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Determination of rhenium and osmium by ICP-MS for galena and sphalerite

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Acta Geochimica 2016年第1期35卷 43-49页

作者： Yingying Liu Liang Qi jianfeng gao Zhilong Huang State Key Laboratory of Ore Deposit Geochemistry Institute of Geochemistry Chinese Academy of SciencesGuiyang 550180 China University of Chinese Academy of Sciences Beijing 100049China

Digestion with aqua regia in a Carius tube and separation of Re with anion exchange resin is commonly employed for Re–Os dating of molybdenite and ***, the recovery of Re is extremely low when this routine anion exchange method is applied to galena,causing difficulty in Re–Os dating of galena. In this study,we investigated the mechanism of Re loss during sample preparation and tested a revised procedure for Re–Os dating of galena and sphalerite.

关键词： Galena Sphalerite Rhenium and osmium Anion exchange resin ICP-MS

Germanium in Magnetite:A Preliminary Review

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Acta Geologica Sinica(English Edition) 2017年第2期91卷 711-726页

作者： MENG Yumiao HU Ruizhong HUANG Xiaowen gao jianfeng State Key Laboratory of Ore Deposit Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China

Magnetite is a very common mineral in various types of iron deposits and some sulfide deposits. Recent studies have focused on the use of trace elements in magnetite to discriminate ore types or trace ore-forming process. Germanium is a disperse element in the crust, but sometimes is not rare in magnetite. Germanium in magnetite can be determined by laser ablation ICP-MS due to its low detection limit（0.0X ppm）. In this study, we summary the Ge data of magnetite from magmatic deposits, iron formations, skarn deposits, iron oxide copper-gold deposits, and igneous derived hydrothermal deposits. Magnetite from iron formations contains relatively high Ge（up to ~250 ppm）, whereas those from all other deposits mostly contains Ge less than 10 ppm, indicating that iron formations can be discriminated from other Fe deposits by Ge contents. Germanium in magmatic/hydrothermal magnetite is controlled by a few factors. Primary magma/fluid composition may be the major control of Ge in magnetite. Higher oxygen fugacity may be beneficial to Ge partition into magnetite. Sulfur fugacity and temperature may have little effect on Ge in magnetite. The enrichment mechanism of Ge in magnetite from iron formations remains unknown due to the complex ore genesis. Germanium along with other elements（Mn, Ni, Ga） and element ratios（Ge/Ga and Ge/Si raios） can distinguish different types of deposits, indicating that Ge can be used as a discriminate factor like Ti and V. Because of the availability of in situ analytical technique like laser ablation ICP-MS, in situ Ge/Si ratio of magnetite can serve as a geochemical tracer and may provide new constraints on the genesis of banded iron formations.

关键词： germanium magnetite controlling factor iron deposits discriminate factor

Land-use induced changes in topsoil organic carbon stock of paddy fields using MODIS and TM/ETM analysis:A case study of Wujiang County,China

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Journal of Environmental Sciences 2008年第7期20卷 852-858页

作者： gao, jianfeng PAN, Genxing JIANG, Xiaosan PAN, Jianjun ZHUANG, Dafang Institute of Resources Ecosystem and Environment of Agriculture Nanjing Agricultural University Nanjing 210095 China Institute of Geographical Science and Natural Resources Chinese Academy of Sciences Beijing 100101 China

Topsoil soil organic carbon (SOC) that plays an important role in mitigating atmospheric carbon dioxide (CO_2) buildup is greatly affected by human *** evaluate the influence of land-use changes on SOC stocks in paddy soils,a new algorithm was developed by integrating MODIS (moderate resolution imaging spectral-radiometer) and TM/ETM data for timely monitoring the land-use change in Wujiang ***,the land-use class-maps derived from MODIS and TM/ETM analyses were further used to estima...

关键词： soil organic carbon (SOC) MODIS TM/ETM rice paddies land-use soil C sequestration

Trace element composition of magnetite from the Xinqiao Fe–S(–Cu–Au) deposit, Tongling, Eastern China: constraints on fluid evolution and ore genesis

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Acta Geochimica 2018年第5期37卷 639-654页

作者： Yichang Wang jianfeng gao Xiaowen Huang Liang Qi Chuan Lyu State Key Laboratory of Ore Deposit Geochemistry Institute of Geochemistry Chinese Academy of SciencesGuiyang 550081 China University of Chinese Academy of Sciences Beijing 100049China

The Xinqiao deposit is one of several polymetallic deposits in the Tongling ore district. There are two types of mineralization in the Xinqiao： skarn-type and stratiform-type. The skarn-type mineralization is characterized by iron oxides such as magnetite and hematite, whereas stratiform-type mineralization is characterized by massive sulfides with small amounts of magnetite and hematite. We defined three types of ores within the strati- form-type mineralization by the mineral assemblages and ore structures. Type Ⅰ ore is represented by magnetite crosscut by minor calcite veins. Type Ⅱ is a network ore composed of magnetite and crosscutting pyrite. Type Ⅲ is a massive ore containing calcite and hematite. Type Ⅰ magnetite is characterized by highly variable trace element content, whereas Type Ⅱ magnetite has consistently higher Si, Ti, V, and Nb. Type Ⅲ magnetite contains more In, Sn, and As than the other two types. Fluid-rock interaction, oxygen fugacity （fO2）, and temperature （T） are the main factors controlling element variation between the different magnetite types. Type I magnetite was formed by more extensive fluid-rock interaction than the other two types at moderate fO2 and T conditions. Type Ⅱ magnetite is thought to have formed in relatively low fO2 and high-Tenvironments, and Type Ⅲ in relatively high fOe and moderate-T environments. Ca ＋ Al ＋ Mn and Ti ＋ V discrimination diagrams show that magnetite in the Xin qiao deposit is hydrothermal in origin and is possibly linked with skarn.

关键词： Xinqiao Skarn Magnetite In-situ analysis Tongling

Design and fabrication of compact Ge-on-SOI coupling structure

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Frontiers of Optoelectronics 2019年第3期12卷 276-285页

作者： jianfeng gao Junqiang SUN Heng ZHOU Jialin JIANG Yang ZHOU Wuhan National Laboratory for Optoelectronics School of Optical and Electronic InformationHuazhong University of Science and TechnologyWuhan 430074China

In this paper, we have proposed and demonstrated a simple approach to fabricate vertical integrated structure for coupling between active germanium (Ge) waveguide and silicon-on-insulator (SOI) waveguide. The active Ge waveguide is sputtered after etching the underlying passive silicon (Si) waveguide. This method scuttles away from the difficulty involved in the waveguide fabrication by avoiding the etching process for the Ge waveguide, and thereby the waveguide quality is improved. The influences of the coupling structural parameters on the coupling loss are analyzed and discussed. The optimizing parameters are obtained for the fabrication. The minimal coupling loss is experimentally measured about 2.37 dB, and variation tendency of coupling loss against the structural parameters is consistent with the theoretical result. The proposed approach offers an effective path for vertical coupling between Ge and SOI optical components.

关键词： taper coupler integrated optics device guided waves silicon-on-insulator (SOI) waveguide germanium (Ge) waveguide active Ge device Ge-on-SOI coupling structure

Strain rate sensitivity of tensile properties in high Nb containing TiAl alloys

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Journal of University of Science and Technology Beijing 2005年第6期12卷 535-539页

作者： jianfeng gao Xiangjun Xu Junpin Lin Xiping Song Yanli Wang Guoliang Chen State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China

The effect of strain rate on the yield strength of high Nb containing TiAl alloy was studied. The results show that the strain rate sensitivity varies with the test temperature, and the yield strength is not sensitive to the strain rate at room temperature but significantly sensitive to the strain rate at high temperature. An increase of the strain rate or a decrease of the temperature results in an obvious change of fracture mode. It is found that the strain rate sensitivity of this alloy varying with temperature is due to the dislocation climb generated at high temperature.

关键词： TiAl alloys strain rate tensile properties thermal activation

Constraints of molybdenite Re-Os and scheelite Sm-Nd ages on mineralization time of the Kukaazi Pb-Zn-Cu-W deposit, Western Kunlun, NW China

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Acta Geochimica 2018年第1期37卷 47-59页

作者： Chengbiao Leng Yuhui Wang Xingchun Zhang jianfeng gao Wei Zhang Xinying Xu State Key Laboratory of Ore Deposit Geochemistry Institute of Geochemistry Chinese Academy of SciencesGuiyang 550081 China Guizhou Central Laboratory of Geology and Mineral Resources Guiyang 550018 China University of Chinese Academy of Sciences Beijing 100049China Tianjin Institute of Geology and Mineral Resources Tianjin 300170 China

The Kukaazi Pb-Zn-Cu-W polymetallic deposit, located in the Western Kunlun orogenic belt, is a newly discovered skarn-type deposit. Ore bodies mainly occur in the forms of lenses and veins along beddings of the Mesoproterozoic metamorphic rocks. Three ore blocks, KⅠ,KⅡ, and KⅢ, have been outlined in different parts of the Kukaazi deposit in terms of mineral assemblages. The KⅠ ore block is mainly composed of chalcopyrite, scheelite,pyrrhotite, sphalerite, galena and minor pyrite, arsenopyrite,and molybdenite, whereas the other two ore blocks are made up of galena, sphalerite, magnetite and minor arsenopyrite and pyrite. In this study, we obtained a molybdenite isochron Re–Os age of 450.5 ± 6.4 Ma(2σ,MSWD = 0.057) and a scheelite Sm–Nd isochron age of 426 ± 59 Ma(2σ, MSWD = 0.49) for the KⅠ ore *** are broadly comparable to the ages of granitoid in the region. Scheelite grains from the KⅠ ore block contain high abundances of rare earth elements(REE, 42.0–95.7 ppm)and are enriched in light REE compared to heavy REE, with negative Eu anomalies(δEu = 0.13–0.55). They display similar REE patterns and Sm/Nd ratios to those of the coeval granitoids in the region. Moreover, they also have similar Sr and Nd isotopes [ ^(87)Sr/ ^(86)Sr = 0.7107–0.7118;ε_(Nd)(t) =-4.1 to-4.0] to those of such granitoids, implying that the tungsten-bearing fluids in the Kukaazi deposit probably originate from the granitic magmas. Our results first defined that the Early Paleozoic granitoids could lead to economic Mo–W–(Cu) mineralization at some favorable districts in the Western Kunlun orogenic belt and could be prospecting exploration targets.

关键词： Molybdenite Re-Os Scheelite Sm–Nd REE Kukaazi Pb-Zn-Cu-W polymetallic deposit Western Kunlun orogenic belt

Re-Os Dating of Galena and Sphalerite from Lead-Zinc Sulfide Deposits in Yunnan Province, SW China

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Journal of Earth Science 2015年第3期26卷 343-351页

作者： Yingying Liu Liang Qi jianfeng gao Lin Ye Zhilong Huang Jiaxi Zhou State Key Laboratory of Ore Deposit Geochemistry Institute of Geochemistry Chinese Academy of Sciences University of Chinese Academy of Sciences

Dating of lead-zinc deposits is of critical importance for better understanding of ore genesis, but has long been a big challenge due to the lack of suitable minerals that can be unequivocally linked to the ore genesis and that can be used for tradition radiometric methods. This kind of deposits have simple mineralogy dominated by galena and sphalerite commonly associated with calcite and other gangue minerals. Both galena and sphalerite have low and high variable Re concentrations and thus Re-Os dating of these minerals have been less promising. In addition, the recovery of Re is extremely low for galena when conventional method was applied, lending additional difficulty in precisely dating galena. In this study, we investigate the recovery of Re using different media for anion exchange separation and reporte a revised preparation method for Re-Os dating of galena and sphalerite. By using the new protocol, two reliable Re-Os isochron ages of galena and sphalerite from the Fule（20.4±3.2 Ma） and Laochang（308±25 Ma） Pb-Zn deposits in Yunnan Province, SW China, are achieved.

关键词： lead-zinc sulfide deposits Re-Os isotope dating separation and concentration of Re galena sphalerite Yunnan

Fractionation characteristics of rare earth elements(REEs) linked with secondary Fe, Mn, and Al minerals in soils

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Acta Geochimica 2016年第4期35卷 329-339页

作者： Chunying Chang Fangbai Li Chengshuai Liu jianfeng gao Hui Tong Manjia Chen Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control Guangdong Institute of Eco-Environmental and Soil Sciences Guangdong Key Laboratory of Contaminated Sited Environmental Management and Remediation Guangdong Provincial Academy of Environmental Science State Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences

Soil secondary minerals are important scavengers of rare earth elements(REEs) in soils and thus affect geochemical behavior and occurrence of REEs. The fractionation of REEs is a common geochemical phenomenon in soils but has received little attention, especially fractionation induced by secondary minerals. In this study, REEs(La to Lu and Y) associated with soil-abundant secondary minerals Fe-, Al-, and Mn-oxides in 196 soil samples were investigated to explore the fractionation and anomalies of REEs related to the minerals. The results show right-inclined chondrite-normalized REE patterns for La–Lu in soils subjected to total soil digestion and partial soil extraction. Light REEs(LREEs) enrichment features were negatively correlated with a Eu anomaly and positively correlated with a Ce anomaly. The fractionation between LREEs and heavy REEs(HREEs) was attributed to the high adsorption affinity of LREEs to secondary minerals and the preferred activation/leaching of *** substantial fractions of REEs in soils extracted byoxalate and Dithionite-Citrate-Bicarbonate buffer solutions were labile(10 %–30 %), which were similar to the mass fraction of Fe(10 %–20 %). Furthermore, Eu was found to be more mobile than the other REEs in the soils, whereas Ce was less mobile. These results add to our understanding of the distribution and geochemical behavior of REEs in soils, and also help to deduce the conditions of soil formation from REE fractionation.

关键词： Rare earth elements Fractionation Secondary minerals Geochemical process - Europium anomaly Cerium anomaly