Deep deformation pattern from electrical anisotropy in an arched orogen (Betic Cordillera, western Mediterranean)
Deep deformation pattern from electrical anisotropy in an arched orogen (Betic Cordillera, western Mediterranean)
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DOI：
10.1130/g31144.1
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发表时间：
2010-08
期刊：
影响因子：
5.8
通讯作者：
A. Ruiz-Constán;J. Galindo‐Zaldívar;A. Pedrera;J. Arzate;J. Pous;F. Anahnah;W. Heise;F. Santos;C. Marín‐Lechado
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文献类型：
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作者：
A. Ruiz-Constán;J. Galindo‐Zaldívar;A. Pedrera;J. Arzate;J. Pous;F. Anahnah;W. Heise;F. Santos;C. Marín‐Lechado
在伊比利亚地块和Betic Cordillera拱形造山带获得的长周期大地电磁数据提供了地中海地区上地幔电各向异性的第一个证据。不同时期的走向分析揭示了地幔中与橄榄石延伸有关的优选结构取向，并指出了一种非均匀的各向异性模式。在深部（周期≥104 s），所有测点都显示出共同的南北向地电走向（北纬170 °E），这可能代表低强度变形，可能与“冻结”的前阿尔卑斯板块构造有关。在10 ~ 103 s的时间段内，Betic Cordillera遗址的南北走向（北纬180 °E）与伊比利亚地块的东西走向（北纬85 °E）形成对比。从伊比利亚地块到Betic Cordillera内部的感应箭头的大小增加可能反映了欧亚-非洲板块边界轴向的更高变形。电各向异性数据与地震各向异性的整合，使我们能够讨论地幔变形模式所产生的拆沉和俯冲，这表明后者的机制可能更适合于阿尔卑斯山的演化西直布罗陀弧。
Long-period magnetotelluric data acquired in the Iberian Massif and the Betic Cordillera arched orogen provide the first evidence of electrical anisotropy in the upper mantle of the Mediterranean region. Strike analysis at different periods reveals preferred structure orientation related to olivine elongation in the mantle, and points to a heterogeneous anisotropy pattern. At deep levels (periods ≥104 s), all the sites show a common north-south geoelectrical strike (∼N170°E), which may represent a low-intensity deformation, possibly related to “frozen” prealpine plate tectonics. For periods between 10 and 103 s, a north-south constant strike (∼N180°E) at the Betic Cordillera sites contrasts with the east-west strike (∼N85°E) in the Iberian Massif. An increase in the magnitude of the induction arrows from the Iberian Massif to the inner part of the Betic Cordillera probably reflects higher deformation toward the axis of the Eurasian-African plate boundary. The integration of electrical anisotropy data with seismic anisotropy allows us to discuss mantle deformation patterns produced by delamination and subduction, suggesting that the latter mechanism may be more suitable for the alpine evolution of the western Gibraltar Arc.