Rice Undergraduate Theses

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Understanding Phosphorus Mobility in Arclogites
(Rice University, 2023) Potemkin, Stella; Cin-ty Lee
Phosphorus (P) is an essential nutrient for life. Throughout geologic time, availability of this element has limited primary productivity. Therefore, understanding how the phosphorus moves through Earth system has important implications for understanding life history. While surface fluxes of phosphorus are well studied, less attention has been given to understanding how P is recycled and moves through igneous systems. This thesis uses arclogites, a type of garnet pyroxene xenolith, as a tool to better understand P mobility in continental arc settings. We collected quantitative mineral chemistry for four thin sections using wavelength-dispersive spectroscopy (WDS). Additionally, we analyzed existing whole-rock major element compositions for our four thin sections and additional arclogite samples with bulk rock P2O5 greater than 0.2 wt%. Mineral volumes were estimated using Image-J and existing point count data. The culmination of these data allowed us to investigate what contributions different mineral phases make towards bulk rock P2O5. Our research suggests that titanite and apatite are the main carriers of P in these rocks, however, questions remain about whether these minerals are primary features. This work expands our understanding of P mobility in arclogites and could have implications for our understanding of how the global P cycle has evolved throughout Earth history.