USGS Mendenhall Postdoc Opp.: Hydration of volcanic glass
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Mendenhall Opportunity 16-5: Hydration of volcanic glass: Relevance to volcanology, archaeology, geochronology, and paleoclimate
Studies of hydrated volcanic glass have impacted the fields of archaeology, geochronology, paleoclimatology, volcanology, and aggregate resources (such as perlite, a massively hydrated and fractured obsidian). Yet very little research has been undertaken in the past 35 years, particularly as regards the "petrology" of glass hydration. There remains no comprehensive study of the actual water contents of hydrated natural glasses and perlites, and few data on any specific localities. How variable are individual samples in their extent of hydration? At what temperatures do perlites form? Based on isotopic evidence, many perlites appear to form in glacial environments. Does introduction of glacial meltwater at elevated temperatures and pressures (including near-boiling conditions) assist the hydration process? Can D/H change with time such that the initial hydration water is replaced? How different is the formation of massive perlite than the formation of hydration rinds on obsidian artifacts? Is perlitization a fundamentally different process (higher temperature) and is there structural information in the glass that can be gleaned from spectroscopic techniques that constrains temperatures of origin? How rapidly do ash beds hydrate and under what conditions is hydration minimized?
We seek a Mendenhall postdoctoral researcher to help resolve topics related to the formation of perlite and other natural hydrated forms of rhyolite. We invite field and laboratory approaches to the study, or a combination of both. Analytical techniques can be used to characterize the incorporation of water in natural samples, experimental samples, or a combination thereof. Relevant micro-spectroscopic techniques include FTIR, Raman, XRD, SEM, XAFS, ion microprobe, nanosims, and NMR. TCEA allows measurement of D/H and wt% H2O. Perlites from around the world are available in museum collections, from USGS colleagues, and through new field sampling in the Western U.S. Drill holes from Yellowstone contain hydrated glass that have resided along a gradient in temperatures and water pressures for tens to hundreds of thousands of years. USGS geochronologists have produced new dates for the Mono and Inyo Craters, samples formerly dated by hydration rind dating that can be used to assess the reasons for success/failure of that method in previous studies. We envision multiple potential projects that could be highly informative and we invite applicants to work with us to tailor individual proposals that match their talents and interests with the technologies and expertise available at the USGS and U. Oregon.
Full project description and contact information:
http://geology.usgs.gov/postdoc/opps/2016/round16/16-5%20Lowenstern.htm
Proposed Duty
Station: Menlo Park, CA or Cascades
Volcano Observatory (CVO), Vancouver, WA
Research Advisors: Jake Lowenstern (Menlo Park), Larry Mastin (CVO), Heather
Wright (CVO) and Ilya Bindeman (U. Oregon)
Application deadline is May 2, 2016. Potential applicants are strongly encouraged to start early and work with the research advisors to develop a suitable proposal.
Please see http://geology.usgs.gov/postdoc/ for more information on the Mendenhall program and how to apply.
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