云南安宁盆地上侏罗统含盐系中粘土矿物特征及其环境意义

粘土矿物在安宁盆地含盐系中分布很广。其矿物学、结晶学及地球化学特征与成盐环境和成盐作用密切相关。石盐层序中主要含伊利石;硫酸盐层序中,除伊利石外尚有绿泥石及绿/蒙混层矿物。这是由于不同盐类沉积阶段,卤水浓度、成分及pH值不同所致。在结构上,粘土矿物以三八面体型组合为特征（伊利石除外）,反映了成盐盆地中相对富Mg²⁺的特点。此外,粘土矿物中硼和钾的含量远高于非盐系地层,因为这些元素在盐盆地中均得到了蒸发浓集。显然,粘土矿物的上述特征,很好地反映了蒸发环境的具体特点,具有良好的指相意义。

CHARACTERISTICS AND ENYIRONMENTAL SIGNIFICANCE OF THE CLAY MINERALS WITHIN THE UPPER JURASSIC SALT-BEARING SERIES IN THE ANNING BASIN,YUNNAN PROVINCE

Clay minerals are widely distributed in the salt-bearing series in the Arming basin. Their mineralogic, crystallographic and geochemical characteristics are closely related to evaporative environments and sal-concentrating processes. Halite-bearing sequences dominantly contain illite, and sulphate-bearing ones contain some chlorite and mixed-layer chlorite-montmorillonites as well as illite, as a result of changes of compositions, concentrations and the pH ratios of brines at different evolution stages. The clay minerals (except illite) here are charac terized by trioctahedral clay associations, reflecting that the basin is richer in cation Mg2 . In addition, the clay minerals contain much more Boron and Potash than in non-evaporite beds, because these elements had ever concentrated in the evaporative basin. Therefore, the characteristics of the clay minerals showing above can well reflect the features of evaporative environments.