Experimental Study of Clinopyroxene Growth and Sector Zoning

单斜辉石是地球和其他岩石行星上的一种主要造岩矿物，也是最早由高温岩浆和熔岩结晶的固体之一。理论上，单斜辉石的化学成分和晶体形状可以用来提取有关形成矿物的液体的信息(例如，温度、压力、成分)。在研究岩石样本时，这种标记的准确性对于破译地球和其他行星体上大量火山和岩浆系统的动力学至关重要。然而，单斜辉石的结晶过程很复杂，人们对它的了解仍然很少，这阻碍了它作为岩浆示踪剂的潜力。这项拟议的工作旨在利用实验室实验和先进的分析方法相结合的方法来改进单斜辉石的结晶过程。这些结果将完善之前的数据集，在微观尺度上提供对这种矿物的新见解，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实验岩石学实验室的学术机构(布朗大学、夏威夷大学和洛林大学)之间的合作，支持两名职业生涯早期研究人员的专业发展，并为三名本科生提供研究机会。单斜辉石是最复杂的火成岩矿物之一，其结构和化学分带的多样性。即使在今天，它错综复杂的复杂性仍然是重建含单斜辉石岩浆历史的重要障碍。该项目的基本原理来自以前对具有复杂扇区分带的自然样品的表征，以及以前对单斜辉石熔体系统的实验。这项新的工作将利用三个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。研究将集中在主要和微量元素组成(精细细节，以捕捉错综复杂的分带)、生长特征(习性、熔体和固体包裹体、晶体缺陷)以及单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显微镜、电子探针和透射电子显微镜以及激光烧蚀电感耦合质谱仪进行分析。总体目标是：记录单斜辉石在不同压力、温度和冷却条件下的结构变化；确定发生扇区分带的条件(冷却速度、过冷度、熔体组成)；以及研究单斜辉石和熔体之间以及单斜辉石中扇区之间的主要和微量元素分配。这些目标旨在推进单斜辉石温压测量的实际应用，通过确定哪些部门和元素真实地记录了岩浆的压力-温度条件。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.