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

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。莫桑比克活动带的岩石形成于太古代，但在两次独立的造山活动中（~2.0 Ga的乌萨加兰造山运动和~600 Ma的泛非造山运动）经历了强烈的加热和再结晶。克拉通-活动带边界也形成了现今大陆裂谷的位置，沿着一个假定的板块先前存在弱点的位置。来自莫桑比克带的样品将用不同的技术进行研究，以确定它们的压力-温度历史，特别是确定富含铀的矿物的年代，这些矿物的放射性时钟在不同的温度下被重置。这些测量将追踪板块厚度随时间的变化，以及在造山活动期间侵入地壳的炽热地幔岩浆的数量。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部弱点定位的参数。这项工作将涉及马里兰大学、达累斯萨拉姆大学和麻省理工学院的科学家。

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.