Geocheminar winter-2015

Oxygen isotopes are used to fingerprint planetary materials. Recently, significant improvement in the precision of ?17O measurements has resulted in a deeper understanding of how mass fractionation can produce small (<50 ppm, 0.05‰) ?17O values depending on the slope or exponent chosen for the (lab) internal reference line. Here we present a new terrestrial rock-based reference frame (San Carlos Olivine reference frame) with which we compare the bulk silicate Earth (BSE) to bulk silicate Moon (BSM) to re-evaluate potential moon-forming scenarios. We will discuss the shergottite Mars meteorites and the potential for a Martian-water-oxygen contribution to impact melt glass. Finally, the (soon to arrive) Nu Instruments Panorama, a large radius gas source mass spectrometer, will allow us to eliminate certain ambiguities concerning our current abilities to make these measurements accurately.