南华北盆地上寒武统白云岩岩石学与地球化学特征及其成因探讨

摘要

南华北地区上寒武统白云岩发育,按结构-成因划分为:晶粒白云岩、残余粒屑白云岩及藻(层纹石、叠层石)白云岩等.应用岩石学与地球化学方法,对其成因进行了探讨.晶粒白云岩伴生矿物少,偶见黄铁矿,阴极发光为中-弱橘红色光,Sr含量较低,该种白云岩为埋藏白云岩;残余粒屑白云岩中含有生物碎屑、内碎屑、藻屑等颗粒组分,白云石矿物表面污浊,阴极射线下呈中弱亮度橙红色,锶值低,接近于零,为成岩阶段早-中期浅埋地下混合水潜流带环境生成;藻白云岩具有纹层、藻叠层等构造,白云石细小,阴极射线下暗红褐色,锶值高,反映交代介质仍然是超盐度咸水,为水上蒸发环境下同生—准同生白云岩.%The upper Cambrian dolomite of southern north China basin can be divided into crystalline dolostone,remnant grain dolostone and straticulate dolostone.According to the structure and mechanism,an origin mechanism of upper Cambrian dolomites was studied by petrology and geochemistry method.Crystalline dolostone shows medium-weak jacinth light in cathode luminescence,with low content of Sr,this kind of dolomite is buried dolomite.Remnant grain dolostone contains biological debris,oolitic and calcirudite,which dolomite mineral surface filth,appears weak orange red in cathode ray,Sr close to O,this dolostone resulted from burial and compaction water.Straticulate dolostone resulte from penecontemporary dolostone,which dolomite small,appears dark brown,high Sr content,and in which parallel laminae,bird-eyes and mud-cracks developed.