Mapping the Moho of the Western Alps by wide-angle reflection seismics
Mapping the Moho of the Western Alps by wide-angle reflection seismics
复制标题
通过广角反射地震绘制西阿尔卑斯山的莫霍面图
DOI：
10.1016/0040-1951(89)90243-6
复制
发表时间：
1989
期刊：
影响因子：
2.9
通讯作者：
F. Merlanti
中科院分区：
文献类型：
--
作者：
A. Hirm;S. Nadir;F. Thouvenot;R. Nicolich;G. Pellis;S. Scarascia;I. Tabacco;F. Castellano;F. Merlanti
利用广角反射地震数据可以获得西阿尔卑斯山下莫霍面的新图像。这张照片，除了清晰度增加之外，还清楚地显示了莫霍面如何加深到链的根区（55公里）。在Briançonnais带下发现了一个25-30 km深的具有上地幔特征的反射层，它覆盖在原地莫霍面之上。这个单位似乎没有连接到所谓的“伊夫雷亚体”，位于更浅和更远的链。它支持了西阿尔卑斯山下欧洲岩石圈剥落的假设。在更远的东部，Po平原下的莫霍面也被清楚地绘制出来，地壳厚度从25公里逐步增加到35公里。将P波莫霍面图与S波莫霍面图进行了比较，讨论了中地壳出现的主要差异。最后，莫霍面的地震响应进行了研究，并被证明是转向低频率的链的内部区域。这可以部分解释为什么配备了高频地震检波器的ECORS-CROP垂直地震测线在识别阿尔卑斯山莫霍面时出现问题。
A new picture of the Moho beneath the Western Alps could be obtained using wide-angle reflection seismic data. This picture, in addition to its increased sharpness, clearly shows how the Moho deepens down to the root zone of the chain (55 km). A 25–30 km deep reflector with upper mantle characteristics is discovered under the Briançonnais zone where it overlies the autochthonous Moho. This unit does not seem to connect to the so-called “Ivrea body”, situated much shallower and farther into the chain. It supports a hypothetical flaking of the European lithosphere beneath the Western Alps. Farther east, the Moho beneath the Po Plain is clearly mapped too, with a crustal thickness increasing in steps from 25 to 35 km. This P-wave Moho picture is compared with an S-wave picture, and major differences appearing in the middle crust are discussed. Finally, the seismic response of the Moho is investigated, and is shown to be shifted towards low frequencies in the inner zones of the chain. This could partly explain why the ECORS-CROP vertical seismic line, equipped with high-frequency geophones, faltered over the identification of the deep Alpine Moho.