Investigation on Modulated Structures and Subsolidus Phase Relations of Intermediate Plagioclase Feldspars Using Integrated Experiment and Simulation Methods

GSTDTAP

项目编号	1530614
	Investigation on Modulated Structures and Subsolidus Phase Relations of Intermediate Plagioclase Feldspars Using Integrated Experiment and Simulation Methods
	Huifang Xu
主持机构	University of Wisconsin-Madison
项目开始年	2015
	2015-08-01
项目结束日期	2018-07-31
资助机构	US-NSF
项目类别	Continuing grant
项目经费	209498(USD)
国家	美国
语种	英语
英文摘要	Plagioclase feldspars are the most abundant minerals in the Earth's crust. They are major minerals in many commercial granite countertops and floor tiles. Precious stones like peristerite, moonstone, and iridescent labradorite are plagioclase feldspars too. The crystal structures and formation mechanisms of the plagioclase feldspars have been an enigma for decades beginning with their first discovery in 1940. The proposed study will help geologists to have quantitative understanding of their structures, stabilities, formation mechanisms, and evolution histories. The research results will be incorporated into both introductory level and graduate level courses taught by the investigators. The team of researchers is committed to the engagement of diverse graduate and undergraduate students in their research. The investigators and graduate students will continue outreach activities through the Geology Museum for K-12 community, mentoring high school students through summer reach opportunity, and developing open source software for learning, such as, AtomTouch, a 3D interactive mobile platform molecular simulation software tool for educational purposes. Because the studied incommensurate modulations in the intermediate plagioclase feldspars occur in a wide compositional range with continuous variation, the proposed study will also benefit the study of incommensurate modulations in other non-conventional (aperiodic) crystalline materials like intermetallic coumpounds with (3+1)D structures that may underlie new materials for future applications. Recent aberration-corrected Z-contrast imaging results from the investigator's group reveal Ca-Na ordering and non-centrosymmetricity in both Na-rich and Ca-rich e-plagioclase feldspars. The multidisciplinary team will investigate the intermediate plagioclase feldspars that span the entire composition range (from ~An25 to ~An75) from different geological environments. Structural refinements of e-plagioclase feldspars will be carried out using new breakthroughs regarding non-centrosymmetricity and super space group characteristics to decipher the intricate nature of e-plagioclase feldspars. The proposed study includes the following 3 tasks: (1) Z-contrast imaging of intermediate plagioclase feldspars using an aberration-corrected scanning transmission electron microscope; (2) Crystal structure determination of e-plagioclase feldspars by single crystal X-ray diffraction method; and (3) Atomistic calculation of the subsolidus phase relations of the plagioclase binary system using density functional theory based phase diagram modeling. Both crystal structure and subsolidus phase relation of the intermediate plagioclase feldspars are very basic and important topics in mineralogy and petrology. Solving the problems of the mysterious incommensurately modulated structures and their subsolidus phase relations will provide improved understanding about behaviors of the plagioclase feldpars and their associations / intergrowths in metamorphic and igneous rocks that have experienced different evolution histories.
来源学科分类	Geosciences - Earth Sciences
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/68378
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Huifang Xu.Investigation on Modulated Structures and Subsolidus Phase Relations of Intermediate Plagioclase Feldspars Using Integrated Experiment and Simulation Methods.2015.