摘要
超临界地质流体以其独特的性质对金属成矿元素具有超强的萃取、层析和搬运能力,在热液矿床成矿机制研究中对揭示成矿物质的源、流和汇起着特殊和重要作用。本文利用分析纯H2MoO4在高温下脱水制备了MoO3(白色斜方晶系),在冷封式高压釜中实验测定了417℃超临界条件下,MoO3在纯水中的溶解度分别为7.3(29MPa)、14.2(45MPa)、21.6(55MPa)、27.7(78MPa)、32.5(100MPa)、和34.2(150MPa)mmol/l,热液中钼的存在形式为H2MoO4。依据前人的实验方案,补充测定了WO3在4.0%NaCl水溶液中于450%条件下的溶解度,其值分别为27.51(50MPa)和30.52(100MPa)mmol/l。结合前人研究结果发现,MoO3、WO3的溶解度在临界区域内具有超临界现象,在超临界条件下其溶解度与石英的超临界溶解度行为基本相似,表现为溶解度随体系温度和压力的升高而增大,这对揭示岩浆热液型和石英脉型钨、钼矿床的形成机制具有重要指导作用。
Supercritical geofluids have strong capabilities of extracting, separating and transporting on metallic ore-forming elements, and play important roles on the study of the ore-forming mechanism of hydrothermal deposit to indicate the source, path and sink of ore materials. The solubility of MoO(3), Which was white color rhombic crystal formed from the dehydration of H(2)MOO(4) at high temperature, was determined at the cold-seal pressure vessel in supercritical pure water system. The solubilities of MoO(3) at 417degreesC were 7.3, 14.2, 21.6, 27.7, 32.5 and 34.2 mmol/l at 29, 45, 55, 78, 100 and 150 MPa respectively, and the dominant species of molybdenum in this system were H(2)MoO(4). The solubilities of WO(3) in NaCl-H(2)O system with 4.0% by weight salt at 450degreesC were 27.51 and 30.52 mmol/l at 50 and 100 MPa respectively. Combined with the former WO(3) experimental results, we found the solubility of MoO(3) and WO(3) in critical region occurred supercritical phenomena, and their solubility behaviors in the supercritical region were similar to those of quartz. The solubility of MoO(3), WO(3) and quartz was increasing With the higher temperature and pressure in the supercritical region, which showed important implications for the ore-forming mechanism of tungsten and molybdenum deposits of magma hydrothermal and quartz vein types.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2005年第1期240-244,共5页
Acta Petrologica Sinica
基金
国家自然科学基金(No.40203006
40234048
40373003)
