Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK.
Nat Commun. 2013;4:1416. doi: 10.1038/ncomms2410.
As continental rift zones mature the tectonic and volcanic processes associated with crustal extension become confined to narrow magmatic rift zones, reminiscent of oceanic spreading ridges. The formation of these rift zones and the development of ocean-ridge type topography is a significant milestone in rift evolution as it signifies the localization of crustal extension and rift-related volcanism. Here we show that lavas, which erupted since ~200 ka along part of the on-land Red Sea rift system in Afar, Ethiopia, have a consistent age-progression from the rift axis outwards, indicating that axial dyke intrusion has been the primary mechanism of segment growth and that focused magmatic accretion and extension in the crust have remained stable here over this period. Our results suggest that as this rift segment has formed, in thinned and intruded continental crust, the time-averaged surface opening rate has closely approximated the total extension rate between Africa and Arabia.
随着大陆裂谷带的成熟，与地壳伸展相关的构造和火山过程逐渐局限于狭窄的岩浆裂谷带，类似于大洋扩张脊。这些裂谷带的形成和洋脊型地形的发育是裂谷演化中的一个重要里程碑，因为它标志着地壳伸展和与裂谷相关的火山作用的本地化。在这里，我们表明，自约 200ka 以来，在埃塞俄比亚阿法尔的部分陆地红海裂谷系统中喷发的熔岩从裂谷轴向外具有一致的年龄递增，表明轴向岩脉侵入一直是段增长的主要机制，并且在此期间，地壳中的集中岩浆增生和伸展保持稳定。我们的结果表明，随着这个裂谷段在变薄和侵入的大陆地壳中形成，平均表面开口率已接近非洲和阿拉伯半岛之间的总伸展率。
