安徽省枞阳县马口铁矿床成矿流体特征研究

STUDY ON METALLOGENIC FLUID CHARACTERISTICS OF THE MAKOU IRON ORE DEPOSIT IN ZONGYANG COUNTY, ANHUI PROVINCE

安徽省枞阳县马口铁矿床位于长江中下游成矿带庐枞矿集区内,是区域与正长岩有关的铁铜铀矿床的典型代表。本文在详细野外地质特征观察的基础上,针对马口铁矿床开展了流体包裹体研究工作,明确从主成矿期磁铁矿化阶段至石英硫化物阶段,成矿流体由高温(350~400℃)向中温(220~280℃)演化,但流体的密度(0.8~1.2g/cm^3)及盐度(18~20%)并未发生明显的改变,指示初始流体为高温热液,后期可能无其他来源流体混合。结合前人工作,推断马口铁矿床的形成与黄梅尖岩体分异的岩浆热液活动有关,基底三叠纪膏盐层及原始沉积的铁矿层可能提供了成矿物质。

The Makou iron ore deposit is located in the Lu-Zong ore-concentrated area in the middle and lower reaches of the Yangtze River,which is a typical representative of the iron-copper-uranium deposits related to syenite in the region.Based on the field observation of geological characteristics in detail,a study on fluid inclusions from the deposit was carried out,and it was made clear that from the main metallogenic stage of magnetite formation to quartz-sulfide stage ore-forming fluid evolved from high temperature (350~400℃) to medium temperature (220~280℃),but the density (0.8~1.2g/cm^3) and salinity (18%~ 20%) of the fluid were not obviously changed,indicating that the initial fluid was high- temperature hydrothermal solution, which was not mixed late with other sources of fluids.Based on the previous work,it is concluded that the formation of the Makou iron ore deposit is related to the magmatic hydrothermal activity of the Huangmeijian rock mass differentiation,and the basement Triassic gypsum-salt layer and the original sedimentary iron ore layer may provide metallogenic materials.