摘要
独居石是常见的稀土矿物之一,常出现在各类岩石中,是重要的成因指示矿物和定年矿物,因此准确测定独居石化学成分不仅具有重要的地质成因意义,同时也为后续的电子探针定年、原位同位素等分析工作提供可靠的参数。电子探针分析方法具有原位无损和高空间分辨率(~1μm)的优势,该研究以SPI公司独居石标样为分析对象,在精细全元素波谱扫描工作基础上,对其化学成分的电子探针测试条件:加速电压、束流和测量时间的设定、分光晶体、分析线系、检测限、干扰系数,标样的选择等多个参数进行了系统研究和讨论,确定最佳测试条件参数,并获得和各元素含量推荐值基本一致的成分数据。文章建立了日本电子JEOL JXA-8530F Plus电子探针下独居石化学成分的最佳分析条件,实现了大罗兰圆大分光晶体(R=140 mm)对微量元素的精准测定,同时各元素含量相对标准偏差均低于20%(范围为0.05%~17.75%),满足了后续实际样品的化学成分和CHIME定年的整合分析测试精度的要求。
Monazite is the bearing-LREE(light rare earth elements)phosphate mineral that occurs all types of rocks.It is an essential mineral for understanding the formation processes and U-Pb dating,thus high precision analysis of monazite chemical composition has an important geological significance,and also provides reliable parameters for follow-up studies,such as EMPA CHIME dating and in-situ isotopic microanalysis.EMPA is an in-situ and non-destructive technique with an excellent spatial resolution(~1μm).Due to that,based on the detailed wavelength scanning for SPI Monazite standard,we focus on discussing the important issues in analytical procedure of monazite chemical composition:accelerate voltage,beam current,time,spectrometer,analysis lines,detected limits,interference factor and standards,and obtain the chemical composition data that are finely consistent with the recommended values of the SPI monazite standard under the optimal analysis conditions.This paper presents the best analytical set-up of JEOL JXA-8530F Plus electron microprobe facility at State key laboratory for mineral deposits research, Nanjing University, particularly establishes the high precision analysis of the trace rare earth elements on large spectrometer of 140 mm Rowland circle. The relative standard deviations (RSD) of all element contents are less than 20% (0.05%-17.75%)and meet the accuracy requirement of integration analysis of monazite composition and geochronology .
作者
胡欢
王汝成
谢磊
张文兰
田恩农
许雅婷
范宏瑞
HU Huan;WANG Rucheng;XIE Lei;ZHANG Wenlan;TIAN Enrong;XU Yating;FAN Hongrui(State key laboratory for mineral deposits research,School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China;Key Laboratory of Mineral Resource,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China)
出处
《高校地质学报》
CAS
CSCD
北大核心
2021年第3期317-326,共10页
Geological Journal of China Universities
基金
中国科学院地质地球物理研究所重点部署项目(IGGCAS-201901)
国家自然科学基金面上项目(41472032,42072320,42072062)
中央高校基本科研业务费专项资金(14380099)联合资助。
关键词
独居石
化学成分
精准测定
monazite
chemical composition
high precision analysis
