MAGMA SYSTEMS RELATED TO THE RED-SEA OPENING
MAGMA SYSTEMS RELATED TO THE RED-SEA OPENING
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DOI：
10.1016/0040-1951(88)90296-x
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发表时间：
1988-07-20
期刊：
影响因子：
2.9
通讯作者：
MCGUIRE, AV
中科院分区：
文献类型：
--
作者：
COLEMAN, RG;MCGUIRE, AV
与红海盆地有关的岩浆环境有四种：(1)现今活跃扩张的轴槽内的洋中脊玄武岩；(2)阿拉伯边缘伸展前寒武纪地壳内的玄武岩脉和层状辉长岩；(3)在伸展前寒武纪地壳中发育的花岗岩和流纹岩；(4)不对称分布在红海阿拉伯侧翼的高原玄武岩。这些岩浆是非洲最初解体和在红海内建立海洋扩张中心的结果。原始的非对称大陆伸展作用发生在渐新世东倾拆离断层上，导致类MORB岩浆侵入伸展的前寒武纪地壳。同时期的小尺度地幔对流引发了阿拉伯板块下方的有限部分熔融，形成了不饱和的碱性-橄榄石高原玄武岩。中新世的缓慢伸展使红海形成了蒸发岩盆地，而阿拉伯板块上形成了少量的裂谷和高原玄武岩。上新世板块运动的微小变化引发了海底在轴向海槽的扩张，在那里MORB岩浆形成了洋壳。软流圈的抬升在受东倾主滑脱断层控制的阿拉伯板块之下产生了小范围的热扰动。小规模地幔对流使阿拉伯板块下的部分熔融(2-5%)向东扩展，产生了更多的不饱和多样性的碱-橄榄石高原玄武岩。这四种岩浆类型的不同化学和同位素特征导致了与地球动力学环境的明显现实关联。
Four distinct magma environments can be recognized in association with the Red Sea basin:1.(1) mid-ocean ridge basalts within the present actively spreading axial trough2.(2) basaltic dikes and layered gabbros within the extended Precambrian crust on the Arabian margin3.(3) granites and rhyolites developed in the extended Precambrian crust; and4.(4) plateau basalts asymmetrically distributed on the Arabian flanks of the Red Sea. These magmas developed as the result of the initial break-up of Africa and the establishment of an oceanic spreading center within the Red Sea. Original asymmetric continental extension occurred on east-dipping detachment faults in the Oligocene and caused MORB-like magmas to invade an extending Precambrian crust. Contemporaneous small-scale mantle convection initiated limited partial melting under the Arabian plate to form the undersaturated alkali-olivine plateau basalts. Slow extension through the Miocene allowed an evaporite basin to develop in the Red Sea, while small volumes of rift and plateau basalts formed on the Arabian plate. A small change in plate motion in the Pliocene initiated the seafloor spreading in the axial trough, where MORB magmas formed oceanic crust. Rise of the asthenosphere produced small-scale thermal perturbations under the Arabian plate controlled by an east-dipping master detachment fault. Small-scale mantle convection extended partial melting (2–5%) eastward under the Arabian plate producing more undersaturated diverse alkali-olivine plateau basalts. Distinct chemical and isotopic signatures of these four magma types lead to obvious actualistic correlations with the geodynamic setting.