A review of the relationships between granitoid types, their origins and their geodynamic environments

Abstract

Granitoids are divided into several types according to their mineral assemblages, their field and petrographical features, and their chemical and isotopic characteristics. This typology complements most of the recent classifications because it is not based solely on chemical and isotopic criteria but also on the field, petrographical and mineralogical criteria. It thus has the advantage of distinguishing the various granitoid types in the field, in most cases. The proposed classification shares many similarities with the twenty most used genetic classifications of granitoids. Both types of peraluminous granitoids are of crustal origin; the «tholeiitic», alkaline and peralkaline granitoids are of mantle origin; and both types of calc-alkaline granitoids are of mixed origin and involve both crustal and mantle materials. Each granitoid type is generated and emplaced in a very specific tectonic setting. Each stage of the Wilson cycle is characterised by typical associations of granitoids. Well-typed and precisely-dated granitoids can then complement structural approaches and indicate on the geodynamic environment. With reference to some case-studies, the use of granitoids as tracers of the geodynamic evolution is also proposed and discussed.