title: Dating the growth of oceanic crust at a slow-spreading ridge.
abstract: Nineteen uranium-lead zircon ages of lower crustal gabbros from Atlantis Bank, Southwest Indian Ridge, constrain the growth and construction of oceanic crust at this slow-spreading midocean ridge. Approximately 75% of the gabbros accreted within error of the predicted seafloor magnetic age, whereas approximately 25% are significantly older. These anomalously old samples suggest either spatially varying stochastic intrusion at the ridge axis or, more likely, crystallization of older gabbros at depths of approximately 5 to 18 kilometers below the base of crust in the cold, axial lithosphere, which were uplifted and intruded by shallow-level magmas during the creation of Atlantis Bank.
authors.affiliation: Department of Geology and Geophysics, University of Wyoming, Laramie, WY 82071, USA.
authors.forename: Joshua J
authors.initials: JJ
authors.lastname: Schwartz
authors.forename: Barbara E
authors.initials: BE
authors.lastname: John
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Cheadle
authors.forename: Elena A
authors.initials: EA
authors.lastname: Miranda
authors.forename: Craig B
authors.initials: CB
authors.lastname: Grimes
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Wooden
authors.forename: Henry J B
authors.initials: HJ
authors.lastname: Dick