Experimental Study of Clinopyroxene Growth and Sector Zoning

斜辉石是地球和其他岩石行星上主要的造岩矿物，也是高温岩浆和熔岩结晶形成的首批固体之一。理论上，斜辉石的化学成分和晶体形状可以用来提取矿物形成的液体的信息（例如，温度、压力、成分）。在研究岩石样本时，这些标记的准确性对于破译地球和其他行星上大量火山和岩浆系统的动力学至关重要。然而，斜辉石的结晶过程复杂，人们对其知之甚少，这阻碍了它作为岩浆示踪剂的潜力。提出的工作旨在通过实验室实验和先进的分析方法相结合来完善斜辉石的结晶过程。这些结果将完善以前的数据集，为微观尺度上的矿物提供新的见解，并为新的研究途径铺平道路。这些任务将促进三个拥有一流岩石学实验实验室的学术机构（布朗大学、夏威夷大学和洛林大学）之间的合作，支持两名早期职业研究人员的专业发展，并为三名本科生提供研究机会。斜辉石是最复杂的火成岩矿物之一，其结构和化学分带的变化。即使在今天，其复杂的复杂性仍然是重建斜辉石质岩浆历史的重大障碍。该项目的基本原理源于以前对具有复杂扇形分区的自然样品的表征，以及以前对斜辉石+熔体系统的实验。这项新工作将利用三种实验设备来解决广泛的结晶条件：加热阶段显微镜，1-atm气体混合炉和活塞缸。研究将集中在主要元素和微量元素组成（以精细的细节捕捉复杂的分区），生长特征（习性，熔体和固体包裹体，晶体缺陷）和斜辉石在合成和天然熔体冷却过程中的结晶动力学。实验产品将使用光学、电子探针、透射电子显微镜和激光烧蚀电感耦合质谱分析。总体目标是：记录斜辉石在不同压力、温度和冷却条件下的结构变化；确定扇区分区发生的条件（冷却速度、过冷、熔体成分）；并研究斜辉石和熔体之间以及斜辉石各部分之间的主元素和痕量元素划分。这些目标旨在通过确定哪些部门和元素忠实地记录岩浆压力-温度条件，推进斜辉石热气压计的实际应用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Clinopyroxene is a major rock-forming mineral on Earth and other rocky planets, and one of the first solids crystallized by high temperature magmas and lavas. In theory, the chemical composition and the crystal shape of clinopyroxene can be used to extract information about the liquid from which the mineral formed (e.g., temperature, pressure, composition). When studying rock samples, the accuracy of such markers is critical in deciphering the dynamics of a large number of volcanic and magmatic systems, both on Earth and other planetary bodies. However, the crystallization processes of clinopyroxene are complex and still poorly understood, which hampers its potential as a tracer of magmas. The proposed work aims to refine the crystallization processes of clinopyroxene using a combination of laboratory experiments and advanced analytical methods. These results will complete previous datasets, provide new insights on the mineral at the microscopic scale, and pave the way for new research avenues. The tasks will nurture a collaboration between three academic institutes with premier experimental petrology laboratories (Brown University, the University of Hawaii, and the Universite de Lorraine), support the professional development of two early-career researchers, and provide a research opportunity for three undergraduate students. Clinopyroxene is one of the most complex igneous minerals in terms of its variability in texture and chemical zoning. Even today, its intricate complexity stands as a significant roadblock to reconstructing the history of clinopyroxene-bearing magmas. The rationale for this project stems from former characterizations of natural samples bearing complex sector zoning, and previous experiments on clinopyroxene + melt systems. This new work will exploit a trio of experimental apparatuses to address a broad range of crystallization conditions: heating stage microscope, 1-atm gas mixing furnace, and piston cylinder. The investigations will focus on major- and trace-element composition (in fine-scale detail to capture intricate zoning), growth features (habits, melt and solid inclusions, crystal defects) and the crystallization kinetics of clinopyroxene during the cooling of synthetic and natural melts. The experimental products will be analyzed using optical, electron probe, and transmission electron microscopies, and laser ablation inductively coupled mass spectrometry. The overarching goals are: to document the textural variation of clinopyroxene at various pressure, temperature, and cooling conditions; to establish the conditions (cooling rate, undercooling, melt composition) at which sector zoning occurs; and to examine major- and trace-element partitioning between clinopyroxene and melt, and between sectors in clinopyroxene. These goals are intended to advance the practical application of clinopyroxene thermobarometry, by establishing which sectors and elements faithfully record magmatic pressure-temperature conditions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.