Thrust-wrench interference between major active faults in the Gulf of Cadiz (Africa-Eurasia plate boundary, offshore SW Iberia): Tectonic implications from coupled analog and numerical modeling

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• 作者：F.M. Rosas^a ; ^b ; ^{frosas@fc.ul.pt} ; J.C. Duarte^a ; ^b ; ^d ; ¹ ; M.C. Neves^a ; ^c ; P. Terrinha^a ; ^d ; S. Silva^a ; ^b ; ^d ; L. Matias^a ; ^e ; E. Grà ; cia^f ; R. Bartolome^f
• 关键词：Gulf of Cadiz ; Thrust&ndash ; wrench tectonics ; Analog and numerical modeling ; Fault interference ; Multi-rupture seismic hazards ; Lithospheric mantle seismicity
• 刊名：Tectonophysics
• 出版年：2012
• 期刊代码：82_00401951
• 类别：ear
• 出版时间：15 June, 2012
• 卷：548-549
• 期：Complete
• 页码：1-21
• 文件大小：7138 K

摘要

Analog and numerical modeling experiments were carried out to investigate the tectonic interference between intersecting major active strike-slip and thrust faults in the Gulf of Cadiz (Africa-Eurasia plate boundary, offshore SW Iberia). The obtained results show that newly mapped tectonic features located in the fault intersection area (corner zone) consist mostly in oblique (dextral-reverse) faults that accommodate significant strain partitioning. Modeling of this corner-zone faults show that they have endured some degree of rotation, displaying successive evolving geometries and kinematics. Numerical modeling results further show that an interbedded shallow soft layer, accounting for a regional (Late Miocene) gravitational 鈥淐haotic鈥?unit, could explain the mild bathymetric expression of the fault pattern in the corner-zone. Moreover, a recognized depth discrepancy, between the (upper crust) interference fault-pattern and the (lithospheric mantle) seismicity, is interpreted as a manifestation of similar thrust-wrench tectonic interference at different lithospheric depths. Accordingly, an intermediate lower crust-upper mantle aseismic (i.e. softened) depth-domain could be explained by pervasive alteration/serpentinization, prompted by fluid percolation through fault-related fractures associated with the newly revealed corner zone fault-network. Overall obtained results reinforce the relevance of a thrust-wrench multi-rupture seismic scenario as the main cause for the moderate seismicity (Mw < 6.0) in the study area.