MICHAEL ANTHONY VELBEL

RESEARCH & ACTIVITY REPORT, 1996

My NSF-funded project to develop teaching exercises in geochemical kinetics (using the dissolution of halite to generate real-time kinetic data) for GLG321 Mineralogy and Geochemistry is now complete. Using microscopes and hot plates, students measure the sizes of multiple halite crystals, and how long it takes each crystal to dissolve, at two different temperatures. The data are then used to select an appropriate rate law, and to calculate the Arrhenius activation energy of the dissolution reaction. The simple lab setup generates numbers well within the range of the actual values for such reactions. Given the importance of rates, rate laws, rate constants, and activation energies in geology, petrology and geochemistry, and in designing remediation strategies for organic contaminants in groundwaters, undergraduate experience in actually applying geochemical kinetic concepts to intepreting real rate data should enhance their preparation for some of the kinds of problems they will encounter in the workplace. We are presently exploring the experiment and the information about rate law and mechanism derived from it in light of the use of halite dissolution as an analog to crystal dissolution in magmas, a current research area by experimentalists in igenous petrology. Erik Munroe (B.S. '95) made a first attempt to reproduce some classic experiments on interlayer diffusion of cations in vermiculite; the preliminary results are very encouraging.

Dave Long and I are among a handful of MSU faculty on a grant from NASA through the Universities Space Research Association, to develop two new undergraduate courses in Earth System Science. We have big plans for this; stay tuned. I resumed (team-)teaching sedimentary geology this spring, after 6-year hiatus.

The staurolite paper coauthored with both of MSU's first two recipients of the Mineralogical Society of America American Mineralogist Undergraduate Award, Chuck Basso (B.S. '93, now at U. Toledo) and Michael Zieg (B.S. '94) appeared in the May issue of the American Journal of Science. Preliminary work on chain silicates is being developed into a larger proposal to a major funding agency.

Some meteorites (esp. some carbonaceous chondrites) experienced aqueous alteration on their parent bodies; some groups of C-chondrites consist mostly of serpentine-like sheet-silicates, which may have been formed by alteration and replacement of primary silicates. Using polished thin-sections supplied by NASA, we are continuing work begun by Cari Corrigan (B.S. '95), and Trent Faust (B.S. '95) on textural evidence for diffusion-limited replacement. This work has implications for questions of rates and time-scales for the replacement reaction.

In the Pennsylvanian of Michigan, Mark Lighthiser (B.S. '95) applied illite crystallinity measurements to clay-minerals of the Pennsylvanian mudrocks of Grand Ledge, drawing inferences about their implications for the thermal history of the basin.

I continue to serve on the SEPM Committee on Hydrogeology and Environmental Geology (now a standing committee) and the SEPM Membership Committee, and just ended my 3-year term on the Council of the Clay Minerals Society. I will be acting Chair of the Department during Prof. Vogel's sabbatical leave Spring semester 1997.