AR-40 AR-39 GEOCHRONOLOGICAL CONSTRAINTS FROM THE SOUTHEASTERNMOST PART OF THE EASTERN SEGMENT OF THE SVECONORWEGIAN OROGEN - IMPLICATIONS FOR TIMING OF GRANULITE-FACIES METAMORPHISM/

The Southwest Swedish Granulite Region is characterized by mafic granu lite- and upper amphibolite-facies rocks, charnockites, and deformed a nd migmatized granitic to intermediate gneisses. A Ar-40/Ar-39 geochro nological study was carried out focusing on the mafic rocks. Three gra nulites and four amphibolites have been analysed. The obtained ages ra nge between 930 and 1030 Ma. The older Ar-40/Ar-39 ages are interprete d to be associated with crustal thickening, while the younger Ar-40/Ar -39 ages may be associated with final orogenic uplift.