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Distinctive melt activity and chromite mineralization in Luobusa and Purang ophiolites, southern Tibet: constraints from trace element compositions of chromite and olivine

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Science Bulletin 2019年第2期64卷 108-121页

作者： Benxun Su Meifu Zhou Jiejun Jing Paul T. Robinson Chen Chen Yan Xiao Xia Liu Rendeng Shi Davide Lenaz Yan Hu Key Laboratory of Mineral Resources Institute of Geology and Geophysics Chinese Academy of Sciences University of Chinese Academy of Sciences Institutions of Earth Science Chinese Academy of Sciences Department of Earth Sciences The University of Hong Kong State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Key Laboratory of Continental Collision and Plateau Uplift Institute of Tibetan Plateau Research Chinese Academy of Sciences Department of Mathematics and Geosciences University of Trieste Department of Earth and Space Sciences University of Washington

To investigate the factors controlling the mineralization in ophiolites we systematically compared the petrology and mineral compositions of the harzburgites/lherzolites, dunites and chromitites in the Luobusa and Purang ophiolites. Generally, the petrological features and trace element compositions of chromite and olivine in peridotite and chromitite are distinctly different between the two ophiolites.In Luobusa, boninitic melts are inferred to have interacted with the harzburgites and modified the distributions of some trace elements(e.g., Ni, Mn and V) in chromite and olivine. The subsequently formed dunites and chromitites experienced significant elemental exchange. In contrast, the Purang ophiolite contains a wider range of chromitite compositions and records diverse melt activities, such as the growth of relatively abundant secondary clinopyroxene. The metasomatic melts were enriched in Al and depleted in Si, Na and highly incompatible trace elements(e.g., Nb, Zr). Such melts resemble MORBlike melts proposed in the literature but are assumed to be more hydrous than typical MORB because of presence of hydrous minerals. The parental magmas of the Purang dunites and intermediate chromitites are inferred to be compositionally intermediate between boninitic and MORB-like melts. In addition,the more refractory nature of the Luobusa harzburgites facilitated a high Cr concentration gradient with the interacting melts, making it easier to increase Cr in the melts. Crystallization of clinopyroxene and amphibole in the Purang ophiolite accommodated significant amounts of Cr and water, respectively,and negatively affected Cr concentration and chromite crystallization. The concentration of chromite to form chromitites requires the presence of focused melt channels.

关键词： Chromite Olivine Ophiolite trace element Tibet

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trace element partitioning between amphibole and hydrous silicate glasses at 0.6–2.6 GPa

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Acta Geochimica 2019年第3期38卷 414-429页

作者： Bo Zhang Xianxu Hu Peng Li Qizhe Tang Wenge Zhou Key Laboratory for High Temperature and High Pressure Study of the Earth's Interior Institute of GeochemistryChinese Academy of Sciences University of Chinese Academy of Sciences Guizhou University of Finance and Economics Guizhou Institute of Technology

Partitioning behavior between amphibole and silicate glass of thirty-three minor and trace elements(Sc,Ti, V, Cr, Co, Rb, Sr, P, Y, Zr, Nb, Cs, Ba, K, La, Ce, Pr,Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, Pb,Th, and U) have been determined experimentally. Products of crystallization of hydrous basalt melts from 0.6 GPa/860 °C up to 2.6 GPa/970 °C were obtained in a multianvil apparatus. Major and trace element compositions of amphibole and glass were determined with a combination of electron microprobe and laser ablation inductively coupled plasma mass spectrometry. The main mineral phase is calcic amphibole, and the coexisting glass compositions are tonalite, granodiorite, and granite. The compatibility of rare earth elements increase at 915 °C and then decrease at 970 °C, but the compatibility of most of these elements shows a continued, significant increase with increasing pressure. For high-field strength elements, large ion lithophile elements, actinide compatibility decrease with increasing temperature or pressure, but transition metals show a continued increase in compatibility within the temperature–pressure conditions. From mathematical and graphical fitting, we determined best-fit values for the ideal ionic radius(r_0, 1.01–1.04 ?), the strain-free partitioncoefficient(D_0, 1.18–1.58), and apparent Young's modulus(E, 142–370 GPa) for the M4 site in amphibole according to the lattice strain model. The D_0^(M4) for rare earth elements rises at 915 °C and then drops at 970 °C at 0.6 GPa.However, the D_0^(M4) values are positively proportional to the pressure for rare earth elements in the amphibole-glass pairs at 0.6–2.6 GPa and 970 °C. Furthermore, the derived best-fit values for r_0^(M4) and E^(M4) are almost constant and trend to increase with rising temperature and pressure,respectively. The partition coefficient is distinctly different for different melt compositions. The rare earth elements become more enriched in amphibole if the quenched glass is granodiorite or granite compared to the ton

关键词： Amphibole Silicate glass trace elements Partition coefficients Lattice strain model

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trace maps over M_3(K) associated with the substitutions

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Science China Mathematics 2002年第2期45卷 165-171页

作者：文志雄 Nonlinear Science Center Lab. of Pure Applied Mathematics Wuhan University Wuhan 430072 China

Let K be a field of characteristic zero and M3(K) the ring of matrices 3 x 3 over K. In this paper, we establish first the certain identities of traces of some algebras of M3(K), then we define the trace mapping of 3 × 3 matrices associated with a substitution over a two-letter alphabet on some algebraic variety and study their properties.

关键词： substitution, trace map, PI-algebras.

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trace element characteristics of partial melts produced by melting of metabasalts at high pressures: Constraints on the formation condition of adakitic melts

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Science China Earth Sciences 2006年第9期49卷 915-925页

作者： J. Adam T.H. Green GEMOC National Key Centre Department of Earth and Planetary Sciences Macquarie University Sydney NSW 2109 Australia GEMOC National Key Centre Department of Earth and Planetary Sciences Macquarie University Sydney NSW 2109 Australia

Experiments were conducted on a natural basalt (with 5 wt.% added H2O) at 1.0―2.5 GPa and 900―1100℃. Experimental products include partial melts (quenched glasses) + residual mineral assemblages of amphibolite or eclogite. Electron microprobe and LAM-ICP-MS were used to determine major and trace element compositions of these quenched melts, respectively. Major ele- ment compositions of all the melts are tonalitic- trondhjemitic, similar to adakite. Their trace element characteristics are controlled by coexisting residual minerals. Signatures of adakite such as high Sr/Y, low HREE and negative Nb-Ta anomaly, etc. are present only in the melts coexisting with residual assemblages containing rutile and garnet (rutile-bearing eclogite or rutile-bearing amphibole-eclogite). Garnet leads to HREE depletion in melts, whereas rutile controls Nb and Ta partitioning during the partial melting and causes negative Nb-Ta anomaly in melts. Therefore, in addition to garnet, rutile is also a necessary residual phase during the generation of adakite or TTG magmas to account for the negative Nb-Ta anomaly of the magmas. The depth for the generation of adakite/TTG magmas via melting of metabasalt must be more than about 50 km based on the approximate 1.5 GPa mini- mum-pressure for rutile stability in the partial melting field of hydrous basalt.

关键词： trace element, adakite/TrG magmas, partial melting of metabasalt, negative Nb-Ta anomaly,rutile.

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Assessment of mobile and potential mobile trace elements extractability in calcareous soils using different extracting agents

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Frontiers of Environmental Science & Engineering 2020年第1期14卷 109-125页

作者： Mohsen Jalali Ziba Hurseresht Department of Soil Science College of AgricultureBu_Ali Sina UniversityHamedanIran

Understanding trace elements mobility in soils,extracting agents,and their relationships with soil components,are essential for predicting their movement in soil profile and availability to plants.A laboratory study was conducted to evaluate extractability of cadmium(Cd),cobalt(Co),copper(Cu),nickel(Ni),and zinc(Zn)from calcareous soils utilizing various extracting agents to be specific CaCU,DTPA,EDTA,HNO3,MgCl2,NaN03,NH4NO3,and NH4OAc.Cluster analysis indicated that DTPA and NH4OAc,HN03 and EDTA,and M gCl2 and NH4NO3 extracting agents yielded comparative values,whereas NaN03 and CaCl2 have shown different behavior than other extracting agents for all studied trace elements.The speciationof extracted trace elements in solutions indicated that in the CaCl2,NaN03,NH4NO3,and MgCl2 extracting agents most extracted Cd,Co,Ni,Zn,and part f Cu were as free ions and may be re-adsorbed on soils,leading to lower extractability,whereas,in the caseof HNO3 extracting agent,the likelihoodof re-adsorptionof trace elements may be little.The resultsof speciationof trace elements using NH4OAc DTPA,and EDTA extracting agents showed that Me-(Acetate)3,Me-(Acetate)2(aq),Me(DTPA)3-3-,Me(EDTA)2-.and MeH(EDTA)-complexes dominated in solutions indicating that the extracted trace elements may not be re-adsorbed on soils,leading to higher extractability.The resultsof this study are useful for short and long-term evaluationsof trace elements mobility and further environmental impacts.

关键词： Mobility Calcareous soils Extracting agents trace elements

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Seasonal variations of PM10 -- trace elements, PAHs and Levoglucosan: Rural sugarcane growing area versus coastal urban area in Southeastern Florida, USA. Part II: Elemental concentrations

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Particuology 2019年第5期17卷 99-108页

作者： Orhan Sevim oglu Wolfgang F. Rogge Department of Environmental Engineering Cebze Technical University Cebze Kocaeli 41400 Turkey School of Engineering and Sierra Nevada Research Institute University of California Merced. 5200 North Lake Road Merced CA 95343 USA

The largest sugarcane-growing area in the United States is in South Florida. An estimated 7 million tons of dry sugarcane leafy biomass is removed from the fields before harvest by burning the leaves off the sugarcane stalks. Preharvest sugarcane leaf foliage burning is a major source of airborne particulate matter (PM), polycyclic aromatic hydrocarbons (PAHs), biogenic trace elements such as K, volatile hydrocarbons and other pollutants. In one harvesting period, approximately 22 million tons of C02, a greenhouse gas, is released, 7 million tons from leaf foliage preharvest burning alone and 15 million tons from burning sugarcane bagasse in the sugar mills for power generation. In this study, PMio was collected from Belle Glade, close to the sugarcane-growing area, and from Delray Beach, an urbanized area along the East Coast of Florida. The PM samples were analyzed for trace elements and close to organic compounds. To elucidate the importance of preharvest sugarcane biomass smoke emissions on air quality, 39 trace elements, 18 PAHs, and levoglucosan were selected to apportion ambient PM constituents. Al, Ca and to a great extend also Mg are the major soil-related trace elements and key markers for fugitive soil dust emissions. Similarly, sea salt aerosol blown from the Atlantic Ocean into Florida added appreciably to PMio trace elements concentration, especially Na and Cl. Approximately half of the sea salt aerosol (PMjo -portion) by mass is removed from the atmosphere during the transport of ocean air from Delray Beach to Belle Glade. Ambient acid displacement reactions caused a substantial portion of the Cl (30%) to be liberated from the sea salt aerosol to the atmosphere during transport as gaseous HC1. The PAH concentrations at Belle Glade were high when the biomass combustion markers levoglucosan and I< also showed the highest concentrations. This indicates that during the sugarcane harvest season, when leaf foliage is burned off just before harvest, most of the ambient PAHs associated with PMio are indeed

关键词： Urban versus rural trace elements Sugarcane burning Rare earth elements Sea salt aerosol Potassium Levoglucosan PAHs

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SOME SEMI-BENT FUNCTIONS WITH POLYNOMIAL trace FORM

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Journal of Systems Science & Complexity 2014年第4期27卷 777-784页

作者： CHEN Hao CAO Xiwang Department of Math Nanjing University of Aeronautics and Aeronautics

这份报纸与在有限领域 \ 上灵活的几个参数被奉献给半偏好函数的学习(\mathbb { F }_{ 2 ^ n }\) 。在\上定义的布尔功能( \mathbb { F }_{ 2 ^ n }\)表格$f_{一， b }^{(r)}(x)= Tr_1 ^ n (斧子^{ r ( 2 ^ m - 1 )})+ Tr_1 ^ 4 ( bx ^{... 详细信息

这份报纸与在有限领域 \ 上灵活的几个参数被奉献给半偏好函数的学习(\mathbb { F }_{ 2 ^ n }\) 。在\上定义的布尔功能( \mathbb { F }_{ 2 ^ n }\)表格$f_{一， b }^{(r)}(x)= Tr_1 ^ n (斧子^{ r ( 2 ^ m - 1 )})+ Tr_1 ^ 4 ( bx ^{ \tfrac {{ 2 ^ n - 1 }}{ 5 }})$并且表格$g_{一， b ， c ， d }^{( r ， s )}(x)= Tr_1 ^ n (斧子^{ r ( 2 ^ m - 1 )})+ Tr_1 ^ 4 ( bx ^{ \tfrac {{ 2 ^ n - 1 }}{ 5 }})+ Tr_1 ^ n ( cx ^{( 2 ^ m - 1 ) \tfrac { 1 }{ 2 }+ 1 })+ Tr_1 ^ n ( dx ^{( 2 ^ m - 1 ) s + 1 })$在哪儿 n = 2m ， m 2 (现代派 4 )，一， c $ \mathbb { F }_{ 16 }$，并且 b $ \mathbb { F } _2 $， d $ \mathbb { F } _2 $，在构造半偏好 f 的新班被调查象 Kloosterman 和那样的一些典型的和和 Weil 和被采用决定上述功能是否是半偏好。

关键词： trace FORM Kloosterman和多项式 ABCD 布尔函数有限域弯曲

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Effect of trace Element on Microstructure and Fracture Toughness of Weld Metal

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Acta Metallurgica Sinica(English Letters) 2020年第3期33卷 425-436页

作者： Ke Xu Tao Fang Longfei Zhao Haichao Cui Fenggui Lu Shanghai Key Laboratory of Materials Laser Processing and Modification School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The microstructure and fracture toughness of weld metal under Ti-free and Ti-containing different fluxes were investigated in this study.It was found that the trace element Ti of flux in submerged arc welding produced significant influence on the fracture toughness.The addition of 60 ppm Ti induced the sharp increase in J0.2 value from 232.78 to 364.08 kJ/m^2.Microstructure characterization revealed that a large number of oxide inclusions prompted the nucleation of acicular ferrites and refined grains,which improved the fracture toughness of Ti-containing weld metal greatly.Moreover,the crack propagation path was more tortuous and bifurcated due to the small amount of carbide precipitations along grain boundaries and blocky martensite-austenite islands for Ti-containing weld metal.Meanwhile,the large-angle grain boundaries caused crack deflection and increased the resistance of crack propagation compared to Ti-free weld metal.

关键词： Fracture toughness Microstructure Weld metal trace element Crack propagation

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Rare-earth and trace elements and hydrogen and oxygen isotopic compositions of Cretaceous kaolinitic sediments from the Lower Benue Trough, Nigeria: provenance and paleoclimatic significance

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Acta Geochimica 2019年第3期38卷 350-363页

作者： Anthony T.Bolarinwa Sunday O.Idakwo David L.Bish Department of Geology University of Ibadan Department of Earth Sciences Kogi State University Department of Geological Sciences Indiana University

This study evaluated the Cretaceous(Campanian–Maastrichtian) kaolinitic sediments of the Ajali/Mamu and Enugu/Nkporo Formations from the Lower Benue Trough of Nigeria. A combined method of inductively coupled plasma–mass spectrometry and isotope ratio mass spectrometry was used to investigate trace and rareearth element geochemistry and hydrogen and oxygen isotopic compositions. These data were then used to infer the sediments' provenance and paleoclimatic conditions during their deposition. The sediments contained low concentrations of most trace elements, with the exceptions of Zr(651–1352 ppm), Ba(56–157 ppm), V(38–90 ppm),and Sr(15.1–59.6 ppm). Average values of Co and Ni were1.5 and 0.7 ppm, respectively. trace and rare earth element values were lower than corresponding values for upper continental crust and Post-Archean Australian Shale, with the exception of Zr. The samples showed only slight light rare-earth enrichment and nearly flat heavy rare-earth depletion patterns, with negative Eu and Tm anomalies,typical of felsic sources. Geochemical parameters such as La/Sc, Th/Sc, and Th/Co ratios support that the kaolinitic sediments were derived from a felsic rock source, likely deposited in an oxic environment.^(18 )O values ranged from+ 15.4 to + 21.2% for the investigated samples, consistent with a residual material derived from chemicalweathering of felsic rock and redeposited in a sedimentary basin(typical values of + 19 to + 21.2%). While in the basin, the sediments experienced extended interactions with meteoric water enriched in d D and d16 O. However,the variation in d D and d16 O values for the investigated samples is attributed to the high temperature of formation(54–91 °C). The d D and d^(18 )O values suggest that the sediments, although obtained from different localities within the Lower Benue Trough, formed under similar hot,tropical climatic conditions.

关键词： Rare-earth and trace elements Oxygen/ hydrogen isotopic composition Kaolinitic sediments Lower Benue Trough Nigeria

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Mechanism Study of Transport and Distributions of trace Metals in the Bohai Bay, China

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China Ocean Engineering 2019年第1期33卷 73-85页

作者： LI Yuan-yi FENG Huan YUAN De-kui GUO Lei MU Di Department of Mechanics School of Mechanical EngineeringTianjin University State Key Laboratory of Hydroscience and Engineering Department of Hydraulic EngineeringTsinghua University Department of Earth and Environmental Studies Montclair State University Guangdong Research Institute of Water Resources and Hydropower School of Marine Science and Engineering Hebei University of Technology

This study shows that there are two regions with high trace metal concentrations in the Bohai Bay, China. The numerical hydrodynamic model coupled with geochemical analysis was applied to understand the mass transport and sedimentation in the bay. The modeling results show that the two regions are located within the residual current vortexes. Results from the particle-tracking model indicate that the trace metals released from the land sources enter the regions and take a relatively long residence time in the vortexes. The sediment radionuclide data indicates that the two regions experienced continuous and high sedimentation, and trace metals are prone to deposit in the regions. The correlations among trace metals, residual currents and radionuclides data suggest that the tides are the governing factor controlling the distributions of the trace metals in the bay. The consistence among these results also supports the reliabilities of the numerical simulation results of water and trace metal transport in this study.

关键词： trace metal sediments sedimentation radionuclides numerical model residual current

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