HYDRATION OF THE UPPER MANTLE AND TECTONICS OF THE OCEANIC CRUST

  • A. M. Gorodnitskiy Shirshov Institute of Oceanology, Russian Academy of Sciences
  • N. A. Shishkina Shirshov Institute of Oceanology, Russian Academy of Sciences
DOI 10.29006/1564-2291.JOR-2018.46(3).9
Keywords Tectonics, upper mantle, oceanic crust, hyperbasites, serpentinization, middle ridges, transform faults, magnetic field, gravity field, heat flux, magnetic modeling, subduction zones, isostasia

Abstract

The joint analysis of the results of geological and geophysical studies of the oceanic lithosphere and modern models of theoretical geodynamics allows us to distinguish three main types of hydration of the upper mantle with ocean water and their subsequent serpentinization. The first type includes frontal hydration, bilateral with respect to the axial zones of the middle ridges on their flanks along the system of microcracks, which leads to the formation of a plastic serpentinite layer with a thickness of about 2 km in the bottoms of the crust. This leads to the formation of cover-thrust structures in the compression zones. The second type is associated with the penetration of ocean water in the zones of stretching along large crust cracks into the upper mantle, where the depth of the Hess isotherm limits serpentinization. In this case, subvertical protrusions and sills are formed in the sides of the faults. The reduced density of serpentinites stimulates a subvertical rise of the overlying blocks of the cortex. The third type is the complex process of the formation of serpentinites in the subduction zones in the moving plate during the hydration with ocean water from above and in the coming plate as a result of dehydration from the bottom. At the same time, the dehydration of the moving ocean plate makes it fragile and can stimulate strong earthquakes. Serpentines formations have a high magnetization and make a significant contribution to the anomalous magnetic field in oceanic areas.

References


  1. Astafurova E.G., Gorodnitskiy A.M., Lukianov S.V, and Mashchenkov S.P. Priroda magnitnykh anomaliy i stroyeniye okeanicheskoy kory Sredinno-Atlanticheskogo khrebta i prilegayushchikh kotlovin v predelakh Kanaro-Bagamskogo geotraversa. (The nature of magnetic anomalies and the structure of the oceanic crust of the Mid-Atlantic Ridge and adjacent basins within the Canar-Bahamas geotraverse), Priroda magnitnykh anomaliy i stroyeniye okeanicheskoy kory. Moskva: Izd-vo VNIRO, 1996, pp. 171–202.

  2. Bostock M., Hyndman R., Rondenay S., and Peacock S. An inverted continental Moho and serpentinization of the forearc mantle. Nature, 2002, Vol. 417(6888), pp. 536–538.

  3. Fox P.J. and Opdykte N.D. Geology of the oceanic Crust: magnetic properties of the oceanic rocks. J. Geophisic. Res, 1973, Vol. 78, No. 23, pp. 5139–5154.

  4. Gordin V.M. and Gorodnitskiy A.M. Obobshchennaya petromagnitnaya model litosfery (Generalized petromagnetic model of the lithosphere). Kiyev: Naukova dumka, 1994, pp.103–107.

  5. Gorodnitskiy A.M. Stroyeniye okeanskoy litosfery i formirovaniye podvodnykh gor (The structure of the oceanic lithosphere and the formation of seamounts). Moskva: Nauka, 1985, 166 p.

  6. Gorodnitskiy A.M., Belyayev I.I., Brusilovskiy Yu.V., Popov K.V., and Shcherbakov V.P. Geomagnitnyye kharakteristiki podvodnogo khrebta Gorrindzh (sevemaya Atlantika). (Geomagnetic characteristics of the submarine ridge Gorringe (North Atlantic)). Okeanologiya, 1988, Vol. 28, No. 5, pp. 814.

  7. Gorodnitskiy A.M., Belyayev I.I., and Filin A.M. Tsentralnaya kotlovina Indiyskogo okeana, Magnitnoye pole okeana. (Central Indian Ocean Basin, Ocean Magnetic Field), Moscow: Nauka, 1993, pp. 156–165.

  8. Gorodnitskiy A.M. and Brusilovskiy Yu.V. Priroda magnitnykh anomaliy i stroyeniye okeanicheskoy kory v zonakh aseysmichnykh khrebtov i vnutriplitovykh dislokatsiy. (The nature of magnetic anomalies and the structure of the oceanic crust in the zones of aseismic ridges and intraplate dislocations), Priroda magnitnykh anomaliy i stroyeniye okeanicheskoy kory. Moskva: Izd-vo VNIRO, 1996, pp. 203–242.

  9. Gorodnitskiy A.M., Brusilovskiy Yu.V., Ivanenko A.N., Popov K.V., Shishkina N.A., and Veklich I.A. Gidratatsiya okeanicheskoy litosfery i magnitnoye pole okeana, Geofizicheskiye issledovaniya. (Hydration of the oceanic lithosphere and ocean magnetic field, Geophysical surveys), 2017, Vol. 18, No. 4, pp. 32–49, doi: 10.21455/gr2017.4-3.

  10. Gorodnitskiy A.M., Brusilovskiy Yu.V., Ivanenko A.N., Popov K.V., and Shishkina N.A. Priroda magnitnykh anomaliy v zonakh subduktsii. (The nature of magnetic anomalies in subduction zones). Fizika Zemli, 1917, No. 5, pp. 1–8.

  11. Gorodnitskiy A.M. and Fedorova T.P. Lateralnyye izmeneniya anomaliy sily tyazhesti v zone SAKh i protsessy serpentinizatsii. (Lateral changes in gravity anomalies in the Sah zone and serpentinization processes), Gravimetricheskiye issledovaniya Mirovogo okeana. Moscow: Vysshaya shkola, 1991, pp. 15–20.

  12. Gorodnitskiy A.M. and Shishkina N.A. Obobshchennaya petromagnitnaya model okeanskoy litosfery (Generalized petromagnetic model of the oceanic lithosphere). Priroda magnitnykh anomaliy i stroyeniye okeanicheskoy kory. Moskva: Izd-vo VNIRO, 1996, pp. 243–252.

  13. Kirby S., EngdahlE., and Denlinge R. Intermediate-depth intraslab earthquakes and arc volcanism as physical expressions of crustal and uppermost mantle metamorphism in subducting slabs, in Subduction. Top to Bottom, edited by Bebout G.E. et al., 1996, pp. 195–214.

  14. Levis B.T.R. Evolution of oceanic crust. seismic velocities, Earth. Planet. Sci., 1978, pp. 377–404.

  15. Linkova T.I., Kashintsev G.L., GorodnitskiyA.M. and Raykevich M.I. Magnitnyye kharakteristiki porod v razreze okeanicheskoy kory razloma Khizena. Okeanologiya, 1982, Vol. 22, No. 3, pp. 446–453.

  16. Linkova T.I. and Raykevich M.I. Paleomagnitnyye issledovaniya korennykh porod zapadnoy chasti Tikhogo okeana. Magadan: SVKNII DVO AN SSSR, 1989, 41 p.

  17. Lobkovskiy L.I. Geodinamika zon spredinga. subduktsii i dvukhyarusnaya tektonika plit. Moskva: Nauka, 1988, 230 p.

  18. Maekawa H., Yamanoto K., Teruaki I., Ueno T., and Osada Y. Serpentinite Sea mounts and Hydrated Mantle Wedge in the Izu-Bonin and Mariana Forearc Regions. Bull. Earthq. Res. Inst. Univ, Tokyo: 2001, Vol. 76, pp. 355–366.

  19. Magnitnoye pole okeana. Moskva: Nauka, 1993, 298 p.

  20. Nazarova E.A. and Gorodnitskiy A.M. Magnitnyye kharakteristiki glubinnykh sloyev okeanicheskoy kory i struktura anomalnogo magnitnogo polya okeanov. Okeanologiya, 1986, Vol. 26, No. 3, pp. 446–450.

  21. Nikolayevskiy V.N. Granitsa Mokhorovichicha kak predelnaya glubina khrupko-dilatansionnogo sostoyaniya gornykh porod. Dokl. AN SSSR, 1979, Vol. 249, No. 4, pp. 817–821.

  22. Oleskevich D., Hyndman R., and Wang K. The up dip and down dip limits to great subduction earthquakes: Thermal and structural models of Cascadia. south Alaska. SW Japan. and Chile. J. Geophys. Res, 1999, Vol. 104(B7), pp. 14.965–14.991.

  23. Stokking L.B., Merrill D.L., Haston R.B., Ali J.R., and Saboda K.L. Rock magnetic studies of serpentinite seamounts in the Mariana and Izu-Bonin regions. Proceedings of the Ocean Drilling Program, Scientific Results, 1992, Vol. 125, pp. 561–579.

  24. Valyashko G.M., Gorodnitskiy A.M., Lukianov S.V, and Popov E.A. Zony sredinnykh khrebtov i glubokovodnykh okeanicheskikh kotlovin, Petromagnitnaya model litosfery. Kiyev: Naukova dumka, 1994, pp. 55–82.

  25. Vlakely R., Brocher T., and Wells R. Subduction-zone magnetic anomalies and implications for hydrated forearc mantle. Geology, 2005, No. 33, pp. 445–448, doi: f10.1130/G21447.

  26. Zonenshayn L.P., Kuzmin M.I., and Lisitsyn A.P. Tektonika riftovoy doliny SAKh mezhdu 26 i 24°s.sh., svidetelstva vertikalnykh peremeshcheniy. Geotektonika, 1989, No. 4, pp. 99–112.

Published
2018-12-26
Issue
Vol 46 No 3 (2018): Journal of Oceanological Research
Section
Marine geology, geophysics and geochemistry

Transfer of copyrights occurs on the basis of a license agreement between the Author and Shirshov Institute of Oceanology, RAS

Most read articles by the same author(s)