The root of the Urals: evidence from wide-angle reflection seismics
The root of the Urals: evidence from wide-angle reflection seismics
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乌拉尔山脉的根源：来自广角反射地震的证据
DOI：
10.1016/0040-1951(95)00058-8
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发表时间：
1995
期刊：
影响因子：
2.9
通讯作者：
L. Jenatton
中科院分区：
文献类型：
--
作者：
F. Thouvenot;S. Kashubin;G. Poupinet;V. Makovskiy;T. V. Kashubina;P. Matte;L. Jenatton
乌拉尔山脉下是否存在地壳根，这将使莫霍的位置偏转约20公里，目前仍存在很大争议。一个法国和俄罗斯的项目在乌拉尔中部进行了一个广角反射地震实验，沿着叶卡捷琳堡北部大约东西方向的175公里剖面对莫霍地形进行了成像。新的数据显示，在造山带中部下方有一个6公里的莫霍偏移。莫霍反射率沿剖面变化，在俄罗斯平台下方（深度45公里）反射非常明显，而在根区（深度51公里）衰减信号较弱。即使这个地壳根不像以前的一些推测所表明的那样厚，乌拉尔山脉也是世界上唯一一个表现出这种特性的古生代造山带。根据均衡平衡，上地壳的一个主要超镁铁质超载会在一定程度上平衡地壳根部。我们最后假设，来自莫霍的尖锐广角反射可以被认为是下地壳分层的指示。俄罗斯地台可能是在奥陶系伸展期形成这种构造的。
The existence of a crustal root beneath the Urals which would deflect the position of the Moho by some 20 km is still largely controversial. A French-Russian project carried out a wide-angle-reflection seismic experiment across the Middle Urals to image the Moho topography along a 175-km profile running approximately east-west north of Ekaterinburg. New data show a 6-km Moho deflection beneath the central part of the orogen. The Moho reflectivity is variable along the section, with very sharp reflections beneath the Russian platform (45-km depth), and fainter attenuated signals in the root zone (51-km depth). Even if this crustal root is not as thick as indicated by some previous speculations, it makes the Urals the only Palaeozoic orogen in the world to show such a peculiarity. A major ultramafic overload in the upper crust would partly balance the crustal root, in accordance with isostatic equilibrium. We finally postulate that sharp wide-angle reflections from the Moho can be considered indicative of a layered lower crust. This would apply to the Russian platform which maybe gained this structuring during the Ordovician extensional régime.