Structural Discontinuity of the Deep Crust

Kalamarides and Berg (1991) demonstrated graphically that the granulites from the Transantarctic Mountains and the Ross Embayment form separate clusters with only minor overlap in coordinates of AI2O3 vs. P O, SiO vs. FeO, and Ba vs. Ni (not shown). However, the most effective separation of the two suites of samples occurs in coordinates of the initial Sr/ Sr ratios vs. values. 

The granulite inclusion from sites in the Ross Embayment have lower values and lower initial Sr/ Sr ratios at 900 Ma than granulite inclusions from the Transantarctic Mountains. These isotopic differences are evident in Fig. 16.9 which also demonstrates that the isotopic compositions of the Kirkpatrick 

The Erebus Glacier forms the Erebus Glacier Tongue which extends from the base of the Hut Point Peninsula into the McMurdo Sound for a distance of 11 km. The ice tongue is a convenient rest stop for geological field parties in Fig. 16.12 on their way to an 

The chemical compositions of the lava flows and pyroclastic deposits of Ross Island range widely from basanite to phonolite (Fig. 16.4). These rocks formed from basanite magmas which differentiated by fractional crystallization in snbsnrface magma chambers. Phonolites are the most highly differentiated products of this process and are probably less voluminous than 

A noteworthy exposure of anorthoclase-phonolite porphyry in Fig. 16.14 occurs near Shackleton s Hut at (iipe Royds. This lava flow may have been erupted by a subsidiary vent on the slopes of Mt. Erebus and flowed into the water of McMurdo Sound which caused the weU-formed pillow structure displayed by this 

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