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Cooling History of Atlantis Bank Oceanic Core Complex: Evidence for Hydrothermal Activity 2.6 Ma Off Axis
Geochemistry Geophysics Geosystems
  • J. J Schwartz
  • Barbara John, University of Wyoming
  • Michael Cheadle, University of Wyoming
  • P. W Reiners
  • A. G Baines
Document Type
Article
Publication Date
8-28-2009
Disciplines
Abstract

We report 26 (U-Th)/He zircon ages from Atlantis Bank, Southwest Indian Ridge, which constrain time scales and rates of lower crustal cooling in ultraslow spreading oceanic crust in this setting. Samples from the detachment fault surface indicate that denuded oceanic crust cooled rapidly (< 1 Ma), yielding cooling rates > 1200 degrees C/Ma, consistent with existing models for the cooling of oceanic crust. (U-Th)/He zircon ages from samples collected along N-S and E-W trending faults scarps record young ages inconsistent with standard cooling models for lower oceanic crust. These samples have a mean (U-Th)/He zircon age 2.6 Ma younger than their corresponding igneous crystallization ages and record cooling through 200 degrees C well outside the rift valley. Similar anomalously young ages are recorded by zircon, sphene, and apatite fission track data from ODP Hole 735B. We interpret these young ages as recording an off-axis thermal/heating event associated with localized high-temperature (> 300 degrees C) hydrothermal fluid flow resulting from underplated mafic magmas.

DOI
10.1029/2009GC002466
Comments

An edited version of this paper was published by AGU. Copyright 2009 American Geophysical Union.

Citation Information
J. J Schwartz, Barbara John, Michael Cheadle, P. W Reiners, et al.. "Cooling History of Atlantis Bank Oceanic Core Complex: Evidence for Hydrothermal Activity 2.6 Ma Off Axis" Geochemistry Geophysics Geosystems Vol. 10 (2009)
Available at: http://works.bepress.com/michael_cheadle/8/