Hello everybody, Is anyone aware of recent (after 1993) or current experiments on quartz-magnetite oxygen isotope fractionation? Will the use of laser have a large advantage, given that magnetite is a difficult phase to react conventionally? When I apply Quartz-Magnetite oxygen isotope thermometers to different zoned tuffs (in order to determine the quenching temperature) and then compare it to the temperature determined using Magnetite-Ilmenite, I mostly discover that former (Quartz-Magnetite) temperature is often >100 C higher. There should be something systematically different in one of these methods. Analytical? Ilya Bindeman Research Associate Department of Geology and Geophysics University of Wisconsin 1215 W Dayton Str Madison WI 53706 USA 608-262-7118 [log in to unmask] http://geology.wisc.edu/~inbindem