Varying styles of magmatic strain accommodation across the East African Rift
Varying styles of magmatic strain accommodation across the East African Rift
复制标题
东非裂谷不同类型的岩浆应变调节
DOI：
10.1002/2015gc005918
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Nicolas Le Corvec
中科院分区：
文献类型：
--
作者：
J. Muirhead;S. Kattenhorn;Nicolas Le Corvec
对活动岩脉侵入的观察提供了岩浆对大陆裂谷作用的现代快照。然而，揭示地壳上部岩脉在大陆裂谷演化时间尺度上的贡献是一个巨大的挑战。为了解决这个问题，我们分析了>；1500火山锥的形态和排列，以推断横跨东非裂谷(EAR)的不同裂谷盆地中上地壳岩脉的分布和趋势。锥体线形数据揭示了由于构造岩浆条件的变化，岩墙侵入体的分布和几何形状沿轴向的变化。在北坦桑尼亚分流的较年轻(<；10 Ma)盆地中，岩脉主要局限于主要裂谷段之间的裂谷-斜断层带，在这里被称为转移带。由于(1)区域应力场、(2)局部岩浆引起的应力场和(3)与裂谷段之间的机械作用有关的应力旋转，锥体线形趋势是高度可变的。我们在EAR西部分支的转移区，如刚果民主共和国的维龙加省，发现了类似的锥形线条趋势。在大陆裂谷演化过程中，耳东支上地壳岩脉的分布和走向有所不同。在早期裂谷(<；10 Ma)中，上地壳岩脉在适应伸展方面的作用有限，因为它们局限于转换带及其周围地区。在埃塞俄比亚的演化裂谷盆地(>；10 Ma)和肯尼亚裂谷，裂谷平行的岩脉容纳了沿盆地全长的上地壳伸展。
Observations of active dike intrusions provide present day snapshots of the magmatic contribution to continental rifting. However, unravelling the contributions of upper crustal dikes over the timescale of continental rift evolution is a significant challenge. To address this issue, we analyzed the morphologies and alignments of >1500 volcanic cones to infer the distribution and trends of upper crustal dikes in various rift basins across the East African Rift (EAR). Cone lineament data reveal along‐axis variations in the distribution and geometries of dike intrusions as a result of changing tectonomagmatic conditions. In younger (<10 Ma) basins of the North Tanzanian Divergence, dikes are largely restricted to zones of rift‐oblique faulting between major rift segments, referred to here as transfer zones. Cone lineament trends are highly variable, resulting from the interplay between (1) the regional stress field, (2) local magma‐induced stress fields, and (3) stress rotations related to mechanical interactions between rift segments. We find similar cone lineament trends in transfer zones in the western branch of the EAR, such as the Virunga Province, Democratic Republic of the Congo. The distributions and orientations of upper crustal dikes in the eastern branch of the EAR vary during continental rift evolution. In early‐stage rifts (<10 Ma), upper crustal dikes play a limited role in accommodating extension, as they are confined to areas in and around transfer zones. In evolved rift basins (>10 Ma) in Ethiopia and the Kenya Rift, rift‐parallel dikes accommodate upper crustal extension along the full length of the basin.
影响因子：
5.8
作者：
Keir, Derek;Hamling, Ian J.;Bennati, Laura
通讯作者：
Bennati, Laura