No 1(17) (2018): Ukrainian Antarctic Journal
Articles

New Geophysical Data About the Pacific Margin (West Antarctica) Magnetic Anomaly Sources and Origin

V. D. Soloviev
S.I. Subbotin Institute of Geophysics, National Academy of Sciences of Ukraine, 32 Akad. Palladin Avenue, Kyiv, 03142, Ukraine
V. G. Bakhmutov
S.I. Subbotin Institute of Geophysics, National Academy of Sciences of Ukraine, 32 Akad. Palladin Avenue, Kyiv, 03142, Ukraine, State Institution National Antarctic Scientific Center, Ministry of Education and Science of Ukraine, 16 Taras Shevchenko Blvd., Kyiv, 01601, Ukraine
I. N. Korchagin
S.I. Subbotin Institute of Geophysics, National Academy of Sciences of Ukraine, 32 Akad. Palladin Avenue, Kyiv, 03142, Ukraine
T. P. Yegorova
S.I. Subbotin Institute of Geophysics, National Academy of Sciences of Ukraine, 32 Akad. Palladin Avenue, Kyiv, 03142, Ukraine
Published June 3, 2019
Keywords
  • West Antarctica,
  • Antarctic Peninsula areas,
  • Pacific Margin Magnetic anomaly,
  • geophysical models,
  • deep crustal structure

Abstract

During the seasonal work in the Ukrainian Antarctic expeditions (1997—2012), a significant amount of geological and geophysical studies were carried out.

The main objective of the study is to obtain new data on the distribution of deep heterogeneities in the structures of the region. It’s allowed to construct the geophysical models and to discuss the existing ideas about the stages of formation and evolution tectonic structures of the West Antarctica near the Antarctic Peninsula (AP). New geophysical models of the Earth's crust were used to study the possible nature of the Pacific Coast magnetic anomaly (PMA) near the AP.

The results of magnetic, seismic and geoelectric surveys in the region of the Antarctic Peninsula showed that active tectonic processes in the Meso — Cenozoic led to the of PMA magnetic sources forming along the edge of the AP. The spatial heterogeneity of the various segments of PMA can also be associated with a variety of depth, thickness and magnetic susceptibility of individual units that form the source of regional anomaly. The magnetic PMA sources in the Earth's crust can be limited in depth (up to 8—10 km) and consist of a series of bodies with different age, composition and magnetization. The shape of the PMA anomalies is significantly affected by numerous local intrusions located in the upper part of the earth's crust. In certain segments of the PMA, they form an additional horizon of magnetized bodies associated with the processes of young volcanism in the structures of the continental margin.

Conclusions. The materials of geophysical surveys and complex geological and geophysical models of the earth's crust and upper mantle were analyzed, which made it possible to identify structural features, evolution, and geodynamic processes of the development of regional structures, as well as to obtain new data on the possible nature of PMA. The total anomaly name (PMA) can formally integrate anomalies of different ages and origins. Numerous local intrusions of young (Cenozoic) age form an additional horizon of magnetized bodies associated with volcanic processes at the top of the crust. Some segments of the PMA may be associated with the processes of tectonic changes near the Antarctic — Scotia paleo-plate boundary, as well as teсtonic and magmatic activity in the areas of paleorift structures detection. New geophysical results for different PMA — segments from the Palmer Land to Powell Basin were used to summarize current ideas about the sources and origins of this positive magnetic anomaly.

References

  1. Burton-Johnson, A., Riley, T. R. 2015. Autochthonous v. accreted terrane development of continental margins: a revised in situ tectonic history of the Antarctic Peninsula. Journal of the Geological Society, August 5. DOI:10.1144/jgs2014-110. https://doi.org/10.1144/jgs2014-110
  2. Catalan, M, Galindo-Zaldivar, J., Davila, J.M. et al. 2013. Initial stages of oceanic spreading in the Bransfield Rift from magnetic and gravity data analysis. Tectonophysics, 585, 102-112. 8. https://doi.org/10.1016/j.tecto.2012.09.016
  3. Civile, D., Lodolo, E., Vuan , A., and Loreto, F.M. 2012. Tectonics of the Scotia-Antarctica plate boundary constrained from seismic and seismological data. Tectonophysics, 550-553, 17-34. https://doi.org/10.1016/j.tecto.2012.05.002
  4. Garrett, S.W. 1990. Interpretation of reconnaissance gravity and aeromagnetic surveys of the Antarctic Peninsula. J.Geophys. Res. , 95 (B5), 6759-6777. https://doi.org/10.1029/JB095iB05p06759
  5. Ferraccioli, F., Jones, P.C., Vaughan, A.P., Leat, P.T. 2006. New aerogeophysical view of the Antarctic Peninsula: more pieces, less puzzle. Geophys. Res. Lett., 33. https://doi.org/10.1029/2005GL024636
  6. Ghidella, M.E., Forsberg, R., Greenbaum, J.S. et al. 2011. Magnetic anomaly data from a regional survey: from Tierra del Fuego to northern Palmer Land, Antarctic Peninsula. Latinmag Letters, 1, (A19), 1-7.
  7. Golynsky, A., et al. 2012. Air and shipborne magnetic surveys of the Antarctic into the 21st century, Tectonophysics. https://doi.org/10.1016/j.tecto.2012.02.017.
  8. Golynsky, A.V. and V.N. Masolov. 1999. Interpretation of ground and aeromagnetic surveys of Palmer Land, Antarctic Peninsula. Annali di Geofisica, 42, 333-351.
  9. Gràcia E., Canals M., Farràn , M. et al., 1996. Morphostructure and evolution of the Central and Eastern the Bransfield (NW Antarctic Peninsula). Marine Geophys. Res. 18, 429-448. https://doi.org/10.1007/BF00286088
  10. Johnson, A.C., 1999. Interpretation of new aeromagnetic anomaly data from central Antarctic Peninsula. J. Geophys. Res. 104, 5031-5046. https://doi.org/10.1029/1998JB900073
  11. Jordan, T.A, Neale, R.F., Leat, P.T., et al. 2014. Structure and evolution of Cenozoic arc magmatism on the Antarctic Peninsula: a high resolution aeromagnetic perspective. Geophys. J. Int., 198, 1758-1774. DOI:https://doi.org/10.1093/gji/ggu233
  12. Levashov, S.P., Yakymchuk, N.A., Korchagin, I.N. et al. 2008. Geophysical models of Drake Passage and Bransfield Strait crustal structure. Ukrainian Antarctic Journal, 6, 9-14.
  13. Lodolo, E., Perez, L. F. 2015. An abandoned rift in the southwestern part of the South Scotia Ridge (Antarctica): Implications for the genesis of the Bransfield Strait. Tectonics, 34. https://doi.org/10.1002/2015TC004041
  14. Maslanyj, M.P., Garrett, S.W., Johnson, A.C. et al. 1991. Aeromagnetic anomaly map of West Antarctica, GEOMAP Series, Geophysical Map and Supplementary Text, British Antarctic Survey, Cambridge, 37.
  15. Renner, R.G.B., Sturgeon, L.J.S. Garrett S.W. 1985. Reconnaissance gravity and aeromagnetic surveys of the Antarctic Peninsula. Brit. Antarct. Surv. Sci. Rep., 110, 50.
  16. Shpyra, V., Bakhmutov V., Bakhmutova L.et al. 2014. Magnetic and density characteristics of igneous rocks near the Ukrainian station Akademik Vernadsky. Ukrainian Antarctic Journal, 13, 81-93. (in Russian).
  17. Soloviev V., Korchagin I., Levashov S. et al. 2017. New geophysical data about the Pacific Margin Magnetic anomaly (PMA) sources and some features of the Western Antarctica geodynamic processes, 16th EAGE International Conference on Geoinformatics - Theoretical and Applied Aspects. https://doi.org/10.3997/2214-4609.201701827
  18. Storey, B. C., Garrett, S.W. 1985. Crustal growth of the Antarctic Peninsula by accretion, magmatism and extension. Geol. Magazine, 122, 5-14. https://doi.org/10.1017/S0016756800034038
  19. Sushchevskaya, N.M., Migdisova, N.A., Dubinin, E.P. et al. 2016. Regional and local magmatic anomalies and tectonics of rift zones between the Antarctic and South American plates. Geochemistry International. 54, 6, 494-508. https://doi.org/10.1134/S0016702916050104
  20. Udintsev, G.B., Beresnev, A.F., Curentsova, N.A. et al. 2010. Drake Strait and Scotia Sea - oceanic gates of Western Antarctic (in Russian). Structure and history of development of lithosphere. Russian contribution to IPY. 4. Moscow. Paulsen. 66-90.
  21. Vaughan, A.P.M., Livermore, R.A. 2005. Episodicity of Mesozoic terrane accretion along the Pacific margin of Gondwana: implications for superplume-plate interactions. in: Vaughan A.P.M, Leal P.T.,Punkhurst R.J.(Eds). Terrane Processes the Margins of Gondwana. Spec. Publ. Geol. Soc. of London, 246, 143-178. https://doi.org/10.1144/GSL.SP.2005.246.01.05
  22. Vaughan, A.P.M., Wareham, C.D., Johnson, A.C., Kelly, S.P. 1998. A lower Cretaceous, syn-extensional magmatic source for a linear belt of positive magmatic anomalies: the Pacific Margin Anomaly (PMA), western Palmer Land, Antarctica. Earth and Planetary Science Letters. 158, 143 - 155. https://doi.org/10.1016/S0012-821X(98)00054-5
  23. Yegorova, T., Bakhmutov, V. 2013. Crust structure of the Antarctic Peninsula sector of the Gondwana margin around Anvers Island from geophysical data. Tectonophysics, 585, 77-89. https://doi.org/10.1016/j.tecto.2012.09.029
  24. Yegorova, T., Bakhmutov, V., Janik, T. & Grad, M. 2011. Joint geophysical and petrological models for the lithosphere structure of the Antarctic Peninsula continental marginm Geophys. J. Int., 184 (1), 90-110. https://doi.org/10.1111/j.1365-246X.2010.04867.x