| 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. |