检索结果-南通市图书馆

The source of CO_2.in lamprophyres from Laowangzhai gold orefield, Yunnan Province, China

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1999年第S2期44卷 201-203页

作者： HUANG Zhilong, LIU Congqiang and XIAO Huayun Open Laboratory of Ore Deposit geochemistry, institute of geochemistry, Chinses {3. of sciences, guiyang 550002. China Open Laboratory of Ore Deposit geochemistry Institute of Geochemistry Chinses Academy of Sciences Guiyang 550002 China

CARBONATES in lamprophyres have various occurrences. The source of CO2.in lamprophyres provides animportant clue for us to understand the relationship between lamprophyres and gold *** et *** the C and O isotopic comp... 详细信息

CARBONATES in lamprophyres have various occurrences. The source of CO2./sub> in lamprophyres provides animportant clue for us to understand the relationship between lamprophyres and gold *** et *** the C and O isotopic composition of various carbonates from Mesozoic lamprophyres in Transdanubian Range of Hungary, and suggested that the carbonates with different occurrences were different in origin. That is to say, the CO2./sub> in lamprophyres has various sources. TheLaowangzhai gold deposits, Yunnan Province, China, is a typical orefield where lamprophyres are temporally and spatially related to gold mineralization. The CO2./sub> contents of relatively fresh lampropyres from theorefield （the range of content is 5.10%-9.56%, averaging 7.45% ） are obviously higher than that ofprimary lamprophyres （about 0.5%）. Huang et *** that the CO2./sub> in relatively fresh lam-

关键词： source of CO2 lamprophyres gold field Yunnan Province.

Trace element compositions of volcanic rocks from Yangba Formation, Bikou Group, Qinling, China: Implications for tectonics

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1999年第S2期44卷 203-204页

作者： DING Zhenju~(1,2. and LlU Congqiang~1 1. institute of geochemistry,{2., {3. 550002. China 2. China University of Ceosciences, Wuhan 43.074, China institute of geochemistry Chinese Academy of Sciences Guiyang 550002 China China University of Geosciences Wuhan 430074 China

THE Yangba Formation of Bikou Group is located in south Qinling, a famous orogenic belt separating chinese continent into two parts: North China plate and Yangtze plate. The Yangba Formation comprises themafic and felsic volcanic rocks formed in an ancient seafloor environment during Proterozoric era. Thesuites of mafic and felsic volcanic rocks petrochemically are divided into tholeiite and calc-alkalinedacite, respectively, showing clearly characteristics of bimodal volcanic rock mainly with lithology andmajor element composition, and a lack of typical intermediate rocks. These indicate that the volcanicrocks of Yangba Formation were generated in rift tectonics setting. The tholeiites of Yangba Formation are similar in trace element compositions to Mid-ridge basalt,displaying a slight depletion to enrichment in light rare earth elements (LREEs) (La/Yb_n=0.6-1.4).slight fractionation between LREE (La/Sm_n=0.55-1.14) and HREE (Gd/Lu_n=1.09-1.50),

关键词： trace element volcanic rocks tectonics.

Temperature variations in the past 6000 years inferred from δ^(18)O of peat cellulose from Hongyuan,China

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2002年第18期47卷 1578-1584页

作者： XU Hai, HONG Yetang, LIN Qinghua, HONG Bing, JIANG Hongbo & ZHU Yongxuaninstitute of geochemistry,{2., {3. 550002. China Graduate School of{2., Beijing 10003., China institute of geochemistry Chinese Academy of Sciences Guiyang China Graduate School of chinese academy of sciences Beijing China

Trends of the temperature variations recorded in δ18O in Hongyuan peat cellulose are similar to those recorded in δ18O of Jinchuan peat cellulose and in δ18O of Dunde ice core. Climate events have been identified to be globally homogeneous. Two notable climate transition periods have been detected in the past 6000 years, namely 4000 aBP with climate shifting from cold to warm and 1500 aBP with climate shifting from warm to relatively cold. Power spectrum analysis was performed to investigate the periodical signals in the δ18O time series. Typical periodicities of 12.0-1087 a, 752.a, 444 a, 3.5 a, 2.3.a, 12.-12.0}a, 88 a, 79 a were discovered, indicating an integrated influence on Hongyuan climate from solar, monsoon and ocean activities. Solar forcing has been addressed to be the main driving forcing of Hongyuan climate.

关键词： Hongyuan oxygen isotopic composition peat tempera-ture.

Trace elements in volcanic rocks from Yangba Formation, Bikou Group, Qinling area, China——Implications for tectonics

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1999年第S2期44卷 44-46页

作者： DING Zhenju~(1,2. and LIU Congqiang~1 1. Open Laboratory of Ore geochemistry, institute of geochemistry,{3., guiyang 550002. China 2. China University of Geosciences, Wuhan 43.074, China Open Laboratory of Ore geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang 550002 China China University of Geosciences Wuhan 430074 China

YANGBA Formation of Bikou Group is located in south Qinling, a famous orogenic belt separating chinesecontinent into two parts: North China plate and Yangzi plate. The Yangba Formation comprises the maficand felsic volcanic rocks formed in an ancient seafloor environment during the Proterozoic era. The suitesof mafic and felsic volcanic rocks are petrochemically divided into tholeiite and calc-alkaline dacite, respectively, showing characteristics of bimodal volcanic rock mainly by lithology and major element content, and a lack of typical intermediate rocks. These signatures indicate that the volcanic rocks of YangbaFormation were generated in rift tectonics setting. The tholeiites of Yangba Formation are similar in trace element content to mid-ridge basalt, displaying a slight depletion to enrichment in light rare earth elements (LREE’s) (La/Yb_n = 0.6-1.4), slightfractionation between LREE (La/Sm_n =0.55-1.14) and HREE (Gd/Lu_n = 1.09-1.50), and relative flat patterns in whole. The decoupling of Eu to its neighboring elements in two samples likely indicates an effect of fractional crystallization in magma evolution. The La-La/Sm, Ni-La, Ni-Th, Ni-Ta,and Ni-Hf diagrams all support a conclusion that the mafic rocks are generated by partial melting pro-

关键词： trace element volcanic rock tectonics setting Bikou Group.

Relationship between δ^(13.C and index of ring width

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1999年第S2期44卷 81-83页

1 Materials and methods THE tree-ring reported here is one of pine discs sampled at 3.2.0 m a.s.l. in Qongtelian Valley in the Tuomu’er Peak region in 1978. The local geographical and climate condition has been introduced in detail. An index series was obtained after the width of tree-rings on 5 different radii was measured andfitted by linear and negative exponential functional regression. Each annual ring has been separated on the whole to simultaneously measure △14 C and δ13./sup> C of treerings. Cellulose was extracted by the standard chemical method, then oxidized by copper oxide to C02./sub>.Carbon isotopic analyses were performed with a Mat-2.2.mass spectrometer. Results are expressed in thestandard δ notation with respect to the PDB standard with a precision of 0.1‰. 2

关键词： tree rings δ13. index of ring width correlation climate changes.

Bio-effects of REE and estimated daily intake allowance

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1999年第S2期44卷 102-104页

作者： ZHANG Hui, ZHU Weifang and FENG Jia State Key Latboratory of Environmental geochemistry, institute of geochemistry,{3., guiyang 550002. China State Key Laboratory of Environmental geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang 550002 China

IT has become an urgent subject with the wider application of REE to study the effects of REE on environ- ment and human health. Some important REE toxicology data were obtained previously based on acuteand sub-chronic toxicity experiments on animals, but these results are indirect and suspectable becausethe REE compounds used in the experiments are different from those in food chains, and there still existsome uncertainties when the results are extrapolated from animals to human beings. This note focuses thebio-effects of REE on population from two typical REE-high areas in South Jiangxi, China, where theweathering crust-ion adsorbed-type REE ore deposits are widespread, and also on the estimation of dailyREE intake allowance in terms of REE contents and distribution in food chains. 1 Geologic setting and studying

关键词： rare earth elements bio-effects daily intake allowance South Jiangxi.

A sodium metasomatism process in Xiaoqingshan lode-copper deposit in Kangdian region, southwestern China

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1999年第S2期44卷 176-178页

作者： WANG Jiangzhen~1, ZHEN Minghua~2.and LU Yan~2.1. lnstitute of geochemistry, chinese academy of sciences, {2. {3. China 2. Chengdu institute of Technology, Chengdu 610059, China institute of geochemistry Chinese Academy of Sciences Guiyang 550002 China Chengdu institute of Technology Chengdu 610059 China

THE Kangdian region is a middle Proterozoic continental rift basin that extends between longitudes 101°3.’and 103.2.’. There are a series of sedimentary strata, named Xiaoqingshan Formation, Yinmin Forma- tion, and Luoxue Formation. The strata were metamorphosed and deformed in Jinning tectonic event between approximately 850 and 750 Ma. There are many lode-copper deposits in the Kangdian region. Xiaoqingshan is a typical one among of them. The orebodies of the deposit occurs in veins and the hostrocks of the deposit are sericite-phyllite and sericite-slate. The deposit is characterized by large-scale pervasive sodium metasomatism （PSM）. It has been identified that albite replaced sericite and chlorite of the original rocks during the *** a result, the pelites were transformed into albitolite, which consists of albite totally. Mass balancecalculations show that the PSM process involved addition of large amount of Na2./sub>O and SiO2./sub>, and

关键词： sodium metasomatism copper deposit southwestern China.

Tracer system on halogen mineralizer from the epithermal deposits in Guizhou Province

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1999年第S2期44卷 159-161页

作者： PAN Jiayong, ZHANG Qian and SHAO Shuxun Open Laboratory of Ore Deposit geochemistry, geochemistry of {2.,{3., guiyang 550002. China Open Laboratory of Ore Deposit geochemistry Geochemistry of Institute Chinese Academy of Sciences Guiyang 550002 China

HALOGENS are typical mineralizer elements and play a very important role in remobilization and resettlement of the ore-forming mental elements in the hydrothermal deposits. Studies of tracer system on halogens mineralizer include the following aspects: (i) halogens’ role as mineralizer in ore-forming action;(ii) halogens importance as tracer elements in formation and evolution of the epithermal ore deposit;(iii) halogens’ significance as guidance in looking for the buried orebodies. Guizhou is a concentrated area of epithermal Hg, Sb and Au deposits, where are distributed famousepithermal deposits such as the Wanshan Hg deposit, the Banpo Sb deposit, the Danzhai Hg-Au depositand the Lannigou Au deposit. Many researches into geological and geochemical characteristics of thesedeposits have been done, but few study on halogen mineralizer.

关键词： tracer system halogens mineralizer epithermal deposits Guizhou.

High resolution environmental records in recent sediments of Erhai Lake, Yunnan Province

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1999年第S2期44卷 88-90页

作者： CHEN Jingan, WAN Guojiang and TANG Degui State Key Laboratory of Environmental geochemistry, institute of geochemistry,{3., guiyang 550002. China State Key Laboratory of Environmental geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang 550002 China

IN the past half a century, the global paleoclimate has been successfully reconstructed by natural recordssuch as ice core, loess and deep-sea sediments. However, these works mostly focused on long-timescale climatic changes. Along with the appearance of modern environmental problems including globalwarming, people are increasingly concerned about short-term climatic variations (annual to century scale)within the historical period. Therefore, it is an urgent and significant task for scientists to obtain continuous and high resolution natural records so as to reconstruct recent climatic changes truly and predict theclimate in the near future. As a main lodging of surface substances, the plateau-lake sediment continuously records the information of regional climate and environment with annual to decade resolution. Undoubtedly it is one

关键词： lake sediments high resolution climatic changes Erhai Lake.