Deep sea drilling: age and composition of an atlantic basaltic intrusion

The fission track age of a basalt recovered from beneath Campanian sediments on the lower western flank of the Mid-Atlantic Ridge is (15.9 +/- 1.6) x 10(6) years. The major element composition of a glassy margin of the basalt is similar to that of oceanic tholeiites except for a markedly higher potassium concentration.