东营沙四段古盐度对碳酸盐岩沉积的控制作用

摘要

We make the content of Boron and the ratio of Sr/Ba、Sr/Ca the target,and calculate the palaeosalinity values of sedimentation epoch in Sha 4 of the south slope in Dongying Depression.The palaeosalinity in vertical direction totally decreases from down to up.The palaeosalinity is higher in early stage of lake invading and becomes lower in later stage.The east is relatively higher in plane and the north is lower.The distribution of palaeosalinity is controlled by palaeowater-depth.The palaeosalinity controls different types of carbonate rock and the palaeosalinity limits is in 10.0 ‰ ～35.0 ‰.The dolomite is mainly distributed in the area with palaeosalinity higher than 15.0 ‰ while the limestone is mainly distributes in the area lower than 20.0 ‰.The high salinity of water supplies the material base and media condition for the dolomite formation and dolomitic diagenetic change.In the area of high salinity the the primary deposition is dolomite,or formed limestone the dolomitisation,the limestone deposition is primary in the area of low salinity.%以硼含量以及Sr/Ba、Sr/Ca作为指标,计算了东营凹陷南坡沙四段各个沉积时期的古盐度值,盐度垂向上由下到上总体上变小,即湖侵初期盐度较高,湖侵后期盐度变低；平面上东部较高,北部较低,盐度分布受到古水深的控制.古盐度对不同类型的碳酸盐岩具有控制作用,碳酸盐岩所要求的古盐度范围为10.0‰～35.0‰,其中白云岩主要分布在古盐度大于15.0‰的区域,石灰岩主要分布在古盐度小于20.0‰的区域.水体的高盐度为白云岩的形成及成岩转化提供了物质基础和介质条件,在古盐度较高的区域以白云岩沉积为主,或者将已经形成的石灰岩白云岩化；在古盐度较低的区域以石灰岩沉积为主.