Dark oligotrophic volcanic ecosystems (DOVEs are good environments for investigations of life in the absence of sunlight as they are poor in organics, rich in chemical reactants and well known for chemical exchange with Earth’s surface systems. Erebus, Antarcticaĭirectory of Open Access Journals (Sweden)įull Text Available The Earth’s crust hosts a subsurface, dark, and oligotrophic biosphere that is poorly understood in terms of the energy supporting its biomass production and impact on food webs at the Earth’s surface. Microbial communities in dark oligotrophic volcanic ice cave ecosystems of Mt. The results of our study should help to elucidate interpretations of other, less well exposed, pyroclastic density current deposits elsewhere in Antarctica and globally. Well-exposed caldera interiors are uncommon and that at Mason Spur is helping understand eruption dynamics associated with a complex large island volcano. Liquid water was not initially present but a steam phase was probably generated during transport and may represent water ingested during passage of the current as it passed over either wet ground, stream, shallow lake or (possibly) snow. Field mapping indicates that the deposit is an ignimbrite and, together with petrological considerations, it is suggested that mixing of dense spatter and pumiceous lapilli tuff in the investigated deposit occurred during emplacement, not necessarily in the same vent, with the mixed fragmental material emplaced as a pyroclastic density current. The caldera filling sequence includes an unusual trachytic spatter-rich lapilli tuff (ignimbrite) facies that is particularly striking because of the presence of abundant black fluidal, dense juvenile spatter clasts of trachytic obsidian up to 2 m long supported in a pale cream-coloured pumiceous lapilli tuff matrix. The near-continuous exposure, 10 km laterally and > 1 km vertically, cuts through Cenozoic alkalic volcanic rocks of the Erebus volcanic province (McMurdo Volcanic Group) and permits the study of an ancient volcanic succession that is rarely available due to subsequent burial or erosion. B.Įrosion has revealed a remarkable section through the heart of a volcanic island, Mason Spur, in the southwestern Ross Sea, Antarctica, including an unusually well-exposed section of caldera fill. Formation of a spatter-rich pyroclastic density current deposit in a Neogene sequence of trachytic-mafic igneous rocks at Mason Spur, Erebus volcanic province, Antarctica
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