Image Credit: B.Hayward Multiple melting points suggest erratic eruptions worldwide Scientists have searched for spatial and temporal trends in Auckland Volcanic Field (AVF) eruptions to no avail. New research suggests discrete melt batches that move at different depths and speeds may explain the erratic spatial and temporal pattern of eruptions in the AVF. The most recent AVF volcano, Rangitoto, suggests a change in the field’s behaviour. It’s the largest in magnitude and erupted alkalic magmas, then subalkalic basaltic composition in separate events. Major and trace element geochemistry – together with Sr–Nd and U–Th–Ra isotopes – provides the basis for modelling melting conditions that have led to the eruption of the chemically different lavas. The alkalic basalts suggest lower degrees of partial melting, higher amounts of residual garnet, a longer melting column, and lower melting and upwelling rates compared with the subalkalic basalts. Such behaviour may have major implications for the evolution of continental volcanic fields worldwide, not just the AVF. An update to this story can be found here: https://www.devora.org.nz/auckland-volcanic-landscape/conundrum-of-aucklands-rangitoto-volcano/ Check it out! Tags:Auckland Volcanic FieldbasalticgeochemistrymeltingmonogeneticpublicationsRangitoto
