Crustal thinning beneath the Rwenzori region, Albertine rift, Uganda, from receiver-function analysis
Crustal thinning beneath the Rwenzori region, Albertine rift, Uganda, from receiver-function analysis
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乌干达艾伯丁裂谷鲁文佐里地区下方的地壳变薄，来自接收函数分析
DOI：
10.1007/s00531-009-0509-2
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发表时间：
2010
影响因子：
2.3
通讯作者：
A. Muwanga
中科院分区：
文献类型：
--
作者：
I. Wölbern;G. Rümpker;A. Schumann;A. Muwanga
乌干达西部的鲁文佐里山脉位于艾伯丁裂谷内，最高海拔超过5000米。我们在山脉的乌干达一侧部署了一个临时地震台网，以研究这段裂谷下方地壳和上地幔的地震速度结构。我们介绍了接收函数研究的结果，揭示了沿东部裂谷侧翼的简单地壳结构，地壳厚度大致均匀，约为30千米。在鲁文佐里区块内，地壳内部结构的复杂性急剧增加。我们应用不同的反演技术来获得可靠的地壳厚度结果。观测揭示了鲁文佐里山脉下方明显较薄的地壳，厚度值在山脉北部和中部下方约20-28公里之间。因此，我们的研究表明，在鲁文佐里地块之下没有地壳根。在爱德华湖和乔治湖盆地下面，我们探测到了15公里深的S波速度显著降低的层的顶部。这种低速层可能归因于最近火山活动区下方存在部分熔融。
The Rwenzori mountains in western Uganda, with a maximum elevation of more than 5,000 m, are located within the Albertine rift valley. We have deployed a temporary seismic network on the Ugandan side of the mountain range to study the seismic velocity structure of the crust and upper mantle beneath this section of the rift. We present results from a receiver-function study revealing a simple crustal structure along the eastern rift flank with a more or less uniform crustal thickness of about 30 km. The complexity of inner-crustal structures increases drastically within the Rwenzori block. We apply different inversion techniques to obtain reliable results for the thickness of the crust. The observations expose a significantly thinner crust beneath the Rwenzori range with thickness values ranging from about 20–28 km beneath northern and central parts of the mountains. Our study therefore indicates the absence of a crustal root beneath the Rwenzori block. Beneath the Lake Edward and Lake George basins we detect the top of a layer of significantly reduced S-wave velocity at 15 km depth. This low-velocity layer may be attributed to the presence of partial melt beneath a region of recent volcanic activity.