Abstract by Collin Jensen
Multi-stage Intrusion and Differentiation: The emplacement and Lithology of the Little Cottonwood Stock
The Little Cottonwood Stock (LCS) is a granitic intrusion in the Wasatch Mountains. It contains two smaller mineralized zones, the Red Pine Porphyry (RP) and the White Pine intrusion (WP), and also hosts pebble dikes. Our study is to determine the chemical and petrographic distinction between these units, remapping the region with our results, and determining whether the RP, WP, and rhyolite in the LCS result from further differentiation of the LCS host magma, or if they are different intrusions with different sources.
XRF geochemical data, petrographic data, and field mapping paint a picture more complex than originally known. There appear to be two distinct WP magmas separated by High Field Strength element levels. One of these WP units seems to have differentiated to the RP. All of these units have been extensively mineralized and altered.
The LCS has an adakitic signature, and we wish to determine if titanite can account for that by fractionating Y out of the melt. To do so we have sampled titanite-rich mafic enclaves to do microprobe or SEM analysis.