In-Situ Pb Isotope Analysis of Olivine-Hosted Melt Inclusions in MORB

Woods Hole Oceanographic Institution, Woods Hole MA

Investigators

Abstract

Recommended project for Pb isotopic analysis of olivine-hosted melt inclusions from mid-ocean ridge baslats (MORBs) from a geochemically anomalous segment of the Mid-Atlantic Ridge (MAR), with a goal of examining the origin, amplitude, and scale lengths of chemical heterogeneity of the MORB source mantle. Analysis will occur by an innovative, new technique using the ion microprobe to analyze melt inculsions that are 40 um or large in size, examining melt inclusion isotopic heterogeneity that occurs within individual olivine crystals, within individual samples, and within an individual ridge segment. About 50 melt inclusions will be analyzed from a number of individual lavas to examine within-flow heterogeneity. The samples to be analyzed are from 12-16 degrees N on the MAR, where a range of PB isotopic composition occurs in host samples, and include individual samples showing great diversity in their melt inclusions compositions. This data will be used to test and calibrate models of mantle melting and melt transport associated with slow spreading ridges such as the MAR.