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从岩石学、矿物学、地球化学等方面研究总结秦岭凤太地区泥盆纪硅质铁白云岩 -硅质岩的地质地球化学特征。硅质岩类中 ,Si O2 >80 % ,(Fe O+Fe2 O3+Mg O ) <10 % ;硅质铁白云岩类中 ,Si O2 为 30 %～ 5 0 % ,(Fe O +Fe2 O3+Mg O)大于2 0 %。提出该类热水沉积岩由热水同生沉积作用、热水混合同生沉积作用、热水同生沉积交代作用、热水爆炸 -液压致裂作用及热水充填 -交代作用形成
From the aspects of petrology, mineralogy and geochemistry, the geochemical characteristics of Devonian siliceous iron dolomite-siliceous rock in Fengtai area of Qinling Mountains are summarized. In the siliceous rocks, Si O 2> 80%, (Fe O + Fe 2 O 3 + Mg O) <10%; Si 2 O 3 is 30% ~ 50% in the siliceous iron dolomites, + Mg O) is greater than 20%. It is suggested that this kind of hydrothermal sedimentary rocks should be formed by syngenetic deposition of hot water, syngenetic deposition of hot water, sedimentary deposition of hot water, hydrothermal explosion-hydrofracturing and hot-water filling-metasomatism