Accessory mineral geochemistry in high-T systems

问题：不相容的痕量元素模式(例如稀土元素)通常被用来模拟高温地质系统的过程。然而，这种副矿物可能控制着不相容的微量元素分布。因此，在将地球化学模拟应用于地质过程时，了解微量元素和副矿物的地球化学之间的联系是至关重要的。目的：了解高温地质系统中副矿物对全岩模式的地球化学影响。这项工作将首先重点研究地壳熔体的形成，以及各种副矿物和不相容的微量元素在不同成分的母岩和由此产生的熔体之间的分布情况。还将研究大型岩浆侵入体中不相容元素的地球化学演化，以提供辅助矿物成分数据库，以充实和扩展目前仅存在于锆石和磷灰石的微量元素数据库。这将使这项研究的结果与岩浆和高温变质系统中副矿物地球化学和不相容的微量元素行为的已建立模型进行更好的比较。方法：拟议的研究将利用现有和新开发的电感耦合等离子体质谱技术，以魁北克大学的一个新设施为中心，开发和应用微量分析技术，以满足拟议的研究目标。位于魁北克省L角和圣富利西的优秀野外考察区已被确定，并将提供各种母岩和熔体类型的通道。意义：将痕量元素地球化学记录与伴生矿物分布联系起来，将有助于更好地理解不相容元素的行为，这反过来将有助于开发更准确的全岩系统地球化学模型。还将提供一个副矿物分配系数和浓度数据库。

The Problem: Incompatible trace-element patterns (e.g. REE) are commonly used to model processes in high-temperature geologic systems. However, accessory minerals such may control incompatible trace-element distributions. Thus, understanding the link between the geochemistry of trace-elements and accessory minerals is crucial when applying geochemical modeling to geologic processes. The Objectives: To understand the geochemical influence of accessory minerals on whole-rock patterns in high-temperature geological systems. This will begin by focusing on an initial examination of crustal melt formation and the distribution of various accessory minerals and incompatible trace-elements between the parent rocks of different compositions and the resulting melts. The geochemical evolution of incompatible elements in large magmatic intrusions will also be studied to provide a database of accessory mineral compositions to augment and expand trace-elements databases which currently only exist only for zircon and apatite. This will allow a better comparison of the results of this research with established models for accessory mineral geochemistry and incompatible trace-element behavior in both magmatic and high-temperature metamorphic systems. Methodology: The proposed research will develop and apply micro-analytical techniques to meet the proposed research objectives using existing and newly developed ICP-MS techniques, centered around a new facility at the University du Québec a Chicoutimi. Excellent field study areas at Cap à l'Aigle and St. Fulgence, Québec have been identified and will provide access to a wide variety of parent rock and melt types. Significance: Linking the trace-element geochemical record with accessory mineral distributions will contribute to a significantly better understanding of incompatible element behavior, which in turn will allow more accurate geochemical models for whole-rocks system to be developed. A database of accessory mineral distribution coefficients and concentrations will also be made available.