14.1 Erebus Volcanic Province chemical compositions

These early reports were followed by investigations that were published after the IGY (1957-1958) Forbes (1963), Beck (1965), Cole and Ewart (1968), and Cole et al. (1971). Recent summaries of the geology, chemical composition, and isotope geochemistry of the Cenozoic volcanic rocks in the Erebus volcanic province are contained in bks edited by McGinnis (1981), LeMasurier and Thomson (1990), and Kyle (1995). 

Mafic phonolite occurs in the form of small plugs and flows throughout Ross Island and elsewhere within the Erebus volcanic province. For examples. Post Office Hill at Cape Crozier and Observation Hill at McMurdo Station are composed of this rock type. Their chemical compositions are quite variable. Normative nepheline can be as high as 30%. Most samples contain more augite and kaersutite than the anorthoclase phonolites. 

The chemical compositions of volcanic rocks of the Erebus volcanic province reported by Goldich et al. (1975) and Stuckless et al. (1981) range widely in Fig. 16.4 from low-silica basanites (Bn) to tephrites (Tp), phonotephrites (Ptp), tephriphonolites (Tpp), benmoreites (Bm), and phonolites (P). The silica concentrations of these rocks range from 41.3% (basanite. Brown Peninsula) to 58.1% (benmoreite. Cape Royds, Ross Island). The basanites in Fig. 16.4 have low... 

Fig. 16.16 The chemical compositions of volcanic rocks in DVDP-1 drilled at McMurdo Station on the Hut Point Peninsula range widely on the total alkali-silica diagram from basanite (Bn), to tephrite (Tp), to phonotephrite (Ptp), and to tephriphonolite (Tpp). Therefore, the rocks in this core (201.5 m) are almost as diversified as the McMurdo Volcanics in the entire Erebus volcanic province in Fig. 16.4. Samples of DVDP-2 and 3 are not shown but range just as widely as the rocks of DVDP-1 (Data from Kyle (1981a))...

Worner et al. (1989) reported chemical analyses for 92 samples of volcanic rocks from ten subdivisions of the Melbourne volcanic field. The analyses included major and trace elements and the resulting normative mineral compositions. Without classifying each one of these specimens, it is sufficient to record that their chemical compositions range widely just as they do in the Erebus volcanic province of southern Victoria Land (Fig. 16.4). Worner et al. (1989) also reported isotope... 

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