Age progressive volcanism in the New England Seamounts and the opening of the central Atlantic Ocean.

Abstract

Radiometric ages (K/Ar and 40Ar/39Ar) have been determined on dredged volcanic rocks from seven of the New England sea-mounts. The 40Ar/39Ar total fusion and incremental heating ages show an increase in sea-mount construction age from SE to NW consistent with northwestward motion of the North American plate over a New England hot spot between 103 and 82 m.y. A linear volcano migration rate of 4.7 cm/yr fits the sea-mount age distribution. These ages fall within a longer age progression from the Corner sea-mounts (70-75 m.y.), at the E end of the New England sea-mounts, to the youngest phase of volcanism in the White Mountain igneous province, New England (100-124 m.y.). The New England hot spot, estimated from the new radiometric ages and motion of North America in the hot spot reference frame to be near 28oN, 38oW, probably generated a short line of mid- to late-Tertiary age sea-mounts on the African plate but appears to be presently inactive.-W.H.B.