Light Element Investigations of Natural and Experimental Zircon

天然和实验锆石的轻元素研究

• 批准号: 1447404
• 负责人: Dustin Trail
• 金额: $ 29.72万
• 依托单位: University of Rochester
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-02-01 至 2019-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1447404&HistoricalAwards=false
• 关键词: Light; Element; Investigations; Natural; Experimental

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.

地球过去的地质事件不仅塑造了当今的星球，而且还将影响地球的进化。 在地质学中，岩石是过去的关键。在许多情况下，它们代表了研究“深度时间”的唯一资源。 但是，在40亿年前之前没有已知的整个岩石。 已知的陆生材料的储层仅限于在世界各地的少数沉积物中发现的非常罕见的“沙粒”。 在没有原始的岩石的情况下，它拥有这些“沙粒”，或者是矿物锆石 - 存在许多挑战。 这项研究将通过两种互补方法解决这些问题。 第一个涉及测量以推断出这些非常罕见的矿物质（锆石）的化学成分，而第二个涉及在高压，高温实验地质实验室的受控环境中合成矿物质的。 这些实验 - 可以改变压力，温度和岩浆成分的地方 - 将用作解释最古老已知的陆生样品的化学的垫脚石。 这些实验在天然样品中的应用将导致有关最早地球（包括岩浆组成）的环境和条件的新知识，因此是了解地球随着时间的推移发展的关键信息来源。 这项工作的更广泛的影响还包括对新型高压 /高温晶体和玻璃合成技术的本科生和研究生的培训。 合成眼镜和晶体构成了当今许多消费产品的组成部分。 学生还将使用现代分析技术（例如激光消融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示威，这些示威解释地质学家如何确定古代岩石和矿物质的年龄。他们还将参与简单图的开发，这些图表解释了地质和地球化学的关键概念，然后可以将其用于班级的指导。该项目的实验工作将使用罗切斯特大学的活塞缸机器进行。 锆石将：（i）用硅质熔体合成；或（ii）在存在流体的情况下，通过时间序列实验的方法平衡元素和同位素组成。 将确定运行产品的分区系数/同位素组成，以锆石和共存阶段的光稳定元素确定。 第一个目标是将融合光元素稳健地校准到锆石晶格中，这是熔体成分，熔体结构和温度的函数。 其次，开发的校准将应用于大帝和哈迪斯锆石。 这些实验和结果的应用将在追求与早期晶体过程中保存在古代锆石中保存的化学特征的追求中起着基本作用。这项工作还将扩展对锆石父岩构图的知识。