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GEOCHRONOLOGICAL STUDY OF THE GRANITES IN NANLING AND ADJACENT REGIONS, SOUTHERN CHINA

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Science in China,Ser.A 1976年第3期 362-384页

作者： laboratory of isotopic geology, kweiyang institute of geochemistry, academia sinica laboratory of isotopic Geochronology, institute of Geological Science of Hupeh Province 中国科学院贵阳地球化学研究所同位素地质研究室湖北省地质科学研究所同位素地质研究室

Problems concerning the existence of Hercynian granite and the space-time relationships with respect to granitic activity in the Nanling region, southern China, are discussed in the light of 249 K-Ar and U-Pb age determinations. Granitic rocks exhibit a northeast trending zonal distribution throughout this region, with three zones recognized from the northwest to the southeast: Zone Ⅰ, made up mainly of Indosinian, Hercynian and Caledonian granites; Zone Ⅱ, Early-Middle Yenshanian granites predominate; Zone Ⅲ, composed essentially of Late-Middle Yenshanian granites. This distribution pattern of granites of various ages indicates that the locus of magmatic activity gradually shifted southeastwards with time. Although both the Nanling region and the Middle and Lower Yangtze Valley are dominated by Yenshanian granites, yet the former is characterized by large, composite phtons of multiple emplacement and tungsten, tin, rare-element mineralizations, and the latter is typified by small, intermediate intru

关键词： Pi La GEOCHRONOLOGICAL STUDY OF THE GRANITES IN NANLING AND ADJACENT REGIONS SOUTHERN CHINA

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铷-锶法测定岩石、矿物的同位素地质年龄

地球化学 1973年第3期2卷 186-194页

作者： The laboratory of isotopic geology, kweiyang institute of geochemistry,academia sinica 中国科学院贵阳地球化学研究所同位素地质年龄实验室

The principle, analytical procedures and applications of Rb-Sr dating for minerals and rocks are described. Sr was separated by ion exchange resin 71-616 (1) (made in China) and inorganic ion-exchanger ZrP (prepared in our laboratory). All Sr determinations were made by isotope dilution and mass spectrometry. The concentration of Rb was analysed by flame spcetrophotometry. Rb-Sr ages of three micas (one from pegmatite from Inner Mongolia, and the other two are from granites from Kiangsi province) are in agreement with the *** and geological observations, indicating that the retention of radiogenic Sr^87 in micas is excellent. But systematic defferenee between K-Ar and Rb-Sr mica ages has been found in the other granite from Kiangsi province, suggesting possible eontaminations of radiogenic Sr^87 from magraas of different resources. Based on the isochrons formed by six total rocks and one feldspar, two metamorphie episodes of Jolmo Lungma series, Tibet, China (659±20, 17±6 m.y.) have been established. A similar conclusion has been reached by the U-Pb two stage model(modified eoncordia) ages, K-Ar dating as well as field investigations. It is believed that if sufficient geological data and suitable specimens are avilable, Rb-Sr isochron method may be a powerful toot to bring out multi-metamorphism in a given geological system.

关键词：同位素地质年龄铷-锶法岩石学矿物学

安龙球粒陨石研究(Ⅰ)——K^(40)-Ar^(40)年龄和宇宙射线暴露年龄测定

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地球化学 1973年第4期2卷 272-275页

作者： The laboratory of isotopic geology, kweiyang institute of geochemistry, academia sinica 中国科学院贵阳地球化学研究所同位素地质研究室

The concentrations of radiogenic Ar^40 and cosmogenic Ar^32 in Anlung chondrite have been measured by the isotopic dilution technique. A ultrahigh-vacuum system have been designed for extracting and purifying the gases in the sample. These data provide a K^40-Ar^40 age of 3.28 b.y. and an exposure age of 3.0 m,y. for this *** on these results, we have discussed the origin and the former environment of stone meteorite.

关键词：安龙球粒陨石 K^40-Ar^40年龄宇宙射线暴露年龄测定质谱同位素稀释法

Analytical Model for the Palaeoenvironmental Evolution of the Nihewan Beds

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Acta Geologica sinica(English Edition) 1991年第1期65卷 77-86页

作者： Yue Jun Wen Qizhong Tianjin institute of geology and Mineral Resources institute of geochemistry, academia sinica Tianjin institute of geology and Mineral Resources China

In this paper, the evolutional characteristics of palaeoclimate and oxidation-reduction conditions as well asacidity-alkalinity environment are discussed by means of the step-regression, cluster, optimal partitioning andcorrelation analyses of CaCO_3, C / P_2O_5, Fe^(2+) / Fe^(3+), pH and Eh values, taking the Xiaodukou section in theNihewan basin as an example. The CaCO_3, C / P_2O_5 and pH were calculated respectively using the optimalpartitioning method. Thus five cold zones and six warm zones as well as five reduction and six oxidation zoneswere distinguished. Then the inductive method was used to produce four numerical groups: 8.10, 8.3-8.4,8.6-8.7 and 8.9-8,97. The above-mentioned results are respectively based on CaCO_3 content, C/P_2O_5 andpH values. From Fig. 3, Tables 1 and 2 it can be seen that the Nihewan Beds were formed mainly under a re-duction and slightly alkaline environment of cold climate, with pH values of 8.3-8.4. Fig. 3 shows that bed 35is approximately near the boundary between the Brunhes and Matuyama polarity epochs, 0.73 Ma in age; bed26 is roughly near the Jaramillo event (base), 0.97 Ma in age; bed 18 coincides roughly with themagnetostratigraphic boundary of 2.00 Ma (?). Bed 13 may be the Pleistocene-Pliocene boundary, 2.48 Ma inage. Thus geochemical zones Ⅰ, Ⅱ, Ⅲ and Ⅳ include respectively cold zones 1; 2 and 3; 4; and 5.

关键词： Analytical Model for the Palaeoenvironmental Evolution of the Nihewan Beds

A Comprehensive Evaluation on the Devonian-Carboniferous Boundary Stratotype Candidate Section in Nanbiancun, Guilin, Guangxi

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Acta Geologica sinica(English Edition) 1990年第1期64卷 69-79页

作者： Yu Changmin Nanjing institute of geology and Palaeontology, academia sinica 2This paper is extracted from some relevant chapters of a monograph. The authors who wrote the monograph are: Yu Changmin Ruan Yiping Xu Hankui Wang Shangqi Zhu Zhaoling Mu Xinan Wang Keliang Yin Bao' an Li Zhengliang Li Yukuan Guo Shuying Yao Zhaogui He Guiying Zhang Yue'e Lu Hongjin Huang Zhicheng Zhu Sizhao Yang Jiedong Wang Yinxi Ye Sujuan and Xu Tongchun.

This paper presents a comprehensive evaluation on the Devonian-Carboniferous Boundary (DCB) sectionin Nanbiancun. Guilin. Guangxi on the basis of Palaeontological, biostratigraphical and sedimentarypetrological studies as well as microfacies analysis. REE and trace element analysis and isotopic dating. The DCB at this section conforms to the definition of this boundary and essentially measure up the criteriaand conditions for selection of the boundary stratotype. Up to 14 fossil groups are contained in the section. Thesection presents a general biostratigraphical framework with multispecies fossils zones, assemblage zones andmultiple groups of fossils and has latent preponderant conditions for magnetostratigraphic andchronostratigraphic studies. The boundary and point occur in a persistent and continuous monofacialcarbonate succession. and the section is located in a tourist city with convenient communication, where variousfacies of DCB sections are developed. allowing the correlation within a small area. So it is an ideal candidateboundary stratotype.

关键词： Guilin Guangxi A Comprehensive Evaluation on the Devonian-Carboniferous Boundary Stratotype Candidate Section in Nanbiancun

Dating Model of Illite Grain Rb-Sr Isochron and Its Application to Precambrian Stratigraphy

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Acta Geologica sinica(English Edition) 1989年第1期63卷 93-102页

作者： Li Yunjun institute of geology, academia sinica, Beijing Jia Zhongpeng institute of geology Academia Sinica Beijing

This paper discusses the Rb-Sr geochemical behaviour of illites in the sedimentary process, and points out that illites of the lmd and lm types could reach Sr-isotopic equilibrium with its environmental medium during the sedimentary process and initial stage of diagenesis, and illite grains of different sizes have various Rb contents. A new dating method for sedimentary rocks----a dating model of illite grain Rb-Sr isochron----is established, in consideration of the geochemical process of Sr-isotopic homogenization and differentiation in the course of their formation and evolution. In addition, the paper concerns the application of the dating model to the Precambrian unmetamorphosed sedimentary rocks in western Henan Province, which gives satisfactory results coincident with the geological facts.

关键词： Dating Model of Illite Grain Rb-Sr Isochron and Its Application to Precambrian Stratigraphy Sr Rb

An SIMS Study on the Fingerprint Characteristics of Minerals with Special Reference to Minerals from the Jinningian Granites in the Yunnan Sector of the Xikang-Yunnan Axis

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Acta Geologica sinica(English Edition) 1991年第3期65卷 251-257页

作者： Zhou Shitao Liu Yongkang institute of geochemistry, academia sinica, Guiyang 550002 institute of geochemistry Academia Sinica Guiyang 550002

In this paper such minerals as apatite, zircon and biotite from granites were determined and analyzed bysecondary ion mass spectrometry (SIMS) for their isotopic ages, REE composition, trace elements and volatilecomponents with an attempt to shed light on the origin and formation environments of the Jinningian granitesin the Yunnan sector of the Kangdian (Xikang- Yunnan) earth's axis. The results show that the apatites,zircons and biotites of different geneses possess different fingerprint characteristics. Some correlations havebeen found between trace elements and volatile components contained in the minerals from granties.

关键词： SIMS An SIMS Study on the Fingerprint Characteristics of Minerals with Special Reference to Minerals from the Jinningian Granites in the Yunnan Sector of the Xikang-Yunnan Axis Axis

Evolution of Apatites in the Diagenesis

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Acta Geologica sinica(English Edition) 1990年第2期64卷 147-162,233+236页

作者： Liu Kuiwu institute of geology, academia sinica, Beijing Liu Linqun Chinese Academy of Geological Sciences Beijing

Apatites occurring in sedimentary rocks are carbonate fluorapatites (C-F apatites) with differentCO_2 contents. During diagenesis. the CO_2 in the C-F apatites gradually decreased with the increasing strengthof diagenesis. resulting in the systematic changes in refractive index. specific gravity, cell parameters and crystalchemistry of apatites. On the basis of X-ray diffraction and IR spectroscopic analyses, the author proposes twoparameters for determining diagenetic stages. i.e.. the crystallinity index (CR) and sharpness index (SH). Thesetwo parameters serve as new criteria for the determination. which due to the common existence of phosphorousnodules and bands and argillo-crystalline cement in sedimentary rocks, most likely have wide prospects for ap-plication.

关键词： Evolution of Apatites in the Diagenesis

Discussion on Rb-Sr Isochron Ages of Granitoids in the Hengduan Mountains

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Acta Geologica sinica(English Edition) 1990年第2期64卷 223-232页

作者： Zhang Yuquan Zhu Bingquan Xie Yingwen institute of geochemistry, academia sinica, Guiyang Chinese Academy of Geological Sciences Beijing

Based on the Rb-Sr isotopic study of the granitoids in the Hengduan Mountains, the classification andgeologic significance of whole-rock Rb-Sr isochrons as well as the factors influencing homogenization of theisotopic systems are discussed. Usually. there is no good linear correlation of isochrons for diorites andalkali-rich intrusive rocks (including alkaline rock and alkalic granite). But by means of the external isochron ofmonominerals from the rocks. isochrons with good linear correlation as well as ages and Sr initial ratios with ahigh confidence can be obtained. In order to obtain a satisfactory isochron, the discriminant parameters shouldbe calculated from the Rb/Sr ratios and estimated ages of samples. Only those that meet the requirements canbe used as the Rb-Sr isochrons. The quality of an isochron should be judged from three factors, i.e. correlationcoefficient. MSWD and homogenization degree.

关键词： Rb Sr Discussion on Rb-Sr Isochron Ages of Granitoids in the Hengduan Mountains