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

Geochronology and geochemistry of the Hegenshan ophiolitic c...

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中国科学院地质与地球物理研究所2008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,{3. 100029,china b {3. shrimp Center,Institute of Geology,chinese academy of geological sciences,{3. 100037,china c Guangzhou Institute of Geochemistry,chinese academy of sciences,Guangzhou 510640,china

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(295±15 and 298±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 293.1 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 244±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

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A New Age Constraint on the Onset of the Neoproterozoic Glaciations in the Yangtze Platform,South china

A New Age Constraint on the Onset of the Neoproterozoic Glac...

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中国科学院地质与地球物理研究所2008学术年会

作者： Qi-Rui Zhang,Xian-Hua Li,~1 Lian-Jun Feng,Jing Huang,and Biao Song~2 State Key laboratory of Lithospheric Evolution,Institute of Geology and Geophysics, chinese academy of {3.,P.O.Box 9825,beijing 100029,china 1 Previous address:Key laboratory of isotope Geochronology and Geochemistry,Guangzhou Institute of Geochemistry,chinese academy of {3.,Guangzhou 510640,china. 2 beijing {13. Center,Institute of Geology,chinese academy of geological {3.,beijing 100037,china.

A sample from the top of the Banxi Group(early Neoproterozoic) in Hunan Province(South china) was dated by the shrimp zircon U-Pb *** resulting age of 725±10 Ma probably solves the debate between the synglacial and the pregkcial correlation of the Liantuo Formation and indicates that the Liantuo Formation most likely correlates with the pregkcial Banxi *** the Banxi(Danzhou) Group is upwardly transitional to the glacial Jiangkou Group,the age becomes a new maximum age constraint on the onset of the Jiangkou glaciation,which therefore most likely correlates with the Sturtian glaciation.

关键词： Online enhancement:appendix table

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Tectonic setting of the Helong Block:Implications for the northern boundary of the eastern North china Craton

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Science china Earth sciences 2005年第10期48卷 1599-1612页

作者： ZHANG Yanbin1, WU Fuyuan1, ZHAI Mingguo1 & LU Xiaoping1,2 1. Institute of Geology and Geophysics, chinese academy of sciences, P.O. Box 9825, {3. 100029, china 2. Regional geological and Mineral Resources Survey of Jilin Province, Changchun 13.062, china chinese academy of sciences Regional geological and Mineral Resources Survey of Jilin Province

LA-ICP-MS zircon U-Pb dating indicates that the Bailiping granitic pluton was em-placed during Late Paleozoic to Early Cretaceous (285―116 Ma) by four distinct magmatic epi-sodes, arguing against the previous thought that the Bailiping granites were emplaced during Archean, Proterozoic or Early Paleozoic. It is suggested that the so-called Archean Jincheng-dong granite-greenstone belt, mainly composed of Bailiping granites, should be broken down. Sr-Nd isotopic compositions of the Bailiping granites are similar to those of the Phanerozoic granites in the Xing’an-Mongolian orogenic belt, suggesting that their parental magmas were mainly derived from a juvenile crust with some contamination of ancient crustal materials during magma rising and/or emplacement. Therefore, the basement of the Helong Block is similar to that in the northern Xing’an-Mongolian Orogenic Belt, but different from that of the North china Craton. It is proposed that the Archean Jinchengdong complex in this area is probably an exotic slice from the North china Craton, which indicates that the Fu’erhe-Gudonghe Fault, located in northern part of the Helong area, is not the boundary between the North china Craton and the Xing’an-Mongolian Orogenic Belt. The possible boundary should be located further southward more than 50 km and near the Baitoushan volcano.

关键词： LA-ICPMS ziron U-Pb dating, Bailiping complex, Helong Block, North china Craton, Sr-Nd isotope.

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Zircon shrimp U-Pb ages of the“Xinghuadukou Group”in Hanjiayuanzi and Xinlin areas and the“Zhalantun Group”in Inner Mongolia,Da Hinggan Mountains

Zircon SHRIMP U-Pb ages of the“Xinghuadukou Group”in Hanji...

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中国科学院地质与地球物理研究所2007学术年会

作者： MIAO LaiCheng~(1+),LIU DunYi~2,ZHANG FuQin~1,FAN WeiMing~1,SHI YuRuo~2 & XIE HangQiang~1 1 Institute of Geology and Geophysics,chinese academy of sciences,{3. 100029,china 2 {3. shrimp Center,Institute of Geology,chinese academy of geological sciences,{3. 100037,china

A report is presented of shrimp zircon U-Pb dating data of meta-igneous and meta-sedimentary rocks of the Xinghuadukou Group(Xinlin-Hanjiayuanzi area,Heilongjiang Province) and meta-volcanic rocks of the Zhalantun Group(Zhalantun district,Inner Mongolia).The shrimp analyses show that the meta-igneous rocks from the Xinghuadukou Group formed at 506±10 -547±46 Ma,belonging to Early-Middle Precambrian,whereas the meta-sedimentary rocks yielded detrital zircons,with ages of 1.0 - 1.2,1.6 - 1.8 and 2.5 - 2.6 Ga,indicative of deposition age at least3.*** data suggest that both the Xinghuadukou and Zhalantun Groups formed during Cambrian and/or Neoproterozoic time,rather than Paleoproterozoic time as previously *** Precambrian inherited zircons in the meta-igneous rocks and numerous Precambrian detrital zircons in the meta-sedimentary rocks imply that these rocks were formed proximal to older *** is inferred that the Xinghuadukou and Zhalantun Groups represent Cambrian and/or Neoproterozoic volcano -sedimentary sequences formed in an active continental margin setting.

关键词： zircon shrimp metamorphic rock Xinghuadukou Group Zhalantun Group Da Hinggan Mountains

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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 geological sciences, beijing 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 (2σ)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

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

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

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中国科学院地质与地球物理研究所2002学术年会

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,{3. 100029,china b.Institute of Mineral Resources,chinese academy of geological sciences,{3. 100037,china c.No.3.Institute of geological Exploration,Yantai 264000,Shandong,china

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(1200-1400)×10

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

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SOME REMARKS ON CHENJIAWO FAUNA──On the First Appearance of Peking Man Fauna

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古脊椎动物学报(中英文） 1996年第1期 50-57页

作者： Xu Qinqi(Zhoukoudian International Paleoanthropological Research Centre, Institute of Vertebrate Paleontology and Paleoanthropology, chinese academy of sciences {3. 100044)

The Chenjiawo fauna includes two stratigraphically distinct groups of mammalian fossils, 14 species of mammals and 4 stratigraphic horizons. They are L5, L6, S6 and L8-S9, representing a wide temporal distribution. The first appearance of Peking Man fauna can be correlated with Event 9 in America and Europe (Repenning, 1987) and is marked by the lowest stratigraphic occurrence of Cricetinus varians (LSD ). In northern Europe, Event 9 is believed to have taken place near the end of the Saale glaciation about 500 000 years ago (Bonifay, 1990). Therefore the geological age of the Chenjiawo fauna is between 500 000-1000 000 years B. P., corresponding to oxygen isotope. Stages 14-23. Through the correlation between the solid earth, atmosphere,hydrosphere, and biosphere, the boundary between the Upper and Lower Lishi Formation should be moved to the S4/L5 boundary.

关键词： Chenjiawo fauna Peking Man Lishi Formation Astroclimatology

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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, chinese academy of geological sciences, {3. 100081, china Institute of Geology & Geophysics, chinese academy of sciences, {3. 100029, china College of Earth sciences Jilin UniversityChangchun130061China Institute of Geomechanics Chinese Academy of Geological SciencesBeijing100081China Institute of Geology & Geophysics Chinese Academy of SciencesBeijing100029China

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 217.1±6.6 Ma, which is consistent with the peak UHPM in the Dabie-Sulu orogenic belt. Some of the inherited zircons (43.-722 Ma) constitute a discordia line with the upper intercept age of 850+85/-68 Ma and a lower intercept age of 261+100/-140 Ma. These ages imply that the granite could be derived from the partial melting of the crustal materials of the South china Block that was intensively superimposed by the UHPM. The UHPM could be the reason for the major Pb loss at ±220 Ma.

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

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Fluid inclusions hidden in coesite-bearing zircons from ultrahigh-pressure metamorphic rocks in southwestern Sulu terrane, eastern china

Fluid inclusions hidden in coesite-bearing zircons from ultr...

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2004年全国岩石学与地球动力学研讨会

作者： LIU Fulai, XU Zhiqin Institute of Geology, chinese academy of geological sciences, beijing 100087, china

Primary fluid inclusions, together with coesite mineral inclusions, are identified in the same zircon domains by Laser Raman spectroscopy, cathodoluminescence (CL) image and micro-texture analysis in paragneiss and retrogressive eclogite from the main drilling hole of chinese Continental Scientific Drilling Project, southwestem Sulu terrane. Most fluid inclusions are characterized by CO (gas) - HO (liquid) two-phase;a few by HO one-phase liquid inclusions. These features indicate that the eclogite and its country-rocks may not be located in the "dry system", but in the "Wet system" circumstance, when the Sulu terrane occurred ultrahigh-pressure metamorphism. The shrimp U-Pb dating suggests that the time for fluid and coesite inclusions trapped in metamorphic recrystallized zircon domains is about 23.-23. Ma (the weighted mean = 23..7±4.3.Ma);this age is in agreement with many reported Triassic UHP metamorphic ages of 23.-245 Ma from eclogites and gneissic rocks in Sulu-Dabie terrane. This research not only shows important significance for an in-depth study of the fluid property and evolutional feature, and fluid-rock interaction mechanism in Sulu-Dabie UHP terrane, but also provides a new method for exactly identifying the primary fluid inclusions preserved in zircons from the ultrahigh-pressure metamorphic rocks in the world.

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Nd and Sr isotope Constraints on the Age and Origin of Proterozoic Meta mafic Volcanic Rocks in the Bainaimiao Wenduermiao District,South central Inner Mongolia,china

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Continental Dynamics 1999年第1期 1-14页

作者： NIE Fengjun Institute of Mineral Deposits, chinese academy of geological sciences, beijing 100037, china Arne BJRLYKKE Department of Geology, University of Oslo, P.O.Box 1047, Blindern, 03.6 Oslo 3. Norway

Sm Nd and Rb Sr isotope data for amphibolites, greenschists and biotite amphibole plagioclase gneisses from Proterozoic volcano sedimentary sequences and younger granodiorite intrusions in the Bainaimiao Wenduermiao district, Inner Mongolia,*** are presented in the paper. Samples of the Baiyinduxi Group amphibolite yielded a Sm Nd isochron age of 13.4±75Ma(2σ). and ε Nd(t)is+7.9±2.1(2σ).This age is interpreted as the time of basaltic eruption, and possibly formation of a primitive mafic crust. Samples of the Bainaimiao Group greenschist gave a Sm Nd isochron age of 1124±57 Ma(2σ)with ε Nd(t)of+0.7±1.1(2σ),which is in agreement with a previously reported U Pb zircon age of 113. *** of the Bainaimiao granodiorite,which intruded into the Bainaimiao greenschist group gave a Sm Nd isochron age of 429±100Ma(2σ)with ε Nd(t)of-2.4±1 7(2σ).This result falls within the metamorphic age range of 3.2-581 Ma of the Bainaimiao greenschist,determined by mineral K Ar methods. The Rb Sr isotope systems in the same suite of rocks have been strongly disturbed. This observation may be consistent with petrographic characteristics, which indicate that all greenschist, amphibolite and granodiorite have undergone Na or K metasomatism to some extent. The initial ratios of the Nd isotopes suggest that the protoliths of both the Baiyinduxi amphibolite and the Bainaimiao greenschist were derived from a higly depleted mantle source. The ε Nd(t) values of the Bainaimiao granodiorite at 429 Ma indicate that it might have formed by partial melting of the biotite amphibole plagioclase gneiss,greenschist and/or amphibolite.

关键词： isotopic age Nd isotope Proterozoic mafic volcanic rocks Inner Mongolia china

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