This award will support the development and application of a geothermometer based on the titanium-content of quartz. The thermometer will be calibrated by equilibrating quartz with rutile and fluid at a range of pressure and temperature conditions. Application of the thermometer will be tested by using it to characterize the thermal history of selected igneous and metamorphic rocks. Although the calibration assumes a TiO2 activity of one, it can be modified to apply to systems lacking a pure TiO2 phase if Ti activity can be estimated by some other means. Because quartz is one of the most abundant minerals in Earth's crust, this thermometer - which has a precision roughly an order of magnitude better than that of most geothermometers in application today - promises to shed new light on the thermal histories of many rock types. The thermometer should prove especially powerful when combined with imaging of cathodoluminescence intensity, which often reveals a detailed record of growth history, and which appears to be strongly correlated with the Ti content of quartz.
