Noble Gas Studies of the Pacific Mantle

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ABSTRACT (0525864) KurzIntellectual Merit: This research will expand the number of heavy noble gas analyses (Ne, Ar, Xe) and CO2 in recently recovered submarine glasses from Fernandino volcano on the western flank of the Galapagos hotspot. These samples have unusual He isotope ratios, indicating that Fernandino volcano sits directly over the central melting zone of the hotspot. The noble gas isotopic ratios observed in Fernandino glasses are thought to originate from deep undegassed reservoirs in the earth. This is controversial because most mantle convection models assume that subducted slabs penetrate into the lower mantle, which is difficult to reconcile with the preservation of any undegassed or "primordial" mantle sources. This research involves the measurement of heavy noble gases (Ne, Ar, and Xe) and CO2 in Galapagos submarine glasses through crushing, heating and trapping of evolved gases and then their analysis by mass spectrometry. The resulting data will help determine the effects of degassing on absolute abundances of these elements in the mantle and can be used to help constrain geodynamic models of mantle convection and stratification. Broader impacts: This project supports researchers, technicians, and students at the Woods Hole Oceanographic Institution. It also supports institutional infrastructure by enhancing the ultra-high vacuum extraction line and mass spectrometer dedicated to heavy noble gases. New instrumentation will be developed and installed, which permits the rapid and simultaneous measurement of the heavy noble gases, Ne, Ar, and Xe.