Soft plates and hot spots : Views from Afar
Soft plates and hot spots : Views from Afar
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软板块和热点：远方的景色
DOI：
10.1029/96jb02118
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发表时间：
1996
影响因子：
--
通讯作者：
N. Hayward
中科院分区：
文献类型：
--
作者：
C. Ebinger;N. Hayward
隆起的埃塞俄比亚高原地区包括非岩浆裂谷盆地和新生海底扩张的盆地。埃塞俄比亚主裂谷和阿法尔南部的裂谷段表现出明显的结构分割，断层带的长度、宽度和间距从南到北减少；阿法尔北部的裂谷段延伸超过 100%，显示出岩浆分段。埃塞俄比亚高原地区的遥感、重力和模拟研究的目标是（1）总结沿裂谷系统长度的形态模式，以及（2）将埃塞俄比亚高原地区岩石圈有效弹性厚度的变化与构造联系起来。来自受地震数据约束的隆起高原裂谷区域的新的和现有的布格重力数据的反演模型被用来将沿轴构造和岩浆分段的几何变化与弯曲刚度的变化联系起来。我们使用重力和地形之间的相干性的波长依赖性来估计岩石圈的弯曲刚度，或者等效地，有效弹性板厚度（Te）。在 300 公里宽的阿法尔洼地内，Te 的估计范围为 17 ± 2 公里至 5 ± 3/−2 公里。这些裂谷内 Te 的估计值远低于在西部隆起但基本上无断层的高原下方发现的值 (Te ≥ 56 km)。这些结果表明，从“大陆分段”到“大洋分段”的转变，对应着裂谷盆地分段长度的减小、断层与岩浆中心的分离、岩浆构造的增加、有效弹性厚度的显着减小。我们认为，海底扩张开始之前伸展段的长度尺度主要受板块强度控制，至少在受地幔柱影响的裂谷区域是这样。
The uplifted Ethiopian plateau region encompasses amagmatic rift basins and basins with nascent seafloor spreading. Rift segments in the Main Ethiopian rift and southern Afar show a distinct structural segmentation, with a south to north reduction in the length, width, and spacing of fault zones; rift segments in northern Afar, where extension exceeds 100%, show a magmatic segmentation. The objectives of remote sensing, gravity, and modeling studies of the Ethiopian plateau area are (1) to summarize morphological patterns along the length of the rift system and (2) to relate variations in effective elastic thickness of the lithosphere within the Ethiopian plateau region to tectonics. Inverse models of new and existing Bouguer gravity data from the rifted regions of the uplifted plateau constrained by seismic data are used to relate the variations in the geometry of the along-axis structural and magmatic segmentation to variations in flexural rigidity. We use the wavelength dependence of the coherence between gravity and topography to estimate the flexural rigidity, or, equivalently, the effective elastic plate thickness (Te), of the lithosphere. Estimates of Te range from 17 ± 2 km to 5 ± 3/−2 km within the 300-km-wide Afar Depression. These estimates of Te within the rift are considerably less than values found beneath the uplifted but largely unfaulted plateau to the west (Te ≥ 56 km). These results show that the transition from a “continental segmentation” to “oceanic segmentation” corresponds to a decrease in rift basin segment length and the separation of faults and magmatic centers, an increase in magmatic construction, and a marked decrease in effective elastic thickness. We suggest that the length scales of extensional segments prior to the onset of seafloor spreading are controlled primarily by plate strength, at least in rift areas affected by mantle plumes.