Nature of crust in the central Red Sea
Nature of crust in the central Red Sea
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DOI：
10.1016/j.tecto.2014.04.029
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发表时间：
2014-07-30
期刊：
影响因子：
2.9
通讯作者：
Park, Yongcheol
中科院分区：
文献类型：
--
作者：
Mitchell, Neil C.;Park, Yongcheol
红海北部陆壳与红海南部洋壳之间的转换与板块构造分离率向南增加和上地幔地震速度降低大体一致。在这里，我们用遗留的地震折射实验结果和最近发布的卫星高度计测量得出的海洋重力异常来重新评估介于红海中部的地壳的性质。在西提斯深部以东采集的折射资料中，与未改变的辉长岩样品的测量速度相似的深部折射层的速度为6.6-6.9公里的S(-1)，从深部延伸到距离轴线65公里的地方。新版本的海洋重力场揭示了穿越红海中部的趋势。它们中的一些与周围非洲-阿拉伯地盾中的主要线状构造相连，而西提斯深部周围的线状构造则向海岸线消亡。它们可以成对穿过海脊，与板块运动略有倾斜，这是典型的海洋断裂带或远离热点的非转换不连续面。综上所述，这些观察结果支持这样的观点，即红海中部的这一部分是海洋地壳，而不是伸展的大陆地壳。缓慢扩展的山脊中间山谷周围的峰顶山脉在扩展不连续面处通常比地面低500-1000米。在提蒂斯深部周围，重力场的模式与缓慢扩张的山脊相似，这表明峰顶山脉可能会不同程度地阻止或阻碍蒸发岩向扩张中心的流动，而不连续面可能标志着流动不受阻碍的区域。在Thetis Deep以外的凌日中收集的有限的多波束数据显示，从这些预测的运动中可以预期到倾斜的结构。(C)2014爱思唯尔B.V.保留所有权利。
A transition between continental crust in the northern Red Sea and oceanic crust in the southern Red Sea coincides broadly with a southward increase in plate tectonic separation rate and with a decrease in upper mantle seismic velocity. We re-evaluate here the nature of crust in the intervening central Red Sea with the results of legacy seismic refraction experiments and recently released marine gravity anomalies derived from satellite altimeter measurements. In the refraction data, collected east of Thetis Deep, velocities of 6.6-6.9 km s(-1) of a deep refracting layer, which are similar to measured velocities of unaltered gabbro samples, extend outside the deep to 65 km from the axis. The new version of the marine gravity field reveals trends crossing the central Red Sea. Whereas some of them connect with major lineaments in the surrounding African-Arabian shield, those around Thetis Deep die out towards the coastlines. They can be paired across the ridge and lie slightly oblique to plate motions, as is typical of oceanic fracture zones or non-transform discontinuities migrating away from hotspots. Taken together these observations support the view that an oceanic rather than extended continental crust underlies this part of the central Red Sea.The crestal mountains around the median valleys of slow-spreading ridges are typically 500-1000 m lower at spreading discontinuities. Around Thetis Deep, the similar pattern in the gravity field to those of slow-spreading ridges suggests that the crestal mountains may variably block or impede flowage of evaporites towards the spreading centre, whereas the discontinuities may mark areas where flowage is unobstructed. Limited multibeam data collected in transits outside Thetis Deep show oblique fabrics as expected from these predicted movements. (C) 2014 Elsevier B.V. All rights reserved.