富有机质沉积岩Re-Os同位素分析方法初探
发布时间：2019-05-19 10:41
【摘要】：富有机质沉积的定年研究在研究古环境、古气候方面具有重大作用,而对于寻找石油以及与沉积有关的金属矿床等更是具有指导意义。但是目前对于富有机质沉积岩年龄的厘定多采用间接的方法,因而常常具有一定的不确定性。Re-Os同位素定年方法是一种可以直接厘定富有机质沉积岩地层年龄的定年方法,但对于Re-Os同位素方法在富有机质沉积岩中的应用,目前还存在着一些技术上的问题。前人研究表明,富有机质沉积岩中反映沉积年龄的Re和Os是赋存在有机质中的,碎屑部分中的Re和Os的混入会影响所得到的Re-Os等时线的准确度和精度。目前最常用的方法是Cr O3-H2SO4溶样法,该方法相比于HCl-HNO3溶样的方法,能尽量避免碎屑物质中Re和Os的溶出,但该方法具有Re流程空白高和环境污染严重等问题。因此,本文尝试在富有机质沉积岩Re-Os同位素定年分析中使用H2O2-HNO3溶样来代替Cr O3-H2SO4溶样。本研究利用国际油页岩标样SGR-1b(USGS)为实验研究对象,对HCl-HNO3溶样、Cr O3-H2SO4溶样和H2O2-HNO3溶样三种溶样方法进行了对比研究。研究表明,H2O2与HNO3的体积比约为5/1的H2O2-HNO3溶液,不仅能保证样品和稀释剂的Re、Os同位素达到同位素交换平衡而且尽可能的避免碎屑物质中Re和Os的溶出。本方法相比于HCl-HNO3溶样,能尽量避免碎屑物质中Re和Os的溶出;而相比于Cr O3-H2SO4溶样,该方法具有本底低、无污染的优点。最后利用H2O2-HNO3溶样方法对广西金秀地区的泥岩样品和广东大宝山地区的炭质页岩样品进行了Re-Os同位素定年分析,分别得到了404±5Ma(IOs=1.57±0.13,n=8,MSWD=50)和211±11Ma(IOs=0.67±0.09,n=5,MSWD=11.1)的等时线年龄,这一结果与HCl-HNO3溶样得到的结果(412±11Ma,IOs=1.18±0.38,n=8,MSWD=311;223±18Ma,IOs=0.59±0.14,n=5,MSWD=63)在误差范围内一致,但更为精确.
[Abstract]:The chronological study of organic deposits plays an important role in the study of paleoclimate and paleoclimate, and is of great significance in the search for oil and sedimentary-related metal deposits. However, at present, indirect methods are often used to determine the age of organic sedimentary rocks, so there is often certain uncertainty. Re-Os isotopic dating method is a direct dating method which can directly determine the formation age of organic sedimentary rocks. However, there are still some technical problems in the application of Re-Os isotopic method in organic sedimentary rocks. Previous studies have shown that Re and Os reflecting sedimentary age in organic sedimentary rocks are present in organic matter, and the mixing of Re and Os in clastic parts will affect the accuracy and accuracy of Re-Os isochron. At present, the most commonly used method is Cr O3-H2SO4 method. Compared with HCl-HNO3 method, this method can avoid the dissolution of Re and Os in clastic materials as far as possible, but this method has some problems, such as high blank of Re process and serious environmental pollution. Therefore, in this paper, H2O2-HNO3 dissolved samples are used instead of Cr O3-H2SO4 in Re-Os isotopic dating analysis of organic sedimentary rocks. In this study, the international oil shale standard sample SGR-1b (USGS) was used as the experimental research object, and three dissolution methods of HCl-HNO3, Cr O3-H2SO4 and H2O2-HNO3 were compared. The results show that the H2O2-HNO3 solution with a volume ratio of H2O2 to HNO3 of about 5 鈮，
本文编号：2480660
[Abstract]:The chronological study of organic deposits plays an important role in the study of paleoclimate and paleoclimate, and is of great significance in the search for oil and sedimentary-related metal deposits. However, at present, indirect methods are often used to determine the age of organic sedimentary rocks, so there is often certain uncertainty. Re-Os isotopic dating method is a direct dating method which can directly determine the formation age of organic sedimentary rocks. However, there are still some technical problems in the application of Re-Os isotopic method in organic sedimentary rocks. Previous studies have shown that Re and Os reflecting sedimentary age in organic sedimentary rocks are present in organic matter, and the mixing of Re and Os in clastic parts will affect the accuracy and accuracy of Re-Os isochron. At present, the most commonly used method is Cr O3-H2SO4 method. Compared with HCl-HNO3 method, this method can avoid the dissolution of Re and Os in clastic materials as far as possible, but this method has some problems, such as high blank of Re process and serious environmental pollution. Therefore, in this paper, H2O2-HNO3 dissolved samples are used instead of Cr O3-H2SO4 in Re-Os isotopic dating analysis of organic sedimentary rocks. In this study, the international oil shale standard sample SGR-1b (USGS) was used as the experimental research object, and three dissolution methods of HCl-HNO3, Cr O3-H2SO4 and H2O2-HNO3 were compared. The results show that the H2O2-HNO3 solution with a volume ratio of H2O2 to HNO3 of about 5 鈮，
本文编号：2480660
本文链接：https://www.wllwen.com/kejilunwen/diqiudizhi/2480660.html
