铷-锶法测定岩石、矿物的同位素地质年龄  

Rb-Sr DATING FOR MINERALS AND ROCKS

作　　者：The Laboratory of Isotopic Geology, Kweiyang Institute of Geochemistry,Academia Sinica 

机构地区：[1]中国科学院贵阳地球化学研究所同位素地质年龄实验室

出　　处：《地球化学》1973年第3期186-194,共9页Geochimica

摘　　要：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 K-Ar.rages 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.The principle, analytical procedures and applications of Eb-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 Eb was analysed by flame spectrophotometry.Eb-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 K-Ar ages and geological observations, indicating that the retention of radiogenic Sr87 in micas is excellent. But systematic defference between K-Ar and Eb-Sr mica ages has been found in the other granite from Kiangsi province, suggesting possible contaminations of radiogenic Sr87 from magmas of different resources.Based on the isochrons formed by six total rocks and one feldspar, two metamor-phic 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 concordia) ages, K-Ar dating as well as field investigations. It is believed that if sufficient geological data and suitable specimens arc avilable, Eb-Sr isochron method may be a powerful tool to bring out multi-metamorphism in a given geological svstem.

关 键 词：同位素地质年龄 铷-锶法 岩石学 矿物学 

分 类 号：P597[天文地球—地球化学]