Sheet QM302 Whakatane : geological resources map of New Zealand 1:250 000

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Cody, A.D.; Christie, A.B. 1993 Sheet QM302 Whakatane : geological resources map of New Zealand 1:250 000. Lower Hutt: Institute of Geological & Nuclear Sciences. Institute of Geological & Nuclear Sciences science report 92/17. 123 p.

Abstract: The geological resources within the Sheet QM302 Whakatane area are mostly related to Quaternary volcanic rocks of the Central Volcanic Region, which cover most of the map sheet, and Jurassic-Cretaceous greywacke exposed in the western and eastern parts of the sheet. The sheet area contains nearly all of New Zealand's high temperature geothermal systems, of which Wairakei (160 MWe) and Ohaaki (116 MWe) are presently exploited for electrical power generation, and Kawerau supplies heat energy for a pulp and paper mill, plus a small amount of power generation. Hot spring fields including Rotorua, Waimangu, Waiotapu, and Orakeikorako are developed for tourism. Resources of high quality aggregate rocks - unweathered indurated greywacke and basalt - are limited or distant from urban areas. Andesite and dacite of reasonable quality for roading and construction is in good supply in the north of the sheet and near Taupo. Rhyolite is a low grade aggregate and is used mainly in the Rotorua and Tauranga areas where resources of higher quality aggregate are limited. Deposits of sulphur, pumice, perlite, diatomite, and obsidian, all formed by the region's volcanism, are mined at present or have been mined in the past. Pozzolan, produced locally from the diatomite, was used in the construction of hydroelectric dams. Clay is found associated with the volcanic and basement rocks, and could potentially be exploited in the future. Limestone has been mined from lenses in the eastern greywacke ranges for use as agricultural lime. Gold and silver mineralisation has been exploited intermittently since the late nineteenth century although no mines are operating today. Known occurrences are in fossil geothermal systems of the Kaimai and Paeroa ranges and at Ohakuri, but none are currently economic. Gold, silver, copper, lead, zinc, lithium, antimony, mercury, and thallium mineralisation is associated with the active geothermal fields. Coal and petroleum resources are unknown, with little or no potential for discovery. Cold groundwater supplies are generally abundant due to the widespread presence of permeable volcanic materials providing good aquifers.