1999 was a transition year for me. The spring and summer terms marked the end of my three year position as department Chair and the fall began my sabbatical year. The final duties as Chair included hosting the department’s very complimentary External Review Committee, presiding at the highly successful Alumni Reunion, and presenting the proposal for an addition to Weeks Hall.
The addition to Weeks Hall has been proposed by every Chair starting in 1987 and will alleviate many needs. Since moving into Weeks Hall, the department has never had enough laboratory or classroom space. Furthermore, the success of the Museum and the changing needs of the Library require expansion and more student study space, respectively. In 1999, the Geology and Geophysics Alumni Board decided to make the addition its top priority and this has been met with strong matching support by Chancellor David Ward, Deans Phillip Certain of Letters and Science and Virginia Hinshaw of the Graduate School, and the trustees of the Wisconsin Alumni Research Foundation.
In August, I traveled with William Peck to Edinburgh, Scotland to begin the first studies of oxygen isotope ratios in zircons using an ion microprobe. This research combines the results of studies of oxygen isotopes in zircon that I started in 1993 and developments of ion probe technique that I began during my last sabbatical in 1989. William an I analyzed zircons from many terranes including: young rhyolites from Yellowstone, Pre-cambrian gneisses from the Grenville Province, and the newly discovered oldest zircon on earth from western Australia. The Grenville studies are the culmination of William’s PhD research which will be completed this year. William has discovered a new igneous domain within the Grenville, marked by high d18O magmas, and has proposed that it results from subduction of sediments along a continental margin during the Elzevirian Orogeny at 1.2Ga. The oldest zircon (>4.3Ga) was discovered last May by co-worker, Prof. Simon Wilde, at Curtin University. More is reported on these projects elsewhere in the newsletter, see "Zircons are Forever."
The Yellowstone project is being conducted by Ilya Bindeman, a post-doctoral fellow working with me. During the past 2Ma, Yellowstone was the site of three of the largest known volcanic eruptions, each up to 2000 times greater than the 1980 eruption of Mt. St. Helens. Ilya has found that oxygen isotope systematics are generally equilibrated in rhyolites, but that profound disequilibria exists during periods of low d18O magmatism that follow each of the largest caldera-forming eruptions. These results have lead to a new model for the genesis of low d18O rhyolites at Yellowstone.
Ilya and I are testing the generality of their new model in the Timber Mtn-Oasis Valley caldera complex of Nevada where they started fieldwork last October. Low d18O rhyolites from the Timber Mtn complex include those on Yucca Mtn that have been tunneled in preparation for the proposed high-level nuclear waste repository. It is anticipated that a spin-off of this work will be answers to questions relating to hydrothermal activity at Yucca Mtn. Concerns have been raised by a controversial proposal that Yucca Mtn is the site of on-going hydrothermal activity that could compromise the safety of any repository. Ilya and I are analyzing zircons that were proposed to be hydrothermal in origin in order to test key tenets of the proposal.
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