Abstract by Porter Henze
Bart Kowallis, Eric Christiansen
Interpreting Growth and Resorption of Titanite in the Jurassic Notch Peak Granite, Western Utah
Titanite is useful in the study of the compositional and thermal character of magmas because of slow element diffusion and its capacity to incorporate a variety of trace elements. Titanite in the Notch Peak granite have cores with oscillatory growth and prominent sector zoning. Cores have relatively high LREEs (0.02-0.03 apfu) and low F (0.03-0.05 apfu). Most cores are bounded by irregular dissolution surfaces and thin irregular rims (with oscillatory to irregular zoning). This late titanite may extend in between surrounding mineral grains as an interstitial phase. The rims have lower LREEs (0.01-0.02 apfu) and higher F (0.06-0.08 apfu). These types of zoning are fairly uniform across the pluton. We interpret the cores of titanite to be magmatic and the irregular rims to be formed from a late hydrothermal fluid. Following complete solidification of the pluton, oxidizing fluids partially broke down titanite into fine-grained secondary minerals such as ilmenite, magnetite, and rutile.