Seismic reflection imaging of active faults and their tectonic behavior in the Northern Moroccan margin. Is the Nekor fa
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ORIGINAL PAPER
Seismic reflection imaging of active faults and their tectonic behavior in the Northern Moroccan margin. Is the Nekor fault a pure strike-slip fault? Ghizlane Bouskri 1 & Mohammed Elabbassi 2 & Abdellah Ammar 2 & Driss El Ouai 1 & Mimoun Harnafi 1
Received: 16 March 2016 / Accepted: 19 September 2016 # Saudi Society for Geosciences 2016
Abstract The study of 1000-km seismic reflection profiles, along the Northern Moroccan margin, allowed browsing new imaging in detail about the regional geological structures and their functioning. To achieve this goal, we elaborated a highresolution depth model and a global tectonic sketch. The influence of recent tectonic activity is manifested by normal and strike-slip faults, trending mainly 70° N and 125° N. In this segment, the Nekor strike-slip fault seems to be connected to a secondary major fault system that changes direction from 30° N to 70° N, and changing behavior to left-lateral strike-slip fault with normal component. Analysis of local seismic activity recorded from 1990 to 2014 with moderate magnitudes activity shows alignments in clear superposition with the detected active faults in seismic reflection lines. Keywords Activetectonics . Nekor fault . Seismic reflection . Seismicity . Alboran Sea . Rif belt . Morocco
Introduction The present paper presents new imaging of active faults in the Northern Moroccan Margin, their tectonic properties, and localizes the continuity of the Nekor fault in the southeastern Alboran basin. Hence, the study region was chosen based on the fact that several earlier studies have been undertaken to * Ghizlane Bouskri [email protected]
1
Department of Geology, Scientific Institute, Mohamed V University, Ibn Battouta Avenue, P. B. 703, 10106 Agdal, Morocco
2
Department of Geology and Faculty of Sciences, Mohamed V University, 4 Ibn Battouta Avenue P. B. 1014 RP, Agdal, Morocco
better understand this region (Fig. 1). We also suggest a new tectonic behavior of several active faults and/or fault systems identified in the area and determine their role in the regional geodynamic processes.
Geological setting The Alboran Sea (150 km across with maximum depth of 2000 m) is bordered by Betic-Rif Cordillera to the north and the south, respectively, and underlain by continental crust (Comas et al. 1992) (Fig. 1). In its Rif Cordillera transect border, the thickness of sediments is clearly decreasing from west to east (Fig. 2) (Alba 2015) by a decrease of the continental crust itself in approximately the same direction (Ben Sari 1978; Tadili et al. 1986). The study region is characterized by Plio-Quaternary volcanic rocks that cause positive residual gravimetric anomalies (Vanié et al. 2005) in the Cap des Trois Fourches (9.8 Ma) (Hernandez and Bellon 1985). The Gourougou volcano varies from calc-alkaline (9–6.6 Ma), shoshonitic (7–5.4 Ma) to alkaline (4.7–2.6 Ma) (Hernandez and Bellon 1985; El Bakkali et al. 1998; El Azzouzi et al. 1999; Roger et al. 2000). Geophysical data affirmed that, consecutively to Miocene co
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