黑龙江省黑河市争光金矿流体包裹体研究及矿床成因

Fluid inclusion constraints on the origin of the Zhengguang gold deposit, Heihe City, Heilongjiang Province

黑龙江省黑河市争光金矿床位于大兴安岭东北缘的多宝山矿集区,矿体呈脉状产于闪长岩体与中奥陶统多宝山组凝灰岩的接触带,受断裂构造控制。流体成矿作用可分为4个阶段:石英-黄铁矿阶段、石英-多金属硫化物阶段、方解石-石英-硫化物阶段、碳酸盐阶段。其中阶段2和3具有复杂的金属硫化物组合并含金,即黄铁矿-闪锌矿-方铅矿-黄铜矿±自然金。石英及方解石中流体包裹体类型单一,主要为气液两相水溶液包裹体,大小集中于3～15μm,气液相比集中于5%～10%。包裹体均一温度介于119～305℃,盐度集中于0.3%～10.4%NaCleqv,密度介于0.76～0.99g/cm3。从阶段2至阶段4,流体均一温度从150～220℃,经140～190℃,降为130～150℃。综合矿床地质特征和成矿流体研究,认为争光金矿床属低硫型浅成低温热液矿床。

The Zhengguang gold deposit, Heihe City, Heilongjiang Province, is located in the Duobaoshan metallogenic belt in the northeastern Great Hinggan Range. The Au-bearing veins occur in the contact zone between diorite pluton and the Middle Ordovician Duobaoshan Formation, and are controlled by faults. Hydrothermal mineralization can be divided into four stages, i.e., quartz-pyrite stage （1）, quartz-polymetallic sulfide stage （2）, calcite-quartz-polymetallic sulfide stage （3） and carbonate stage （4）, with stages 2 and 3 as the main Au mineralization stages and characterized by complicated metallic mineral assemblage of pyrite-sphalerite-galena-chalcopyrite±native gold. Fluid inclusions in quartz and calcite are aqueous （NaCl-H2O） inclusions and 3-15μm in size, with bubbles accounting for 5vol%-10vol%. These inclusions yield total homogeneous temperatures of 119-305℃, salinities of 0.3%-10.4% NaCleqv, and densities of 0.76-0.99g/cm^3. The homogeneous temperatures of fluid inclusions decrease gradually, from 150-220℃ at stage 2, through 140-190℃ at stage 3, to 130-150℃ at stage 4. Based on the geological and fluid inclusion features, we conclude that the Zhengguang deposit is a typical low sulfidation epithermal deposit.