An Integrated Analysis of Lithospheric Structure in Southern Kenya: Anatomy of an Active Plume

9316868凯勒1985年和1989年肯尼亚裂谷国际地震项目(KRIP)实验的结果90提供了肯尼亚裂谷中部和北部岩石圈结构的一幅出人意料的绝佳图景。从肯尼亚穹顶(奈瓦沙湖附近)向北，地壳变薄，裂谷的地貌表现为加宽，裂谷谷底和裂谷肩部失去海拔，伸展程度增加。地幔内的两个界面也向北加深。岩石圈地幔的减薄程度远远大于地壳，这表明有一个活动过程在起作用。这些观察结果引出了一个显而易见的问题，那就是裂谷南部会发生什么。肯尼亚裂谷南部是本次研究的重点。在这个项目中，美国研究团队将与卡尔斯鲁厄大学、莱斯特大学、都柏林高级研究院、波茨坦大学以及肯尼亚同事一起在肯尼亚南部进行各种地球物理和岩石学研究。这些研究的主要重点将是确定岩石圈结构和形成裂谷演化的综合模型。卡尔斯鲁厄大学将专注于裂谷的东侧，并将他们的结果与最近的岩石学结果联系起来。莱斯特大学和德克萨斯大学埃尔帕索分校将专注于一条横跨坦桑尼亚边境以北的裂谷的长长轮廓。通过使用维多利亚湖和印度洋的炮点，这条700公里长的剖面提供了一个独特的机会来探测活跃的羽流的深层结构。德克萨斯大学埃尔帕索分校还将专注于小型地震阵列的操作，包括宽带记录、重力研究、岩石学研究以及综合结果的综合分析。***

9316868 Keller The results of Kenya Rift International Seismic Project (KRISP) experiments in 1985 and 1989 90 provide an excellent and unexpected picture of lithospheric structure in the central and northern portion of the Kenya rift. From the apex of the Kenya dome (near Lake Naivasha, northward) the crust thins, the physiographic expression of the rift widens, the floor of the rift valley and the rift shoulders lose elevation, and the amount of extension increases. Two interfaces within the mantle also deepen to the north. The lithospheric mantle is thinned considerably more than the crust indicating that an active process is at work. These observations lead to the obvious question of what happens in the southern portion of the rift. The southern portion of the Kenya rift is the focus of this research. In this project, the U.S. team of researchers will join with the University of Karlsruhe, The University of Leicester, the Dublin Institutes for Advanced Studies, the University of Potsdam, and Kenyan colleagues to conduct a variety of geophysical and petrological studies in southern Kenya. The primary emphasis of these studies will be determining lithospheric structure and formulating an integrated model of the evolution of the rift. The University of Karlsruhe will concentrate on the eastern flank of the rift and tie their results to recent petrologic results. The University of Leicester and the University of Texas at El Paso will concentrate on a long profile crossing the rift just north of the Tanzanian border. By using shotpoints in Lake Victoria and the Indian Ocean, this 700km long profile provides a unique opportunity to probe the deep struct ure of an active plume. The University of Texas at El Paso will also concentrate on the operation of a small seismic array including broadband recording, gravity studies, petrological studies, and the integrated analysis of the combined results. ***