河北宣龙地区铁质包壳粒及其形成的微生物作用

Iron Coated Grains and Microorganic Process in Their Formation from the Xuanlong Area,Hebei Province

通过对宣龙地区“鲕状矿石”的详细镜下切片观察，与叠层石结构、形态和成分的对比，以及稳定同位素和有机地球化学特征分析研究，提出“鲕状矿石”实际上均为微生物成因的铁质包壳粒，并按其形态分为核形石，微生物鲕石、微生物豆石三种类型。对铁质包壳粒的微生物矿化作用也作了初步探讨。

Based on the detailed determination under microscope,the comparison with the texture,shape and composition of iron stromatolites,as well as on the analyses and studies of stable isotopes and organic geochemistry of oolitic ores from the Xuanlong area,the paper proposed preliminarily that oolitic ores actually are coated grains by the formation of microorganisms.They can be divided into oncolites,microorganic oolites and piolites in the terms of shape.Moreover,the paper disscussed the microorganic mineralization of iron coated grains.