摘要
沥青样品中Re、Os含量较低,且组成复杂,因含有大量有机质,在溶样过程中会释放大量CO2,需要大量氧化剂。控制样品称样量和氧化剂比例、用量对保证Os的回收率以及测量信号的稳定性非常重要。本文根据沥青样品组成特点改进了Re-Os同位素分析技术方法,称样量由原来的0.2 g增加到0.4 g,氧化剂由原来的3 mLHCl、6 mL HNO3改为3 mL HCl、4 mL HNO3、3 mL H2O2,改进的方法所得到Os的信号强度提高了大约2倍。考察了改变溶剂组成对不同称样量沥青的氧化效果,研究了氧化剂中加入H2O2对不同称样量沥青样品溶解效果,以及对Os的回收率和仪器测量信号强度的影响程度。采用2 mL HCl、5 mL HNO3、2 mL H2O2作为氧化剂,Carius管高温密闭溶样,直接蒸馏法或传统蒸馏法分离富集Os,丙酮萃取法分离纯化Re,用电感耦合等离子体质谱法(ICP-MS)对采自云南某铅锌矿床的沥青样品Re-Os同位素进行分析测定。沥青的Re-Os同位素等时线年龄为(60±2)Ma(MSWD=2.5,n=7),初始187Os/188Os值为4.36±0.14,表明该沥青样品中Re-Os同位素体系的封闭性较好,而且物质来源为典型的壳源性质。建立的方法能够用于沥青年龄厘定与来源示踪方面的研究。
The content of Re-Os in asphalt samples is relatively low,and CO2 are released in digestion because of large amounts of organic matter.It is important to control the amount of asphalt in the sample and the proportion of oxidant to ensure the Os recovery and stability of the measured signal.The method for the Re-Os isotope was improved because of large amounts of organic matter contained in bitumen samples.The Oxidants was changed to 3 mL HCl,4 mL HNO3 and 3mL H2O2 from the original 3 mL HCl and 6 mL HNO3,the improved method making the Os measured signal approximately 2 times larger than before.Changes in oxidants composition increase the amount of the bitumen sample weight greatly from th eoriginal 0.2 g to 0.4 g.Influence of H2O2 added with routine reverse aqua regia and direct distillation from a Carius tube on the signal intensity of osmium measured by Inductively Coupled Plasma-Mass Spectrometry（ICP-MS）.was studied.Bitumen samples were dissolved and equilibrated with a known amount of 185Re and 190Os tracers in 2 mL HCl,5 mL HNO3 and 2 mL H2O2 by a Carius tube at 200℃ for 12 h and 240℃ for 12 h,with the Os and Re separated using direct distillation or routine distillation and solvent extraction techniques,respectively.187Re/185Re,187Os/190Os and 192Os/190Os were determined by ICP-MS.Bitumen samples in lead-zinc deposits from Yunnan Province were analyzed.The isochron ages was（60±2） Ma（MSWD=2.5,n=7）,and the initial 187Os/188Os values was 4.36±0.14.The results show that Re-Os isotope is an effective tool to date bitumen samples and the Os in the bitumen originated from the crust.The established method can be used to date and trace the source of bitumen samples.
出处
《岩矿测试》
CAS
CSCD
北大核心
2011年第6期688-694,共7页
Rock and Mineral Analysis
基金
“深部探测技术与实验研究”专项--南岭成矿带地壳岩浆系统结构探测实验(SinoProbe-03-01)
国土资源地质大调查项目--全国重要矿产区域成矿规律研究(1212010633903),国土资源地质大调查项目--全国危机矿山“桂东粤西地区铅锌金等矿床成矿规律总结研究”(20089946)
