Processes of Isotopic Resetting in the Contact Aureole of the Laramie Anorthosite Complex

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The principal objective of this research project is to understand isotopic resetting processes for the U-Pb and Sm- Nd systems in minerals in the contact aureole of the Laramie Anorthosite Complex. The time-temperature profile of the aureole will be refined using conventional phase equilibria, oxygen isotope thermometry and Ar-Ar biotite and hornblende cooling ages. The resulting profile will then be used to place constraints on the closure temperatures and resetting processes for the U-Pb and Sm-Nd systematics in minerals such as ilmenite, sphene, apatite, garnet and monazite. Comparison of the temperatures at which the U-Pb and Sm-Nd ages reset in minerals from reactive and non-reactive rock types in the aureole will permit examination of the effects of mineral reactions and volume diffusion on reequilibration of the various isotopic sytems.