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Effect of F-Rich Fluids on the A-Type Magmatism and Related metal Mobilization:New Insights from the Fogang-Nankunshan-Yajishan Igneous Rocks in Southeast China

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Journal of Earth Science 2022年第3期33卷 591-608页

作者： Xing Ding Koulin Su Haibo Yan Jinlong Liang Weidong Sun State Key Laboratory of Isotope Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China CAS Center for Excellence in Deep Earth Sciences Guangzhou 510640China Geological Survey Institute of Guangzhou Guangzhou 510640China Center of Deep Sea Research Institute of OceanographyChinese Academy of SciencesQingdao 266071China Laboratory for Marine Mineral Resources Qingdao National Laboratory for Marine Science and TechnologyQingdao 266237China Department of Geochemistry Chengdu University of TechnologyChengdu 610059China

About 45%of tungsten,~20%of tin,and~9%of fluorite of known world reserves are associated with Late Mesozoic igneous rocks,Southeast(SE)China.Here we demonstrate that Fogang granite,the largest inland batholith,is mainly of A2-type that is commonly found in post-orogenic settings and experienced plate subduction induced metasomatism.In contrast,the Yajishan syenite and Nankunshan granite intruding the Fogang granite~20 Ma later are of A1-type formed in intraplate settings.We found that F-rich fluid fractionation,which could make the decline of Ga/Al ratio,total(Nb+Y+Ce+Zr)and Zr concentrations,Nb/Ta and Zr/Hf ratios,leads to chemical variations of a few Fogang granites changing from A2-type to highly fractionated or I-and S-type granitoids.Crystal and Frich fluid fractionations,as well as crustal contamination most likely derived from the Fogang granite,result in some Nankunshan granites developing from A1-type into A2-type.These late-or post-magmatic processes should be taken into account carefully when discriminating the petrogenetic types of igneous rocks,especially for the A2-type suites.Combining with the distribution of 180-140 Ma A1-and A2-type igneous rocks,rare metal deposits,and fluorite deposits in SE China,we highlight the significant role of slab-released F-rich fluids in formation of A-type suites and subsequent chemical differentiation and rare metal and fluorine mineralization.A model of flat-slab northeastward rollback is thus proposed,in which the subduction front reached somewhere near Fogang and then started to roll back at~165 Ma.The inland Jurassic granites of SE China represent a unique locality for formation of A-type suites and their associated mineralization.These granites are not anorogenic,but they are the result of slab rollback from a flat slab,founding of that slab at shallow levels,and metasomatism of by F-rich fluids related to slab heating by the asthenosphere.

关键词： A-type granite alkaline F-rich fluids slab rollback rare metal rare earth elements Nb/Ta

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Dealloying corrosion of anodic and nanometric Mg41Nd5 in solid solution-treated Mg-3Nd-1Li-0.2Zn alloy

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Journal of Materials Science & Technology 2021年第24期83卷 161-178页

作者： Gui-Jia Gao Mei-Qi Zeng En-Liang Zhang Rong-Chang Zeng Lan-Yue Cui Dao-kui Xu Feng-Qin Wang M.Bobby Kannan Corrosion Laboratory for Light metals College of Materials Science and EngineeringShandong University of Science and TechnologyQingdao266590China School of Materials Science and Engineering Zhengzhou UniversityZhengzhou450002China Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Engineering University of NewcastleCallaghanNew South Wales 2308Australia

The microstructure and chemical compositions of the solid solution-treated Mg-3 Nd-1 Li-0.2 Zn alloy were characterized using optical microscope,scanning electron microscope(SEM),transmission electron microscope(TEM),electron probe micro-analyzer(EPMA)and X-ray photoelectron spectroscopy(XPS).The corrosion behaviour of the alloy was investigated via electrochemical polarization,electrochemical impedance spectroscopy(EIS),hydrogen evolution test and scanning Kelvin probe(SKP).The results showed that the microstructure of the as-extruded Mg-3 Nd-1 Li-0.2 Zn alloy containedα-Mg matrix and nanometric second phase Mg_(41)Nd_(5).The grain size of the alloy increased significantly with the increase in the heat-treatment duration,whereas the volume fraction of the second phase decreased after the solid solution treatment.The surface film was composed of oxides(Nd_(2)O_(3),Mg O,Li_(2)O and Zn O)and carbonates(Mg CO3 and Li_(2)CO3),in addition to Nd.The as-extruded alloy exhibited the best corrosion resistance after an initial soaking of 10 min,whereas the alloy with 4 h-solution-treatment possessed the lowest corrosion rate after a longer immersion(1 h).This can be attributed to the formation of Nd-containing oxide film on the alloys and a dense corrosion product layer.The dealloying corrosion of the second phase was related to the anodic Mg_(41)Nd_(5)with a more negative Volta potential relative toα-Mg phase.The preferential corrosion of Mg_(41)Nd_(5)is proven by in-situ observation and SEM.The solid solution treatment of Mg-3 Nd-1 Li-0.2 Zn alloy led to a shift in corrosion type from pitting corrosion to uniform corrosion under long-term exposure.

关键词： Magnesium alloy Corrosion Second phase rare metal Dealloying

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Role of yttrium in glass formation of Ti-based bulk metallic glasses

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rare metals 2009年第1期28卷 68-71页

作者： HAO Guojian REN Fei ZHANG Yong LIN Junpin State Key Laboratory for Advanced metals and Materials University of Science and Technology Beijing Beijing 100083 China

Starting with Zr of two different purities, Ti-based bulk metallic glasses （BMGs） with a nominal composition of Ti40Zr25Cu12Ni3Be20 were prepared. The effect of the addition of yttrium at levels of 0.2 at.%, 0.4 at.%, 0.5 at.%, 0.6 at.%, and 1 at.% on the glass forming ability （GFA） of the alloy has been investigated by means of metallography, X-ray diffraction, and differential scanning calorimetry. Experimental data in-dicates that high impurity content dramatically reduces the glass forming ability. Microalloying with 0.5 at.% Y is effective in suppressing the crystalline phase formation and alleviating the detrimental effect of oxygen in the low-purity alloy. On the contrary, in the alloy contain-ing high-purity element, the effective yttrium addition is less than 0.4 at.%. The results indicate that the beneficial effect of the optimum dopants is mainly due to scavenging the oxygen impurity via the formation of innocuous phase.

关键词： bulk metallic glass titanium microalloying rare metal glass forming ability

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