Products and processes in Pliocene–Recent, subaqueous to emergent volcanism in the Antarctic Peninsula: examples of englacial Surtseyan volcano construction |
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| Authors: | J L Smellie M J Hole |
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| Institution: | (1) British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, UK Fax: +01223 362616 e-mail: J.Smellie@bas.ac.uk, GB;(2) Department of Geology and Petroleum Geology, Meston Building, King's College, University of Aberdeen, Aberdeen AB9 2UE, UK, GB |
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| Abstract: | Pliocene–Recent volcanic outcrops at Seal Nunataks and Beethoven Peninsula (Antarctic Peninsula) are remnants of several
monogenetic volcanoes formed by eruption of vesiculating basaltic magma into shallow water, in an englacial environment. The
diversity of sedimentary and volcanic lithofacies present in the Antarctic Peninsula outcrops provides a clear illustration
of the wide range of eruptive, transportational and depositional processes which are associated with englacial Surtseyan volcanism.
Early-formed pillow lava and glassy breccia, representing a pillow volcano stage of construction, are draped by tephra erupted
explosively during a tuff cone stage. The tephra was resedimented around the volcano flanks, mainly by coarse-grained sediment
gravity flows. Fine-grained lithofacies are rare, and fine material probably bypassed the main volcanic edifice, accumulating
in the surrounding englacial basin. The pattern of sedimentation records variations in eruption dynamics. Products of continuous-uprush
eruptions are thought to be represented by stacks of poorly bedded gravelly sandstone, whereas better bedded, lithologically
more diverse sequences accumulated during periods of quiescence or effusive activity. Evidence for volcano flank failure is
common. In Seal Nunataks, subaerial lithofacies (mainly lavas and cinder cone deposits) are volumetrically minor and occur
at a similar stratigraphical position to pillow lava, suggesting that glacial lake drainage may have occurred prior to or
during deposition of the subaerial lithofacies. By contrast, voluminous subaerial effusion in Beethoven Peninsula led to the
development of laterally extensive stratified glassy breccias representing progradation of hyaloclastite deltas.
Received: 5 February 1996 / Accepted: 17 January 1997 |
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| Keywords: | Volcanism Lithofacies Surtseyan Hyaloclastite Antarctic Englacial |
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