Zircon dating of oceanic crustal accretion.
Most of Earth's present-day crust formed at mid-ocean ridges. High-precision uranium-lead dating of zircons in gabbros from the Vema Fracture Zone on the Mid-Atlantic Ridge reveals that the crust there grew in a highly regular pattern characterized by shallow melt delivery. Combined with results from previous dating studies, this finding suggests that two distinct modes of crustal accretion occur along slow-spreading ridges. Individual samples record a zircon date range of 90,000 to 235,000 years, which is interpreted to reflect the time scale of zircon crystallization in oceanic plutonic rocks.
Lissenberg
C Johan
CJ
Equipe de Géosciences Marines, Institut de Physique du Globe de Paris, 4 Place Jussieu, 75252 Paris Cedex 05, France. lissenbergcj@cardiff.ac.uk
Rioux
Matthew
M
Shimizu
Nobumichi
N
Bowring
Samuel A
SA
Mével
Catherine
C