Architecture and evolution of hydrovolcanic deltas in Marie Byrd Land, Antarctica
Published:January 01, 2002
W. E. Le Masurier, 2002. "Architecture and evolution of hydrovolcanic deltas in Marie Byrd Land, Antarctica", Volcano–Ice Interaction on Earth and Mars, J. L. Smellie, M. G. Chapman
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The Marie Byrd Land volcanic province is a late Cenozoic alkaline basalt-trachyte volcanic field on the Pacific coast of West Antarctica. Most of these volcanoes are partially buried beneath the West Antarctic ice sheet, but in some, a combination of tectonic uplift and lowering of ice level has exposed basal hydrovolcanic sections produced by eruptions in an englacial environment. Some of the largest and best preserved hydrovolcanic structures are delta-like in form, with gentle distal slopes, and foreset bedded deposits composed of hyaloclastites, pillow breccias, pillow lavas, subaerial flows and air fall tephras. Three broad categories of processes related to delta evolution are described here; (1) flow of lava from a subaerial to an englacial environment; (2) intrusion of dykes and sills; and (3) edifice settling, which includes a variety of down-slope movement phenomena. This paper focuses on documenting post-depositional structures that are superbly exposed in these deltas. It describes the apparently province-wide lack of pillow lava cores in Marie Byrd Land englacial volcanoes, and factors that may be related to this anomaly, and it describes characteristics of hyaloclastites that are relevant to future glaciological, sedimentological and geophysical studies of the West Antarctic ice sheet.
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Volcano–Ice Interaction on Earth and Mars
This volume focuses on magmas and cryospheres on Earth and Mars and is the first publication of its kind to combine a thematic set of contributions addressing the diverse range of volcano-ice interactions known or thought to occur on both planets. Understanding those interactions is a comparatively young scientific endeavour, yet it is vitally important for a fuller comprehension of how planets work as integrated systems. It is also topical since future volcanic eruptions on Earth may contribute to melting ice sheets and thus to global sea level rise.
Papers included here are likely to influence the choice of sites for future Mars missions in exobiologically important areas. On Earth, snow and ice are widespread, not only in extensive icecaps but also as alpine glaciers at high elevations in tropical regions. By contrast, Mars today is an arid volcanic planet with only small polar ice-caps although an abundance of water is believed to be trapped in the cryolithosphere. It is also thought that the planet may have sustained extensive frozen oceans early in its history. The presence of a former hydrosphere, a cryosphere and coincident volcanism thus make Mars the likeliest prospect for the first discoveries of life away from Earth. Much research has assumed that terrestrial volcano-ice systems are plausible analogues for putative Martian examples, but until mankind finally sets foot on Mars, there is no simple test for that assumption.
Our hope is that the knowledge presented here will stimulate research among planetary geologists in this exciting, rapidly expanding field for many years to come.