高精度铅同位素比值MC-ICP-MS测试方法及岩石标样铅同位素组成  

High-precision analysis of Pb isotope ratios using MC-ICP-MS and the Pb isotope compositions of rock standard samples

作　　者：卢山松 童喜润[1,2,3] 谭娟娟 邱啸飞[1,2,3] 杨红梅 LU Shansong;TONG Xirun;TAN Juanjuan;QIU Xiaofei;YANG Hongmei(Wuhan Center,China Geological Survey(Geosciences Innovation Center of Central South China),Wuhan 430205,Hubei,China;Hubei Key Laboratory of Paleontology and Geological Environment Evolution,Wuhan 430205,Hubei,China;Research Center for Petrogenesis and Mineralization of Granitoid Rocks,China Geological Survey,Wuhan 430205,Hubei,China)

机构地区：[1]中国地质调查局武汉地质调查中心(中南地质科技创新中心),湖北武汉430205 [2]古生物与地质环境演化湖北省重点实验室,湖北武汉430205 [3]中国地质调查局花岗岩成岩成矿地质研究中心,湖北武汉430205

出　　处：《地质通报》2023年第9期1516-1530,共15页Geological Bulletin of China

基　　金：国家自然科学基金项目《北大别始太古代基底岩系的组成、地球化学特征及其对早期地壳演化的制约》(批准号:42272229);国家自然科学基金青年基金项目《MC-ICP-MS高效准确测定Pb同位素标准参考物质绝对比值的分析方法研究》(批准号:42003017);原国土资源部公益性行业专项《同位素地质样品分析方法行业标准(DZ/T 0184.1~22—1997)修订》(编号:201411075);古生物与地质环境演化湖北省重点实验室开放研究基金项目《鄂西神农架群碎屑锆石年龄特征及其对扬子北缘演化的制约》(编号:PEL-202205);中国地质调查局花岗岩成岩成矿地质研究中心开放基金项目《磷灰石矿物包裹体微区原位Sr同位素组成精确测定及其对扬子克拉通太古宙花岗岩成因的制约》(编号:PM202302)。

摘　　要：利用多接收电感耦合等离子体质谱仪(Neptune plus)建立了高精度铅同位素比值MC-ICP-MS测试方法。建立该方法的过程中,重点评估了加入的Tl标准溶液对铅同位素比值测试结果的影响,并最终确定Tl标准溶液的浓度为25 ng/mL,同时样品溶液Pb的浓度应该大于25 ng/mL(即Pb/Tl浓度比应大于1)。利用该方法对铅同位素标准物质SRM 981进行了长期监控(2020年7月—2021年6月),测试结果为:206 Pb/204 Pb=16.9415±0.0010、207 Pb/204 Pb=15.4985±0.0009、208 Pb/204 Pb=36.7204±0.0023,与统计的文献报道值一致。长期监控的全流程空白均小于0.25 ng,能满足地质样品高精度铅同位素比值测试的需要。同时运用该方法,对4个元素含量标样(BCR-2、AGV-2、BHVO-2和BIR-1a)进行了铅同位素比值测试,测试结果与文献报道的测试结果和精度一致,表明建立的方法是准确、可靠的。A method for high-precision analysis of Pb isotope using MC-ICP-MS(Neptune plus)was established in Wuhan Centre,China Geological Survey.This study has focused on the influence of Tl standard solution of various concentration on the test results of Pb isotope ratio,and the optimal concentration of Tl standard solution has been determined to be 25 ng/mL,and the Pb concentration in the sample solution should be higher than 25 ng/mL(i.e.the Pb/Tl concentration ratio should be higher than 1).The Pb isotope reference material SRM 981 has been tested with this method for 11 months(July 2020~June 2021).The isotope ratios for SRM 981 are 206 Pb/204 Pb=16.9415±0.0010,207 Pb/204 Pb=15.4985±0.0009 and 208 Pb/204 Pb=36.7204±0.0023,which are identical to the published data.The blank of long-term monitoring is less than 0.25 ng,which can meet the needs of high-precision lead isotope ratio test of geological samples.Meanwhile,we determined the Pb isotope composition of four trace element standard samples(BCR-2、AGV-2、BHVO-2 and BIR-1a)by using the same procedure.The results are consistent with the published data,hence this method is accurate and reliable.

关 键 词：铅同位素 MC-ICP-MS USGS标准物质 岩石标样 

分 类 号：P597.3[天文地球—地球化学] P58[天文地球—地质学]