Granitic rocks granitoids

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)...

The granitoid pluton is mostly massive, with some isolated off-shoots of the pluton in the east show foliation in the NW-SE direction with moderate dips towards SW (Fig.1), which is parallel to the schistosity of the country-rock metapelites. Pegmatites and pegmatitic quartz veins occur in metasediments, spatially associated with the granites. 

Rimsaite, J. 1982. Mineralogical and petrochemical properties of heterogeneous granitoid rocks from radioactive occurrences in the Grenville structural province, Ontario and Quebec. In Maurice, Y.T. (ed) Uranium in Granite. Geological Survey of Canada, SI-23, 19-30. 

Many granitic plutonic rocks throughout the world have relatively uniform 0-contents with 5 0-values between 6 and 10%c. Granitoids at the low 0 end of the normal group have been described from oceanic island - arc areas where continental crust is absent (e.g., Chivas et al. 1982). Such plutons are considered to be entirely mantle-derived. Granites at the high end of the normal 0-group may have... 

Graham IJ, Palmer K (1987) New precise Rb-Sr mineral and whole-rock dates for I-type granitoids from Granite Harbor, south Victoria Land, Antarctica. New Zealand Antarctic Record 8(l) 72-80... 

Chemical and isotopic data by Borg et al. (1986, 1987) indicate that the Admiralty Intmsives are primarily 1-type granitoids in contrast to the Granite Harbor hitrusives which include both 1-type and S-type rocks. Nevertheless, regional trends in the chemical compositions of the Admiralty Intmsives suggest that cmstal rocks of sialic composition contributed to their petrogenesis and that the involvement of cmstal rocks increased in a northeasterly direction across the Robertson Bay Terrane. 

The tectonic map of the Shackleton Range in Fig. 8.22 reveals that the Read Mountains are a window that exposes the granitic gneisses and granitoid intru-sives of the East Antarctic craton (Talarico and Kroner 1999). These rocks are unconformably overlain by the undeformed and unmetamorphosed sedimentary rocks of the Watts Needle Formation which contains Neoproterozoic stromatolites. The crystalline basement rocks of the Read Moimtains and their sedimentary cover-rocks (Unit IV) were over-ridden by the metasedimentary rocks of Unit III which were originally mapped by a Clarkson (1982) as the Turnpike... 

Fig. 8.23 The continental collision model considers that the structure of the Shackleton Range is the result of compression caused by the collision of the East Antarctic craton with the African continent. The resulting closure of the Mozambique ocean is recorded by the Mozambique fold belt. The Ross Orogen, which underlies the Transantarctic Mountains formed by compression of sedimentary and volcanic rocks in an active subduction zone followed by intrusion of the anatectic granitoids of the Granite Harbor Intrusives. Both tectonic processes affected the deposition and subsequent deformation and metamorphism of the basement rocks of the Shackleton Range (Adapted from Tessensohn et al. 1999a)...

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