Short communicationMaar-diatreme volcanism relating to the pyroclastic sequence of a newly discovered high-alumina basalt in the Maroa Volcanic Centre, Taupo Volcanic Zone, New Zealand

- An unknown succession of high-alumina basalt was discovered at the southern part of Maroa Volcanic Centre
- Volcanic activity was characterised by phreatomagmatic and Strombolian eruptive styles
- The described pyroclastic succession is typical of maar-diatreme volcanoes
- Deep-seated explosive activity produced a polymict country rock breccia with extrusive rocks have no surface appearance

Diatreme sequences have previously been described from drill holes within the Taupo Volcanic Zone. The newly discovered Te Hukui Basalt exhibits deep excavation of country rocks that do not appear elsewhere at the surface. The basalt is characterized by proximal deposition of pyroclastic deposits relating to phreatomagmatism. The geochemical composition classifies these rocks as high-alumina basalts. They erupted along the Orakeikorako Fault at the same location where rhyolitic activity of Puketerata occurred at a later point in time. The petrological characteristics of the basalts indicate the mixing of mafic melt with crystalline mush relating to more evolved magmas. The new basaltic occurrence supports frequent mafic recharge of shallow magma reservoirs, inducing basaltic eruptions, in this case the mafic magma intruding into highly crystallized mush zones. This may explain why basaltic eruptions mostly occur on the edge of the central extensional part of the Taupo Volcanic Zone.