四川盆地龙女寺储卤构造深层地下卤水的水文地球化学特征及成因

HYDROGEOCHEMICAL CHARACTERISTICS AND FORMATION OF SUBSURFACE BRINES OF DEEP AQUIFERS IN LONGNU TEMPLE BRINE-BEARING STRUCTURE, SICHUAN BASIN

本文将龙女寺储卤构造深层地下卤水与不同浓缩阶段的黄海水两者的化学组分进行比较,以及对不同储卤层卤水之间的化学组分进行比较,结果表明该储卤构造地下卤水以高矿化度和富含Br,I,Sr,Ba等元素为特征,可分为两种类型,即碎屑岩储卤层的Cl NaCa型卤水和碳酸盐岩储卤层的Cl Na型卤水。前者来源于以陆相为主的同生沉积水,泥岩和页岩的隔膜渗滤作用可能对卤水化学组分的富集有着重要的影响;而后者则来源于海相同生沉积残余卤水。

<ABSTRACT> Hydrochemical constituents of subsurface brines in Longnu temple brine-bearing structure are compared with those of Yellow Sea water at different concentrating stages and among different brine-bearing aquifers, from which we can draw a conclusion that brines in this structure are characterized by high TDS and abundant trace elements such as Br. I, Sr, Ba. Two types of brines are identified, which are the CI-Na-Ca type brine in clastic rocks and the CI-Na type brine in carbonate rocks. Brines in clastic aquifers originated mainly from connate continental sedimentary water, and membrane filtration of mudstones and shales have possibly played an important role in the concentration of chemical constituents of the brines. Brines in carbonate aquifers originated from bittern connate marine sedimentary water, their chemical compositions were mainly controlled by precipitation of evaporites.