| 湖相碳酸盐岩元素测试方法研究 |
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| 引用本文： | 贾文博,关平,刘沛显,于川淇,庞磊.湖相碳酸盐岩元素测试方法研究[J].沉积学报,2018,36(4):842-852. |
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| 作者姓名： | 贾文博 关平 刘沛显 于川淇 庞磊 |
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| 作者单位： | 北京大学造山带与地壳演化教育部重点实验室, 北京大学地球与空间科学学院, 北京 100871 |
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| 基金项目： | 国家重点基础研究发展计划(973 计划)项目(2012CB214801) |
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| 摘 要： | 湖相碳酸盐岩因形成于大陆环境，通常陆源硅酸盐组分含量较高并影响元素组成特征，不应简单地套用海相碳酸盐岩的方法进行元素测试。对柴西茫东地区红山梁剖面始新统下干柴沟组-中新统下油砂山组湖相碳酸盐岩采用酸溶法、电子探针、LA等多手段进行的地球化学综合研究，结果显示，各种测试方法应用于湖相碳酸盐岩分析时都存在适用性与局限性问题。酸溶法的局限性在于所获得的K等碱金属元素含量不能用于后续分析。而对微区测试方法而言，首先LA与探针两种微区测试方法能否进行数据上的通用需要比较二者的相关性；其次由于光斑大小的限制，对泥晶组分而言，需在判断陆源的干扰程度并进行相应扣除后，才能反映沉积水体的元素组成特征。因此，在分析陆源硅酸盐组分对湖相碳酸盐岩元素含量影响程度的基础上，提出两种排除陆源硅酸盐组分对泥晶组分元素含量影响的方法，可以实现微区测试方法在湖相碳酸盐岩中的有效应用。
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| 关 键 词： | 柴达木盆地 新生代 湖相碳酸盐岩 陆源硅酸盐组分 地球化学 |
| 收稿时间： | 2017-03-14 |
Study on the Testing Method for Elemental Composition of Lacustrine Carbonates |
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| JIA WenBo,GUAN Ping,LIU PeiXian,YU ChuanQi,PANG Lei.Study on the Testing Method for Elemental Composition of Lacustrine Carbonates[J].Acta Sedimentologica Sinica,2018,36(4):842-852. |
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| Authors: | JIA WenBo GUAN Ping LIU PeiXian YU ChuanQi PANG Lei |
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| Institution: | MOE Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing 100871, China |
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| Abstract: | Lacustrine carbonates are formed in continental environments, normally containing high content of terrestrial silicate component that may affect their elemental composition and also the measuring results. Thus, many methods commonly used for marine carbonates, such as acid-soluble method, Electron Probe Microanalysis (EPMA) and Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) can not simply be used for lacustrine carbonates. Lacustrine carbonates are widely developed in the Tertiary strata of the Qaidam Basin and provide very suitable materials for the study to select suitable methods. By means of comprehensive geochemical study on the lacustrine carbonates, which spread from Xiaganchaigou Formation to Xiayoushashan formation of the Hongshanliang section in Mangdong area, the south area of western Qaidam Basin, the limitation of each method was investigated and their related influence was also discussed for the geochemical characteristics of lacustrine carbonates by terrestrial silicate components. For examples, the limitation of acid-soluble method is the testing results of alkali metals such as K non-suitable for subsequent analysis, which may come from acid-dissolving process. For the micro-area test method including EPMA and LA, there are two limitations. Firstly, the data by LA and EPMA can be used only when the results using these two methods have some correlation and relatively small errors. Secondly, the testing results can not be used directly for the lacustrine carbonates with muddy components including a large degree of terrestrial silicate component. This limitation can be explained by the relative size of the sampled spot and the mineral particle. When the sampled spot size is larger than the mineral particle, the testing results will be mixed and interfaced with surrounding components. As a result, the muddy portion may represent the characteristics of sedimentary water only by excluding terrestrial interference. Based on the analysis for the effect of terrestrial silicate components on the geochemical characteristics of lacustrine carbonates, we proposed two possible ways to exclude terrestrial effects. The first one is selecting baseline and screening, and the other one is calculating by reverse deduction. |
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