晚震旦世时,在扬子板块东南大陆边缘地带发育一套层状硅质岩建造,岩石化学成分纯净,SiO2含量在90%以上,其它化学成分含量均很低。但Fe和Mn相对富集,而Al,Ti,Mg相对贫乏。微量元素含量变化大,大部分微量元素含量相对地壳克拉克值偏低,仅U,As,Sb,Ag,Ba等富集。岩石的δ30Si为0.0‰～0.7‰,δ18O为20.2‰～23.6‰,δ30Si和δ18O值及岩石的形成温度清楚地表明组成岩石的二氧化硅矿物来源于热水 Late Nepali period, in the Yangtze plate southeastern continental margin developed a set of layered silicalite rock, pure chemical composition, SiO2 content of 90% or more, other chemical composition content is very low. However, Fe and Mn are relatively enriched while Al, Ti and Mg are relatively scarce. The contents of trace elements vary greatly, and the content of most trace elements is lower than that of the crust, only U, As, Sb, Ag, Ba and so on. The δ30Si of the rocks ranges from 0.0 ‰ to 0.7 ‰ and the δ18O ranges from 20.2 ‰ to 23.6 ‰. The δ30Si and δ18O values ​​and the rock formation temperature clearly show that the silica minerals that make up the rock come from hot water