四川成都盆地某深层富钾卤水的地球化学特征及成因

Geochemical Characteristics of Deep Formation Brine,Leikoupo Formation of Middle Triassic Sichuan Province

本文报道了四川成都盆地某深层富钾层卤水的化学组成，氧、氢、硫和硼同位素组成以及２５℃等温蒸发析盐过程中，从卤水中获得的固相物质组成。在此基础上讨论了卤水的成因，认为该卤水是蒸发浓缩的海相卤水、非海相卤水以及埋藏成岩过程中封存卤水对地层中海相蒸发盐溶滤作用形成的混合水。

A kind of deep formation brine,very rich in potassium, boron and bromine,with reservoir depth of 4 300 m approximately,was found in the strata of Leikoupo Formation,Middle Triassic,Sichuan Province.The content of K + in this brine is about 50 g/L,Na + more than 92 g/L,B 2O 3 more than 12 g/L,Br - more than 2.36 g/L ,and I + about 0.030 g/L.It has very high value economically and scientifically.The solid phase from evaporating of this brine at 25℃ includes KB 5O 8·4H 2O,K 2B 4O 7·3H 2O,MgCl 2·6H 2O and KMgCl 3·6H 2O.The δ 18 O of this brine is from 2.2‰ to 2.8‰(SMOW),δD from -38‰ to -53‰(SMOW),δ 34 S 15.6‰,and δ 13 B from 13.5‰ to 15.1‰.Based on these geochemical characters,specially isotope of boron,it is suggested that composition of the brine consists of marine brines from middle Triassic,nonmarine brines from Upper Triassic and the dissolution of marine evaporites in burial strata of Middle Triassic.