华南地质与矿产2017，Vol.33Issue(4)：344-353,10.DOI:10.3969/j.issn.1007-3701.2017.04.003
闪锌矿分相Rb-Sr体系定年机理初探
Preliminary Research on the Rb-Sr Dating Mechanism of Sphalerites with Diluted Acid Leachating
摘要
Abstract
Rb-Sr dating of sphalerites has been shown a promising and effective technique for the direct dating of Pb-Zn deposits.However,this technique is still questioned by some scholars due to the divergent opinions about the occurrence of Rb and Sr and the dating mechanism.Therefore,This study analyzed the contents of Rb,Sr,Pb, Zn,Fe,Ca,Mg and Al in the hand-picked sphalerites,diluted HCl acid leachates and sulfide residues(Aqua regia dissolving phases),respectively.The analytical data shows that 79.19%-97.61%(averaged 90.47%)Rb is dis-tributed in the sulfide residues with Pb,Zn and Fe,while 70.30%-98.12%(averaged 82.92%)Sr is concentrated in the diluted HCl leachates with Ca and Mg,and there is an approximately positive correlation between the con-tents of Sr and those of Ca and Mg,which indicates that the common Sr in carbonate inclusions demonstrated by Electron Microprobe analysis can be eliminated through the diluted HCl leachating,so the radioactive Sr(2.34%-9.79%)in minerals can't be masked by the high common Sr in the carbonate inclusions,then the Rb/Sr ratios and their variation range of the sulfide residues become bigger,which is of great significance for the successful Rb-Sr dating of sphalerites.Meanwhile,these results show the Rb-Sr dating of sphalerites is probably based on the Rb and Sr in the sulfide residues not on those in the fluid or carbonate inclusions,which preliminarily con-firms this dating method is of geological significance in principle.What's more,through several condition experi-ments,it's verified that the common Sr in the carbonate inclusions can be removed thoroughly by the diluted HCl leachating,and that all Rb-Sr isotope data points are distributed along the same Rb-Sr isochrones no matter what the leachating acid concentration or soaking time is. That is, the Rb-Sr isochrone age is reliable, showing the analysis process of the Rb-Sr dating of sphalerites is stable and reliabale.关键词
Rb-Sr体系/定年机理/分相/闪锌矿Key words
Rb-Sr isotope/dating mechanism/diluted acid leachating/sphalerite.分类
地质学引用本文复制引用
杨红梅,刘重芃,蔡红,段瑞春,蔡应雄,卢山松,谭娟娟,张利国,李华芹..闪锌矿分相Rb-Sr体系定年机理初探[J].华南地质与矿产,2017,33(4):344-353,10.基金项目
中国地质调查局扬子工程湘西-鄂西成矿带神农架-花垣地区地质矿产调查二级项目(No.DD20160029) （No.DD20160029）
地调局科研项目(No.12120114005701、1212011121102) （No.12120114005701、1212011121102）
国土资源部公益性行业科研专项(No.201411075、201011027-3). （No.201411075、201011027-3）
