西天山阿希浅成低温热液金矿床剥蚀改造过程探讨

阿希金矿床是新疆西天山成矿带上与晚古生代火山岩有关的典型浅成低温热液型金矿床。矿区包括热液成因和沉积成因2种类型的金矿体。其中，热液成因金矿体明显受近南北向断裂控制，并遭受一定的剥蚀改造，矿体空间形态变化特征及黄铁矿热电性标型特征显示矿床南段比北段剥蚀程度高，矿体金品位和厚度质量参数空间分布特征显示矿体具有向北侧伏特征；沉积底砾岩型金矿体角度不整合于热液成因矿体之上，其含矿砾石类型和稀土元素分布特征与热液型矿体基本一致，为热液型矿体遭受剥蚀并在北东部阿恰勒河组中沉积的产物。基于以上认识，并结合矿床的形成、产状变化特征、区域构造地质演化等资料的深入分析，建立了阿希浅成低温热液型金矿床的剥蚀改造模式。

Erosion and post-mineralization change of Axi epithermal gold deposit in Western Tianshan Mountains

Located in the Western Tianshan metallogenic belt, the Axi gold deposit is a large-size volcanics-related epithermal gold deposit formed in Late Paleozoic. Two genetic types of orebodies occur in the gold ore district, i.e., hydrothermal and sedimentary ones. The hydrothermal orebodies are controlled strictly by the NS-tren-ding fault and have suffered some denudation, and the characteristics of morphology and spatial distribution of these orebodies as well as the typomorphic features of pyrites suggest that the southern part has experienced deeper denudation than the northern part; in addition, the spatial distribution of the grade and thickness shows that the deposit pitches northward. The sedimentary orebody, with highly similar types and REE characteristics of mineralized gravels, shows angular unconformity with the hydrothermal orebody, suggesting that it resulted from the erosion and later deposition in the Aqialehe Formation. Based on these recognitions as well as further study of the deposit formation and structural evolution, the authors constructed a new dynamic model of subduction erosion and post-mineralization change for the Axi epithermal gold deposit.