Mountain building events are commonly accompanied by emplacement of granitic magmas, the origins of which are currently in debate. In many cases, granitic magmas are hybrids which form when hot magmas derived from the mantle combine with crustal rocks. In other cases, granitic magmas show isotopic and elemental evidence of a purely crustal origin. A crustal origin typically requires transfer of heat sufficient to cause melting. Many investigators call on heat extracted from hot, mantle-derived magmas as the primary source of such crustal melting. In the Velfjord area of north-central Norway, a group of mantle-derived plutons are nearly surrounded by a rind of granitic rocks that were apparently derived by local melting; heat was provided by intrusion of the mantle-derived plutons. Because of the small scale, this setting provides an excellent opportunity to investigate the relationship between crustal melting and heat provided by hotter magmas. Research will focus on determination of the conditions of melting, the thermal requirements for melting, mobility of the granitic melts, and chemical interaction between the crustal melts and their magmatic "heat source". The results will provide a direct analogue to melting that occurs on a crustal scale.
