Constraining timescales of focused magmatic accretion and extension in the Afar crust using lava geochronology
Constraining timescales of focused magmatic accretion and extension in the Afar crust using lava geochronology
复制标题
使用熔岩地质年代学约束阿法尔地壳集中岩浆增生和延伸的时间尺度
作者：
D. Ferguson;A. Calvert;D. Pyle;J. Blundy;G. Yirgu;T. Wright
随着大陆裂谷带的成熟，与地壳伸展有关的构造和火山作用局限于狭窄的岩浆裂谷带，使人联想到大洋扩张脊。这些裂谷带的形成和洋脊型地形的发育是裂谷演化的一个重要里程碑，因为它标志着地壳伸展和与裂谷有关的火山活动的局部化。在这里，我们表明，熔岩，喷发自~200 ka沿着部分陆地红海裂谷系统在阿法尔，埃塞俄比亚，有一个一致的年龄进展从裂谷轴向外，表明轴向岩墙侵入已成为主要机制的部分增长和集中在地壳中的岩浆增生和扩展在此期间保持稳定。我们的研究结果表明，由于这个裂谷段已经形成，在变薄和侵入的大陆地壳，时间平均的表面开口率已接近非洲和阿拉伯半岛之间的总扩展速率。在成熟的大陆裂谷中，岩浆侵入似乎可以容纳显著的地壳伸展。在这里，熔岩的放射性年龄表明，这种风格的集中岩浆吸积和裂谷保持稳定的埃塞俄比亚地壳至少~200 kyr，真正的海洋扩张开始之前。
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. In mature continental rifts, magma intrusion appears to accommodate significant crustal extension. Here, radiometric ages for lavas suggest that this style of focused magmatic accretion and rifting remained stable in the Ethiopian crust for at least ~200 kyr, prior to the onset of true oceanic spreading.
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影响因子：
4.9
作者：
L. Field;J. Blundy;A. Calvert;G. Yirgu
通讯作者：
L. Field;J. Blundy;A. Calvert;G. Yirgu
影响因子：
5.8
作者：
Keir, Derek;Hamling, Ian J.;Bennati, Laura
通讯作者：
Bennati, Laura
对正在进行的达巴胡裂谷事件的大地测量观测：2006 年和 2007 年新的堤坝入侵
影响因子：
2.8
作者：
Hamling I
通讯作者：
Hamling I
影响因子：
2.8
作者：
Ebinger, C. J.;Keir, D.;Buck, W. R.
通讯作者：
Buck, W. R.
影响因子：
18.3
作者：
Bastow, Ian D.;Keir, Derek
通讯作者：
Keir, Derek