Spatial and Temporal Variations in Mid-Ocean Ridge Basalt Geochemistry Along and Across the East Pacific Rise Crest, 9-10N

Woods Hole Oceanographic Institution, Woods Hole MA

Investigators

Abstract

The PIs will measure Uranium series isotopes (230Th/238U, 226Ra/230Th, 231Pa/235U) in order to place constraints on the eruption ages of axial and off-axis lava flows in the 9-10N area of the East Pacific Rise (EPR), which has been well mapped and intensively studied with Alvin for the last decade. These U-series dates, together with new data on Sr, Nd, Pb, and Hf isotopes will be used to evaluate the petrogenesis of the samples and to evaluate the extent of near off-axis vs. axial additions to the ocean crust in this area, which seismic studies indicate should be an important process (off0axis thickening of lawer 2A). The samples will be "selected" by a "randomizing" process in order to determine theproportion of the crust that is added off-axis.