关键词: 锰银矿, 稀土元素, Ce, Eu异常, 稀土分馏

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