Dalton, C. L.2025-07-232025-07-232022https://hdl.handle.net/2440/146267This item is only available electronically. Whole thesis (as available).Movement of copper within volcanic systems is poorly understood. Arenal provides an unique insight into metal movement in young magmas. Due to its young age (<100 years) (210Pb/226Ra)0 is a useful indicator of fluid degassing or accumulation within a system. This work compares Cu isotopic analyses over Arenal’s last 30 years of continual eruptions against prior analyses (210Pb/226Ra)0. Copper was found to be enriched (83.10 ppm – 130.20ppm) within this eruption period. δ65Cu had a range of 0.650 to -0.90726 with the initial positive δ65Cu being linked with a (210Pb/226Ra)0 above 1 and initially high Ba/Th ratios. As δ65Cu decreased, (210Pb/226Ra)0 effectively stayed around 1, an indicator that these lighter copper isotopes were not fluid controlled. Multiple elements (Co, Cr, Th and Si) were compared to copper isotope evolution which showed decoupling of copper from systems that would otherwise fractionate it (fractional crystallisation, assimilation). Thus, magmatic volatiles may fractionate copper within this system. This being true means that copper is being moved by magmatic volatiles within these active volcanics. These fresh fluids are preferentially taking the heavier δ65Cu and erupting it. This follows a Rayleigh fractionation curve but assumes that the parental magma much be enriched in Cu (250ppm). A potential model showing Arenal’s eruptions was constructed showing this. Cu isotope analysis furthers our understanding of economic metal movement and can be applied to ore-forming environments.enHonoursGeologycopper isotopesactive volcanicsArenal VolcanoRayleigh Fractionationuranium seriesThesis