Collaborative Research: Thermal Structure of Continental Lithosphere Through Time

GSTDTAP

项目编号	1524796
	Collaborative Research: Thermal Structure of Continental Lithosphere Through Time
	Alan Whittington
主持机构	University of Missouri-Columbia
项目开始年	2015
	2015-08-15
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	184017(USD)
国家	美国
语种	英语
英文摘要	The processes by which the crust of the Earth formed and grew in the first 2 billion years of earth history ? the Archean eon - remain a major unknown because tectonics and meteor bombardment removed most of the rock record from that time. Major crustal consolidation and growth occurred at the end of this era but debate still continues about the mechanisms. Critical to making progress is a better understanding of the thermal regime of the crust at this time since many proposed models depend on thermal-driven buoyancy to explain this major episode of crustal growth. To that end, this collaborative project would determine the thermal properties of rocks at elevated temperatures in order to better estimate the thermal properties of early Archean crust. The results would be used as the basis for modeling of Archean crust, which would improve our understanding of the strength of the lithosphere in this early phase of crustal growth and evolution. The experimental approach is cutting edge and would provide valuable constraints to the broader community interested in modeling of early crustal processes as well as to other fields such as geophysics, geodynamics, and materials science. The project would advance desired societal outcomes through: (1) full participation of women in STEM; (2) improved STEM education and educator development through development of K-12 teaching materials, teacher workshops, and classroom outreach; (3) development of a globally competitive STEM workforce through graduate and undergraduate student training; and (4) increased partnerships through collaboration with scientists in Australia and Canada. The Tectonics Program and NSF's Office of International Science and Engineering support the project. This project examines the thermal structure of the continental lithosphere over time with particular emphasis on the thermal properties and rheology of Archean lithosphere. The research team will determine thermal diffusivity data for lower crustal minerals as well as for rocks from the Kapuskasing Structural Zone (Ontario, Canada), which provides a cross section through a Late Archean greenstone belt into the mid- to lower-crust. These data will be used as the basis for numerical models of Archean lithosphere rheology. The first objective is to explore the range of thermal diffusivity and conductivity of the continental lower crust, and how it varies with rock type and temperature. This will involve: (1) thermal diffusivity measurement of lower crustal minerals and Archean rocks from the Kapuskasing zone and elsewhere to high temperature by Laser Flash Analysis; (2) comparison of room-temperature optical scanning method and Laser Flash Analysis; (3) heat capacity measurement to high temperature by differential scanning calorimetry; and (4) development of a model for calculating thermal conductivity of rocks to high temperatures from their mineralogy and porosity. The second objective of the project is to estimate the rheology of typical Archean continental crust, its effects on tectonic style, and changes through time. This involves: (1) combining thermal modeling with available surface heat flow data to determine the nature of the crust as based on the Kapuskasing section; (2) test thermal models of this same section in Archean times against pressure-temperature conditions recorded by the rocks; and (3) calculate rheological profiles for Archean crust, to find out if the crust was weak, strong, or had weak layers into which deformation was concentrated.
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/68464
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Alan Whittington.Collaborative Research: Thermal Structure of Continental Lithosphere Through Time.2015.