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A Study of the Rhenium-Osmium Geochronometry of Molybdenites

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Acta Geologica Sinica(English Edition) 1995年第2期69卷 171-181页

作者： Du Andao, He Hongliao, Yin Ningwan, Zou Xiaoqiu,Sun Yali, Sun Dezhong, Chen Shaozhen and Qu Wenjun Institute of Rock and Mineral Analysis, chinese academy of {2. Sciences, {3. Fei Zhenbi Institute of Rock and Mineral Analysis Chinese Academy of Geological Sciences Beijing

This study deals with the first application of the isotope dilution - inductively coupled plasma mass spectrometry in the rhenium-osmium geochronometry in china. The chemical separation procedure included decomposition of samples by means of alkali fusion, extraction of rhenium by acetone and extraction of osmium by distillation. The recovery of both elements in the entire process was more than 90% . The blanks of analyses were 0.07 ng for rhenium and 0.01 ng for 187Os. The mineralization ages of molybdenites from four molybdenum deposits in china were determined by using this method, with a precision (2.)of about ±3. . These results agree satisfactorily with their {3. backgrounds. The Re-Os method can directly determine ages of metal deposits and reflect the true ages more reliably than other dating methods that only determine the ages of country rocks from which mineralization ages are inferred. As many hydrothermal sulphide deposits usually contain molybdenites, this method has bright prospects of wide application.

关键词： rhenium-osmium method molybdenite ore-forming age determination isotope dilution inductively coupled plasma source mass spectrometry

LATE MESOZOIC SUBDUCTION PROCESS BENEATH SOUTHEASTERN china AS REVEALEDBY THE SPATIAL- TEMPORAL PATTERN OFMAGMATISM

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Geotectonica et Metallogenia 2001年第1期25卷 68-70页

作者： WANG Yang 1, DENG Jin fu 1, WANG Ji yang 2.and XIONG Liang ping 2.(1. Division of Petrology, china University of Geosciences, beijing 10008{2. china 2. Institute of Geology and Geophysics, {{2. academy of Sciences, beijing 10002., china) Division of Petrology China University of GeosciencesBeijing 100083China Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029China

Southeastern china covers an extensive area from the lowerreaches of the Yangtze Riverto the southeast coastof china *** of its main {2. features isthe extensiveJura- Cretaceous (Yanshanian) magmatism and related metallogenesis. Recently,some re-searchers advocate the mantle plume model as an explanation,but all of their evidences artoo ***,the seaward convex shape of the SE china coastline,which isdominantly composed of Jura- Cretaceous batholiths and volcanic strata,implies thatit was aconvergent margin between SE china continent and the palaeo- Pacific plate during the lateMesozoic *** betterunderstanding on the relation among magmatism,tectonic regimeand dynamics,the spatial- temporal pattern of late Mesozoic (180 - 90 Ma) igneous rocks isconstructed by nearly2.0 0 isotope age valuesfrom *** these age values,mostwere obtained by Rb- Sr isochron method,and others from zircon U- Pb or40　 Ar- 3

关键词： LATE MESOZOIC SUBDUCTION PROCESS BENEATH SOUTHEASTERN china AS REVEALEDBY THE SPATIAL TEMPORAL PATTERN OFMAGMATISM AS

Geochronology and geochemistry of the Hegenshan ophiolitic complex:Implications for late-stage tectonic evolution of the Inner Mongolia-Daxinganling Orogenic Belt,china

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Geochronology and geochemistry of the Hegenshan ophiolitic c...

中国科学院地质与地球物理研究所2.08学术年会

作者： Laicheng Miao~(a,*),Weiming Fan~a,Dunyi Liu~b,Fuqin Zhang~a,Yuruo Shi~b,Feng Guo~c a Institute of Geology and Geophysics,chinese academy of Sciences,{2. 10002.,{3. b {2. shrimp Center,Institute of Geology,chinese academy of geological Sciences,{2. 10003.,{3. c Guangzhou Institute of Geochemistry,chinese academy of Sciences,Guangzhou 510640,{3.

The Hegenshan ophiolite in the Inner Mongolian-Daxinganling Orogenic Belt(IMDOB),northern china,consists of several discontinuous blocks composed dominantly of serpentinized ultramafic rocks with subordinate cumulate gabbros,mafic lavas and dikes, intruded by younger granodiorite *** ultramafic rocks are highly depleted,serpentinized harzburgites with minor dunite,characterized by relative enrichment in large ion lithophile elements(LILE,e.g.,Ba and Rb) and light rare earth elements(LREE).They are interpreted to be oceanic mantle that has undergone extensive melt extraction and variable degrees of *** cumulate rocks consist mainly of gabbro and troctolite with LREE-depleted chondrite-normalized REE patterns showing significant positive Eu *** are enriched in LILE,depleted in Nb,and have high positiveε(t)(+8 to +11),suggesting derivation from a subduction-modified N-MORB-like *** gabbros and mafic dikes have essentially the same age(2.5±15 and 2.8±9 Ma,respectively). The mafic dikes have flat to LREE-depleted,chondrite-normalized REE patterns,are depleted in Nb,enriched in LILE and have NMORB-type Nd isotopic signatures(ε(t)=+8.1 to +10).The mafic lavas,erupted at 2.3.1 Ma,can be divided into two groups;one composed of strongly deformed metabasalts similar in chemical and Nd-Sr isotopic compositions to the mafic dikes,and the other composed of undeformed and unmetamorphosed basalts with oceanic island basalt(OIB)-like trace element signatures and Nd isotopic *** granodiorite dikes,which were intruded at 2.4±4 Ma,have LREE-enriched,chondrite-normalized REE patterns with no Eu *** abnormally highε(t) values(+6.3.to +6.8) and low I(0.70412.to 0.70450) suggest formation from melts derived from thickened oceanic crust during or shortly after closure of the Paleo-Asian *** structure,lithology and geochemistry of the Hegenshan ophiolite suggest that it is a Cordilleran-type body formed in a supra-subduction

关键词： Ophiolite Geochronology Geochemistry Late Paleozoic Inner mongolia

shrimp zircon U-Pb dating in Jingshan "migmatitic granite", Bengbu and its geological significance

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中国科学：地球科学英文版 2005年第2期48卷 185-191页

作者： XU Wenliang, WANG Qinghai, YANG Debin, LIU Xiaochun & GUO Jinghui College of Earth Sciences, Jilin University, Changchun 13.061, china Institute of Geomechanics, {2. academy of {3. Sciences, beijing 100081, china Institute of Geology & Geophysics, {2. academy of Sciences, beijing 10002., china 1. College of Earth Sciences Jilin University 130061 Changchun China 2. Institute of Geomechanics Chinese Academy of Geological Sciences 100081 Beijing China 3. Institute of Geology & Geophysics Chinese Academy of Sciences 100029 Beijing China

The petrographic characteristics of Jingshan "migmatitic granite" and the occurrence of the magmatic zircons indicate that the granite was formed by normal crystallization of felsic melts. All zircons in the granite have inherited cores and fine-scale oscillatory zoning rims of magmatic origin. It is realized that the granite was formed at 160.2.1.3.Ma through dating magmatic zircons. The generation of the granitic magma could be related to the lithospheric mantle and/or lower crust delamination after the ultrahigh pressure metamorphism (UHPM) in Triassic. Most inherited zircons yield the ages of 2.7.1±6.6 Ma, which is consistent with the peak UHPM in the Dabie-Sulu orogenic belt. Some of the inherited zircons (43.-72. Ma) constitute a discordia line with the upper intercept age of 850+85/-68 Ma and a lower intercept age of 2.1+100/-140 Ma. These ages imply that the granite could be derived from the partial melting of the crustal materials of the South{2. Block that was intensively superimposed by the UHPM. The UHPM could be the reason for the major Pb loss at ±2.0 Ma.

关键词： zircon, U-Pb dating, migmatitic granite, geological significance, Bengbu.

The Big Bending of Yanshan Orogenic Belt, its Origin and Environmental Effect

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The Big Bending of Yanshan Orogenic Belt, its Origin and Env...

中生代以来中国大陆板块作用过程学术研讨会

作者： WANG Yang JI Guangyi Key laboratory of isotope Geochronology and Geochemistry, Guangzhou Institute of Geochemistry, {2. {3. of Sciences, Guangzhou, 510640 School of Earth Science and Mineral Resources, china University of Geosciences, beijing, 100083.geological Institute of beijing Municipality, beijing, 100011

＜正＞AlongthestrikingofMesozoicstructureanditsdominatedtopography,YanshanorogenicbeltofNorthchinaexhibitsabi***110-150°***-westdirectioninthenorthernHebeiprovince,butturnstonorth-northeastdirectioninWestLiaoningande...

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AGE OF THE ALTYN TAGH STRIKE—SLIP FAULT

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地学前缘 2000年第S1期7卷 208-209页

作者： Li Haibing 1, Yang Jingsui 1, Xu Zhiqin 1, Wu Cailai 1, Zhang Jianxin 1, Wan Yushen 1, Shi Rendeng 1, Juhn G. Liou 2.Trevor R. Ireland 2.(1 Institute of Geology, chinese academy of {2. Sciences,{3., china 2.Department of

A 100～500m\|wide mylonite zone in the Altun Group of Lower Proterozoic age was discovered along the Altyn Tagh strike\|slip fault. The zone is mainly composed of amphibolitic and granitic mylonites. The planar joints of the rocks strike in NE70 and dip steeply (nearly vertical), coincident with the striking of Altyn Tagh fault zone, and their stretched lineations are nearly horizontal. Shear strains are well developed and show sinistral sheared. The amphibolitic and granitic mylonites are most probably the products of deep\|seated melting caused by sinistral strike\|slip shearing as suggested by the evidence below: (1) The migmatization is intensely developed and spatially controlled by the shear zone, and the rock has a set of NNE perspective foliation which is in accord with the direction of the Altyn Tagh strike\|slip fault zone. (2. The recrystallized hornblende aggregate is distributed in band with obvious nebulous texture, indicating the characteristics of anatexis, and the hornblendes are oriented and form the nearly horizontal stretching lineation; some hornblendes have titanite inclusions, and magmatic long\|columnar zircons are in directional arrangement.(3. The banded felsic material is developed, and the plagioclase is characteristic of high\|temperature plastic deformation and shows sinistral shear stain. (4) In mylonites, all the axis C fabric of quartz shows the feature of sinistral shearing and the majority is generally middle to low temperature fabric, but there also exists high temperature fabric, which suggests that high temperature shearing occur in the early stage of strike\|slip deformation and it is characterized by middle to low temperature shearing at the beginning of anatexis or in the late stage of the deformation. (5) On the XZ plane of mylonite and mylonitized rocks, there exists the consistent sinistral shear stain, which suggests the products of the same strike\|slip *** were separated from three samples of mylonitized gra

关键词： Altyn Tagh fault Tibet plateau shrimp dating mylonite

Tracing the protolith, UHP metamorphism and exhumation ages of orthogneiss from the SW Sulu terrane (eastern china): shrimp U-Pb dating of mineral inclusion-bearing zircons

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Tracing the protolith, UHP metamorphism and exhumation ages ...

2.04年全国岩石学与地球动力学研讨会

作者： Fulai Liu~*, Zhiqin Xu, Huaimin Xue Institute of Geology, chinese academy of {2. Sciences,{3., china

Orthogneisses are the major country-rocks hosting eclogites in the Sulu UHP terrane, eastem china. All of the analyzed orthogneiss cores from the main drilling hole of the chinese Continental Scientific Drilling Project (CCSD-MH) have similar major and trace element compositions and a granite protolith. These rocks have relatively high LREE/HREE ratios, strong negative Eu anomalies (Eu/Eu=0.2.-0.{2.) and negative Ba anomalies (Ba/Ba=0.2.-0.64). Coesite and coesite-bearing UHP mineral assemblages are common inclusions in zircons separated from orthogneiss, paragneiss, amphibolite, and (retrograded) eclogite of the CCSD-MH. This suggests that the eclogite, together with its country-rocks, experienced in situ ultrahigh-pressure (UHP) metamorphism. Laser Raman spectroscopy and cathodoluminescence (CL) images show that zircons from the orthogneisses are zoned and that they have distinct mineral inclusions in the different zones. Most zircons retain early magmatic cores with abundant low-pressure mineral inclusions, which are mantled with metamorphic zircon containing inclusions of coesite and other UHP minerals. The outermost rims on these grains contain low-pressure mineral inclusions, such as quartz and albite. shrimp U-Pb dating of the zoned zircons gives three discrete and meaningful groups of ages: Proterozoic ages for the protolith, 2.7±2.Ma for the coesite-bearing mantles, and 2.9±{2.Ma for the amphibolite-facies retrograde rims. The widespread occurrence of UHP mineral inclusions in zircons from the Sulu metamorphic belt dated at about 2.7 Ma suggests that voluminous continental crust experienced late Triassic subduction to depths of at least 12. km and perhaps more than 2.0 km. 18 Ma later the terrane was rapidly exhumed to mid-crustal levels, and the UHP rocks were overprinted by amphibolite-facies metamorphism. The exhumation rate deduced from the zircon age data and previously obtained metamorphic P-Tdata is estimated to be 5.6-11.0 km/Ma. Such rapid exhumation

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Termination of the Emeishan flood volcanism and relationships to the end-Guadalupian mass extinction: shrimp dating of detrital zircons from the post-volcanic Xuanwei Formation, SW china

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Termination of the Emeishan flood volcanism and relationship...

International Conference on Continental Volcanism

作者： Bin He Yi-Gang Xu Xiao-Long Huang Zhen-Yu Luo Yu-Ruo Shi Qi-Jun Yang Song-Yue Yu Key laboratory of isotope Geochronology and Geochemistry Guangzhou Institute of Geochemistry {2. {3. of Science Guangzhou 510640 china Institute of Geology {2. {3. of geological Sciences beijing 10003. china

＜正＞Clastic rocks of the lowermost Xuanwei Formation （Group 1）, which directly overlie the Emeishan large igneous province （LIP）, have a geochemical affinity to the Emeishan felsic volcanic rocks, whereas the overlying sediments （Group 2. are compositionally more akin to mafic components of the Emeishan traps. This is the reverse of volcanic sequence of the Emeishan LIP where the felsic extrusives sit above predominantly mafic rocks. It is likely that

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Genesis and Dynamic Condition of Hexi Gold Deposit in Northwest Jiaodong Area

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Genesis and Dynamic Condition of Hexi Gold Deposit in Northw...

中国科学院地质与地球物理研究所2.02.术年会

作者： Xu Guizhong~a,Ying Hanlong~a,Zhourui~a,She Hongquan~b,Yanzhen~a, Wang Yifen~a,Li Bing~c a.Institute of Geology and Geophisis,chinese academy of Sciences,{2. 10002.,{3. b.Institute of Mineral Resources,chinese academy of geological Sciences,{2. 10003.,{3. c.No.3.Institute of geological Exploration,Yantai 2.4000,Shandong,{3.

The Hexi gold deposit,located in the Xincheng-Jiaojia gold field of Northwest Jiaodong penensula,is a typical gold deposit of *** orebodies were hosted in early Cretaceous Linglong altered biotite granite and controlled by NE-trending *** initial 87Sr/86Sr ratios demonstrate that both Linglong biotite granite and guojialing granodiorite are derived from deep melted crustal *** and isotopic chronological data indicate that gold mineralization occurred in early *** sulfur isotope composition of ore minerals in Hexi gold deposit implies that solfur materials for mineralization are mainly derived from the deep remelted granitic *** isotope is steady and varies in a very small range,suggesting that the source of hydrothermal fluids is *** on characteristics of stable isotopic data,we candraw the conclusion that matallization of the hexi gold deposit is probably related to the fluid activity of Guojialing *** metallogenic temprature is mainly moderate and the pressure is about(12.0-1400)×10

关键词： gold metallization genesis of gold deposit geodynamic condition tectonic-magmatic activety Xincheng-Jiaojia gold field Hexi gold deposit