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Title: Geological Results from Drilling in the Poihipi (Western) Sector of the Wairakei Geothermal Field, NZ

Four wells drilled into the Poihipi Sector on the Western margin of the Wairakei geothermal field have found a similar lithostratigraphy to that encountered in wells previously drilled in the general area. Young pumice breccias overly the Huka Falls Formation, with the latter containing intercalations of the Rautehuia Breccia. This in turn overlies ignimbrites and tuffaceous sediments of the Waiora Formation, which contains flows of Haparangi Rhyolite. This sequence is cut by steeply dipping normal faults which strike to the northeast and for the most part dip towards the northwest. Hydrothermal alteration is virtually limited to the Waiora and Haparangi units where a sequence of interlayered illite-smectite and illite clays are found along with chlorite, quartz, pyrite and calcite. There is a minor occurrence of zeolites. Despite large changes in the area's hydrology in response to exploitation, changes in alteration are limited to a comparatively deep occurrence of kaolinite and minor overprinting of epidote by illitic clay.
Authors:
; ;
Publication Date:
OSTI Identifier:
895916
Report Number(s):
GEO-PROC-95-02
TRN: US200703%%794
Resource Type:
Conference
Resource Relation:
Conference: Proceedings of The 17th New Zealand Geothermal Workshop 1995
Research Org:
Kingston Morrison Ltd, Auckland, NZ
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; CALCITE; CLAYS; DRILLING; EPIDOTES; HYDROLOGY; HYDROTHERMAL ALTERATION; ILLITE; KAOLINITE; PYRITE; QUARTZ; SEDIMENTS; WAIRAKEI GEOTHERMAL FIELD; ZEOLITES; Geothermal Legacy