Abstract by Porter Henze
A Tale of Two Granites: Zonation in Titanite from Notch Peak and Little Cottonwood Stocks, Utah
Titanite is useful in petrogenetic studies due to its slow element diffusion and its capacity to incorporate a variety of trace elements. The textures and compositions of titanite from the Notch Peak (NP) and Little Cottonwood (LC) granites allow us to infer different histories for each pluton. In the NP, magmatic titanite has relatively high LREEs (0.02-0.03 apfu) and low F (0.03-0.05 apfu) while secondary titanite contains lower LREE (0.01-0.02 apfu) and higher F (0.06-0.08 apfu). Magmatic titanite crystallized ~166 Ma while secondary titanite crystallized ~165-160 Ma. Unlike NP’s typical sector zoning, LC titanite has magmatic interiors with patchy zoning and inclusions of rounded ilmenite, suggesting that ilmenite precipitated first in a lower f02 magma that then mixed with a higher fO2 magma causing the dissolution of ilmenite and stabilization of titanite. Secondary LC titanite is similar to secondary NP titanite with low REE and high F. LC magmatic titanite crystalized ~32 Ma, while secondary titanite crystalized ~28-27 Ma.