College of Earth Sciences, Jilin University, Changchun 130026, China

In order to further understand the ore characteristics and metallogenic age of Yuanjiacun iron deposit in Shanxi,the mineral composition characteristics of iron ore were studied on the basis of field investigation and microscopic observation.Magnetite,hematite,goethite and pyrite of different stages were identified according to their texture and structure features.Two sets of ²⁰⁷Pb/²⁰⁶Pb ages have been obtained by ICPMS isotope dating of magnetite quartzite,of which the zircon age with metamorphic origin is 1 916 ±88 Ma,representing the main metamorphic age of iron deposit.Another group of magmatic zircons with rhythmic zones are of 2 280 ±30 Ma age,representing the diagenetic age of iron formation.In addition,scattered age records after metamorphism in-dicate frequent hydrothermal events after mineralization.Based on the mineral fabric characteristics and the age data of zircons of different origins,it is known that the deposit has undergone sedimentary mineralization peri-od,metamorphic mineralization period,hydrothermal mineralization period and weathering mineralization peri-od.