Single grain Rb-Sr isotopic analysis of GA-1550 biotite,LP-6 biotite and Bern-4M muscovite 40Ar-39Ar dating standards
会议名称：《中国科学院地质与地球物理研究所2008学术年会》
会议日期：2009年
学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学]
基 金：supported by the National Natural Science Foundation of China(NSFC project No. 40525007) the Ministry of Science and Technology of China (Project No.2006CB403505)
关 键 词：Rb-Sr isotopic systematics standard mica GA-1550 biotite LP-6 biotite Bern-4M muscovite
摘 要：Three standard minerals GA-1550 biotite,LP-6 biotite and Bern-4M muscovite used for K-Ar and Ar-Ar dating have been investigated by the single grain Rb-Sr *** to the K-Ar and Ar-Ar results previously reported,these mica standards nevertheless show complex characteristics in the Rb-Sr isotopic *** on eight individual grains of GA-1550 biotite gives a Rb-Sr isochron age of 98.7±1.9 Ma,consistent with previous dating results of the K-Ar and stepwise heating and laser ablation Ar-Ar *** evidence of the laser ablation Ar-Ar analyses in many previous studies demonstrates that LP-6 biotite is considerably inhomogeneous in the K-Ar isotopic system,Rb-Sr isotopic analyses on ten individual biotite grains show achievement of Sr isotopic equilibrium during crystallization.A Rb-Sr isochron age of 128.2±2.2 Ma calculated from the analytical results is concordant with those previously reported K-Ar and Ar-Ar ages obtained from c.30 mg aliquots of biotite *** age reproducibility on Bern-4M muscovite was previously achieved by K-Ar and Ar-Ar dating by total fusion in c.30 mg aliquots of muscovite grains,but single grain Rb-Sr analytical results in this study demonstrate considerable disequilibrium of Sr isotopic system during crystallization of *** discordance in the Rb-Sr and K-Ar isotopic systems of two standard minerals indicates complex factors that can influence isotopic disequilibrium of both isotopic systems.