Analysis of Twin Seamounts and Their Correlation to Proximal Lavas

Document Type

Student Presentation

Presentation Date

April 2016

Faculty Sponsor

Dorsey Wanless


Lava samples collected from twin volcanic cones off the coast of Isla Santiago in the Galapagos were analyzed for trace and major element contents using inductively coupled plasma mass spectrometry (ICP-MS). These samples are from basaltic cones located south of the island and were collecting using a remotely operated vehicle (ROV). Lavas from the two cones are chemically distinct in major and trace element abundances, but share the same incompatible trace element patterns. The variability in major element contents suggests differing levels of fractional crystallization between the two cones and within their stratigraphy. Decreasing MgO contents of the lavas suggest significant crystallization of olivine, while the CaO/Al2O3 ratios indicate that lavas from one cone may have crystallized pyroxene. Fractional crystallization for the cones is modeled using PetroLog, a petrologic modeling program. Lavas from both cones have trace element patterns that are enriched in light rare earth elements and depleted in heavy rare earth elements and are similar to the mildly-alkaline basalts series of Santiago characterized by Gibson et al. (2012). This suggests that the cones are formed by the same processes that form the Santiago basalts.

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