碳酸氢钠介质铀溶解温压条件制约模拟实验研究
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摘要
成矿流体的温度、压力等物理条件变化影响铀溶解、沉淀能力,在热液型铀矿研究中对揭示铀富集沉淀机制具有重要意义。以沙子江铀矿床为主要研究对象,进行微量元素化学分析和物理化学条件模拟实验。变温实验和恒压变温实验结果表明在饱和蒸气压及6.89 MPa条件下,铀在0.5%NaHCO3介质中的优势溶解温度为80℃;在20 MPa条件下,相当于地下埋深约702～800 m, 150℃为铀的优势溶解温度; 200℃恒温条件下,随压力的增加,铀在0.5%NaHCO3介质中的溶解能力逐渐降低。研究表明来自地壳深部的含铀成矿流体随多期次的岩浆活动引起的温度波动有利于铀富集沉淀,减压作用中压力变化并非铀富集沉淀的直接因素。
Temperature, pressure and other physical conditions of ore-forming fluids affect the capacity of uranium dissolution and precipitation, which is of great significance in revealing the enrichment mechanism of uranium in hydrothermal uranium deposits. The chemical analysis of trace elements and physicochemical conditions simulation experiments were carried out with the samples from Shazijiang uranium deposit. The temperature experiment with and without pressure constrain showed that under the condition of saturated vapor pressure and 6.89 MPa, the advantage uranium dissolved temperature was 80 ℃ in 0.5% NaHCO3 and 150 ℃ was the advantage dissolved temperature under 20 MPa which is equivalent to about 702 to 800 m underground depth. Under 200 ℃ condition, the uranium dissolved capacity in 0.5% NaHCO3 medium gradually reduce with the increase of the pressure. It shows that the temperature fluctuation of uranium-bearing ore-forming fluid from crust with multiple periods of magmatic activities is favorable for uranium enrichment and precipitation, and the pressure change during the decompression is not a direct factor for uranium enrichment and precipitation.
Temperature, pressure and other physical conditions of ore-forming fluids affect the capacity of uranium dissolution and precipitation, which is of great significance in revealing the enrichment mechanism of uranium in hydrothermal uranium deposits. The chemical analysis of trace elements and physicochemical conditions simulation experiments were carried out with the samples from Shazijiang uranium deposit. The temperature experiment with and without pressure constrain showed that under the condition of saturated vapor pressure and 6.89 MPa, the advantage uranium dissolved temperature was 80 ℃ in 0.5% NaHCO3 and 150 ℃ was the advantage dissolved temperature under 20 MPa which is equivalent to about 702 to 800 m underground depth. Under 200 ℃ condition, the uranium dissolved capacity in 0.5% NaHCO3 medium gradually reduce with the increase of the pressure. It shows that the temperature fluctuation of uranium-bearing ore-forming fluid from crust with multiple periods of magmatic activities is favorable for uranium enrichment and precipitation, and the pressure change during the decompression is not a direct factor for uranium enrichment and precipitation.
引文
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[4]李子颖.华南热点铀成矿作用[J].铀矿地质,2006, 22(2):65-69,82.
[5]王传文.花岗岩型和火山岩型铀矿化的成因[J].矿床地质, 1983,(2):59-67.
[6]李妩巍,王敢,许来生,等.沙子江铀矿床铀成矿条件分析及成因浅析[J].矿床地质, 2010, 29(S1):143-144.
[7]邵飞,李嘉,何晓梅,等.华南铀成矿省火山岩-花岗岩型铀成矿作用[J].世界核地质科学, 2010,27(1):1-5,54.
[8]刘正义,刘红旭.花岗岩铀成矿作用的模拟实验[J].地学前缘, 2009, 16(1):99-113.
[9]刘吉芳,徐德明.热液中铀迁移形式的初步实验研究[J].矿物岩石, 1984,(1):70-78.
[10]李妩巍,王敢,许来生,等.沙子江铀矿床走滑构造控矿规律及控矿机制[J].铀矿地质, 2011,27(3):146-151.
[11]许健俊,邵飞.华南花岗岩型铀矿成矿元素运移及沉淀机理研究综述[J].世界核地质科学,2015, 32(3):132-138.
[12]石少华,胡瑞忠,温汉捷,等.桂北沙子江铀矿床流体包裹体初步研究[J].矿床地质, 2011, 30(1):33-44.
[13]郑永飞,傅斌,龚冰.六二一七热液铀矿床形成的物理化学条件研究[J].矿物学报, 1996,(1):20-27.
[14]王文全.砂岩铀矿石高温高压溶解实验研究[D].北京:中国地质大学(北京), 2009.
[15]方适宜,陈卫峰,梁永东,等.双滑江铀矿床低温热液铀酰矿物富集成矿作用[J].铀矿地质,2009, 25(5):270-276, 311.
[16]白丹丹,胡宝群,孙占学,等.相山铀矿田邹家山矿床流体包裹体研究[J].铀矿地质, 2012, 28(5):290-296.