title: Zircon dating of oceanic crustal accretion.
abstract: 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.
authors.affiliation: Equipe de Géosciences Marines, Institut de Physique du Globe de Paris, 4 Place Jussieu, 75252 Paris Cedex 05, France. lissenbergcj@cardiff.ac.uk
authors.forename: C Johan
authors.initials: CJ
authors.lastname: Lissenberg
authors.forename: Matthew
authors.initials: M
authors.lastname: Rioux
authors.forename: Nobumichi
authors.initials: N
authors.lastname: Shimizu
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Bowring
authors.forename: Catherine
authors.initials: C
authors.lastname: Mével