Shield volcanoes of Marie Byrd Land, West Antarctic rift: oceanic island similarities, continental signature, and tectonic controls
The Marie Byrd Land volcanic province is largely defined by 18 large (up to ~1,800 km3) alkaline shield volcanoes, each surmounted by a summit section of varied felsic rocks dominated by trachytic flows. They are distributed over a 500 × 800-km block-faulted dome within the West Antarctic rift. The basement contact of volcanic sections is ~500 masl at one site and 3,000 mbsl at another, 70 km away, which illustrates the scale of block faulting but complicates an understanding of volcanic structure. Furthermore, the continental ice sheet buries 16 volcanoes to progressively greater heights inland. However, five are sufficiently exposed to allow meaningful comparisons with alkaline oceanic island volcanoes; these comparisons are used as a guide to estimate the structure of Marie Byrd Land volcanoes. The type example for this study is Mt. Murphy, the most completely exposed volcano. It consists of a 1,400-m section of alkaline basalt overlain by trachyte and benmoreite flows that make up ~7–13 % of the volcano volume. In gross structure and composition, Mt. Murphy is similar to Gran Canaria volcano, Canary Islands, but the percent of felsic rock may be three times that of Gran Canaria, if the estimate is approximately correct. Departures from the oceanic island example are believed to represent the imprint of the Marie Byrd Land lithosphere and tectonic environment on volcano evolution. These include a lack of order in the sequence of felsic rock types, lack of progression toward more silica undersaturated compositions with time, absence of a highly undersaturated mafic resurgent stage, and perhaps, a relatively large volume of felsic rock.
KeywordsShield volcanoes Alkaline oceanic islands Evolutionary stages Order of eruption
I am pleased to acknowledge the support of the National Science Foundation through grant # 536526, administered by the Office of Polar Programs. John Andrews and Cristina de Ignacio San José provided much appreciated critiques of an early draft of the manuscript. Formal reviews by Jim Cole, Valentin Troll, and two anonymous reviewers provided helpful and authoritative critiques of Gran Canaria, Mt. Murphy, and other sections, for which I am very grateful. I am much obliged to Associate Editor Ben van Wyk de Vries for well-balanced reviews and thoughtful editorial oversight that greatly improved the manuscript.
- Bentley CR, Clough JW (1972) Antarctic subglacial structure from seismic refraction measurements. In: Adie RJ (ed) Antarctic geology and geophysics. Universitetsforlaget, Oslo, pp 683–691Google Scholar
- Drewry DJ (1983) Antarctica: glaciological and geophysical folio: Scott Polar Research Institute, University of Cambridge, 9 sheetsGoogle Scholar
- LeMasurier WE, Thomson JW, eds (1990) Volcanoes of the Antarctic Plate and southern oceans. AGU. Antarct Res Ser 48, 487 pGoogle Scholar
- LeMasurier WE, Choi SH, Kawachi Y, Mukasa SB, Rogers NW (2011) Evolution of pantellerite-trachyte-phonolite volcanoes by fractional crystallization of basanite magma in a continental rift setting, Marie Byrd Land, Antarctica. Contr Miner Petrol 162:1175–1199. doi:10.1007/s00410-011-0646-z CrossRefGoogle Scholar
- Rogers NW (2006) Basaltic magmatism and the geodynamics of the East African Rift system. In: Yirgu G, Ebinger CJ, Maguire PKH (eds) The Afar Volcanic Province within the East African Rift system. Geol Soc Lond Spec Publ 259. Geological Society London, Bath, pp 77–93Google Scholar
- Schmincke H-U, Sumita M (2010) Geological evolution of the Canary Islands: a young volcanic archipelago adjacent to the old African continent. Görres-Verlag, Koblenz, n.d., 200pGoogle Scholar
- Sinton JM (1990) Waianae, Oahu, Hawaii. In: Woods CA, Kienle J (eds) Volcanoes of North America: United States and Canada. Cambridge University Press, Cambridge, pp 323–324Google Scholar
- Smellie JL (2001) Lithofacies architecture and construction of volcanoes constructed in englacial lakes: Icefall Nunatak, Mount Murphy, eastern Marie Byrd Land, Antarctica. In: White JDL, Riggs N (eds) Lacustrine volcaniclastic sedimentation, vol 30, Spec Publs Int Assoc Sedimentol., pp 9–34Google Scholar
- van den Bogaard P, Schmincke H-U (1998) Chronostratigraphy of Gran Canaria. In: Weaver PPE, Schmincke H-U, Firth JV, Duffield W (eds) Proceedings of the Ocean Drilling Program, vol 157, Scientific Results., pp 127–140Google Scholar
- Viñuela JM (2007) The Canary Islands hot spot. www.MantlePlumes.org
- Wilch TI, McIntosh (2002) Lithofacies analysis and 40Ar/39Ar geochronology of ice–volcano interactions at Mt. Murphy and the Crary Mountains, Marie Byrd Land, Antarctica. In: Smellie JL, Chapman MG (eds) Volcano–ice interaction on Earth and Mars. Geological Society Special Publication 202, London, pp 237–253Google Scholar
- Wilch TI, McCuddy SM, McIntosh WC (2000) Middle and late Wisconsinan expansions of the West Antarctic ice sheet at Mt. Takahe volcano (abs). In: Volcano/ice interaction on Earth and Mars abstract volume. August 13–15, 2000. University of Iceland, Reykjavik, ppGoogle Scholar