新疆金坝金矿成矿作用的地质和流体包裹体证据

金坝金矿作为额尔齐斯构造成矿带的典型金矿，人们对其构造蚀变特征、成矿流体演化以及成矿热液来源还缺乏深入研究，区内岩浆活动与金坝金矿之间的关系尚不明确.在矿床地质特征研究基础上，详细分析矿化蚀变特征，使用扫描电镜阴极发光（SEM-CL）分析石英显微结构，通过流体包裹体研究和S-D-O同位素分析对成矿流体和矿质来源进行探讨.区内黄铁矿化、绢云母化、硅化普遍发育，是重要的找矿标志.矿区斜长花岗岩和闪长岩的钻孔样品由矿化中心向外蚀变及矿化逐渐减弱，变化明显.SEM-CL显示石英微结构具有热液石英特征的穿插结构和重结晶结构，表明变形变质作用强烈.热液成矿分为4个阶段:磁铁矿-石英阶段、金-黄铁矿-石英阶段、金-多金属硫化物-石英阶段和石英-碳酸盐化阶段.金坝金矿的流体包裹体多以水溶液包裹体为主，并有CO₂-H₂O包裹体及碳质流体包裹体.成矿温度主峰为260~280 ℃和380~400 ℃，盐度范围在0.88%~13.72% Nacleqv，流体密度为0.90~0.95 g/cm3.表明成矿流体体系为中高温热液、中低盐度、中低密度的H₂O-NaCl-CO₂体系.成矿流体有从中高温富CO₂向低温盐水溶液演化的特点.矿床硫质来源具有深源硫特征.流体包裹体中δD_H2O值为-78.0‰~-80.5‰，成矿溶液的δ18O_H2O值为1.49‰~5.31‰，表明成矿热液流体由成矿早期的岩浆水向晚期成矿流体的大气降水演化. 

The Mineralization of the Jinba Gold Deposit,Xinjiang, China: Evidence from Geology and Fluid Inclusions

Jinba gold deposit is typical of the Ertix tectonic metallogenic belt, however, exsiting studies on its characteristics of tectonic alteration, evolution of ore-forming fluid and the source of hydrothermal fluid are insuffienct and the relationship between magmatic activity and Jinba gold deposit in the area is not clear. We carried out hydrothermal alteration, fluid inclusions and mineral sources based on the study of the geological characteristics of the deposit so as to provide useful information and reference for the genesis, mineralization and prospecting of Jinba gold deposit. It is found that sericitization, pyritization, silicification develop widely, which is an important sign of prospecting. Gold mineralization in the area is closely related to plagioclase granite and diorite, the drilling rock samples show gradual weakening mineralization and alteration from the center to the outside, with significant changes. The interpenetration texture and recrystallized texture characteristics of SEM-CL show that the deformation and metamorphism are very strong. And it has the characteristics of hydrothermal quartz. The hydrothermal mineralization is divided into four mineralization stages:magnetite quartz stage, gold-pyrite-quartz stage, gold-polymetallic sulfide-quartz stage, and quartz-carbonatation stage. Through the study on fluid inclusions, it is confirmed that the types of fluid inclusions in the Jinba gold deposit are:aqueous inclusions (L_H2O-V_CO2), CO₂-H₂O inclusions (L_CO2-L_H2O) and carbonic fluid inclusions. H₂O and CO₂ are the main ore-forming fluids in the gold deposit. There are two homogenization temperature peaks:260-280℃ and 380-400℃, with salinity from 0.88% to 13.72% Nacleqv and density from 0.90 to 0.95 g/cm3, so the fluid characteristics reflect that it is in medium-high temperature, low salinity and low-density environment. The composition of sulfur isotope present the ore-forming materials are derived from the deep crust. The data of δ18O_H2O (1.49‰-5.31‰) and δD_H2O (-78.0‰——80.5‰) suggest that meteoric water involves in the mineralization.