Suchergebnisse

This study was supported by projects CGL2016-80687-R AEI/FEDER, P18-RT-3275, B-RNM-301-UGR18 and RNM148 (Junta de Andalucia/FEDER); ALBAMAR JCJC ANR-17-CE030004; the EUROFLEETS program (FP7/2007-2013; no 228344); project FICTS-2011-03-01; and the FPU PhD grant (16/04038), and also by the Spanish Government through the 'Severo Ochoa Centre of Excellence' accreditation (CEX2019-000928-S). ; The IHS KINGDOM software package was utilized in the present study. We also to the marine surveys, MARLBORO2 and SARAS (https://campagnes.flotteoceanographique.fr/ campagnes/12450090/; https://campagnes.flotteoceanographique. fr/campagnes/12000010/). ; Automation of the throw backstripping method has proven to be an effective tool for the determination of the evolution of tectonic activity in wide fault zones. This method has been applied to the Al Hoceima Bay (southwesternmost Mediterranean, Alboran Sea) for a time period covering the last 280 kyr on 672 faults imaged on 265 high-resolution seismic reflection profiles. This area was affected by major earthquakes and corresponds to a transtensional basin deformed by growth faults. The automated application of throw backstripping allowed for a faster deciphering of the migration of tectonic activity. Results show a westward migration of the deformation with quickly increasing deformation rates in the most recent time frames near Al Hoceima, one of the most populated cities. This migration is in agreement with the current seismicity, the GPS data, and recent brittle deformation data. Vertical throw rates of up to 0.47 mm/year have been calculated, for the most recent time periods, in segments of the Bokkoya fault zone. The westward migration of the deformation fits with the reconstruction suggested by the westernmost Mediterranean geodynamic models during the Pleistocene epoch, and it might be the consequence of the interaction between the northwest (NW) movement of the South Alboran indenter and the back Rif south-westward displacement. The highly accurate constraints of the evolution of the tectonic activity offered by this automation will substantially improve the seismic hazard assessment. ; Junta de Andalucia European Commission CGL2016-80687-R AEI/FEDER P18-RT-3275 B-RNM-301-UGR18 RNM148 ; ALBAMAR JCJC ANR-17-CE030004 ; EUROFLEETS program (FP7/2007-2013) 228344 ; German Research Foundation (DFG) 16/04038 ; Spanish Government through the 'Severo Ochoa Centre of Excellence' accreditation CEX2019-000928-S ; FICTS-2011-03-01

14 pages, 9 figures, supplementary data https://doi.org/10.1016/j.margeo.2021.106696 ; In the Alboran Sea there are a few well exposed Neogene and Quaternary volcanic zones, often geographic highs, that are generally associated with magnetic anomalies. In this paper, we present a characterization of these magnetic anomalies based on a recent and accurate magnetic data compilation for the Abloran Sea area. The anomalies reveal the distribution of magmatism and shed light into the discussion about the origin and evolution of the westernmost Mediterranean. One of the most relevant magnetic anomalies is the Nador dipole, which extends from the Gourougou volcano to the Chafarinas Islands, and is related to an E-W crustal scale intrusion. However, the main NE-SW elongated continuous dipoles of the central Alboran Sea are not related to any surface structure, but they are parallel to the Alboran Ridge, which is the main volcanic high in the Alboran Sea, and are located to the north of it. These anomalies extend discontinuously eastward along the NW-SE dipoles located along the Yusuf fault zone. The results of our 2D magnetic forward modeling suggest that the causative bodies of these main magnetic dipoles are deep igneous bodies. According to the tectonic evolution of the region, and the high magnetic susceptibility values obtained, these igneous bodies probably are made of a basic igneous rocks. Their emplacement may represent the westward tip of the rift axis of the AlKaPeCa Domain, which is related to the Oligocene-Miocene NW-SE extension, and associated with the southern slab retreat stage and oceanic spreading of the Algerian basin. Afterwards, these bodies were displaced toward the west, together with the Alboran Domain, and affected by the STEP fault located at its southern limit. Since the Late Miocene, the north Alboran Ridge elongated intrusions acted as a backstop that conditioned the folding and uplift of the Alboran Ridge in a tectonic indentation setting. In this setting, the STEP fault is deformed and the eastern part of the bodies were segmented along the Yusuf transtensional fault system. Simultaneously, the E-W crustal body related to the Nador magnetic dipole was emplaced, possibly evidencing a slab tearing process. The deep seated basic igneous bodies constitute main crustal heterogeneities that reveal and drive the Alboran Sea tectonic inversion ; This study was supported by projects CGL2016-80687-R AEI/FEDER, P18-RT-3275, B-RNM-301-UGR18 and RNM148 (Junta de Andalucía/FEDER). Y.M.M was supported by NASA under award number 80GSFC17M0002. V.T.S. was supported by the FPU PhD grant (16/04038). ICM-CSIC author acknowledges the Severo Ochoa funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2019-000928-S). University of Granada supported this study by funding the APC for publishing as an Open Access articile through an agreement with Elsevier ; Peer reviewed