内蒙古乌奴耳铅锌银钼矿床蚀变矿物分带及原生晕特征

Zonation of Alteration Mineral and Primary Halo in the Wunuer Pb-Zn-Ag-Mo Ore Deposit, Inner Mongolia, NE China

乌奴耳矿床位于内蒙古东部大兴安岭造山带中段中生代火山岩覆盖区,为近年来新发现的陆相火山岩型多金属矿床.为了对该矿区的进一步深部找矿勘查工作提供围岩蚀变和岩石地球化学信息,对乌奴耳矿床进行了详细的野外地质特征研究、岩石蚀变分带研究和原生晕研究.乌奴耳矿床中存在多期多阶段矿化特征:第1阶段斑岩型钼矿化,主要产于矿床深部的花岗斑岩体内;第2阶段岩浆热液(隐爆角砾岩)型铅锌矿化,主要产于花岗斑岩体顶部及其附近围岩的隐爆角砾岩中;第3阶段浅成低温热液型铅锌银矿化,主要产于浅部张性断裂构造中.矿区内存在至少两期与成矿关系密切的构造事件,张性断裂构造是重要的控矿因素和找矿标志.乌奴耳矿床中具有明显的围岩蚀变分带特征,蚀变矿物分布与已知矿体产状具有较好的对应关系,是重要的找矿标志之一.岩石原生晕异常分布与已知矿体具有较好的对应关系,具有明显的前缘晕-近矿晕-尾晕元素组合分带特征,能够为乌奴耳矿床深部找矿提供可靠信息.综合以上主要找矿信息特征,预测在乌奴耳矿床II矿段207勘探线剖面深部有盲矿体存在.

The Wunuer ore deposit is a newly found terrestrial volcanic type deposit, which is located in the middle segment of the Great Xing’an range where is covered by Mesozoic volcanic rocks. In order to provide information for deep prospecting and exploration in this area, in this study, detailed field deposit geology, alteration mineral zonation and primary halo of wall rocks in the deposit were studied. There are obvious multi-stage mineralization characteristics in the Wunuer deposit, including(1) the first stage porphyry type molybdenum mineralization, which mainly occurs in the apical portion of the granite porphyry deep in the deposit;(2) the second stage magmatic hydrothermal fluid(cryptoexplosive breccia) type lead-zinc mineralization, which mainly occurs in cryptoexplosive breccia in the apical portion of the granite porphyry and surrounding wall rocks;(3) the third stage epithermal type lead-zinc-silver mineralization, which mainly occurs in fractures hosted by wall rock in shallow. We have identified at least two tectonic events closely related to ore forming process, which are important ore-controlling factors and prospecting markers. There is obvious wall rock alteration zone in the Wunuer deposit, and the altered mineral assemblage distribution has a good correspondence with the occurrence of ore body, which is one of the important processing markers. Primary halo anomalies of wall rocks are also well correlated with ore bodies, which show obvious lead-near-tail-halo elements zonation, which can provide reliable information for prospecting in the deep of the Wunuer deposit. Based on the above characteristics of ore prospecting information, it is predicted that there is blind ore body deep in the 207 exploration line in II of the Wunuer deposit.