Some features of the structure of the mantle of the East Mediterranean and their geodynamic interpretation
Journal Title: Геофизический журнал - Year 2016, Vol 38, Issue 1
Abstract
We consider specific velocity anomalies and the corresponding mantle structures of the East Mediterranean-Black Sea-Caspian region. The anomalies are located on latitudinal and longitu¬dinal seismic tomography sections obtained by constructing 3D P-velocity model of Eurasia ap¬plying the Taylor approximation method. The depth of the study is of 50—2900 km. The accura¬cy of determination of the velocity Vp is about ± 0,015 km/s. Velocity sections are shown in residual values A Vp . Physical and mineralogical mantle model of Pushcharovsky was used for the cross sections specification. In the 25—30°E cross sections between latitudes of the 34—48°N high-velocity slabs sink¬ing from the northern edge of the African plate and the southern parts of the East-European plate towards each other are seen. Slabs are connected at a depth of about 600 km in the upper mantle transition zone in the area of 42—43°N. Below the slabs junction high-velocity mantle zone thickens and extends to a depth of 1000—1200 km that occurs as a result of slabs relatively high-velocity material accumulation. From this area down-welling begins which can be traced on latitude sections of 35—45°N as an almost continuous inclined layer of ~ 1100 km width and ~ 1900 km length. Down-welling submerges from a depth of 450—550 km at Moesian and Aegean micro-plates area to a depth of 1600—1900 km beneath the East Black Sea, Anatolian micro-pla¬tes and the northern part of the Arabian plate. The mechanism of the inclined layer formation is discussed with the involvement of global seismic tomography data, and the numerical simula¬tion performed by L. I. Lobkovsky. In the 42—44°N and 34—36°E sections we trace column type vertical structure, which cros¬ses almost the entire mantle at depths of 50—100 to > 2500 km. In the middle of the column on its axis there is a relatively high-velocity anomaly, which reduces in size and values downward. The shape and structure of the mantle column resembles a "tornado". We consider two possible alternative mechanisms of its formation: a) steep subduction of the West Black Sea micro plate beneath the Central Black Sea Ridge, "wedging" of the mantle and the extension stresses occur¬rence in border zone I and middle mantle; b) rising of the plume from zone D'', formation of extension area in middle and upper mantle, lithosphere pulling inward and the subduction zone formation.
Authors and Affiliations
O. B. Gintov, T. A. Tsvetkova, I. V. Bugaenko, A. Murovskaya
Keywords
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