New seafloor sampling methods for noble gases

Mark D. Kurz, Marine Chemistry and Geochemistry

DOEI Project Funded: 2005

1) What are the primary questions you are trying to address with this research?
The primary question we are evaluating with this research is the role of atmospheric contamination in noble gas measurements on seafloor basalt glasses. Seafloor basalts are quenched rapidly to form glass on contact with seawater at high pressure. These glasses provide an important sample of magmatic gases from deep in the earth. Atmospheric noble gases are also found in seafloor glasses, but it is unknown where this "contaminant" is introduced: during magma transport, on eruption, during sampling, or in the laboratory. Separating the atmospheric and magmatic noble gases in mantle samples is a key obstacle to interpreting and modeling the measurements. We hope to better understand the source of atmspheric contamination by developing new sampling techniques for ocean floor samples.

2) What is the significance of this research for others working in this field of inquiry and for the broader scientific community?
Understanding the noble gases in the mantle is a key aspect to evolution models for the earth. At present, noble gases provide one of very few arguments for primordial material deep in the earth, and are a subject of debate among earth scientists. Many geophysical models include whole mantle convection which would stir the mantle from top to bottom and may not easily accommodate such ancient reservoirs, even in the deep mantle.

3) What is the significance of this research for society?
This research relates to the origin of the earth and atmosphere, which are important to understanding how the earth and life have evolved.

4) When and where will this investigation be conducted?
The field work will take place at Loihi Seamount, Hawaii, during a scheduled 2006 Jason II cruise (K. Edwards, PI) where the sampling methods will be tested. The samples will then be brought back to the noble gas laboratory at WHOI for measurements.

5) What are the key tools or instruments needed to conduct this research?
We will develop new stainless steel samplers, and shipboard handling techniques, to collect seafloor glasses without exposure to atmosphere. The measurements will be carried using a specially designed noble gas mass spectrometer and ultra-high-vacuum extraction line.

6) Is this research part of a larger project or program?
The field studies will be carried out in collaboration with Dr. K. Edwards, who is leading a team of microbiologists to Loihi seamount. The labwork is part of long-term program at WHOI to understand the noble gases in the mantle, ocean crust, and seafloor systems.