GEOCHEMISTRY AND MICROFABRIC OF OOLITIC IRONSTONE IN THE XUANLONG AREA OF HEBEI PROVINCE, NORTHERN CHINA

摘要

Xuanlong-type Iron Formation distributes in Xuanhua and Longguan area of Hebei province, northern China. As the oldest depositional iron deposit, it is characterized by oolitice and stromatolitic ironstone. SEM ((scanning electron microscopy) and EMPA (electron microprobe analysis) show that most Ferruginous oolids are composed of continuous and concentric sheaths (cortices) which are made up of Dark and light layers. These layers are made of flakes, platelets, and granules of hematite or siderite and Show large variation in major oxide compositions, especially in FeO and SiO_2 contents.