Lithospheric Evolution in the Tanzanian Craton and Adjoining Mozambique Belt, East Africa: Perspectives From the Lower Crust

东非坦桑尼亚克拉通和毗邻莫桑比克带的岩石圈演化：来自下地壳的视角

• 批准号: 0337255
• 负责人: Roberta Rudnick
• 金额: --
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-01-15 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0337255&HistoricalAwards=false
• 关键词: Lithospheric; Evolution; Tanzanian; Craton; Adjoining

This work will determine the thermal history of Tanzanian continental crust to understand mantle and plate tectonic processes. Rocks of the Mozambique mobile belt formed in the Archean, but were strongly heated and recrystallized during two separate mountain-building events: the ~2.0 Ga Usagaran orogeny and the ~600 Ma pan-African orogeny. The craton-mobile belt boundary also forms the site of present-day continental rifting, along a presumed site of pre-existing weakness in the plate. Samples from the Mozambique Belt will be studied with various techniques to determine their pressure-temperature history, especially dating uranium-rich minerals whose radioactive clocks are reset at different temperatures. The measurements will track the evolving thickness of the plate through time, and the amount of hot, mantle-derived magmas that intruded the crust during the mountain-building events. These results will shed light on the behavior of continental plates during mountain building and rifting, as well as the parameters responsible for localization of weakness within the continental plate. The work will involved scientists from the University of Maryland, the University of Dar-es-Salaam, and MIT.

这项工作将确定坦桑尼亚大陆地壳的热历史，以了解地幔和板块构造过程。莫桑比克移动带的岩石形成于太古宙，但在两次独立的造山活动期间被强烈加热和再结晶：~2.0 Ga 乌萨加兰造山运动和~600 Ma 泛非洲造山运动。 克拉通活动带边界也形成了当今大陆裂谷的位置，沿着板块中预先存在的弱点的推测位置。莫桑比克带的样本将通过各种技术进行研究，以确定其压力-温度历史，特别是对放射性时钟在不同温度下重置的富铀矿物进行测年。这些测量将跟踪板块随时间变化的厚度，以及造山活动期间侵入地壳的炽热、源自地幔的岩浆量。 这些结果将揭示大陆板块在造山和裂谷过程中的行为，以及负责大陆板块内弱点定位的参数。这项工作将涉及来自马里兰大学、达累斯萨拉姆大学和麻省理工学院的科学家。