新疆阿希金矿浅成低温流体特征

The characters of the mineralization fluid of Axi gold deposit in Xinjiang

阿希金矿的成矿分 5个阶段 ,流体成分以K+为主 ,其次是Na+、SO2 - 4、Cl- 、NO- 3 ,Ca2 +和Mg2 +少量。气相成分以H2 O为主 ,其次是CO2 、H2 和O2 。矿化度平均 9 68g/L ,pH为5 7～ 8 8,成矿早期氧逸度为 - 37～ - 38 3,晚期为 - 37～ - 39。温度平均为 173 9℃ ,压力4 16 7× 10 5～ 511× 10 5Pa。流体属于H2 O NaCl CO2 体系 ,来自于大气降水。大气降水渗滤到地下 ,受到来自火山和地温梯度的热力影响 ,形成近地表地下热循环水 ,吸取大量成矿物质 ,构成成矿流体。在lgfO2 —pH图中显示了 2个稳定区间 ,因此 ,阿希金矿应为浅成低温热液型。

The mineralization fluid in Axi gold deposit was divided into five stages. Study on the fluid inclusions shows that the ionic component in fluid was composed of mainly K +, less Na +,SO - 4, Cl - and NO - 3 and minor Ca 2+ and Mg 2+ .The gas component was composed of mainly H 2O, less CO 2, H 2 and O 2. The mineralization fluid with averaging 9 168 g/L in degree of mineralization and with range from 5 7 to 8 8 in pH value, was detected that the lg f O 2 value changed from -37 to-38 3 in early mineralization stage and from -37 to -39 in late. The mineralization mean temperature was 173 9 ℃ and the pressure changed from 416 7×10 5 to 511×10 5 Pa. The fluid was belong to H 2O NaCl CO 2 type system and mainly derived from meteoric water. There were two stable areas in the fluid lg f O 2 pH figure. The Axi gold deposit was supposed to be epithermal deposit.