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新疆吐哈地区有色金属矿山上部氧化带中,发现了一种新的含K硫酸盐矿物-斜钾铁矾(KFe(SO4)2),含K量较高.若能应用40Ar/39Ar法测定该矿物年龄,可以研究该地区干旱化的时间、过程,从而探讨青藏高原隆升或两极冰盖的形成演化对于该地区气候的影响.但是,吐哈地区温度可达60℃,长时间的高温是否会引起矿物中的Ar的丢失?矿物颗粒细小是否会引起矿物中的Ar的丢失?这对于矿物年龄的解释具有重要意义.本文根据扩散理论,应用阶段加热的方法进行Ar的扩散特性研究,在此基础上,应用简单的内生长-扩散模型模拟了可能的高地表温度和矿物颗粒大小对样品年龄的影响.实验结果表明斜钾铁矾中Ar的扩散频率因子logD0/a2=13.71/s,活化能Ea=71.30kcal/mol,封闭温度Tc为294℃(假设冷却速率为10℃/Ma),活化能和封闭温度较高.而且,模拟结果表明斜钾铁矾形成后,在外界环境下温度和矿物颗粒大小对年龄几乎没有影响.在误差范围内重复性测试结果基本一致,进一步证明斜钾铁矾适用于40Ar/39Ar定年.
In the upper oxidation zone of nonferrous metal mines in Turpan-Hami region, Xinjiang, a new K-containing sulfate mineral, KFe (SO4) 2, is found in the upper oxidation zone of the non-ferrous metal mines, The mineral age can be used to study the time and course of aridification in the region to explore the influence of the Tibetan Plateau uplift or the formation and evolution of the polar ice sheet on the climate in the area. However, the temperature in Tuha region can reach 60 ℃, Will it cause the loss of Ar in the mineral? Whether the fine mineral particles will cause the loss of Ar in the mineral? This is of great significance for the interpretation of mineral age.According to the diffusion theory, Based on this, the influence of the possible upper surface temperature and the size of mineral particles on the sample age was simulated with a simple model of in-growth-diffusion.The experimental results show that the diffusion frequency factor Ar of logarithmic arosite is logD0 / a2 = 13.71 / s , The activation energy Ea = 71.30 kcal / mol, the closure temperature Tc 294 ℃ (assuming the cooling rate of 10 ℃ / Ma), the activation energy and the closure temperature is higher .And the simulation results show that ettringite formation, in the external environment Under temperature and minerals Grain size is almost no influence of age. Reproducible test results are in agreement within an error range, further evidence of the swash jarosite suitable for 40Ar / 39Ar dating.