Calderas and Geothermal Systems in the Taupo Volcanic Zone, New Zealand

Abstract

Silicic calderas and geothermal systems in Taupo Volcanic Zone (TVZ) of New Zealand are spatially related. Eight calderas, active since 1.6 Ma, occupy 45% of the Boundaries of calderas arc often speculative, but of 20 geothermal systems considercd, 15 occur on or next to a caldera margin where there is enhanced deep permeability: the best examples are at Haroharo where systems occur at the intersection of volcanic lineations and caldera embayments, and at Rotorua. Drillhole evidence supports a realignment of caldera margin through the Wairakeigeothermal field. Four geothermal systems have no known caldera associations. Most calderas were shaped by eruptions around 0.35-0.15 Ma, and possibly many of the currently active geothermal systems originated in this period. However, there is no strong geological evidence for a genetic link between sub-caldera magma chambers and geothermal systems in the TVZ.