Element Geochemical Micro-areas Analysis of Sandstone Reticulated and Its Indicative Significance
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摘要: 【目的】中国南方网纹红土是第四纪环境变化的良好地质载体,但目前对基岩网纹化的微观研究较少,不利于全面认识网纹化。【方法】通过微区分析技术、地统计、因子分析等方法,对郎溪剖面基岩层和网纹层白色网纹微区进行了元素地球化学分析。【结果】1)砂岩白色网纹微区元素含量:Fe2O3(1.14~13.29%),Mn(87×10-6~3230×10-6)等铁族元素呈现从白色网纹中心向边缘增加的趋势,而其他常量元素及Ti(1294×10-6~2454×10-6)、Zr(171×10-6~197×10-6)等稳定性元素含量的空间分布趋势则与其相反。基岩层元素含量空间分布与网纹层基本一致。2)通过聚类分析和散点图将Ti/Zr(基岩层:7.23~12.89;网纹层:12.82~21.84)和Ti/Al2O3(基岩层:0.013~0.018;网纹层:0.044~0.062)划分为两个组群,二者具有不同的了物源;3)基岩层(CIA:86.37%~87.49%; SA:5.23~5.76)风化程度略高于网纹层(CIA:85.10%~86.07%; SA:6.91~8.16),基岩微区内部Al2O3(17.3%)、Fe2O3(73.91%)、MnO(76.68%)等元素和网纹层微区内部Al2O3(15.78%)、Fe2O3(70.39%)和MnO(74.84%)等元素淋溶强度均呈现从白色网纹中心向边缘降低的趋势;4)基岩层和网纹层的白色网纹微区皆以因子1为主,主要体现铁和铁族元素等在白色网纹中的淋溶迁移,以及Al2O3、SiO2、K2O等常量元素和Ti、Zr等稳定性元素的相对富集过程。【结论】基岩层和网纹层白色网纹内部组成物质都是非空间均质的,网纹化过程都是从中心向外围扩展的空间过程。网纹化过程中皆以铁和铁族元素的淋溶占主导,但其他元素也存在一定的迁出,主要表现为网纹中心淋溶强而外围淋溶相对较弱的空间特征,两者的网纹化过程较为相似。Abstract: [Objective]The reticulated laterite in southern China is a good geological carrier for Quaternary environmental changes, but there is currently relatively little microscopic research on bedrock reticulation,Not conducive to a comprehensive understanding of reticulation [Methods]Through micro-area analysis techniques, geostatistical and factor analysis, and other methods to conducted elemental geochemical analysis on the white vein micro-area of the bedrock and variegated?horizon in the Langxi profile. [Results]1) Element content in the white vein micro-area of sandstone: The content of iron group elements such as Fe2O3 (1.14-13.29%) and Mn (87×10-6 -3230×10-6) showed a trend of increasing from the center of the white veins to the periphery. However, the spatial distribution of other major elements and stable elements such as Ti (1294×10-6~ 2454×10-6) and Zr (171 ×10-6~ 197×10-6) showed the opposite trend. The spatial distribution of element content in the bedrock layer is basically consistent with that of the variegated?horizon. 2) Ti/Zr (bedrock layer: 7.23-12.89; reticulated layer: 12.82-21.84) and Ti/Al2O3 (bedrock layer: 0.013-0.018; reticulated layer: 0.044-0.062) were divided into two groups through cluster analysis and scatter plot.They have different provenance 3) The weathering of the bedrock layer (CIA: 86.37%~87.49%; SA: 5.23~5.76) is slightly higher than that of the variegated?horizon (CIA: 85.10%~86.07%; SA: 6.91~8.16;). The leaching intensity of elements such as Al2O3 (17.3%)、 Fe2O3 (73.91%) and MnO (76.68%)in the bedrock white vein micro-area and Al2O3 (15.78%) 、Fe2O3 (70.39%) and MnO (74.84%) in the variegated?horizon white vein micro-area showed a trend of decreasing from the center of the white veins to the periphery. 4) The common feature of factors in the white vein micro-area of the bedrock layer and the reticulated layer is that they are mainly factor 1, which reflects the leaching migration of iron and iron group elements in the white vein, as well as the relative enrichment process of constant elements such asAl2O3、SiO2and K2O and stable elements such as Ti and Zr. [Conclusion] The composition of the white reticulated interior of the bedrock layer and the variegated?horizon are non-spatially homogeneous, and the process of reticulation is a spatial process that extends from the center to the periphery.During reticulation, the leaching of iron and iron group elements dominates, but other elements also have a certain degree of migration, mainly characterized by strong leaching at the center of the reticulation and relatively weak leaching at the periphery. The reticulation process of the two is quite similar.
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Key words:
- reticular red clay /
- bedrock layer /
- variegated?horizon /
- micro-area analysis /
- reticulated mechanism
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