- tectonic evolution,
- mantle flow,
- tomography,
- density anomaly,
- deep structure
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Abstract
Drake Passage opening is associated with important milestones of the Earth’s history: formation of the Antarctic Circumpolar Current, initiation of the cryogenic zone on the Antarctica continent and effect of this sphere on global climate. Movement of water masses from the Pacific Ocean to the Atlantic Ocean via Drake Passage is only a consequence of geodynamic processes of the lithospheric plates’ shifting and mantle flows of the Earth’s interior. The aim of our work is to model of deep structure and distribution of dense inhomogeneities, as well as to restore geodynamic processes in the lithosphere and mantle of the Drake Passage’s transition zone. Our gravity tomography method was used for modeling (Greku et al., 2009). It is based on realization of the Professor Moritz’s theoretical approach that equipotential surfaces of the Earth coincide with surfaces of constant density, as well as using of his algorithm for determination of harmonic density anomalies by spherical harmonics of the gravitational potential. The method includes following procedures: determination of depths for disturbing masses; determination of density for disturbing masses by the EGM 2008 geoid model. Tomographic models have been created as the vertical cross-sections and lateral slices (maps) for different depths. The work of Barker (2001) on tectonic evolution of the Scotia Sea in view of the Alvarez’s hypothesis (Alvarez, 1982) on the driving mechanism for mantle flow was used for interpretation and analysis of the tomographic models. The crosssection along latitude of 58°S is showing mantle flow on the sub-lithospheric layer of the Pacific Ocean at the depth of 183 km at a distance of 2000 km to the westward from the Shackleton Fracture Zone. Mantle flow loses integrity (continuity) at shallower depths due to interaction with others bodies and it is represented as fragments. Mantle flow’s possible penetrations into the Scotia Sea’s subcrustal layers are marked at depths of 10 km and 3 km. Lateral expansions of mantle flow are shown at the depths of 183 km, 77 km, 30 km, 10 km, 3 km and 2 km on maps in geographical detail. The method allows to model more detailed transformations of the flow at other intermediate depths.
References
- Bakhmutov, V. G. (2002). Geologicheskie i paleomagnitnyie issledovaniia v Zapadnoi Antarktike (raion Argentinskih ostrovov) i ih znachenie dlia paleotektonicheskih rekonstrukciy Antarkticheskogo poluostrova [Geological and paleomagnetic research in the West Antarctica (the Argentine Islands region) and its significance for paleotectonic reconstructions of the Antarctic Peninsula]. Bulletin of UAC, 4, 11-24. (in Russian)
- Gainanov, A. G. (1981). Geologiia i geofizika dna vostochnoi chasti Indiiskogo okeana [Geology and geophysics of the bottom of the Eastern Indian ocean]. M., Nauka. (in Russian)
- Lobkovskiy, L. I., Nikishin, A. M., & Khain, V. Ie. (2004). Current problems of geotectonics and geodynamics. М., Nauchniy mir. (in Russian)
- Moritz, H. (1994). Figura Zemli. Teoreticheskaia geodeziia i vnutrennee stroienie Zemli [The Figure of the Earth. Theoretical geodesy and the internal structure of the Earth]. (in Russian).
- Puscharovskiy, Yu. M., & Puscharovskiy, D. Yu. (1999). Geosfery mantii Zemli [Geospheres of the Earth’s mantle]. Geotektonika, 1, 3-14. (in Russian)
- Sokolov, S. Yu. (2008). Novyi mehanizm gorizontal’nogo dvizheniia tektonicheski aktivnyh mass zemnoy kory i litosfery [A novel mechanism of horizontal movement of the tectonically active masses of the Earth’s crust and lithosphere]. Obschiie i regional’nyie problemy tektoniki i geodinamiki. Materialy XLI tektonicheskogo soveschaniia, V. 2. М., GEOS, 278-282. (in Russian)
- Shymbirev, B. P. (1975). Teoriia figury Zemli [Theory of the figure of the Earth]. М, Nedra.
- Allan, R. R. (1975). Depth of sources of gravity anomalies. Nature Physical Science, 236, 63, 22-23.
- Alvarez, W. (1982). Geological evidence for the geographical pattern of mantle return flow and the driving mechanism of plate tectonics. Journal of Geophysical Research: Solid Earth, 87(B8), 6697-6710.
- Barker, P. F. (2001). Scotia Sea regional tectonic evolution: implications for mantle flow and palaeocirculation. Earth-Science Reviews, 55, 1-39.
- Bowin, C. (2000). Mass Anomaly structure of the Earth. Reviews of Geophysics, 38, 3, 355-387.
- Dalziel, I. W. D., Lawyer, L. A., Pearce, J. A., Barker, P. F., Hastie, A. R., Barfod, D. N. Schenke, H.-W., & Davis, M. B. (2013). A potential barrier to deep Antarctic circumpolar flow until the late Miocene? Geology, 41, 9, 947-950.
- Detrick, R. S., Buhl, P., Vera, E., Mutter, J., Orcutt, J., Madsen, J., & Brocher, T. (1987). Multichannel seismic imaging of an axial magma chamber along the East Pacific Rise between 9° and 13° N. Nature, 326, 35-41.
- Greku, R. Kh., Gozhik, P. F., Litvinov, V. A., Usenko, V. P., & Greku, T. R. (2009). Atlas of the Antarctic Deep Structure with the Gravimetric Tomography. Kyiv
- Larter, R. D., & Barker, P. F. (1991). Effects of ridge-crest trench interaction on Antarctic Phoenix spreading: forces on a young subducting plate. Journal of Geophysical Research: Solid Earth, 96(B12), 19583-19607.
- Majdański, M., Kozlovskaya, E., Swieczak, M., & Grad, M. (2009). Interpretation of geoid anomalies in the contact zone between the East European Craton and the Palaeozoic Platform - I. Estimation of effects of density inhomogeneities in the crust on geoid undulations. Geophysical Journal International, 177(2), 321-333.
- Ghiglione, M. C., Yagupsky, D., Ghidella, M., & Ramos, V. A. (2008). Continental stretching preceding the opening of the Drake Passage: Evidence from Tierra del Fuego. Geology, 36, 8, 643-646.
- Nerlich, R., Clark, S. R., & Bunge, H.-P. (2013). The Scotia Sea gateway: No outlet for Pacific mantle. Tectonophysics, 604, 41-50.
- Rapp, H., Wang, Y. M., & Pavlis, N. K. (1991). Geopotential and Sea Surface Harmonic Coefficient Models, Report # 410. Department of Geodetic Science and Surveying, Ohio State University.
- Ricard, Y., Richards, M., Lithgow-Bertelloni C., & Le Stunff, Y. (1993). A geodynamic model of the mantle heterogeneity. Journal of Geophysical Research, 98(B12), 21895-21909.
- Ritzwoller, M. H., Shapiro, N. M., Levshin, A. L., & Leahy, G. M. (2001). Crustal and upper mantle structure beneath Antarctica and surrounding oceans. Journal of Geophysical Research, 106(B12), 12, 30645-30670.
- Thomas, C., Livermore, R., & Pollitz, F. (2003). Motions of the Scotia Sea plates. Geophysical Journal International, 155(3), 789-804.
- Turcotte, D. L., & Schubert, G. (2002). Geodynamics, 2nd ed. Cambridge.
- Verard, C., Flores, K., & Stampfli, G. (2012). Geodynamic reconstructions of the South America-Antarctica plate system. Journal of Geodynamics, 53, 43-60.