|Author:||Moukhsil and Côté, 2017|
|Reference section:||Charnockite outcrop (16-LC-4076A)|
|Type area:||NTS sheet 31P12|
|Geological province:||Grenville Province|
|Lithology:||Charnockite, mangerite, granite, quartz monzodiorite, jotunite|
The Tower Plutonic Suite was defined during the work of Moukhsil and Côté (2017) in the Wemotaci area, Haut-Saint-Maurice.
The Tower Plutonic Suite forms an intrusion of felsic to intermediate rocks with or without orthopyroxene that outcrops primarily in sheet 31P12. From a geochemical perspective, these rocks have contents of 68 to 75% SiO2, they are metaluminous (Maniar and Piccoli, 1989) and plot in the field of Type I granites (igneous origin, Chappel and White, 1974). Analyzed samples plot in the fields of volcanic arc granites and intraplate granites.
Charnockite, usually of syenogranitic composition, is coarse grained and locally porphyritic. It is composed of large quartz zones, perthitic K-feldspar phenocrystals (<2 cm long), plagioclase, orthopyroxene, biotite and traces of garnet. Accessory minerals are zircon and magnetite.
The mangerite (orthopyroxene monzonite) is also porphyritic, greenish in fresh exposure and whitish in altered surface. The main minerals are quartz, feldspars, orthopyroxene, biotite, hornblende and trace clinopyroxene.
Monzodiorite and quartz monzodiorite are whitish to greyish in fresh exposure, medium grained and foliated. These rocks are magnetic and contain biotite, feldspars and some millimetric to centimetric garnet porphyroblasts.
Lastly, jotunite (orthopyroxene monzodiorite) resembles the monzodioritic facies, but is magnetic and contains more ferromagnesian minerals such as orthopyroxene, clinopyroxene and biotite.
The Tower Plutonic Suite forms an irregular intrusion approximately 18 km by 25 km located in sheet 31P12.
Does not apply.