Tephra on the Allan Hills Ice Fields

The tephra layers exposed on the ice fields west of the AUan HiUs were mapped by Dunbar (1995a, b) who also attanpted to date anorthoclase crystals contained within them by the Ar/ Ar method. The outcrop patterns of these tephra layers in Fig. 17.48 demonstrate their linear continuity and the structural deformation of the ice in this area. The same investigators also sampled dnst layers on other ice fields associated with the AUan HiUs, such as the ice around the Elephant and Redding moraines, the Ear Western, Ear Northern, and Meteorite City ice fields, ice adjacent to Carapace Nunatak, and other localities on the margin of the East Antarctic ice sheet in southern Victoria Land. 

The tephra from these localities are classifiable as basanite, trachyte, phonolite, and even rhyolite. Dunbar et al. (1995a, b) attributed these tephra to volcanic eruptions of Mt. Erebus (Kyle et al. 1992 Dunbar et al. 1994), of Mt. Melbourne (Wbmer et al. 1989), and The Pleiades (Kyle 1990). 

Five samples of tephra in dusty ice collected by Marvin (1990) on the ice sheet adjacent to the Allan Hills in Fig. 17.49 (sites 1 and 2) are identified in 

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