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

Granitoids are divided into several types according to their mineral assemb lages, their field and petrographical features, and their chemical and isot opic characteristics. This typology complements most of the recent classifi cations because it is not based solely on chemical and isotopic criteria bu t also on the field, petrographical and mineralogical criteria. It thus has the advantage of distinguishing the various granitoid types in the field, in most eases. The proposed classification shares many similarities with th e twenty most used genetic classifications of granitoids. Both types of per aluminous granitoids are of crustal origin; the "tholeiitic", alkaline and peralkaline granitoids are of mantle origin; and both types of calc-alkalin e granitoids are of mixed origin and involve both crustal and mantle materi als. Each granitoid type is generated and emplaced in a very specific tecto nic setting. Each stage of the Wilson cycle is characterised by typical ass ociations of granitoids. Well-typed and precisely-dated granitoids can then complement structural approaches and indicate on the geodynamic environmen t. With reference to some case-studies, the use of granitoids as tracers of the geodynamic evolution is also proposed and discussed, (C) 1999 Elsevier Science B.V. All rights reserved.