| 激光显微探针40Ar/39Ar 定年方法研究 |
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| 引用本文：陈文,罗修泉,郑宝英,张思红.1994.激光显微探针40Ar/39Ar 定年方法研究[J].地球学报,15(1,2):197-205. |
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| 中文摘要:实验结果表明，在激光探针40Ar/36Ar年龄和常规40Ar/39Ar年龄之间有较好的吻合性，多次测定BSP-1角闪石国际标样年龄值大部分在2020-20900Ma之间，多次测定周口店花岗岩中ZBH-25国内标样年龄值大部分在130-135.9Ma。分析区域可小到30μm以下（激光束本身可被聚集到10μm以下）。研究表明，激光显微探针技术在下述工作中将是一个极有前途的工具①测定不易大量获取的样品年龄；②研究遭受多期地质历史事件作用因而有复杂Ar状态的岩石年代；③研究在岩石样品中填充在不同结构位置上的矿物年 |
| 中文关键词:激光显微探针 40Ar/39Ar定年方法 |
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| Reserch on laser microprobe 40Ar/39Ar dating |
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| Abstract:Our laboratory has successfully developed a laser microprobe 40Ar/39Ar geoloical dating technique,the technical principle of which is to find the measuring mineral on a piece of polished rock section (1-2mm thick)under a high-power microscope and then to introduce the pulsed laser beam into the light path of the microscope through a prism and to focus it on the surface of the mineral making the latter melting. Ar gas thus released is used for dating.Our research includes feasibility study for the method within China,adjustment of the high-gaining electron multiplier in a mass spectrometer,adjustement of the laser,test for absorbability of samples to laser,designing and manufacturing high-vaccum sample melting chamber,sample processing,research on sample irradiation and J values,detecting atmosphric argon,blank and age, exploration and optmization of experimental circuit,etc.Experimental results show relatively close coindidence of laser microprobe 40A/39Ar ages with conventional ones.The BSP-1 amphibole international standard ages determined though repeated measurements range mainly between 2020-2090 Ma and most of the ZBH-25 domestic standard ages obtained through repeated meaurements in granite in Zhoukoudian are between 130-135.9Ma.The analysis area can be minimized to less than 30μm in diameter(and the laser itself can be focused within limits of less than 10μm in diameter).Investigations indicate that the laser microprobe technique supplies an extremcly prospecting tool for following researches:(1)measurement of the age for samples which are difficultly collected in large quantity; (2)research on the age for rocks that are of cmoplex Ar regime because of the effect of multiphase events in geologic history;(3)research on the age of those minerals infilling various textural positions in rock samples and comparing data from inside of every crystal grain and between different grains; and(4) measurement of the 40Ar/39Ar age for young K-rich samples. It is clear that the laser dating plays particular role in research on structural,metamorphic and mineral deposit chronologies. |
| keywords:laser microprobe 40Ar/39Ar dating |
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