Abstract
The Precambrian Silent Lake pluton, Cardiff township, Ontario, consists of granitic rocks containing, in many localities, abundant quartz-sillimanite nodules. The intrusive form of the Pluton and massive character of most rocks suggests a magmatic origin. Lack of (a) sharp contacts, (b) apophyses, (c) contact metamorphism, (d) evidence of systematic magma evolution in the haplogranite system, (e) country-rock xenoliths, suggest non-magmatic origin. Polyhedral textures indicate annealing after emplacement. Bulk chemical composition, including very low Ca, low Mg, low Sr, high Sr/Ca indicate sedimentary (arkosic) origin. The rocks appear to be Hermon formation leptites mobilized and emplaced by ductile flow, followed by annealing. Structural, mineralogical, chemical and oxygen isotopic evidence indicate the nodules to have formed by deformation and de-alkalization of quartz-feldspar veins within the mobilized leptites.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
