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Mantle xenoliths from Late Cretaceous basalt in eastern Shandong Province: New constraint on the timing of lithospheric thinning in eastern china

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Chinese science Bulletin 2003年第19期48卷 2139-2144页

作者： YAN Jun, CHEN Jiangfeng, XIE zhi & ZHOU Taixi School of earth and space sciences, university of science and technology of china, hefei 2.002., china Yarmouk university Irbid - Jordan School of earth and space sciences University of Science and Technology of China Hefei 230026 China

The age of the alkali basalt from Daxizhuang in Jiaozhou, eastern Shandong, was determined to be 73.5±0.3 Ma by 40Ar-39Ar technique. The basalt gave high eNd(t) values of +7.5 and +7.6, suggesting that the primitive magma was derived from depleted asthenospheric mantle with a formation depth of about 65—95 km. Spinel-lherzolite xenoliths have been discovered in the basalt. The Fo values of olivine from the xenoliths range from 88 to 89. The estimated equilibrium P-T conditions of spinel-lherzolite xenoliths are about 2.0 GPa and 1010—1140℃, suggesting an equilibrium depth of about 65 km. Geochemical characteristics of the Late Mesozoic (125—115 Ma) mantle-derived rocks in Shandong Province suggest an enriched lithospheric mantle along the southern margin of the North china block. However, geochemical characteristics of the Late Cretaceous basalts in Daxizhuang and the equilibrium P-T condition estimated from the xenoliths suggest that the lithosphere at 73 Ma ago was as thick as that of the Cenozoic in the region. Additionally, the xenoliths are rich in basaltic-component, suggesting a derivation from a newly-formed lithosphere. Therefor, lithospheric thinning took place at a time interval between about 120 and 73 Ma along the southern margin of the North china block.

关键词：覆盖捕虏岩白垩纪玄武岩山东东部地区岩石圈稀释化 ^40Ar-^39Ar技术

Petrogenesis and Geochemistry of Neogene Basalts in Eastern Anhui

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Acta Geologica Sinica(English Edition) 1995年第4期69卷 406-419页

作者： zhi Xiachen, Chen Daogong and Yang JinDepartment of earth and space sciences, university of science andtechnology of china, hefei, Anhui Jiang M inxi Department of earth and space sciences University of Science and Technology of China Hefei Anhui

The basalt terrain of the Neogene Huangguoshan and. Guiwu Formations of eastern Anhui on the east side of the Tancheng-Lujiang fault belt is one of a few Cenozoic basalt terrains in eastern china for which detailed geochemical study has not been conducted. This paper reports the abundances of major elements and more than 20 trace elements (including REE) of 22 samples and the Nd, Sr and Pb isotopic compositions of 11 samples from the eastern Anhui basalt terrain, thus more or less systematically revealing the geochemical characteristics of this continental basalt suite. The paper discusses the origin of the basalt suite and the character and process of its mantle source. The basalt suite was derived from a heterogeneous continental lithospheric mantle with end members characteristic of the EMI-type oceanic basalt mantle, which was affected by mantle metasomatism (or enrichment of trace elements) and was characterized by a multi-stage evolution under open conditions.

关键词： continental alkali basalt EM I-type mantle end-member eastern Anhui

Re-Os isotopic composition of the Dongling ⅢCD iron meteorite

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Chinese science Bulletin 2001年第6期46卷 518-520页

作者： SUN Weidong, DU Andao, YANG Gang, XIE zhi & CHEN JiangfengDeparlmenl of earth and space sciences, Laboratory tor Chemical Geodynamics. university of science and technology of china, hefei 2.002.. china:Institute of Rock and Mineral Analysis, Chinese Academy of Geological sciences. Beijing 100037, china Department of earth and space sciences Laboratory for Chemical Geodynamics University of Science and Technology of China Hefei China Institute of Rock and Mineral Analysis Chinese Academy of Geological Sciences Beijing China

Re, Os concentrations and Os isotopic compositions of the Dongling ⅢCD iron meteorite were determined by N-TIMS technique. The result was compared with that of the other irons and chondrites. The Re and Os concentrations of the Dongling iron meteorite were plotted on the trends of the group ⅢA and ⅣA irons. The Pt-Os relation of the Dongling iron meteorite is similar to that of the group ⅡA irons. That suggests a higher fractionation for the Dongling iron meteorite.

关键词： Dongling iron meteorite Re-Os isotopes N-TIMS.

Pb isotope geochemistry of lead, zinc, gold and silver deposit clustered region, Liaodong rift zone,northeastern china

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science china earth sciences 2005年第4期48卷 467-476页

作者： CHEN Jiangfeng1, YU Gang1, XUE Chunji2, QIAN Hui1, HE Jianfeng1, XING zhi1 & ZHANG Xun1 1. School of earth and space sciences, university of science and technology of china, hefei 2.002., china 2. Department of Geology, Chang’an university, Xi’an 710054, china 1. School of earth and space sciences University of Science and Technology of China 230026 Hefei China 2. Department of Geology Chang’an University 710054 Xi’an China

Pb isotopic analyses were reported for sulfide and hydrothermal carbonate minerals and marble of the Xiquegou lead-zinc, the Zhenzigou zinc-lead and the Gaojiapuzi silver deposits from the Qingchengzi ore field and the Beiwagou zinc-lead deposit in the west, Proterozoic Liaodong rift zone. Pb isotopic ratios of the marble from the Qingchengzi ore field range from 18.24 to 30.63 for 206 Pb/204Pb, 15.59 to 17.05 for207Pb/204Pb and 37.43 to 38.63 for 208Pb/204Pb. The marble gives a Pb-Pb isochron age of 1822±92 Ma, which is interpreted as the age of the metamorphism of the marble. Ore Pb, including Pb of sulfide and hydrothermal car- bonate minerals, from the Qingchengzi ore field shows limited variation with 206 Pb/204Pb=17.66- 17.96, 207 Pb/204Pb=15.60-15.74 and 208Pb/204Pb=37.94-38.60. In contrast, ore Pb from the Beiwagou deposit gives different Pb isotopic ratios with 206Pb/204Pb=15.68-15.81, 207 Pb/204Pb= 15.34-15.45 and 208Pb/204Pb=35.30-35.68. Pb of all deposits from the Liaodong rift zone is derived from the upper crust. Ore Pb of the Qingchengzi deposits is derived from a young upper crust. The model Th/U ratios of 4.40 to 4.74 for ore Pb are significantly different from that of 1.7 to 4.4 given by the marble of the Qingchengzi ore field, suggesting that marble is not the source of the ore Pb. Ore Pb of the Beiwagou deposit is extracted from its source and the deposit is formed at the Paleoproterozoic era. Different Pb isotopic ratios of the Qingchengzi ore field and the Beiwagou deposit are due to different ages of the deposits and suggest that the two types of deposits are derived from different sources and are possibly formed by different ore-forming processes.

关键词： Pb isotopes, source(s) of the ore-forming materials, origin of ore deposits, Liaodong rift zone.

Oxidation Experiment of Natural Megacrystal Ch'nopyroxene: Implications for Assignment of Mossbauer Spectra

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Acta Geologica Sinica(English Edition) 2001年第1期 51-58页

作者： zhi Xiachen, CHEN PengDepartment of earth and space sciences, university of science and technology of china Laboratory of Chemical Geodynamics, USTC Advanced Research Center for earth science and Astronomy in USTC, Third World Academy of science, hefei 2.002. LIN Chengzhong, CHEN Shuqing, ZHANG GuilanInstitute of Mineral Resources, Chinese Academy of Geology sciences, Beijing 100037LI Yuzhi and LIN Lei Open Laboratory of Structure Analysis, USTC, hefei 2.002.

The Mossbauer spectra of natural megacrystal clinopyroxene are usually fitted by 4 sets of symmetric doublets, A-A', B-B', C-C' and D-D', respectively, in terms of increasing Qs value in literature. But the assignments of those doublets are quite different, except the D-D' doublet assigned to Fe3+ at the lattice site Ml in previous papers. Particularly, the assignment and interpretation of the C-C' doublet are *** oxidation experiments of natural megacrystal clinopyroxene collected from the Hannuoba basalt, North china, were performed under controlled conditions of temperature at 1000℃ and oxygen fugacity of FMQ buffer in 1, 2, 3 and 5 days respectively. The oxidized samples were then measured by X-ray diffraction spectrometry and Mossbauer spectrometry. The oxidation of clinopyroxene is characterized by Fe2+→ Fe3+ at Ml under the subsolidus conditions, which is consistent with the increase of the area of the D-D' doublet when the heating time increases. Accordingly, the area of the A-A' and B

关键词： megacrystal clinopyroxene Mossbauer spectrum oxidation experiment anomalous doublet

GEOCHEMISTRY OF MAFIC-ULTRAMAFIC ROCKS FROM NORTHERN DABIE COMPLEXAND ITS IMPLICATION

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Scientia Geologica Sinica 1998年第4期 513-519页

作者： Chen Daogong Wu Yuanbao Cheng Hao Xia Qunke and zhi Xiachen(Department of earth and space sciences, university of science and technology of china, hefei, 2.002.)

Twelve samples ofJiaoziyan gabbroic rocks and four Zhujiapu pyroxenites from Northern Dabie complexwere analysed for major, REE and trace elements. Major elements of gabbroic rocks show fractionalcrystallization during its magma evolution. The LREE-enriched and HFSE- depleted characters of gabbrosand pyroxenites, together with their Nd and Sr isotopes indicate the involvement of terrestrial material inmantle source, probably related to its subduction. The chemical and isotopic signals for gabbros andpyroxenites aren't correlated to oceanic ophiolitic melange, but reflect their affinity of transition fromactive continental margin to island arc magmatism.

关键词： ITS Rb Ba GEOCHEMISTRY OF MAFIC-ULTRAMAFIC ROCKS FROM NORTHERN DABIE COMPLEXAND ITS IMPLICATION Zr Arc

A STORABE PROCESS OF THE MAGNETICENERGY RESULTS FROM THE UNSTEADY PLASMA FLOW FIELD IN THE DISTURBANCE REGIONS OF COMETARY TAIL AND ATMOSPHERE

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紫金山天文台台刊 1998年第2期 97-100页

作者： Li Zhong-yuan Shi zhi-dong Chen Yao(Department of earth and space science, university of Sciece and technology of china, Anhui, hefei, 2.002. P.R.C (Advanced Centre for Sciece and Astronomy, Third World Academy of sciences.)

In this paper we discuss coupling processes between a magnetic field and an unsteady plasma motion, and analyze the features of energy storage and conversions in the cometary disturbance regions.

关键词： Comet Disturbance in comet Energy conversions and evolution space plasma pro-cess

Effect of isotope diffusion in solids on isochron ages under -pper mantle conditions

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Chinese science Bulletin 1997年第6期42卷 492-495页

作者： zhi Xiachen, CHEN Zengbing, ZHANG Xuehua and ZHENG Yongfei1. Department of earth and space sciences, university of science and technology of china, hefei 2.002., china: 2 Advanced Centre for earth science and Astronomy, USTC, Third World Academy of science, hefei 2.002., china

DODSON presented the concepts of closure temperature (T_c), transitional temperature range (T_h—T_l) and T_lT_l, the effect of matter transfer by diffusion on radiometric dating is not negligible in the transitional ... 详细信息

DODSON presented the concepts of closure temperature (T_c), transitional temperature range (T_h—T_l) and T_learth crust, geochronometers work usually under cooling conditions of Tearth mantle at T>T_l, the effect of matter transfer by diffusion on radiometric dating is not negligible in the transitional temperature range

关键词： diffusion in solids temperature transitional range isochron age lithospheric mantle.

AGES, Nd AND Sr ISOTOPIC COMPOSITIONS OF THE JIAOZIYAN GABBROIC INTRUSION FROM THE NORTHERN DABIE TERRAIN

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Scientia Geologica Sinica 1998年第1期 30-36页

作者： Chen Daogong and Wu Yuanbao Department of earth and space sciences, university of science and technology of china, hefei, 2.002.Wang Yinxi and zhi Xiachen Center of Modern Analyses, Nanjing university, Nanjing 210093Xia Qunke Department of Ear

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关键词： Nd AND ISOTOPIC Sr AGES