ROBERT T. GREGORY

GEOLOGICAL SCIENCES

ROBERT T. GREGORY
Ph.D., California Institute of Technology Professor
Director of Graduate Studies

Stable Isotope Geology and Geochemistry
Evolution of Earth's Fluid Envelope and Lithosphere

obert Gregory's research centers on the application of isotope geochemistry to the evolution of the Earth's fluid envelope and lithosphere. Stable isotope retions of hydrogen, carbon and oxygen such as D/H, 13C/12C and 18O/16O or 17O/16O are tremendously important for understanding the Earth's dynamic systems, the solar system, and the cosmos. Current projects address diverse topics ranging from the origin of quartz veins in the continental crust to the climate history of the Earth.

A long term interest is in the interaction of seawater with the cooling oceanic crust at midocean ridges. By this massive exchange between rock and seawater, every molecule of water in the ocean interacting with rock once every 10 million years. The process has profound implications for the chemistry of the oceans and the global cycles of many elements. In these global cycles, stable isotopes trace the interactions between rock reservoirs which communicate through exchange with fluids. The style of fluid-rock interaction is most sensitive to the ddimensionless parameter u/k, the ration of the fluid flux to the reaction rate as illustrated here.

Selected Publications
Quick, J.E., and Gregory, R.T., 1995, Significance of melt-wall rock reaction: a comparative anatomy of three ophiolites, J. Geology, 103, 187-198.

Robertson, D.P., and Gregory, R.T., 1995, Variations in the major cation concentration and stable isotope ratios during storm runoff events in the White Rock Creek, Dallas, Texas, Proceedings of the 24th Water for Texas Conference, R. Jensen (ed) Texas Water Resources Institute, 647-655.

Hercod, D.J., Brady, P.V., and Gregory, R.T., 1995, Geochemical and stable isotope variations in baseflow from an urbanized watershed: White Rock Creek, Dallas, Texas, Proceedings of the 24th Water for Texas Conference, R. Jensen (ed) Texas Water Resources Institute, 641-645.

Gregory, R.T. and Gray, D.R., 1994, Oxygen istotope composition of veins and host rocks as tracers of fluid rock interaction in the crust, Mineralogical Magazine, 58, 352-353.

Gray, D.R., Gregory, R.T., and D.W. Durney, 1991, Rock-buffered fluid-rock interaction in deformed quartz-rich turbidite sequences, eastern Australia, J. Geophysical Research, 96, 19,681-19,704.

Gregory, R.T., 1991, Oxygen isotope history of seawater revisited: 3.5 billion years of the greenstone record and its implication for the stability of seawater 18O, in H.P. Taylor, Jr., J.R. O'Neil, and I.R. Kaplan (eds.) Stable Isotope Geochemistry: A Tribute to Samuel Epstein, Geochemical Society Special Publication 3, 65-76.

Dr. Robert T. Gregory Department of Geological Sciences Dallas, Texas 75275-0395 voice: (214) 768-3075 fax: (214) 768-2701 email: bgregory@mail.smu.edu