Experimental Study of Clinopyroxene Growth and Sector Zoning

单斜辉石生长及扇区分区的实验研究

• 批准号: 2316451
• 负责人: Benoit Welsch
• 金额: $ 37.99万
• 依托单位: Macalester College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-12-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2316451&HistoricalAwards=false
• 关键词: Experimental; Study; Clinopyroxene; Growth; Sector

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.

Clinopyroxene是地球和其他岩石行星的主要岩石矿物，也是高温岩浆和熔岩结晶的第一批固体之一。从理论上讲，可以使用化学成分和晶体形状来提取有关矿物形成的液体的信息（例如温度，压力，组成）。在研究岩石样品时，这种标记的准确性对于破译大量火山和岩浆系统的动力学至关重要，无论是地球还是其他行星体。然而，斜二烯的结晶过程是复杂的，并且仍然鲜为人知，这阻碍了其作为岩浆的示踪剂的潜力。提出的工作旨在通过实验室实验和高级分析方法的组合来完善斜氧烯的结晶过程。这些结果将完成以前的数据集，以微观规模为矿物提供新的见解，并为新的研究途径铺平道路。这些任务将培养三家学术机构与主要实验性质学实验室（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，并为三名培训学生提供研究机会。就其在质地和化学分区方面的可变性而言，斜氧烯是最复杂的火成岩矿物之一。即使在今天，其复杂的复杂性仍然是重建含有斜氧化石岩浆岩浆史的历史的重要障碍。该项目的基本原理源于具有复杂扇区分区的天然样品的以前特征，以及先前在斜氧烯 +熔体系统上进行的实验。这项新工作将利用三个实验设备来解决各种结晶条件：加热阶段显微镜，1-ATM气体混合炉和活塞缸。研究将集中于主要元素和痕量元素组成（细节细节，以捕获复杂的分区），生长特征（习惯，融化和固体夹杂物，晶体缺陷）以及在冷却合成和自然熔体过程中临床py的结晶动力学。实验产物将使用光学，电子探针和透射电子显微镜进行分析，以及激光消融电感量耦合质谱法。总体目标是：记录在各种压力，温度和冷却条件下斜py氧烯的质地变化；建立发生区域分区的条件（冷却速率，过冷，熔化组成）；并检查斜氧烯和熔体之间的主要和微量元素分配，以及斜氧烯中的领域。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 - 温度条件来推动斜氧烯热量测量法的实际应用。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的审查标准来通过评估来支持的。