大气降水量对成矿流体热场的影响——以锡矿山锑矿床成矿流体为例

成矿流体热场直接影响矿床的成矿作用.依据湘中盆地的水文地质特征, 以锡矿山锑矿床成矿流体为例, 利用热-重力驱动型流体运移模型, 选择具有代表性的龙山岳坪峰-锡矿山(AB)剖面, 研究大气年降水量的大小对成矿流体热场的影响.首先选取一个对比降水量1200 mm/a, 计算出区域的温度场分布, 然后分别取年平均大气降水量为600、1800和2400 mm/a与对比降水量的温度场进行对比, 得出2种温度场的差值图.模拟结果表明: 大气降水的水量大小对区域流场影响较大, 而对区域温度场的影响不大, 在不同降水量条件下, 其对温度的影响在5%~20%之间.研究结论认为, 大气降水量对成矿流体的热场影响不大. 

Effect of Annual Precipitation to Geotherm of Ore-Forming Fluid: A Case of Antimony Deposits in Xikuangshan

The geotherm of ore-forming fluid affects ore formation directly. This article studies the effect of annual precipitation on the geotherm of ore-forming fluid, according to the geohydrologic conditions of the central Hunan basin. Ore-forming fluid in antimony deposits in Xikuangshan was taken as an example and a representative section of Xikuangshan-Yuepingfeng was chosen. Heat and gravity driven modes of fluid movement were considered. A contrastive rainfall Q=1 200 mm/a was chosen, the distribution of the area temperature field was calculated, and the difference of two temperature fields was obtained by taking the annual precipitation of 600 mm/a, 1 800 mm/a and 2 400 mm/a compared with the temperature field of the contrastive rainfall. The simulation result shows that precipitation affects the fluid field more than the temperature field. The effect of precipitation on the temperature stays between 5%-20%. The effect of precipitation on the geotherm of ore-forming fluid is negligible.