Search

Mount Early and Sheridan Bluff (87° S) are the above-ice expression of Earth's southernmost volcanic field and are isolated by > 1000 km from any other exposed Cenozoic volcano in Antarctica. These monogenetic, Early Miocene volcanoes consist of olivine-phyric basaltic pillow lavas and breccias (Mount Early) and pāhoehoe lavas (Sheridan Bluff) whose differentiation is controlled by the fractional crystallization of olivine with lesser quantities of clinopyroxene, plagioclase and magnetite. Fractional crystallization or contamination by crust cannot account for the coexistence of olivine tholeiite and alkaline compositions but their relationship can be explained by change from higher (5–6%) to lower (1.5–2%) degrees of partial melting concurrent with a decrease in peridotite‒melt reaction in a mantle that is heterogeneous on a small-scale. Both magma types have geochemical and isotopic signatures that differentiate them from most of the volcanism found within the West Antarctic rift system. Data trends in Sr–Nd–Pb isotope space indicate mixing of at least two-distinct mantle sources: (1) a relatively depleted component similar to sources for mid-ocean ridge basalt from the extinct Antarctic–Phoenix spreading center, and (2) an enriched component similar to sources for mafic magmas of the Jurassic Karoo‒Ferrar large igneous provinces. The availability of these mantle source types was facilitated by the detachment, sinking and heating of metasomatized continental lithosphere (enriched source) that released volatiles into the surrounding asthenosphere (depleted source) to promote flux melting. Volcanism triggered by lithospheric detachment is, therefore, explicitly applied to Mount Early and Sheridan Bluff to explain their isolation and enigmatic tectonic setting but also to account for source heterogeneity and the ephemeral change in degree of mantle partial melting recorded in their mafic compositions. [ABSTRACT FROM AUTHOR]

Neogene volcanic centres are uncommon in the Transantarctic Mountains but at least three basaltic examples occur within 300 km of South Pole, above 2200 m asl and inland of the margin of the West Antarctic Rift System. They are the southernmost volcanoes on Earth and have yielded Early—mid Miocene isotopic ages. Two of the centres, at Mt Early and Sheridan Bluff, have been examined. The centre at Mt Early is unequivocally glaciovolcanic. It formed a tall monogenetic volcanic edifice at least 1 km high and > 1.5 km in diameter. It erupted under significantly thicker-than-modern ice, which was probably a fast-moving ice stream at the eruptive site and resulted in a distinctive constructive architecture and lithofacies. It is the first described example of a glaciovolcano erupted beneath an ice stream. The characteristics of the second centre at Sheridan Bluff indicate that it was also a monogenetic volcano but with a shield-like profile, originally c. 6 km in basal diameter but just c. 400 m high. It probably erupted in a substantial pluvial lake in an ice-poor or ice-free environment. The strongly contrasting eruptive settings now identified by the volcanic sequences at both centres examined testify to a highly dynamic Antarctic Ice Sheet during the Early—mid Miocene. [ABSTRACT FROM AUTHOR]

Correction to: Mantle sources and melting processes beneath East Antarctica: geochemical and isotopic (Sr, Nd, Pb, O) characteristics of alkaline and tholeiite basalt from the Earth's southernmost (87° S) volcanoes B Correction to: Contributions to Mineralogy and Petrology (2022) 177:51 b https://doi.org/10.1007/s00410-022-01914-9 In the original version of this article, the symbols shown in the key within Fig. That is, SB-01 tholeiite should be the green triangle with inset black cross and SB-06 hawaiite should be the light-green diamond symbol with inset orange cross. [Extracted from the article]

Correction to: Lithofacies and eruptive conditions of the southernmost volcanoes in the world (87° S) B Correction to: Bulletin of Volcanology (2021) 83: 49 b https://doi.org/10.1007/s00445-021-01475-y In this article, reference Cole et al. 2021 was incorrect and should have been 'Cole R, White J, Dürig T, Büttner R, Zimanowski B, Bowman M, Conway C, Leonard G, Pure L, Townsend D (2021) Controls on Andesitic glaciovolcanism from field and experimental studies. The original article can be found online at https://doi.org/10.1007/s00445-021-01475-y. [Extracted from the article]