Rare Earth Elements Tracing Crustal Evolution Through Time: A Detrital Zircon Study

GSTDTAP

项目编号	1725002
	Rare Earth Elements Tracing Crustal Evolution Through Time: A Detrital Zircon Study
	Mihai Ducea
主持机构	University of Arizona
项目开始年	2017
	2017-07-01
项目结束日期	2020-06-30
资助机构	US-NSF
项目类别	Standard Grant
项目经费	209563(USD)
国家	美国
语种	英语
英文摘要	Multiple recent lines of evidence suggest that the onset of modern-like plate tectonic processes started rather abruptly in the Archean (about 3 billion years ago) and that tectonically, the Earth has evolved through several distinctive dynamic stages. The overarching question here is to test the hypothesis of several step-like changes in the tectono-magmatic evolution of the Earth. Such change should be reflected in the geochemical composition of intermediate and felsic igneous rocks - the basic building blocks of continental masses. If this did happen, can we better constrain the age of that change, was it sudden or gradual? Unraveling tectonics stages and transitions between them on our dynamic planet has important implications for our overall understanding of resource distribution as well as feedbacks with other evolutionary processes in the mineral and biologic realms. In the project, the researchers will use detrital zircon U-Pb ages and trace elemental concentrations (with a focus on the rare earth elements) on grains from sediments and sedimentary rocks that satisfy the following conditions: (1) are draining sizable segments of the continental mass, and (2) contain zircons encompassing large geologic time intervals, especially from the Precambrian. The age range target will especially focus on the Hadean, Archean and Proterozoic area. Recent work shows that whole rock geochemical parameters measured on young igneous rocks correlate positively with crustal thickness globally and regionally. La/Yb and other trace elemental ratios are calibrated against crustal thickness on intermediate igneous rocks from modern subduction systems and have been used to show variations in crustal thickness over time in a few Phanerozoic orogenic regions. The implied variation in crustal thickness is consistent with the tens of million years cyclicity of crustal thickness in continental areas being affected by modern plate tectonics and is also indicative of the fact that the deepest parts of the continental crust (regardless of its thickness) are the factories of differentiation leading to the diversity of intermediate igneous rocks found in subduction and collision systems.
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/71205
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Mihai Ducea.Rare Earth Elements Tracing Crustal Evolution Through Time: A Detrital Zircon Study.2017.