K-Ar and 40Ar/39Ar ages of central Kerguelen Plateau basalts

Abstract

Presents results for basaltic samples retrieved during Ocean Drilling Program Leg 120. The results suggest that the formation of the basement of the Central Kerguelen Plateau was closed at 110 m.y. This is in agreement with a K-Ar age of 114 ± 1 m.y. mentioned in the literature for a basalt dredged in the 77°E Graben. The still scant amount of data indicates that the outpourings of the Central Kerguelen Plateau correspond with widespread continental magmatism in Gondwanaland that is believed to mark the incipient opening of the eastern Indian Ocean. This implies a huge head for the mantle plume at the source of these liquids. Nevertheless, on land and at sea the exact duration of magmatism remains unknown. Therefore, a catastrophic pattern similar to that invoked for the Deccan Traps at the end of the Cretaceous, though possible, is not yet required by present geochronologic data. -from Authors