Geochemistry and genesis of thin-layered gabbroids of the Peterman Island (West Antarctica)

1Artemenko, GV
1 M.P. Semenenko Institute of Geochemistry, Mineralogy and Ore-Formation of the NAS of Ukraine, Kyiv
Dopov. Nac. akad. nauk Ukr. 2019, 11:57-65
https://doi.org/10.15407/dopovidi2019.11.057
Section: Geosciences
Language: Russian
Abstract: 

In the intrusion of gabbroids of the Andean complex on the Peterman island (West Antarctica), a xenolith (3×8 m) of thin-layered gabbro, in which there is an alternation of strips 3 cm wide of gabbroids with dif fe rent amounts of dark-colored minerals, is revealed. The origin of this stratification is explained by the sorting of crystal nuclei during the laminar flow of the melt in the inlet channel of a still hot intrusion that underwent the rapid bulk crystallization. In terms of chemical composition, thin-layered gabbro do not differ from containing uniform gabbros. Gabbroids of the Piterman island were formed from a high temperature plume melt. They are charac terized by a low content of silica and potassium. The main magma source for them was the PM mantle. Gabbroids are contaminated with a core material, as indicated by the low ratio (Nb/La)N = (0.22-0.86). This contamination is probably due to the regressive metamorphism of gabbroids caused by the introduction of later intrusions of granitoids of the Andean complex. The xenolith of thin-layered gabbro is probably a fragment of one of the supply channels for the final intrusive phases of the gabbroid massif.

Keywords: amphibolization, Andean complex, Antarctic Peninsula, contamination, gabbro, Peterman island, REE, thin-layered gabbro
References: 

1. Gladkochub, D., Bakhmutov, V., Vodovozov, V. & Vaschenko, V. (2006). New achievements in geological-geophysics investigations at the Academic Vernadsky Station area (Western Antarctica): petrology, geochronology and mineral resources. Proceedings of the III International Conference Scientific investigations in Antarctica (p. 36), Kyiv: UAC.
2. Pankhurst, R. J., Riley, T. R., Fanning, C. M. & Kelley, S. P. (2000). Episodic Silicik Volcanism in Patagonia and the Antarctic Peninsula: Chronology of Magmatism Associated with the Break-up of Gondwana. J. Petrology, 41, No. 5, pp. 605-625. doi: https://doi.org/10.1093/petrology/41.5.605
3. Tangeman, J. A., Mukasa, S. B. & Grunow, A. M. (1996). Zircon U-Pb geochronology of plutonic rocks from the Antarctic Peninsula: Confirmation of the presence of unexposed Paleozoic crust. Tectonics, 15, No. 6, pp. 1309-1324. doi: https://doi.org/10.1029/96TC00840
4. Сondie, K. C. (2005). High field strength element ratios in Archean basalts: a window to evolving sources of mantle plumes? Lithos, 79, pp. 491-504. doi: https://doi.org/10.1016/j.lithos.2004.09.014
5. Elliot, D. H. (1964). The petrology of the Argentine Islands. British Antarctic Survey Scientific Reports, No. 41. London: Publ. British Antarctic Survey.
6. Sharkov, E. V. (2006). Formation of stratified intrusions and associated mineralization. Moscow: Nauchnyiy mir (in Russian).