摘要
陕西青木川—苍社地区位于勉略宁三角区的南带,区内金的矿化类型有蚀变岩型、石英脉型及磁铁石英岩型等。金矿体均赋存于碧口群地层中,其空间定位和富集严格受N E和N E E向韧性剪切带的控制。对该成矿带旧房梁、小燕子沟、金厂沟及火峰垭金矿的流体包裹体、硫同位素及稀土元素进行分析。研究结果表明：含金石英脉中仅见富液相水溶液包裹体,其均一温度集中在1 8 0～3 4 0℃之间,盐度（质量分数）一般小于5%,成矿流体属中温低盐度的N a C l-H2O体系,成矿压力范围峰值为4 5～8 5 M P a,成矿深度较浅,达1.6 7～3.1 5 k m,可能代表韧性剪切带中浅部脆性变形域中的矿化。不同类型矿石的稀土配分模式与其围岩极为相似,暗示成矿流体和成矿物质来源可能来自地层。金矿石中黄铁矿的硫同位素组成一般为负值,均接近陨石硫,暗示成矿物质可能来源为碧口群地层。该区韧性剪切带型金矿中不同类型的金矿化在同一矿床中叠加出现可能与矿化形成过程中韧性剪切带不断被抬升剥蚀有关。
Various gold mineralization including altered rock type, gold bearing quartz vein type and magnetite-quartzite type were discovered in the Qingmuchuan-Cangshe area in the south of the Mian-Lue-Ning triangle region. These ore bodies are all enveloped in the Bikou group stratum and their distribution are strictly controlled by the NE and NEE trending ductile shear zone. Fluid inclusion, sulfur isotope and rare earth elements characteristics of Jiufangliang, Xiaoyanzigou, Jinchanggou and Huofengya gold deposits located in this area were studied. Only liquid rich inclusions were observed in gold bearing quartz veins. The results indicate that fluid inclusions are mainly homogenized between 180 ~C and 340 ~C with salinity generally lower than 5% （mass fraction）, implying the ore-forming fluid belongs to the NaC1-H20 system. Calculated ore-forming pressure is 45-85 MPa, corresponding to a lithostatic depth of 1.67-3.15 km, implying a shallow ore forming circumstance probably represents the mineralization developed in the brittle fracture of the ductile shear zone. REE patterns of different ore types are similar to their surrounding wall rocks, suggesting the ore-forming fluid and sources are derived from the stratum. Sulfur isotopic compositions of pyrite in the ores are negative and are close to aerolite, indicating the ore forming source has a stratum origin. Different gold mineralization types superimposed occur in the ductile shear zone of the same deposit probably resulted from the continuous uplifting and erosion during ductile shear zones forming.
出处
《中南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2015年第3期1082-1093,共12页
Journal of Central South University:Science and Technology
基金
陕西省地质矿产勘查开发局地质勘查及科研专项基金项目(陕地财发[2009]34号)~~
关键词
韧性剪切带
矿床地球化学
金矿床
青木川—苍社
陕西省
ductile shear zone
deposit geochemistry
gold deposit
Qingmuchuan-Cangshe area
Shaanxi Province
