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| 沉积物中铁氧化物的定量方法及其 在白垩纪大洋红层中的应用 | |
| 引用本文： | 李响,蔡元峰.沉积物中铁氧化物的定量方法及其 在白垩纪大洋红层中的应用[J].高校地质学报,2014,20(3):433. |
| 作者姓名： | 李响 蔡元峰 |
| 作者单位： | 武汉地质调查中心;南京大学地球科学与工程学院;南京大学内生金属矿床成矿机制研究国家重点实验室; |
| 基金项目： | 国家重点基础研究发展项目(2012CB822001);国家青年科学基金项目(41302033)联合资助 |
| 摘 要： | 赤铁矿和针铁矿是自然界中最稳定的两种铁氧化物，广泛存在于地球的各个圈层。很多沉积物的颜色都是由它们引 起的，它们的形成和保存具有重要的环境指示意义。实验室中赤铁矿和针铁矿的表征和鉴定手段很多，但受其含量低、结 晶差、颗粒细小难分离等因素的困扰以及某些测试方法自身的限制，能用于铁氧化物定量分析的方法很少。文中就常用的 基于X射线衍射（XRD） 和漫反射光谱（DRS） 的铁氧化物定量方法进行了系统评价。在定性分析的基础上，采用基于 XRD的K值法获得西藏床得剖面红色页岩中赤铁矿的含量为3.81％~8.11％，采用DRS与多元线性回归相结合的方法获得北 大西洋ODP1049C孔12X岩芯段棕色层中赤铁矿和针铁矿的含量分别为0.13％~0.82％和0.22%~0.81％，橙色层中赤铁矿和 针铁矿的含量分别为0.19%~0.46％和0.29%~0.67％。与其它分析结果的比较表明，这两种定量方法在白垩纪大洋红层中的 应用是可行的。但在实际应用时，首先要通过XRD和DRS相结合来提高定性分析的准确性，然后通过综合分析铁氧化物的 预判含量范围和结晶程度来选择合适的定量方法。 |
| 关 键 词： | 铁氧化物 定量分析 X射线衍射 漫反射光谱 白垩纪大洋红层 |
The Quantitative Analysis Methods for Iron Oxides in Sediment and Their Application in Cretaceous Oceanic Red Beds |
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| LI Xiang,CAI Yuanfeng.The Quantitative Analysis Methods for Iron Oxides in Sediment and Their Application in Cretaceous Oceanic Red Beds[J].Geological Journal of China Universities,2014,20(3):433. | |
| Authors: | LI Xiang CAI Yuanfeng |
| Abstract: | Hematite and goethite are the most stable iron oxides in nature and widely present in different compartments of the global system. They are responsible for the color origin of many types of sediment. In addition, the formation and preservation of hematite and goethite have been used to track palaeoenvironmental information. There are several approaches to characterizing and distinguishing hematite and goethite, but the quantifying of the concentrations of hematite and goethite in natural samples has been restricted by low concentration, relative poor crystalline and fine-grained as well as the limits of specific analysis methods used. In this paper, the most common quantitative methods of hematite and goethite, including X-ray diffraction (XRD) and diffuse reflectance spectroscopy (DRS), have been introduced. Based on the qualitative analysis of the Cretaceous Oceanic Red Beds (CORBs) samples, we used the K-value method to quantify the hematite contents in the red shale samples from the Chuangde section in Tibet and obtained the hematite contents ranging from 3.81% to 8.11%. Analysis using DRS with multiple linear regression was performed to obtain the absolute contents of iron oxides within Aptian-Albian cyclic oceanic red beds in ODP Hole 1049C 12X Core, North Atlantic. The results reveal that the brown beds contain 0.13~0.82% hematite and 0.22~0.81% goethite. The orange beds contain 0.19~0.46% hematite and 0.29~ 0.67% goethite. The comparison of the calculated results with the test data shows that both methods were feasible for the quantitative analysis of iron oxides in CORBs. In actual practice, the accuracy of qualitative analysis of iron oxides must firstly be improved by the combination of XRD with DRS and then the choosing of quantitative analysis method can be achieved through the comprehensive analysis of both the predicted contents and crystalline of iron oxides. |
| Keywords: | iron oxides quantitative analysis X-ray diffraction Diffuse reflectance spectroscopy Cretaceous Oceanic Red Beds |
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