Mineral magnetic properties of granodiorite, metagabbro and microgabbro of Petermann Island, West Antarctica

Vitalii Pavlovych Ponomar, Liubomyr Igorovych Gavryliv

10.5817/CPR2018-1-7

The research focuses on studying the magnetic properties and mineralogy of iron-bearing minerals of granodiorite, metagabbro, and microgabbro of Petermann Island, West Antarctica. The predominant iron-bearing minerals of the rocks are ilmenite, magnetite, and iron sulphides. Magnetite in metagabbro and microgabbro is pointed out to be present as two morphological types with different grain size and morphology. The rocks owe their magnetic properties to the presence of different amounts of magnetite with the Curie temperatures of 570–575°C for granodiorite, 555–560°C for metagabbro and 560–565°C for microgabbro. Magnetite in the rocks is stable under heating to 650°C. A slight decrease in magnetisation at 350–400°C is attributed to the conversion of maghemite or maghemite-like phase into hematite. Variation of the magnetite content within each sample has a strong expression in the saturation magnetisation. The latter increases in sequence: granodiorite (0.8–1.3 Am²/kg), microgabbro (1.8–3 Am²/kg) and metagabbro (3.1–3.5 Am²/kg). The saturation magnetisation of rocks increases with the increasing content of iron. However, the inverse relation is observed for metagabbro and microgabbro due to the replacement of titanite for magnetite in the latter. The magnetic fraction of microgabbro reveals the wasp-waisted hysteresis loop suggesting bimodal size distribution. According to X-Ray Diffraction, the characteristic peaks (d-spacing) of pure magnetite are identified for magnetic fraction of granodiorite and metagabbro, while magnetite of microgabbro form stable intergrowth with titanite and chlorite.

Graham Land, rock magnetic properties, magnetite, thermomagnetic analysis

References:

Artemenko, G. V., Bakhmutov, V. G. and Bakhmutova, L. N. (2011): The results of geochemical investigations of ore mineralization at the Antarctic Peninsula Batholith rocks. Ukrainian Antarctic Journal, 10–11: 13-25. (In Russian).

Artemenko, G. V., Bakhmutov, V. G., Samborskaya, I. A., Bakhmutova, L. N. and Shpyra, V. V. (2013): Magmatic layering of the Antarctic Peninsula Batholith gabbroids. Ukrainian Antarctic Journal, 1, 2. (In Russian).

Bakhmutov, V. G., Gladkochub, D. P. and Shpyra, V. V. (2013): The age, geodynamics and paleomagnetism of the intrusive complexes of West Antarctica. Geophysical Journal, 3: 3-30. (In Russian).

Chen, Y.H. (2013): Thermal properties of nanocrystalline goethite, magnetite, and maghemite. Journal of Alloys and Compounds, 553: 194-198. doi:10.1016/j.jallcom.2012.11.102

Cornell, R. M., Schwertmann, U. (2003): The iron oxides: structure, properties, reactions, occurrences and uses. John Wiley & Sons. 703 p.

Curtis, R. (1966): The petrology of the Graham coast, Graham Land (Vol. 50). British Antarctic Survey. 51 pp.

De Boer, C. B., Dekkers, M. J. (2001): Unusual thermomagnetic behaviour of haematites: neoformation of a highly magnetic spinel phase on heating in air. Geophysical Journal International, 144: 481-494.

Dekkers, M. J., Linssen, J. H. (1989): Rockmagnetic properties of fine-grained natural low-temperature haematite with reference to remanence acquisition mechanisms in red beds. Geophysical Journal International, 99: 1-18. doi:10.1111/j.1365-246X.1989.tb02012.x

Frank, U., Nowaczyk, N. R. (2008): Mineral magnetic properties of artificial samples systematically mixed from haematite and magnetite. Geophysical Journal International, 175: 449-461. doi:10.1111/j.1365-246X.2008.03821.x

Frederichs, T., von Dobeneck, T., Bleil, U. and Dekkers, M. J. (2003): Towards the identification of siderite, rhodochrosite, and vivianite in sediments by their low-temperature magnetic properties. Physics and Chemistry of the Earth, 28: 669-679. doi:10.1016/S1474-7065(03)00121-9

Guenthner, W. R., Barbeau, D. L., Reiners, P. W. and Thomson, S. N. (2010): Slab window migration and terrane accretion preserved by low‐temperature thermochronology of a magmatic arc, northern Antarctic Peninsula. Geochemistry, Geophys. Geosystems, 11: 1-13.

Isambert, A., Valet, J.-P., Gloter, A. and Guyot, F. (2003): Stable Mn-magnetite derived from Mn-siderite by heating in air. Journal of Geophysical Research: Solid Earth, 108: 2283. doi:10.1029/2002JB002099

Kim, W., Suh, C.-Y., Cho, S.-W., Roh, K.-M., Kwon, H., Song, K. and Shon, I.-J. (2012): A new method for the identification and quantification of magnetite–maghemite mixture using conventional X-ray diffraction technique. Talanta, 94: 348–352. doi:http://dx.doi.org/10.1016/ j.talanta.2012.03.001

Kudryavceva, G. P. (1988): Ferrimagnetism of natural oxides. Nedra, Moscow, Russia. 232  p.

Lattard, D., Engelmann, R., Kontny, A. and Sauerzapf, U. (2006): Curie temperatures of synthetic titanomagnetites in the Fe-Ti-O system : Effects of composition, crystal chemistry , and thermomagnetic methods. Journal of Geophysical Research: Solid Earth, 111: 1-18. doi:10.1029/2006JB004591

Le Maitre, R. W., Streckeisen, A., Zanettin, B., Le Bas, M. J., Bonin, B. and Bateman, P. (Eds.). (2002): Igneous rocks: a classification and glossary of terms: recommendations of the International Union of Geological Sciences Subcommission on the Systematics of Igneous Rocks. Cambridge University Press. 237 p.

Mytrokhyn,  A. V., Bakhmutov V. G., Gavryliv L. I. and Aleksieienko A. G. (2017): Geological Setting Of The Petermann Island (Wilhelm Archipelago, West Antarctica) (in press). Geological Visnyk of Taras Shevchenko National University of Kyiv.

Pankhurst, R. J. (1982): Rb-Sr geochronology of Graham Land, Antarctica. Journal of the Geological Society, London, 139: 701-711. doi:10.1144/gsjgs.139.6.0701

Ponomar, V. P., Dudchenko, N. O. and Brik, A. B. (2017): Phase transformations of siderite ore by the thermomagnetic analysis data. Journal of Magnetism and Magnetic Materials, 423: 373-378. doi:10.1016/j.jmmm.2016.09.124

Salazar-Camacho, C., Villalobos, M., Rivas-Sánchez, M. de la L., Arenas-Alatorre, J., Alcaraz-Cienfuegos, J. and Gutiérrez-Ruiz, M. E. (2013): Characterization and surface reactivity of natural and synthetic magnetites. Chemical Geology, 347: 233-245. doi:10.1016/ j.chemgeo.2013.03.017

Strangway, D. W., Honea, R. M., McMahon, B. E. and Larson, E. E. (1968): The magnetic properties of naturally occuring goethite. Geophysical Journal International, 15: 345-359.