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The Heterogeneity and Volatile Content of Earth’s Mantle, Magmas and Crust

Benjamin Urann, Ph.D., 2021
Veronique Le Roux, Co-Advisor
Henry Dick, Co-Advisor
This thesis explores the volatile content of the mantle, subducted oceanic crust, and arc magmas as well as the structure of ocean crust and the heterogeneity of Earth’s upper mantle. In Chapter 2, I explore the halogen (F and Cl) content of mantle minerals in situ, then use these measurements to assess the halogen content of the upper mantle.  In Chapter 3, I investigate the volatile content of Raspas eclogites (SW Ecuador), a proxy for deeply subducted oceanic crust. In Chapter 4, I use the H2O content of nominally anhydrous minerals in plutonic arc cumulates to elucidate the H2O content of the melts from which the rocks crystallized. In Chapter 5, I show that mantle peridotite exposed along the 16ºN region of the Mid-Atlantic Ridge originated in an arc setting and has been remixed into sub-ridge mantle. Chapter 6 surveys the life cycle of oceanic core complexes through zircon geochronology.