The P and S wave velocity structure of the mantle beneath eastern Africa and the African superplume anomaly
The P and S wave velocity structure of the mantle beneath eastern Africa and the African superplume anomaly
复制标题
东非地幔纵横波速度结构及非洲超地幔柱异常
DOI：
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
A. Nyblade
中科院分区：
文献类型：
--
作者：
G. Mulibo;A. Nyblade
2007年至2011年期间，在乌干达、坦桑尼亚和赞比亚部署的60多个临时AfricaArray宽带地震台站记录的地震P和S相对到达时间残差，以及以前部署记录的地震相对到达时间残差，已被反演为延伸到东非1200 km深度的地幔波速变化的层析成像图像。该图像显示了在新生代东非裂谷系统的东部和西部分支以及赞比亚西北部的浅层（100-200 km）处发育良好的低波速异常（LWA），以及在东非高原的中部和北方以及赞比亚的东部和中部的深度≤ 350 km处的快波速异常。在深度≥350 km处，LWA在东非高原中部和南部最明显，在赞比亚北方下方向西南倾斜，延伸到至少900 km的深度。LWA的幅度与150-300 K的热扰动一致，其深度范围表明，最初被确定为下地幔异常的非洲超级地幔柱可能是一个完整的地幔结构。从核幔边界延伸到地表的超级地幔柱意味着新生代伸展、火山活动和非洲东部高原隆升的起源都植根于下地幔的动力学。
P and S relative arrival time residuals from teleseismic earthquakes recorded on over 60 temporary AfricaArray broadband seismic stations deployed in Uganda, Tanzania, and Zambia between 2007 and 2011 have been inverted, together with relative arrival time residuals from earthquakes recorded by previous deployments, for a tomographic image of mantle wave speed variations extending to a depth of 1200 km beneath eastern Africa. The image shows a low‐wave speed anomaly (LWA) well developed at shallow depths (100–200 km) beneath the Eastern and Western branches of the Cenozoic East African rift system and northwestern Zambia, and a fast wave speed anomaly at depths ≤ 350 km beneath the central and northern parts of the East African Plateau and the eastern and central parts of Zambia. At depths ≥350 km the LWA is most prominent under the central and southern parts of the East African Plateau and dips to the southwest beneath northern Zambia, extending to a depth of at least 900 km. The amplitude of the LWA is consistent with a ∼150–300 K thermal perturbation, and its depth extent indicates that the African superplume, originally identified as a lower mantle anomaly, is likely a whole mantle structure. A superplume extending from the core‐mantle boundary to the surface implies an origin for the Cenozoic extension, volcanism, and plateau uplift in eastern Africa rooted in the dynamics of the lower mantle.
影响因子：
3.5
作者：
S. Fishwick
通讯作者：
S. Fishwick
影响因子：
5.3
作者：
Davies, D. Rhodri;Goes, S.;Ritsema, J.
通讯作者：
Ritsema, J.