秦岭泥盆系成矿带内很多矿床中都产硅质岩，这些硅质岩是泥盆纪沉积柱中的重要组成部分。他们的硅（δ３０Ｓｉ为－０．０５％～－０．０１％）、氧（δ１８Ｏ为１．８６％～２．０９％）同位素组成指示了其海底热液沉积成因方式；微晶石英沉淀的介质温度（８２．１～９４．８℃）高于正常海水温度；随热液沉积演化，硅、氧同位素均向重同位素方向产生动力学分馏；硅质岩层底盘硅化体是热液沉积时的同生蚀变产物，两者硅质同源，硅质岩中的石英脉或团块则是沉积期后硅质岩本身ＳｉＯ２活化产物。 Many of the deposits in the Devonian metallogenic belt of the Qinling Mountains produce siliceous rocks, which are an important part of the Devonian sedimentary column. Their isotopic compositions of silicon (δ30Si -0.05% -0.01%) and oxygen (δ18O 1.86% -2.09%) indicate the origin of the seafloor hydrothermal sedimentary pattern. The microcrystalline quartz precipitated The temperature of medium (82.1-94.8 ℃) is higher than that of normal seawater. With the evolution of hydrothermal deposits, both silicon and oxygen isotopes are kinetic fractionated toward heavy isotopes. The same alteration products, the two are silicic, the quartz veins or clumps in the chert are the SiO2 activation products of the chert hematite after the sedimentary period.