南海北部湾海绿石的研究

样品产于南海北部湾滨岸浅滩胶结较松散的长石石英砂岩中,属于上第三系下洋组。本文从海绿石形态、矿物的物理化学测试结果以及形成介质条件等方面,探讨该区海绿石特征和形成环境。

STUDY OF GLAUCONITES FROM BEIBU BAY OF THE SOUTH CHINA SEA

This paper deals mainly with the mineralogy of glauconites from the fine-grained feldspar-quartz sandstones of Xiayang Formation of Neogene in the Beibu bay of the South China Sea.According to the shape, the glauconites of these regions can be divided into three groups as follow spherulitic, irregular granular and irregular cement-like glauconites. The internal microstmctures of the crystals can be distinguished in two classes microcrystalline and fine flaky microcrystalline.In the light of the characteristics of glauconites and formation condition, the author has the following preliminary recognitions.1. The basic framework of glauconite is of 4M-1Md micaceous structure with a relatively high content of Fe³⁺ and Silicon, Glauconites in this region are hydrous silicates of high iron and silicon content.2. Glauconites are formed under a condition from weak oxidation to oxidation(Eh = 71mv)in a alkaline medium(pH = 9.24).