Modelling of CHROMium Enrichment in the mantle and the crust

地幔和地壳中铬富集的模拟

• 批准号: 521637679
• 负责人: Professor Dr. Roman Botcharnikov, Ph.D.
• 金额: --
• 依托单位: Arbeitsgruppe Petrologie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/521637679?language=en
• 关键词: Modelling; CHROMium; Enrichment; mantle; crust

The main objective of the CHROME project is to develop thermodynamically consistent multiphase flow models that can explain the formation of podiform chromite deposits in ophiolite units. Ophiolites consist of rocks that show evidence of melting/crystallization processes during their formation. Since chromium is a highly compatible element, it is expected to remain in the residuum during melting. However, our preliminary experimental results show that Cr spinel becomes unstable with increasing H2O content and melts together with the other silicate minerals (mainly pyroxenes). This consumption of Cr spinel leads to a dramatic increase in the Cr content of the melt. However, despite this enrichment process, this Cr concentration is not sufficient to form chromite deposits. Thus, we conclude that additional mobilization and Cr enrichment of these melts is necessary. To model the processes of melt transport, the dynamics of reactive multiphase flows in H2O-rich, Cr-saturated magmas from the Earth's mantle must be considered. By modeling the various end-members of Cr enrichment (e.g., convection or reactive transport), we will be able to confirm/reject or even refine some of the available hypotheses for the formation of podiform Cr deposits. We plan to conduct phase equilibrium experiments on the peridotitic rocks containing the Cr ores. These experiments will allow us to draw conclusions needed for further development of reactive transport models. We plan to apply multiphase reactive flow models to gain insight into the processes associated with ore formation. These models will be run in parallel with experiments in which melts are re-equilibrated with mantle rocks. Our combined modeling/experimental approach will provide a thorough review of the proposed modeling approaches. Our goal is to use reactive multiphase flow models to model ore formation processes (from source to deposit). In doing so, our proposed model will consider petrologic and field evidence from natural podiform chromite deposits.

Chrome项目的主要目标是开发能够解释蛇绿岩单元中豆荚状铬铁矿矿床形成过程的、具有一致性的多相流模型。蛇绿岩由岩石组成，在其形成过程中显示出熔融/结晶过程的证据。由于铬是一种高度相容的元素，预计在熔化过程中会保留在残渣中。然而，我们的初步实验结果表明，铬尖晶石变得不稳定，随着水含量的增加和熔融与其他硅酸盐矿物（主要是辉石）。铬尖晶石的这种消耗导致熔体中铬含量的急剧增加。然而，尽管有这种富集过程，但这种Cr浓度不足以形成铬铁矿矿床。因此，我们得出结论，额外的动员和铬富集这些熔体是必要的。为了模拟熔体输送过程，必须考虑来自地球地幔的富H2O、Cr饱和岩浆中反应性多相流的动力学。通过模拟Cr富集的各种端元（例如，对流或反应运输），我们将能够确认/拒绝，甚至完善一些豆荚状铬矿床形成的现有假设。我们计划对含铬矿石的橄榄岩进行相平衡实验。这些实验将使我们能够得出进一步发展反应性运输模型所需的结论。我们计划应用多相反应流模型来深入了解与成矿相关的过程。这些模型将与熔体与地幔岩石重新平衡的实验并行运行。我们的建模/实验相结合的方法将提供一个全面的审查所提出的建模方法。我们的目标是使用反应多相流模型来模拟成矿过程（从矿源到存款）。在这样做时，我们提出的模型将考虑天然豆荚状铬铁矿矿床的岩石学和现场证据。