Niobium, zirconium, titanium, and rare earth elements in alkaline silica-undersatured magmas: experimental determination of solubility, complexation and phase relations and implications for the formation of magmatic Nb-Zr-REE deposits

碱性二氧化硅-欠饱和岩浆中的铌、锆、钛和稀土元素：溶解度、络合和相关系的实验测定以及对岩浆铌-锆-稀土矿床形成的影响

• 批准号: 441268636
• 负责人: Dr. Christian Schmidt
• 金额: --
• 依托单位: Saint Petersburg University
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/441268636?language=en
• 关键词: Niobium; zirconium; titanium; rare; earth

Peralkaline magmatic rocks host some the largest accumulations of Zr, Nb, Ta and rare earth elements (REE) on Earth. Of particular importance at present or in the near future are or will be deposits in silica-undersaturated alkaline rocks (Khibiny and Lovozero massifs, Kola Peninsula, Russia and deposits in the Gardar province, southern Greenland), which are characterized by a complex mineralogy. So far, these rocks are little studied experimentally, and thus fundamental data on solubility and complexation of these elements and even on phase relationships are missing. In the project proposed here, we would like to address some of the open questions and determine the solubility of Nb, Zr, Ti and REE from minerals that crystallize early upon cooling (lueshite, perovskite, loparite, eudialyte, parakeldyshite, zircon, baddeleyite) in alkali aluminosilicate melts as function of peralkalinity, and of the concentrations of F, Cl, CO2, and H2O). These experiments will also provide information on phase relationships. Moreover, we plan to study the coordination chemistry of Nb, Zr, Ti and REE in the produced glasses and the complexation of Nb in the melt in situ at high temperature.

近碱性岩浆岩中含有地球上最大的锆、铌、钽和稀土元素 (REE) 积累量。目前或不久的将来特别重要的是或将是硅不饱和碱性岩中的矿床（俄罗斯科拉半岛的希比内和洛沃泽罗地块以及格陵兰岛南部加尔达尔省的矿床），其特征是复杂的矿物学。到目前为止，对这些岩石的实验研究很少，因此缺少这些元素的溶解度和络合甚至相关系的基本数据。在此提出的项目中，我们希望解决一些悬而未决的问题，并确定冷却后早期结晶的矿物（绿辉石、钙钛矿、洛帕石、eudialyte、parakeldyshite、锆石、斜锆石）中 Nb、Zr、Ti 和 REE 的溶解度碱金属铝硅酸盐熔体中的过碱度以及 F、Cl、CO2 和 H2O 浓度的函数）。这些实验还将提供有关相位关系的信息。此外，我们计划研究所生产的玻璃中Nb、Zr、Ti和REE的配位化学以及Nb在高温熔体中的络合。