massimo CHIARADIA Chao WU Huayong CHEN key laboratory of mineralogy and Metallogeny Guangzhou Institute of Geochemistry Chinese Academy of Sciences University of Chinese Academy of Sciences Department of Earth Sciences University of Geneva Guangdong Provincial key laboratory of Mineral Physics and Materials

Porphyry copper deposits（PCDs） supply the majority of the world's copper（Cu） as well as significant amounts of molybdenum（Mo） and gold（Au）. The formation of these deposits is controlled by a variety of geological factors, among which the magmatic oxidation is one of the focuses of current research. This study investigates the redox characteristics of arc magmas by analyzing the ratio of vanadium（V） to scandium（Sc） and its correlation with the oxygen fugacity （fO2） of magmas from arcs of various crustal thicknesses globally. We compiled an extensive dataset of published V/Sc values and studied the partition coefficients of Vand Sc between minerals and silicate melts across various magmatic environments. The results demonstrate that fractional crystallization of magnetite markedly reduces V/Sc values of the residual melt. Furthermore, magnesium number（Mg#） at the onset of magnetite fractionation is strongly positively correlated with fO2of the equilibrium magma. Based on this,the oxidation of arc magmas from different crustal thicknesses can be evaluated. The result suggests that magmas generated in crusts thicker than 20 km tend to be more oxidized with increasing crust thickness. This trend is attributed to enhanced intracrustal differentiation processes involving garnet and amphibole, particularly in mature island and continental arcs. In contrast,magmas in thinner arc crusts（<20 km）, which are significantly influenced by subducted slab materials, display higher oxidation states than most of their thicker crust counterparts. These findings suggest that both subduction dynamics and crustal thickness play a vital role in determining the oxidation state of arc magmas and, consequently, their capacity to generate PCDs. Highly oxidized, primitive arc magmas are less favorable for PCD formation due to that they tend to experience magnetite fractionation and thus sulfide saturation in the early stage of magma evolution, a process leading to copper depletion. On the contra

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First-order character of the displacive structural transition in BaWO_4

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Chinese Physics B 2012年第8期21卷 365-373页

作者：谭大勇肖万生周微陈鸣熊小林宋茂双 key laboratory of mineralogy and Metallogeny Guangzhou Institute of GeochemistryChinese Academy of Sciences

Nearly all displacive transitions have been considered to be continuous or second order, and the rigid unit mode （RUM） provides a natural candidate for the soft mode. However, in-situ X-ray diffraction and Raman measurements show clearly the first-order evidences for the scheelite-to-fergusonite displacive transition in SaWO4： a 1.6% volume collapse, coexistence of phases, and hysteresis on release of pressure. Such first-order signatures are found to be the same as the soft modes in BaWO4, which indicates the scheelite-to-fergusonite displacive phase transition hides a deeper physical mechanism. By the refinement of atomic displacement parameters, we further show that the first-order character of this phase transition stems from a coupling of large compression of soft BaOs polyhedrons to the small displacive distortion of rigid WO4 tetrahedrons. Such a coupling will lead to a deeper physical insight in the phase transition of the common scheelite-structured compounds.

关键词： BaWO4 pressure-induced phase transitions X-ray diffraction Raman scattering

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Metallogenesis and major challenges of porphyry copper systems above subduction zones

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Science China Earth Sciences 2020年第7期63卷 899-918页

作者： Huayong CHEN Chao WU key laboratory of mineralogy and Metallogeny Guangzhou Institute of GeochemistryChinese Academy of Sciences

Porphyry copper±molybdenum±gold deposits(PCDs) are the most representative magmatic-hydrothermal metallogenic system above subduction zones with important economic value. Previous studies revealed that large PCDs are generally formed from initial arc magmas(from subduction-induced partial melting of the mantle wedge), which eventually ascend to the shallow crust(3–5 km) for mineralization after a series of complex evolution processes. These processes include(1) the dehydration or partial melting of subducting slab, which induces partial melting of the metasomatized mantle wedge;(2)the ascent of mantle-derived magma to the bottom of the lower crust, which subsequently undergoes crustal processes such as assimilation plus fractional crystallization(AFC) or melting, assimilation, storage and homogenization(MASH);(3) the magma chamber formation at the bottom of the lower, middle and upper crust;(4) the final emplacement and volatilization of porphyry stocks;and(5) the accumulation of ore-forming fluids and metal precipitation. Despite the many decades of research, many issues involving the PCD metallogenic mechanism still remain to resolve, such as(1) the tectonic control on the geochemical characteristics of ore-forming magma;(2) the reason for the different lifespans of the long-term magmatic arc evolution and geologically "instantaneous" mineralization processes;(3) the source of ore-forming materials;(4) the relative contributions of metal pre-enrichment to mineralization by the magma source and by magmatic evolution;and(5) the decoupling behaviors of Cu and Au during the pre-enrichment. These issues point out the direction for future PCD metallogenic research, and the resolution to them will deepen our understanding of the metallogenesis at convergent plate boundaries.

关键词： Subduction zone Porphyry Cu deposit Metallogenesis

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Study on Late Cretaceous-Cenozoic exhumation of the Yanji area,NE China: insights from low-temperature thermochronology

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Acta Geochimica 2019年第6期38卷 815-833页

作者： Xiaoming Li key laboratory of mineralogy and Metallogeny Guangzhou Institute of Geochemistry Chinese Academy of Sciences

The Yanji area,northeastern China,a part of the orogenic collage between the North China Block in the south and the Jiamusi-Khanka Massifs in the northeast,is the most likely location where the Pacific Plate subduction・related magmatic activities and subsequent exhumation processes ***,we report new low-temperature thermochronology of apatite and zircon data from the granitoid samples in the Yanji *** exhumation rates of Tianfozhishan,Yanji area,were〜0.049 and〜0.073 mm/year,interpreted from the elevations and apatite and zircon fission track ages,*** exhumation,integrated with the geological setting,suggested that the paleogeothermal gradient of the Tianfozhishan,even extending to the Yanji area,was possibly to be greater than 35℃/km in the Late *** thermal history modeling of the data indicates a basically similar pattern,but the various timing for different samples between the Oligocene-Early Miocene and the Middle Miocene in the Yanji *** hence conclude that a fourstages of cooling,from〜6.7℃/Ma(during the Late Cretaceous),to〜0.8℃/Ma(during the Late Cretaceous to the Oligocene-Early Miocene),then to〜2-3℃/Ma with varied styles(between the Oligocene-Early Miocene and the Middle Miocene),and finally to3 km under a reasonable paleogeothermal gradient(>35℃/km),speculated from the possible exhumation rate of *** with the tectonic setting,this exhumation,including two stages of pronounced tectonic uplift and denudation and two stages of weak exhumation driven by the low regional erosion rate,is possibly related to the subduction of the Pacific Plate beneath the Eurasian Plate since the Late *** study used more robust evidence to propose higher paleogeothermal gradient(>35℃/km),reflecting exhumation of>3 km in the Yanji area since the Late Cretaceous.

关键词： Low-temperature thermochronology Exhumation Pacific Plate subduction Yanji area Late Cretaceous-Cenozoic

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A peculiar composite M-and W-type REE tetrad effect:Evidence from the Shuiquangou alkaline syenite complex,Hebei Province,China

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Chinese Science Bulletin 2010年第24期55卷 2684-2696页

作者： ZHAO ZhenHua BAO ZhiWei QIAO YuLou key laboratory for metallogenic Dynamics Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China

A new type of REE tetrad effect,a composite M-and W-type,was recognized in the K-feldsparthized and silicificated Shuiquangou alkaline syenites,Dongping,Hebei *** analytical methods such as ICP-MS and isotopic dilution thermal ion mass spectrometer were exploited to verify the REE concentrations of the samples in three laboratories in China,France and *** results are reliable and consistent within *** situ quantitative analysis of REE concentrations of individual zircons and apatites extracted from the very same sample has shown that fractional crystallization of magma and the superimposed hydrothermal alteration might have taken place in at least two-stage hydrothermal activities to generate the composite M-and W-type REE tetrad *** coexisting melt and aqueous phases,the superimposed alteration by volatile(Cl,CO2) -and Si,K, Al-enriched high temperature hydrothermal fluids might be the important facts for this new MW-type of REE tetrad *** addition,the peculiar MW-type tetrad effect might be an indicator for Au mineralization of reworked plutons.

关键词：四重效应碱性正长岩水泉沟河北省稀土 W型复合中国

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Late Mesozoic magmatism and tectonic evolution in the Southern margin of the North China Craton

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Science China Earth Sciences 2017年第11期60卷 1959-1975页

作者： GAO XinYu ZHAO TaiPing key laboratory of mineralogy and Metallogeny Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China

Late Mesozoic granitic magmatism(158–112 Ma) are widespread in the southern margin of the North China Craton(NCC), contemporary with many world-class Mo-Au-Ag-Pb-Zn polymetallic deposits. There are abrupt changes in the elements and isotopic compositions of these granites at about 127 Ma. The early stage(158–128 Ma) granites show slightly or no negative Eu anomalies, large ion lithophile elements enriched and heavy REE depleted(such as Y and Yb), belonging to typical I-type granite. The late stage(126–112 Ma) granites are characterized by A-type and/or highly fractionated I-type granite, with higher contents of SiO2, K2 O, Y, Yb and Rb/Sr ratio and lower contents of Sr, δEu value and Sr/Y ratio than that of the early-stage ***, the whole rock Nd and Hf isotopic compositions of the granites younger than 127 Ma show more depleted than those of the older one. The two stages of Late Mesozoic granites were derived from a source region of the ancient basement of the southern margin of the NCC incorporated the mantle material. The late stage(126–112 Ma) granites contain more fractions of mantle material with depleted isotopic composition than the early ones. The granites record evidence for a strong crust-mantle interaction. They formed in an intracontinental extensional setting which was related to lithospheric thinning and asthenospheric upwelling in this region, which was possibly caused by westward subduction of the Paleo-Pacific plate. 127 Ma is an critical period of the transformation of the tectonic regime.

关键词： Southern margin of the North China Craton Late Mesozoic Granite Origin Tectonic evolution

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An element-free Galerkin method for ground penetrating radar numerical simulation

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Journal of Central South University 2015年第1期22卷 261-269页

作者：冯德山郭荣文王洪华 School of Geosciences and Info-Physics Central South University key laboratory of metallogenic Prediction of Nonferrous Metals Ministry of Education(Central South University)

An element-free Galerkin method(EFGM) is used to solve the two-dimensional(2D) ground penetrating radar(GPR)modelling problems, due to its simple pre-processing, the absence of elements and high accuracy. Different from element-based numerical methods, this approach makes nodes free from the elemental restraint and avoids the explicit mesh discretization. First, we derived the boundary value problem for the 2D GPR simulation problems. Second, a penalty function approach and a boundary condition truncated method were used to enforce the essential and the absorbing boundary conditions, respectively. A three-layered GPR model was used to verify our element-free approach. The numerical solutions show that our solutions have an excellent agreement with solutions of a finite element method(FEM). Then, we used the EFGM to simulate one more complex model to show its capability and limitations. Simulation results show that one obvious advantage of EFGM is the absence of element mesh, which makes the method very flexible. Due to the use of MLS fitting, a key feature of EFM, is that both the dependent variable and its gradient are continuous and have high precision.

关键词： element-free Galerkin method moving least-squares method ground penetrating radar forward simulation

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An experimental study on metal precipitation driven by fluid mixing: implications for genesis of carbonate-hosted lead–zinc ore deposits

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Acta Geochimica 2019年第2期38卷 202-215页

作者： Yan Zhang Runsheng Han Xing Ding Junjie He Yurong Wang Geological Survey Center for Non-ferrous Mineral Resources Kunming University of Science and Technology State key laboratory of Isotope Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences CAS Center for Excellence in Tibetan Plateau Earth Sciences key laboratory of mineralogy and metallogenic Guangzhou Institute of Geochemistry Chinese Academy of Sciences University of Chinese Academy of Sciences

A type of carbonate-hosted lead–zinc(Pb–Zn)ore deposits, known as Mississippi Valley Type(MVT)deposits, constitutes an important category of lead–zinc ore deposits. Previous studies proposed a fluid-mixing model to account for metal precipitation mechanism of the MVT ore deposits, in which fluids with metal-chloride complexes happen to mix with fluids with reduced sulfur, producing metal sulfide deposition. In this hypothesis, however, the detailed chemical kinetic process of mixing reactions, and especially the controlling factors on the metal precipitation are not yet clearly stated. In this paper, a series of mixing experiments under ambient temperature and pressure conditions were conducted to simulate the fluid mixing process, by titrating the metal-chloride solutions, doping withor without dolomite, and using NaHS solution. Experimental results, combined with the thermodynamic calculations, suggest that H_2S, rather than HS^-or S^(2-),dominated the reactions of Pb and/or Zn precipitation during the fluid mixing process, in which metal precipitation was influenced by the stability of metal complexes and the pH. Given the constant concentrations of metal and total S in fluids, the pH was a primary factor controlling the Pb and/or Zn metal precipitation. This is because neutralizing or neutralized processes for the ore-forming fluids can cause instabilities of Pb and/or Zn chloride complexes and re-distribution of sulfur species, and thus can facilitate the hydrolysis of Pb and Zn ions and precipitation of sulfides. Therefore, a weakly acidic to neutral fluid environment is most favorable for the precipitation of Pb and Zn sulfides associated with the carbonate-hosted Pb–Zn deposits.

关键词： Metal precipitation Fluid mixing Sulfur species MVT lead-zinc ore deposits Carbonate-hosted lead-zinc deposits

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Chemical and boron isotopic compositions of tourmaline in the Longtoushan hydrothermal gold deposit, Guangxi, China:implications for gold mineralization

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Acta Geochimica 2019年第2期38卷 277-291页

作者： Lihua Qian Jianqing Lai Shugen Zhang Lifang Hu Rong Cao Shilong Tao key laboratory of metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring Ministry of Education School of Geosciences and Info-Physics Central South University

The Longtoushan hydrothermal gold deposit is located in the southwestern region of the Dayaoshan *** is widespread in the Longtoushan gold deposit and is mainly distributed in the rhyolite porphyry and associated cryptoexplosive breccia. The spatial distribution of tourmaline enrichment is similar to that of the gold orebody. Feldspar has been largely replaced by tourmaline in the rhyolite porphyry and cryptoexplosive *** microprobe analysis revealed that tourmalines in the Longtoushan deposit belong mainly to the alkali group and partly to the X-vacant group; they mostly fell in the schorl-dravite series field. Two distinct sets of dominant substitutions were observed: MgFe_(-1) and Al□(NaR2+)-1,where R = Fe, Mg. In addition, minor substitutions include(CaMg)(NaAl)_(-1) and FeAl_(-1). The calculated d11 B value for the mineralizing fluids ranged from-12.8 to-9.7%,which is typical of S-type granites, and boron-enriched fluids predominantly derived from rhyolitic melt. Part of the tourmaline from the rhyolite porphyry crystallized during the magmatic-hydrothermal stage, whereas most tourmalines from the deposit formed in the post-magmatic hydrothermal stage. The tourmalines were deposited from a relatively reduced and acidic fluid system, and the gold predominantly precipitated during the post-magmatic hydrothermal stage in the Longtoushan deposit.

关键词： Longtoushan gold deposit Tourmaline Oreforming fluids Boron isotopes

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Major and Trace Elements of Magnetite from the Qimantag metallogenic Belt: Insights into Evolution of Ore–forming Fluids

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Acta Geologica Sinica(English Edition) 2015年第4期89卷 1226-1243页

作者： YI Liwen GU Xiangping LU Anhuai LIU Jianping LEI Hao WANG Zhiling CUI Yu ZUO Hongyan SHEN Can key laboratory of metallogenic Prediction of Nonferrous Metals and Geological Environment Monitor Ministry of Education School of Geosciences and Info–Physics Central South University

Magnetite, as a genetic indicator of ores, has been studied in various deposits in the world. In this paper, we present textural and compositional data of magnetite from the Qimantag metallogenic belt of the Kunlun Orogenic Belt in China, to provide a better understanding of the formation mechanism and genesis of the metallogenic belt and to shed light on analytical protocols for the in situ chemical analysis of magnetite. Magnetite samples from various occurrences, including the ore-related granitoid pluton, mineralised endoskarn and vein-type iron ores hosted in marine carbonate intruded by the pluton, were examined using scanning electron microscopy and analysed for major and trace elements using electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry. The field and microscope observation reveals that early-stage magnetite from the Hutouya and Kendekeke deposits occurs as massive or banded assemblages, whereas late- stage magnetite is disseminated or scattered in the ores. Early-stage magnetite contains high contents of Ti, V, Ga, AI and low in Mg and Mn. In contrast, late-stage magnetite is high in Mg, Mn and low in Ti, V, Ga, AI. Most magnetite grains from the Qimantag metallogenic belt deposits except the Kendekeke deposit plot in the ＂ Skarn ＂ field in the Ca＋AI＋Mn vs Ti＋V diagram, far from typical magmatic Fe deposits such as the Damiao and Panzhihua deposits. According to the （MgO＋MnO）- TiO^-AI203 diagram, magnetite grains from the Kaerqueka and Galingge deposits and the No.7 ore body of the Hutouya deposit show typical characteristics of skarn magnetite, whereas magnetite grains from the Kendekeke deposit and the No.2 ore body of the Hutouya deposit show continuous elemental variation from magmatic type to skarn type. This compositional contrast indicates that chemical composition of magnetite is largely controlled by the compositions of magmatic fluids and host rocks of the ores that have reacted with the fluids. Moreover, a co

关键词： Magnetite trace element LA-ICP-MS ore genesis Qimantag metallogenic belt

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