Silicate liquid immiscibility and the formation of Fe (±Ti ±P ±F ±REE) ore deposits

硅酸盐液体不混溶性与Fe(±Ti±P±F±REE)矿床的形成

基本信息

批准号：
268008671
负责人：
Professor Dr. Jürgen Koepke
金额：
--
依托单位：
Institut für Mineralogie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2015
资助国家：
德国
起止时间：
2014-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/268008671?language=en
关键词：
Silicate liquid immiscibility formation Fe

项目摘要

The role of immiscibility between two silicate melts (ferrobasalt-rhyolite) on differentiation and ore-forming processes is under debate since decades. Clear evidence for the separation of two silicate melts in natural systems is rarely recorded in rocks because of the transient nature of immiscibility during cooling and solidification. Thus, experimental approaches are crucial to test the importance of melt immiscibility in magmatic and associated ore-forming processes. In this study, we propose to use a twofold approach to understand the role of silicate liquid immiscibility in the formation of Fe (±Ti ±P ±F ±REE) ore deposits: (1) we will study melt inclusions trapped in apatite of some major iron deposits which will give us direct constraints on the equilibrium liquid compositions and (2) we will perform a detailed experimental approach to understand the conditions for the onset of immiscibility (magma compositions, temperature, pressure, oxygen fugacity and fluid content), and the partitioning of major elements between paired melts. The role of melt immiscibility will be tested for three well known natural examples, all containing Fe- and P-rich associations and covering a broad compositional range: tholeiitic basaltic system (Bushveld complex), ferropicritic/high-Ti basaltic system (Emeishan large igneous province), and Kiruna-type systems (Vergenoeg deposit). In selected experiments, we will also study the effect of immiscibility on trace elements fractionation between Fe-rich and Fe-poor silicate melts. The results will provide crucial data allowing us to discuss quantitatively the role of melt immiscibility on differentiation processes in basaltic systems, on the formation of some economically important Fe ore deposits and on enrichment mechanisms of trace elements (especially REE).

自数十年以来，两种有机硅熔体（牛bas-rhyolite）之间的不混溶性在分化和形成矿石形成过程中的作用正在争议。由于冷却和凝固过程中不混溶性的短暂性质，很少记录在天然系统中两种有机硅熔体分离的明确证据。这对于测试熔融和相关矿石形成过程中熔体不混溶的重要性至关重要。在这项研究中，我们建议使用两倍的方法来了解硅酮液体不混蛋在Fe（±ti±ti±p±f±±ree）形成中的作用：（1）我们将研究被困在某些主要铁沉积物中的息肉夹杂物中，这将在某些主要铁矿石中提供对等级液体液体构图和细节的方法（我们将在equilibrium contrention of Anderible of Anderible of Anderible of Anderible of Anderible of And）中的作用（2）不混溶性（岩浆成分，温度，压力，氧气散热性和流体含量），以及对配对熔体之间的主要元素的分配。融化不信用性的作用将测试三个众所周知的自然示例，其中均包含Fe-和P-Rich的关联，并涵盖了广泛的组成范围：Tholeitic玄武岩系统（Bushveld Complex）（Bushveld Complex），亚铁/高型玄武岩系统（Emeishan大型省省）（Emeishan大型无知省），以及Kiruna-type Systems（kiruna-type sepcemente）（Vergenpe）。在选定的实验中，我们还将研究不混溶性的影响。关于富含铁和富裕的硅酮熔体之间的微量元素分馏。结果将提供至关重要的数据，使我们能够定量讨论熔体不混溶性对玄武岩系统中分化过程的作用，形成某些经济上重要的Fe矿床以及痕量元素（尤其是REE）的富集机制。