Light Element Investigations of Natural and Experimental Zircon

地球过去的地质事件不仅塑造了今天的地球，而且还将影响地球未来的演变。 在地质学中，岩石是研究过去的关键;在许多情况下，它们是研究“深时间”的唯一可用资源。“然而，在40亿年前没有已知的完整岩石存在。 已知的陆地物质的储集层仅限于在全世界少数沉积物中发现的非常罕见的“沙粒”。 在缺乏承载这些“沙粒”的原始岩石的情况下，或者特别是矿物锆石，存在许多挑战。 本研究将通过两种互补的方法来解决这些问题。 第一种方法是通过测量来推断这些非常稀有的矿物（锆石）的化学成分，而第二种方法是在高压、高温实验地质实验室的受控环境中合成矿物。 这些实验--压力、温度和岩浆成分都可以变化--将成为解释已知最古老的陆地样品化学成分的垫脚石。 将这些实验应用于自然样品将导致对最早期地球的环境和条件（包括岩浆的组成）的新知识，因此是了解地球随时间演变的关键信息来源。 这项工作的更广泛的影响还包括在新的高压/高温晶体和玻璃合成技术的本科生和研究生的培训。 合成玻璃和水晶是当今许多消费品的组成部分。 学生还将使用现代分析技术（如激光烧蚀电感耦合等离子体质谱仪）对这些材料进行测量。 最后，中学科学教师将受益于实验室演示，解释地质学家如何确定古代岩石和矿物的年龄;他们还将参与简单图表的开发，解释地质学和地球化学的关键概念，然后他们可以在课堂上使用。该项目的实验工作将在罗切斯特大学使用活塞缸装置进行。 锆石将：（i）在无水熔体中合成;或（ii）在流体存在下通过时间序列实验接近平衡元素和同位素组成。 将确定锆石和共存相中轻稳定元素的分配系数/同位素组成。 第一个目标是稳健地校准轻元素作为熔体组成、熔体结构和温度的函数并入锆石晶格中。 其次，开发的校准将适用于太古代和冥古宙锆石。 这些实验和结果的应用将在寻求将保存在古代锆石中的化学特征与早期晶体过程联系起来方面发挥重要作用。这项工作也将扩大知识的锆石母岩组成很久以前了。

The geological events of Earth's past not only shaped the present-day planet, but will also influence the evolution of Earth in the future. In geology, rocks are the key to the past; in many cases they represent the only resource available to study "deep time." However, no known whole rocks exists from before 4 billion years ago. The reservoir of known terrestrial material is limited to very rare "grains of sand" found in only a handful of sediments throughout the world. In the absence of the original rock that hosted these "grains of sand," - or specifically the mineral zircon - there are numerous challenges. This research will address these problems through two complementary approaches. The first involves measurements to deduce the chemical composition of these very rare minerals (zircons), while the second involves the synthesis of the mineral in the controlled environment of a high pressure, high temperature experimental geology laboratory. These experiments - where pressure, temperature, and magma composition can be varied - will serve as a stepping stone to interpret the chemistry of the most ancient known terrestrial samples. The application of these experiments to natural samples will result in new knowledge about the environments and conditions of the earliest Earth (including the composition of magmas), and is therefore a key source of information to understand the evolution of Earth through time. Broader impacts of this work also include the training of undergraduate and graduate students in novel high pressure / high temperature crystal and glass synthesis techniques. Synthetic glasses and crystals make up a component of many consumer products today. Students will also conduct measurements of these materials using modern analytical technology such as a laser ablation inductively coupled plasma mass spectrometer. And finally, secondary school science teachers will benefit from laboratory demonstrations that explain how geologists determine the ages of ancient rocks and minerals; they will also participate in the development of simple diagrams that explain key concepts of geology and geochemistry that they can then use for instruction in their classes. The experimental work for this project will be conducted using a piston cylinder apparatus at the University of Rochester. Zircons will: (i) be synthesized in silicic melts; or (ii) approach equilibrium elemental and isotopic compositions through time series experiments in the presence of fluids. Partition coefficients/isotope compositions of run products will be determined for light stable elements in zircon and co-existing phases. The first goal is to robustly calibrate the incorporation light elements into the zircon lattice as a function of melt composition, melt structure, and temperature. Second, the developed calibrations will be applied to Archean and Hadean zircons. These experiments and the application of the results will play a fundamental role in the quest to link chemical signatures preserved in ancient zircons with early crystal processes. This work will also extend knowledge of the zircon parent rock composition long since gone.