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.

过碱性岩浆岩是地球上最大的Zr、Nb、Ta和稀土元素富集区。目前或在不久的将来，特别重要的是或将是硅不饱和碱性岩石中的矿床（俄罗斯科拉半岛的Khibiny和Lovozero矿床以及格陵兰南部Gardar省的矿床），其特征是矿物学复杂。到目前为止，对这些岩石的实验研究很少，因此缺少关于这些元素的溶解度和络合作用甚至相关系的基本数据。在这里提出的项目中，我们想解决一些悬而未决的问题，并确定Nb，Zr，Ti和稀土元素的溶解度从矿物结晶早期冷却后（lueshite，钙钛矿，loparite，eudialyte，副钾长石，锆石，斜锆石）在碱性铝硅酸盐熔体作为过碱度的函数，和F，Cl，CO2的浓度，和H2O）。这些实验还将提供关于相位关系的信息。此外，我们计划研究Nb，Zr，Ti和REE在所生产的玻璃中的配位化学以及Nb在高温下在熔体中的原位络合。