Wisconsin Range Batholith

The granitic basement rocks of the Wisconsin Range Batholith are the dominant lithology in the Quartz Hills and Caloplaca Hills west of Reedy Glacier (Fig. 7.4). They also form the main part of the exposed basement rocks east of the Reedy Glacier and extend east as far as the Long Hills. These granitic basement 

The Wisconsin Range Batholith contains several textural varieties of granitic rocks which Murtaugh (1969) described as  

Foliated porphyroblastic Massive porphyroblastic Equigranular Tourmaline granite Porphyritic 

The bulk of the Wisconsin Range Bathohth is composed of foliated and massive porphyroblastic facies. The tourmaline-bearing granite occurs on Savage Nunatak (Fig. 7.6) and is illustrated in Fig. 7.8. The tourmaline occurs in the form of ovoid rosettes up to 

15 cm in diameter which are surrounded by hght-colored haloes (see also Fig. 17 of Murtaugh 1969). 

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Fig. 7.4 The geology of the Wisconsin Range and of the Long Hills is dominated by the Granite Harbor Intrusives of the Wisconsin Range Batholith. These granitic rocks intruded the metasedimentary rocks of the LaGorce Formation and the metavolcanic rocks of the Wyatt Formation, both of which also...

Fig. 7.8 Equigranular and unfoliated granitoid of the Wisconsin Range Batholith on Savage Nunatak containing rosettes of black tourmaline surrounded by haloes of light-colored granitic rock (Photo by G. Faure)...

Fig. 7.10 The Kukri Peneplain is exposed on Tillite Spur in the Wisconsin Range Batholith. John G. Murtaugh is pointing to the valley of the Olentangy Glacier (Fig. 7.2) where Permian tillites imconformity a this site (Photo by G. Fauie) rest unconformably on unfoliated and porphyritic facies of the...

The Rb-Sr date (494 5 Ma) and low initial Sr/ Sr ratio (0.7055 0.0014) indicate that the rocks of the post-tectonic facies of the Wisconsin Range Batholith crystallized during the Late Cambrian to Early Ordovician from magma that was not a derivative of the syntectonic magmas that formed the gneissic granitoids. Moreover, the wide distribution of the post-tectonic... 

The Todd Ridge pyroclastic rocks may have been intruded by the porphyritic facies of the Wisconsin Range Batholith in which case the felsic pyroclastic rocks should be older than 497 4 Ma (Table 7.2). Actually, Faure et al. (1968b) reported a whole-rock Rb-Sr date of 521 38 Ma (Early Cambrian) for six specimens of the Todd Ridge pyroclastics (recalculated to >. = 1.42 X 10 year"0 ... 

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