Crustal structure of Southwestern Saudi Arabia
Crustal structure of Southwestern Saudi Arabia
复制标题
沙特阿拉伯西南部的地壳结构
DOI：
10.3133/ofr83638
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发表时间：
1986
影响因子：
2.9
通讯作者：
J. Healy
中科院分区：
文献类型：
--
作者：
M. Gettings;H. Blank;W. Mooney;J. Healy
根据地震深折射、区域重力、航磁、热流和地表地质数据的综合解释，建立了阿拉伯地盾南部和红海帕尔的自洽区域地壳和上地幔模型。地盾由两层20公里厚的地壳组成，上地壳的平均压缩波速度约为6.3公里/秒，下地壳约为7.0公里/秒。地壳突然变薄，在断面西南端附近不到20公里，在那里前寒武纪露头邻接新生代岩石，并在法拉桑群岛下面8公里。前寒武纪露头向西的红海地区的数据用大洋地壳模型进行了满意的拟合。主要的速度不连续发生在整个屏蔽体的相同深度，表明前寒武纪地壳的水平变质分层。在屏蔽体的上地壳和下地壳中，已经确定了几种体积物理性质的横向不均匀性，表明体积成分的变化。该模型的地壳下部分是由一个热的，低密度的岩石圈和软流层下面的红海是系统的冷和密度的东北。这个模型提供了一个机制，解释了观测到的地形隆起，区域重力异常模式，热流，地幔地震速度。这样的岩石圈可能是由红海下面的热软流圈上涌，然后在阿拉伯板块岩石圈下面横向流动而产生的。
A self-consistent regional-scale model of the crust and upper mantle for the southern Arabian Shield and Red Sea paar has been constructed from an integrated interpretation of seismic deep refraction, regional gravity, aeromagnetic, heat flow, and surface geologic data. The Shield consists of two 20-km-thick layers of crust with an average compressional wave velocity in the upper crust of about 6.3 km/s and in the lower crust of about 7.0 km/s. This crust thins abruptly to less than 20 km near the southwestern end of the transect, where Precambrian outcrops abut the Cenozoic rocks, and to 8 km beneath the Farasan Islands. The data over the Red Sea westward of Precambrian outcrop are fit satisfactorily by an oceanic crustal model. The major velocity discontinuities occur at about the same depth across the entire shield and indicate horizontal metamorphic stratification of the Precambrian crust. Several lateral inhomogeneities in bulk physical properties have been identified in both the upper and lower crust of the shield, indicating bulk compositional variations. The subcrustal portion of the model is composed of a hot, low-density lithosphere and asthenosphere beneath the Red Sea which is systematically cooler and denser to the northeast. This model provides a mechanism that explains the observed topographic uplift, regional gravity anomaly pattern, heat flow, and mantle seismic velocities. Such a lithosphere could be produced by upwelling of hot asthenosphere beneath the Red Sea which then flows laterally beneath the lithosphere of the Arabian plate.