Field and microstructural investigation of strain localization processes, texture development, and the rheology of naturally deformed lower crust

GSTDTAP

项目编号	1808117
	Field and microstructural investigation of strain localization processes, texture development, and the rheology of naturally deformed lower crust
	Seth Kruckenberg
主持机构	Boston College
项目开始年	2018
	2018-06-15
项目结束日期	2021-05-31
资助机构	US-NSF
项目类别	Standard Grant
项目经费	312566(USD)
国家	美国
语种	英语
英文摘要	The rheology (i.e. the deformational behavior) of Earth's crust and upper mantle exerts a fundamental control on a range of planetary processes, from accurately modeling plate tectonics, to estimating patterns of post-glacial rebound and the propagation of seismic deformation. Models of sea level rise are similarly influenced by our understanding of the viscosity structure of the crust and upper mantle, having direct consequences for humans in coastal communities that base their future planning and development on model predictions. Thus, our ability to accurately predict the societal effects of global and local sea level change is, in part, dependent upon a nuanced understanding of the conditions and processes that control the deformational behavior of Earth materials. This study will produce empirical estimates of rheology from some of the least accessible, and least understood, deep crustal materials, thus informing on various model inputs and global processes. Teaching and training of graduate and undergraduate students are cornerstones of the integrated research efforts outlined in this study, with a particular focus on the participation of women in international STEM (Science, Technology, Engineering and Mathematics) research experiences. This study further aims to leverage the development of new digital databases and scientific tools (e.g., the StraboSpot database for structural analysis) to facilitate the free dissemination of primary data and scientific findings, and it seeks to develop new tools used for the characterization of crystalline solids, offering potential for technology transfer and breakthroughs in other STEM fields. The viscous rheologies of many minerals (e.g., olivine, quartz) and mineral aggregates (e.g., olivine and orthopyroxene) in the lithosphere have been studied for some time, yet rheologies for polyphase aggregates (e.g., gabbro -- the dominant lithology comprising the lower crust) remain poorly constrained. Because plagioclase and pyroxene are among the most common minerals in the lower crust, investigating the micromechanical processes that govern their deformation is fundamental to advancing the understanding of a range of geodynamic processes, particularly in active orogenic settings where the ability to make tectonic inferences from indirect methods of observation rests upon knowledge as to the origin of structural fabrics and crystallographic textures developed during high-temperature viscous flow. Rheological information obtained from field-based and microstructural investigations of exhumed deep crustal lithospheric sections thus remain critical as these exposures record within them the rock microstructures, deformation mechanisms, and crystallographic textures formed in the deep crust during deformation under natural conditions. This research focuses on naturally deformed, compositionally heterogeneous deep crustal granulite exposures in the Mount Hay block of central Australia and is rooted in field-based investigation, and integrated with microstructural studies, strain analysis, and textural analysis using electron backscatter diffraction. Using these methods, this research will provide quantitative constraints on: (i) deformation heterogeneity and strain localization processes in the deep crust; (ii) the compositional and tectonic controls the micromechanics of deformation in polyphase aggregates; and (iii) the rheology of heterogeneous lower crustal lithologies. Further, this study aims to explore the role of strain geometry on the development of crystallographic preferred orientation (CPO) in plagioclase-dominated rocks (e.g., gabbro), offering immense potential for improving the interpretation of lithospheric processes that depend on fabric anisotropy (e.g., seismic anisotropy, viscous anisotropy, melt percolation). 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.
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/72744
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Seth Kruckenberg.Field and microstructural investigation of strain localization processes, texture development, and the rheology of naturally deformed lower crust.2018.