어센션군

Ascensión Island, just west of the Mid-Atlantic Ridge ~2,250 km E of the eastern-most point of Brazil, is the 12-km-diameter emergent summit of a stratovolcano that rises ~3,000 m above the seafloor. The isolated island has more than 100 youthful cones and lava domes, many aligned along two fissures. Basaltic rocks dominate on the island, but trachytic lava domes are also present, mostly on the eastern side. Two of the youngest lava flows were erupted from flank vents and reached the sea on the N and S coasts. Argon-Argon dating by Preece and others (2018) identified three eruptions within the past 2,000 years. No eruptive activity has occurred since it was visited on Ascensión Day in 1501 by the Portuguese navigator Joao da Nova.