A POSSIBLE RELATIONSHIP BETWEEN DEEP EARTHQUAKES AND THE STRUCTURAL TRANSITION OF SUBMOLECULAR SiO2 FRAGMENTS IN ROCKS OF A SUBDUCTING OCEANIC SLAB
M.I. Kuzmin1, R.G. Khlebopros2,3, A.N. Didenko4, S.G. Kozlova5,6, V.E. Zakhvataev2,3
1A.P. Vinogradov Institute of Geochemistry, Siberian Branch of Russian Academy of Sciences, ul. Favorskogo 1A, Irkutsk, 664033, Russia
2Federal Research Center Krasnoyarsk Scientific Center, Siberian Branch of the Russian Academy of Sciences, pr. Svobodnyi 78, 660041, Krasnoyarsk, Russia
3Siberian Federal University
4Pacific National University, ul. Tikhookeanskaya 136, Khabarovsk, 680035, Russia
5A.V. Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Lavrent’eva 3, Novosibirsk, 630090, Russia
6V.G. Shukhov Belgorod State Technological University, ul. Kostyukova 46, Belgorod, 308012, Russia
Keywords: Phase transitions, deep-focus earthquakes, upper-lower mantle, lithospheric plate, subduction
Abstract
Quantum-chemical calculations show a tendency of SiO2 molecule to transform from linear to isomeric cyclic (bent) form and back. In the latter case, the energy released during the transition isomeric SiO2 ® linear SiO2 is about 240 kJ/mole. This hypothetic structural transition of submolecular SiO2 fragments in mantle minerals is supposed to initiate deep-focus high-energy earthquakes at the upper-lower mantle boundary. It is at this depth (600-670 km) that the subducting oceanic slab is delaminated: Its upper part moves «horizontally» along the upper-lower mantle boundary, while its lower part separated into blocks subsides into the lower mantle and reaches the D″ layer to accumulate there.
DOI: 10.15372/RGG2019038
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