Paired magnetic susceptibility and geochemistry of young volcanism in Iceland and Tengchong, China.

Two recent Quaternary volcanic provinces in Iceland and Tengchong, China were investigated with magnetic susceptibility and geochemistry. Despite their similar age, the two volcanic systems have different tectono-magmatic settings (influencing primary magmatic compositions) and different latitudes (influencing secondary emplacement cooling/weathering histories). We present magnetic susceptibility (k), thermomagnetic susceptibility (k-T), and X-ray fluorescence (XRF) major element analysis of 28 volcanic sites, 10 from Iceland at ~64°N latitude and 18 from Tengchong, China at ~25°N latitude. The k and k-T data may reflect primary magma compositions and secondary post-emplacement cooling and alteration histories. The major element chemistry data (e.g., SiO2, TiO2, MgO, P2O5, etc.) also may reflect magma composition and can be used to calculate the loss on ignition (LOI), chemical index of alteration (CIA), modified index of alteration (MIA), and chemical index of weathering (CIW) that may inform post-emplacement alteration and weathering. Both geophysical and geochemical datasets will provide critical constraints for comparing Quaternary volcanism in terms of both contrasting tectono-magmatic and climatic settings.