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Title: The Ngatamariki Geothermal Field, NZ: Surface Manifestations - Past and Present

The Ngatamariki geothermal field, located 7 km south of Orakeikorako, discharges dilute chloride-bicarbonate waters of almost neutral pH from springs mostly on the margins of the field. Rhyolite tuffs in the northwestern part of the field are weakly silicified, probably due to their having reacted with heated groundwaters. Sinter deposits are common at Ngatamariki but are mostly relict from former activity. In 1994, the natural heat loss from the field was 30 {+-} 5 MW{sub thermal}. There has been a shift of thermal activity southward over the past 60 years; the changes were recognized by comparing air photographs taken in 1941 and 1991. In 1948, a hydrothermal eruption deposited breccia around its crater, which is now occupied by a pool at 52.5 C. Another pool at 88 C, first noticed in 1993, deposits a mixture of silica and calcite.
Authors:
; ;
Publication Date:
OSTI Identifier:
895919
Report Number(s):
GEO-PROC-95-02
TRN: US200703%%744
Resource Type:
Conference
Resource Relation:
Conference: Proceedings of The 17th New Zealand Geothermal Workshop 1995
Research Org:
Geothermal Institute and Geology Department, University of Auckland, NZ
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; CALCITE; GEOTHERMAL FIELDS; IMAGES; MIXTURES; RHYOLITES; SILICA; Geothermal Legacy