ELEMENT GEOCHEMISTRY OF QIDASHAN IRON DEPOSIT IN LIAONING PROVINCE

The Qidashan iron deposit is tectonically located in western Liaodong anteklise of North China Platform, with iron ore layers hosted in the Yingtaoyuan Formation of Anshan Group. The ore-bearing formation is sandy mudstonemudstone (Algoma type), with metamorphic facies of greenschist. By study on the REE geochemistry of ores and wall rocks, the REE patterns show enrichment of LREE in the ores with LREE/HREE of 3.43, whereas slight depletion of HREE in the wall rocks with LREE/HREE of 0.97. The primitive mantle-normalized REE spiderdiagram shows weak positive anomalies of Eu (δEu=1.03-1.50), without anomalies of Ce (δCe=0.54-1.15) in iron ores, which is consistent with the characteristics of submarine exhalative sedimentation. There is no significant anomalies of Eu (average δEu 1.16) and Ce (δCe=0.18-1.01) in the wall rocks. The features above suggest that the iron deposit should be the product of marine chemical deposition in Early Precambrian in the tectonic background of oceanic island arc and provenance type of uncut magmatic arc.