Physical Sciences and Mathematics Commons^™

Cooling Rates And The Depth Of Detachment Faulting At Oceanic Core Complexes: Evidence From Zircon Pb/U And (U-Th)/He Ages, C. B. Grimes, Michael Cheadle, Barbara John, P. W. Reiners, J. L. Wooden

Barbara John

Oceanic detachment faulting represents a distinct mode of seafloor spreading at slow spreading mid-ocean ridges, but many questions persist about the thermal evolution and depth of faulting. We present new Pb/U and (U-Th)/He zircon ages and combine them with magnetic anomaly ages to define the cooling histories of gabbroic crust exposed by oceanic detachment faults at three sites along the Mid-Atlantic Ridge (Ocean Drilling Program (ODP) holes 1270D and 1275D near the 15 degrees 20'N Transform, and Atlantis Massif at 30 degrees N). Closure temperatures for the Pb/U (similar to 800 degrees C-850 degrees C) and (U-Th)/He (similar to 210 …