Abstract: Xiaokouhuaying silver-manganese deposit, which exists in the volcanic rock of late Jurassic and relates to the granite-porphyry intruded the volcanic rocks, is a typical low temperature epithermal vein-type deposit. The vein, volcanic rock and granite-porphyry all enrich LREE. The REE distribution pattern of volcanic rock is similar to that of granite-porphyry, and the REE distribution pattern of vein is different from that of volcanic rock and granite-porphyry in obviously positive Ce and Eu anomalies and lower extent of HREE enrichment comparing with both of them. The search of the REE pattern illustrates that both volcanic rock and granite-porphyry have a common source. The fractionation of REE occurring in the REE migration and deposition, which due to the leaching and circulation of meteoric water in the volcanic rocks and granite-porphyries, might account for the obvious difference of the REE pattern of the volcanic rocks and granite-porphyry. Comparing with home-rock, the ore-forming hydrothermal solution is rich in Ce, Eu, Y and HREE. The deposited hydrothermal minerals are richer in Ce and Eu than the solution,and a second fractionation between HREE and LREE occurs during the process of minerals deposition.

Key words: Ag-Mn deposit, REE, Ce, Eu anomalies, fractionation

摘要： 小扣花营锰银矿床是一个浅成低温热液脉状矿床，主要物质成分为石英、碳酸盐和硫化物。矿体的稀土元素分配型式以明显的Ce、Eu正异常区别于容矿的侏罗系陆相火山岩以及矿体附近的花岗斑岩潜火山岩体。研究表明，在大气降水淋滤火山岩和岩体中的稀土元素并使之发生迁移和沉淀的成矿过程中发生的稀土分馏可以解释火山岩和岩体的稀土元素分配型式与矿体的明显差异。稀土元素的淋滤迁移应使热液比母岩相对富集Eu、Ce、Y和HREE；沉淀过程中热液矿物和热液相比应相对富集Eu和Ce，并再次发生轻重稀土的分馏。

关键词: 锰银矿, 稀土元素, Ce, Eu异常, 稀土分馏