The Orakeikorako and Te Kopia geothermal fields lie 7 km apart near the southern end of the Paeroa Fault in the Taupo Volcanic Zone of the North Island. Whether or not the two fields are connected hydrologically, and if so how, has been long argued but most maps show them as separate.

Recent mapping in the area between Orakeikorako and Te Kopia shows clear evidence for geothermal activity in the past, including the presence of:
1. Hydrothermally altered rocks exposed over an area of about 30 km2. These contain a wide variety of hydrothermal minerals including assemblages of: a) kaolinite ± alunite ± cristobalite; b)mordenite+ montmorillonite and c) adularia+quartz (± illite).

2. Silica sinter at two locations. One contains laminated stromatalitic-type and well-preserved filamentous microbes.

3. Three hydrothermal eruption breccias older than 26,600 years but younger than 60,000 years. These were locally derived and contain matrix-supported clasts of sinter and other lithologies. Many clasts were hydrothermally altered, before they were ejected. Their alteration assemblages are the same as those present in the surficial rocks.

Several previously unreported thermal manifestations also occur. These consist of dilute acid sulfate pools, gently steaming ground and thermally stressed vegetation. Temperatures 15 cm below the ground surface are locally up to 79?C.

These features show that thermal activity was once both extensive and intense in the area between the Te Kopia and Orakeikorako geothermal fields. Prior to 26,600 years ago alkali chloride springs discharged there, steaming ground was more widespread and at least three hydrothermal eruptions occurred. Subsequently the surficial thermal activity has declined to the present-day rather feeble manifestations. However, a usable geothermal resource may still be present below them.

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