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湘西、桂北地区晚震旦世沉积了一大套层状硅岩。岩石由泥晶—微晶石英组成,几乎不含其他矿物。SiO_2含量介于92.64％～97.17％之间,平均95.29％,其他氧化物含量绝对值均很低,但Fe_2O_3、FeO、MnO含量相对富集,而Al_2O_3、TiO_2、MgO含量相对贫乏。岩石富含Ba、As、Sb、Ag、U等微量元素,其平均含量分别是地壳克拉克值的21.2、5.2、47.5、18.6、3.3倍,而其他元素平均含量均低于其地壳克拉克值。上述元素地球化学特征表明组成岩石的硅质矿物来源于热水。Fe/Ti、(Te+Mn)/Ti、Al(Al+Fe+Mn)及U/Th比值分别介于67～202、73～215、0.07～0.25、34.9～2.6之间,平均值分别为112、
In western Hunan and northern Guangxi, a large number of layered siliceous rocks were deposited in the late Sinian. The rock is composed of clay-microcrystalline quartz with almost no other minerals. The content of SiO_2 is between 92.64% and 97.17% with an average of 95.29%. The absolute values of other oxides are very low. However, the contents of Fe_2O_3, FeO and MnO are relatively rich while the contents of Al_2O_3, TiO_2 and MgO are relatively poor. The rocks are rich in trace elements such as Ba, As, Sb, Ag and U with the average contents of 21.2, 5.2, 47.5, 18.6 and 3.3 times of the crustal Carat values, while the average contents of other elements are lower than the crustal Carat values. The above elemental geochemical characteristics indicate that the siliceous minerals that make up the rock come from hot water. The ratios of Fe / Ti, (Te + Mn) / Ti, Al (Al + Fe + Mn) and U / Th ranged from 67 to 202,73 to 215,0.07 to 0.25,34.9 to 2.6, 112,