Natural heat flow from the thermal areas of Taupo Sheet District (N 94)

Gregg, D. R.

doi:10.1080/00288306.1958.10422795

Cited by 22 publications

(11 citation statements)

References 2 publications

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“…The natural heat escape from the whole of the Wairakei hydrothermal field, prior to exploitation, has been given as 1· 5 X 10 5 kcal/sec, or 2'1 X 10 9 BThU/hr (Gregg, 1958: Table 3, sub-sheet N94/4; heat flow referred to 0°C). The author has pointed out in a previous paper (Studt, 1957) that there has been a substantial rise in surface heat flow as a result of exploitation; in fact, between the winters of 1955 and 1958, the mean heat output from drillholes has almost equalled the pre-existing natural heat escape.…”

Section: Introductionmentioning

confidence: 99%

The Wairakei hydrothermal field under exploitation

Studt¹

1958

New Zealand Journal of Geology and Geophysics

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Heat flow through drillholes in the Wairakei hydrothermal field now equals the pre-existing natural heat escape, while this heat escape itself is little diminished. The total heat flow at surface has thus been doubled, and the source of this increase has an important bearing on the life of the field under exploitation.The drillholes tap the Waiora aquifer, in which the low density of the hot water gives rise to pseudo-artesian pressure, here designated thermo-artesian. There has been a general decline in this pressure, consequently cold water must be encroaching on the field, although drill hole temperatures show little evidence of this. Some of the increased heat flow must therefore come from heat stored in the rocks and ground water, and this is a wasting asset.The history of Wairakei's hot springs, and the very uniform physical and chemical conditions in the aquifer, indicate a long-established state of equilibrium. This is now being destroyed by exploitation, revealing at least one point, on the Waiora Fault, at which hot water is fed into the aquifer.. The feed channel is found to have so Iowan impedance that it may be possible to increase the rate of feed, by suitably placed holes, without excessive drawdown or exhaustion of storage. A limit to this increase will be set by the danger of blockage by calcite deposits; blockages can be cleared from the drillholes, but not from the feed channel.If the heat supply to the aquifer i,s thus increased, adjacent sections of th« Waiora Fault may then channel cold water into the field, and thus tend to curtail the utilization of stored heat.

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Section: Introductionmentioning

confidence: 99%

The Wairakei hydrothermal field under exploitation

Studt¹

1958

New Zealand Journal of Geology and Geophysics

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“…Direct comparisons between the heat flow estimates for Taupo of this survey and those of 1951-52 (Gregg, 1958) are believed to be not valid because of improved measurement techniques and new knowledge gained in the interval. Heat flow figures for the two surveys, together with a revised estimate for 1951-52, are given in Table 5.…”

Section: Comparisons Of Natural Heat Flowsmentioning

confidence: 92%

“…The results, and a comparison with this author's estimates for Wairakei, 1951-52 and1958, are given in Table 6. The heat flow by conduction through the soil was assumed to be completely lost by atmospheric convection and radiation involving no mass discharge, but the heat radiated from water surfaces was included in evaporation, because the radiation contribution to the total heat lost by such surfaces is very small and the accuracy of the enthalpy calculation does not warrant separate treatment.…”

Section: Comparisons Of Natural Heat Flowsmentioning

confidence: 94%

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Shallow heat survey of taupo borough and adjacent country

Fisher¹

1965

New Zealand Journal of Geology and Geophysics

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“…A geophysical arid geological study of parts of the region was begun in 1937 and intensified in 1950, when a search for natural steam for the generation of electricity was instigated (Grange, 1955;Gerard and Lawrie, 1955;Banwell et at. ) 1957; Modriniak and Studt, 1959;Gregg, 1958;Lloyd, 1959;Healy, 1961Healy, , 1962. Recently published maps include those by Grindley (Sheet N85, 1959;N96, 1961;and 1 : 250,000 Sheet 8, 1960) and by Kear (1 : 250,000 Sheet 4, 1960).…”

Section: Introductionmentioning

confidence: 93%

Quaternary Volcanism of the Central Volcanic Region

Thompson¹

1964

New Zealand Journal of Geology and Geophysics

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The main rock types of the Central Volcanic Region of the North Island of New Zealand are distributed in a roughly symmetrical fashion about an axis trending north-north-east from Tongariro National Park to near Maketu on the Bay of Plenty. Adjoining the outer margins of the Region are northward-div,erging greywacke ranges, between which are extensive ignimbrite plateaus. Downfaulting along the inner margins of these plateaus has produced the north-north-east-trending Taupo-Rotorua graben, notable for containing (a) a north-north-east-trending zone of recently active normal faults, which cuts across (b) two main and one minor groups of Quaternary rhyolite domes and associated pumice-breccia deposits. Basaltic rocks lie around the periphery of the rhyolite domes. In the east, Quaternary andesitic cones lie in a north-north-east-trending line along the western edge of the Kaingaroa Plateau; in the west, the cones form a north-trending line close to the eastern edge of the greywacke ranges.The generalised sequence of eruption is andesite (oldest), ignimbrite, rhyolite and dacite, and basalt, although andesite is still being erupted in Tongariro National Park. An assessment of possible future volcanism suggests that activity will probably be confined mainly to the Taupo Volcanic Zone. The main dangers are from the eruption of rhyolite, pumice breccia, and basalt in rhyolite districts and from hydrothermal eruptions in hot spring areas. Further eruptions are expected in Tongariro National Park and along the eastern margin of the Central Volcanic Region. ' There is a much smaller likelihood of eruption of ignimbrite and dacite. Faulting, especially in the Taupo Volcanic Zone, may continue.

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Natural heat flow from the thermal areas of Taupo Sheet District (N 94)

Cited by 22 publications

References 2 publications

The Wairakei hydrothermal field under exploitation

The Wairakei hydrothermal field under exploitation

Shallow heat survey of taupo borough and adjacent country

Quaternary Volcanism of the Central Volcanic Region

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