New Zealand Journal of Geology and Geophysics abstracts

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Note An occurrence of allophane from Mangaturuturu River, Tongariro National Park, North Island, New Zealand

GREG H. BROWNE
RAYMOND SOONG

Institute of Geological & Nuclear Sciences
P.O. Box 30 368
Lower Hutt, New Zealand

Abstract  A white X-ray amorphous material from the Mangaturuturu River, Tongariro National Park, is identified as allophane. The allophane is being precipitated from the cold river water and forms a deposit lining the base and banks of the river. The Mangaturuturu River precipitate is unusual for allophane in that no discrete peaks exist in the X-ray diffraction (XRD) trace. The allophane precipitates from riverine waters which are fed by springs enriched with CO2 that enters the groundwater system from a geothermal source. If the cause for allophane precipitation is geothermally derived CO2, we speculate that precipitation of allophane would increase leading up to and during an active phase of volcanism. The relative abundance of allophane may therefore be a guide to geothermal gas movement within the mountain and, hence, an indicator of geothermal activity of the volcano. This locality is only the second occurrence of allophane reported as a precipitate from riverine waters in New Zealand. The other occurrence at Silica Springs is also in the Tongariro National Park.

Keywords  Tongariro National Park; Mt Ruapehu; Mangaturuturu River; allophane

New Zealand Journal of Geology and Geophysics, 1997, Vol. 40: 253-256

0028-8306/97/4002-0253 $7.00/0 (c) The Royal Society of New Zealand 1997

PDF file of entire paper: medium quality (1853K); (scanned from paper original: notes about this process)

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