Mantle Transition Zone Thickness beneath the Middle East: Evidence for segmented Tethyan slabs, delaminated lithosphere and lower mantle upwelling

• Published in: Journal of Geophysical Research: Solid Earth
• Main Authors: Kaviani, Ayoub, Sandvol, Eric, Moradi, Ali, Rümpker, Georg, Tang, Zheng, Mai, Paul Martin
• Other Authors: Earth Science and Engineering Program, Physical Sciences and Engineering (PSE) Division, Institute of Geosciences, Goethe-University Frankfurt; Frankfurt/Main Germany, Department of Geological Sciences; University of Missouri-Columbia; USA, Institute of Geophysics, University of Tehran; Iran
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Geophysical Union (AGU) 2018
• Subjects: Eida; Seismological Facilities for the Advancement of Geoscience and EarthScope
• Online Access: http://hdl.handle.net/10754/628407; https://doi.org/10.1029/2018jb015627

We use a very large seismic data set to provide a comprehensive image of the mantle transition zone (MTZ) beneath the Middle East. We utilized the technique of Common Conversion Point stacking of P wave receiver functions to investigate the topography on the 410- and 660-km discontinuities defining the upper and lower boundaries of the MTZ. Our results show significant topography on the 410- and 660-km discontinuities and corresponding variations in the MTZ thickness. The MTZ topography is broadly consistent with the results of seismic tomography studies, implying the presence of both cold thermal anomalies imparted by detached Tethyan slabs and lithospheric segments and hot thermal anomalies induced by upwelling of lower mantle material. The MTZ topography in the northern Middle East is dominated by the presence of patches of cold material that are intermittently separated by regions of hot to normal MTZ. Our results suggest that instead of a continuous slab, the Tethyan slab in the Middle East is strongly segmented along the strike of the subduction boundary. Furthermore, we find evidence for a significant gap in subduction extending from the eastern edge of the Cyprean arc to NW Iran. The southern Middle East is dominated by the processes related to the mantle upwelling beneath the Afar depression. Our results imply that buoyant lower mantle material enters the MTZ beneath the Afar depression and then spreads laterally to the northeast beneath the western Arabia, flowing within the MTZ and in the upper mantle. The data set from the stations operated by the Kandilli Observatory Digital Broadband Seismic Network and Israel National Seismic Network was downloaded from the European Integrated Data Archive (EIDA). The facilities of IRIS Data Services and specifically the IRIS Data Management Center were used for access to waveforms and related metadata from temporary stations and global permanent stations used in this study. IRIS Data Services are funded through the Seismological Facilities for the Advancement of Geoscience and EarthScope (SAGE) Proposal of the National Science Foundation under cooperative agreement EAR-1261681. The Iranian Seismological Center (Institute of Geophysics, University of Tehran) and International Institute of Earthquake Engineering and Seismology (IIEES) gratefully provided the waveform data from the permanent broadband stations in Iran. Receiver function data for Saudi Arabia are calculated from broadband recordings of the Saudi National Seismic Network (SNSN) operated by the Saudi Geological Survey. The manuscript benefited from constructive comments by two anonymous reviewers.