9405443 Fisher This project is to examine the abundances and isotopic composition of Xe trapped from mantle sources by various species of MORB, with particular attention paid to the anomaly at mass 129, which has been by some workers but not found by others. In the work performed under the original proposal a new mass spectrometer system was set up and multiple aliquots of vesicles in two typical MORB were crushed. No mass-129 anomaly was seen. In this proposal we hope to extend that work to many more samples, to utilize stepwise-heating in conjunction with the crushing experiments, and to measure the isotopic and elemental abundances of all the rare gases to better characterize the results.
