In this study we will use the Canary Islands archipelago as a natural laboratory to examine the effects on melt composition as a passive continental margin is approached, transitioning from underlying lithosphere that is dominantly oceanic to increasingly continental in its nature. The study is anticipated to focus on the island of La Palma, where at the time of writing, volcanic activity is intense, and the erupted material has the potential for providing a snapshot of the nature of the mantle from which the erupted material is being generated.
This study will concentrate on melt inclusions trapped in early crystallising phases such as olivine. Melt inclusions provide a snapshot of primary mantle melt composition, therefore preserving evidence of potential compositional heterogeneity in the mantle source. Melt inclusions are, however, small (sub-mm diameter) and, until recently, analysis of more than one potential tracer of mantle source in a melt inclusion had been challenging. Using a powerful combination of major, trace and volatile elements with Sr, Nd and Pb isotope measurements, and using methods recently developed by the supervisors and their collaborators (see Harvey et al., 2009; Reinhard et al., 2017, 2018), his project will fingerprint the nature of the chemical and isotopic that are representative of the ingredients that formed the Canary Islands lavas. This combination of tracers will not only provide a unique perspective on the scale, magnitude and distribution of mantle heterogeneities within the mantle plume that has underlain this island archipelago, but also provide valuable insights into whether interaction of a melt with the North African passive continental margin diminishes across the Canary Islands archipelago. In addition, differences between melt inclusion compositions and final erupted magmas will reveal any changes in the nature of shallow contamination through interaction with the local lithosphere.