TIMING OF HOT SPOT-RELATED VOLCANISM AND THE BREAKUP OF MADAGASCAR AND INDIA

Widespread basalts and rhyolites were erupted in Madagascar during the Late Cretaceous. These are considered to be related to the Marion hot spot and the breakup of Madagascar and Greater India. Seventeen argon -40/argon-39 age determinations reveal that volcanic rocks and dikes f rom the 1500-kilometer-long rifted eastern margin of Madagascar were e mplaced rapidly (mean age = 87.6 +/- 0.6 million years ago) and that t he entire duration of Cretaceous volcanism on the island was no more t han 6 million years. The evidence suggests that the thick lava pile at Volcan de l'Androy in the south of the island marks the focal point o f the Marion hot spot at similar to 88 million years ago and that this mantle plume was instrumental in causing continental breakup.