Protracted Construction of Gabbroic Crust At a Slow Spreading Ridge: Constraints from 206Pb/238U Zircon Ages from Atlantis Massif and Iodp Hole U1309D (30°N, MAR)
Sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon ages of 24 samples from oceanic crust recovered in Integrated Ocean Drilling Program (IODP) Hole U1309D and from the surface of Atlantis Massif, Mid-Atlantic Ridge (MAR) (30 degrees N) document a protracted history of accretion in the footwall to an oceanic detachment fault. Ages for 18 samples of evolved Fe-Ti oxide gabbro and felsic dikes collected 40-1415 m below seafloor in U1309D yield a weighted mean of 1.20 ± 0.03 Ma (mean square of weighted deviates = 7.1). However, the ages range from 1.08 ± 0.07 Ma and 1.28 ± 0.05 Ma indicating ...
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