摘要:
提要：蒙古国乌兰铅锌矿与查夫、甲乌拉、查干不拉根铅锌矿共同构成了中蒙克鲁伦—满洲里成矿带铅锌矿矿集区。本文从含矿地层、控矿构造、赋矿岩脉、围岩蚀变特征、矿体特征等方面对该矿床地质特征展开阐述。样品岩石地球化学特征研究结果表明：乌兰铅锌矿容矿围岩为一套中?高硅、中铝、高钾钙碱性火山岩；样品稀土元素总量（∑REE）为412.25×10?6~999.06×10?6，轻重稀土元素分馏明显（（La/Yb）N=4.41~43.10），呈现轻稀土（LREE）富集的右倾趋势，负Eu异常明显（δEu=0.56~0.88）；普遍富集大离子亲石元素（LILE）Ba、Rb、Ce，高场强元素Nb、Ta、Th及Zr，明显亏损Li、Sr、Y等元素。锆石LA-ICP-MS U-Pb同位素分析结果表明，围岩成岩时代为晚侏罗世（（150.8±4.4） Ma~（164.7±3.1） Ma）。初步限定乌兰铅锌矿形成于140~155 Ma期间外贝加尔—大兴安岭转换挤压弧形成之后的裂谷环境，成因类型为受爆破角砾岩控制的浅成热液脉型铅锌矿床。
Abstract:
Abstract: The Ullan lead-zinc deposit in Mongolia, together with Tsav, Jiawula, Chaganbulagen lead-zinc deposits, forms a lead-zinc ore concentration area in the Kerulen-Manchuria metallogenic belt. Geological characteristics of the Ullan deposit were described in the aspects of ore-bearing strata, ore-controlling structure, ore-bearing dike, wall rock alteration and orebody characteristics. Rock geochemical studies show that ore-bearing rocks are calc-alkaline volcanic rocks with medium-high Si, medium-Al and high K. The rocks are enriched in large-ion lithophile elements (Ba, Rb, Ce), high field-strength elements (Nb, Ta, Th), Zr and depleted in Li, Sr, Y, with the data ∑REE=412.25×10?6-999.06×10?6,（La/Yb）N=4.41-43.10 and strong Eu anomalies (δEu=0.56-0.88). Zircon LA-ICPMS U-Pb isotope ages indicate that wall rocks formed in Late Jurassic (from （150.8±4.4） Ma to （164.7±3.1） Ma). The authors also determined that Ullan lead-zinc deposit was formed in a rift setting after the formation of Transbaikal-Da Hinggan Mountains?transpressional?arc in the period of 140-155 Ma and hence belongs to the hypabyssal hydrothermal vein-type deposit controlled by explosion breccia.
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