New evidence of delamination in the Western Alboran Sea: Geodynamic evolution of the Alboran domain and its margins |
| |
| Institution: | 1. Department of Cardiovascular Medicine, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan;2. Division of Regeneration and Medicine, Medical Center for Translational and Clinical Research, Hiroshima University Hospital, Hiroshima, Japan;3. Department of Gastroenterology and Metabolism, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan;4. Department of Biostatistics and Data Science, Osaka University Graduate School of Medicine, Osaka, Japan;5. Hiroshima International University, Hiroshima, Japan;6. Department of Cardiovascular Regeneration and Medicine, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan;7. Nagakubo Hospital, Tokyo, Japan;8. Department of Urology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan;1. Research Center for Aquatic Genomics, National Research Institute of Fisheries Science, 2-12-4 Fukuura, Kanazawa-ku, Yokohama, Kanagawa 236-8648, Japan;2. AXIOHELIX Co. Ltd., 5-11 Hakozaki, Nihonbashi, Chuouku 103-0015, Tokyo, Japan;3. Research Center for Subtropical Fisheries, Seikai National Fisheries Research Institute, 148-446 Fukai-Ohta, Ishigaki, Okinawa 907-0451, Japan;4. National Research Institute of Fisheries and Environmental of Inland Sea, 2-17-5 Maruishi, Ohno, Hatsukaichi, Hiroshima 739-0452, Japan |
| |
| Abstract: | The presence of continuous upper crustal blocks between the Iberian Betics and Moroccan Rif in the western and middle Alboran Sea, detected with tomography, can add new information about the lithosphere structure and geodynamic evolution in this region. A large volume of seismic data (P and S wave arrival times) has been collected for the period between 1 December 1988 and 31 December 2008 by 57 stations located in northern Morocco (National Institute of Geophysics, CNRST, Rabat), southern Portugal (Instituto de Meteorologia, Lisbon) and Spain (Instituto Geografico National, Madrid) and used to investigate the lithosphere in the western Alboran Sea region. We use a linearized inversion procedure comprising two steps: (1) finding the minimal 1-D model and simultaneous relocation of hypocenters and (2) determination of local velocity structure using linearized inversion. The model parameterization in this method assumes a continuous velocity field. The resolution tests indicate that the calculated images give near true structure imaged at 5 km depth for the Tanger peninsula, the Alhoceima region and southern Spain. At 15, 30 and 45 km depth we observe a near true structure imaged in northern Morocco, and southern Spain. At 60 and 100 km, southern Spain and the SW region of the Alboran Sea give a near true structure. The resulting tomographic image shows the presence of two upper crustal bodies (velocity 6.5 km/s) at 5–10 km depth between the Betics, Rif, western and central Alboran Sea. Low velocities at the base of these two bodies favor the presence of melt. This new evidence proves that the Tethysian ocean upper crust was not totally collapsed or broken down during the late Oligocene–early Miocene. These two blocks of upper crust were initially one block. The geodynamic process in the eastern of the Mediterranean is driven by slab rollback. The delamination process of the lithospheric mantle terminates with the proposed slab rollback in the western part of the Mediterranean. This can be explained by the removal of the major part of the lithosphere beneath the area, except in the SW part of the Alboran Sea where a small part of the lithospheric mantle is still attached and is extends and dips to SE beneath the Rif, slowly peeled back to the west. A second detached lithospheric mantle is located and extends to eastern part of the Rif and dips to the SE. The removal of lithosphere mantle from the base of the crust was replaced and heated by extrusion of asthenospheric material coming from depth to replace the part of crust detached. A combination of isostatic surface/topographic uplift and erosion induced a rapid exhumation and cooling of deep crustal rocks. |
| |
| Keywords: | Alboran Sea Seismic tomography Crustal velocity Tectonics blocks |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
