THE REE CONSTRAINTS ON ORE SOURCES OF THE DONGGOUBA POLYMETALLIC DEPOSIT
DING Zhenju1,LIU Congqiang2,YAO Shuzhen1,ZHOU Zonggui1,YANG Mingguo1 (1. Faculty of Earth Resources, China University of Geosciences, Wuhan430074,China;2. Institute of Geochemistry, CAS, Guiyang550002,China)
REE geochemistry method has been used to trace the resources of the oreforming materials in the Donggouba polymetallic deposit. The REE contents of the ores and its host rocks were analyzed respectively and the ores have apparent positive Eu and weak Ce negative anomalies in the chondrite- normalized REE distribution patterns of the ores, indicating the oreforming hydrothermal fluids had a high temperature (greater than 250℃) and were relatively reductive. The coexistence of both apparent positive Eu anomalies and weak negative Ce anomalies in the ores indicate the convectively mixing of hydrothermal fluids with a small amount of seawater when the ores were precipitated on ancient seafloor. The REE distribution patterns of ores are similar to those of the host rocks on the whole except for Eu and Ce, which implicates the oreforming metallic elements came mainly from the volcanic rocks of the Douba Group. The presence of large amount of barite, the enriched LREE and apparent positive Eu anomaly and weak negative Ce anomaly suggests that the SO2-4 were a dominant anion in the oreforming fluid and was related to a degassing processes of magmatic components.