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Contorted stratification with clay lobes in volcanic ash beds, Raglan-Hamilton region, New Zealand

Abstract
Contorted stratification in basal volcanic ash beds of the Pleistocene Hamilton Ash Formation incorporates halloysitic clay lobes which project upward into a bed of predominantly allophanic material. The forms produced are similar to convolute laminations described in other marine and non-marine sedimentary sequences. The halloysitic clay lobes have been described previously as concretions and as the products of differential weathering processes. A third hypothesis is proposed to explain the formation of the clay lobes and associated contorted stratification of these basal ash beds, namely, that the beds were deformed by plastic flowage of halloysitic clay into a sensitive allophanic bed. This deformation was possibly a result of water-saturated beds rapidly losing strength as a result of cyclic reversals of stress and strain produced by earthquake shock waves.
Type
Journal Article
Type of thesis
Series
Earth Science Journal
Citation
Tonkin, P.J. (1970). Contorted stratification with clay lobes in volcanic ash beds, Raglan-Hamilton region, New Zealand. Earth Science Journal, 4(2), 129-140.
Date
1970
Publisher
Waikato Geological Society, The University of Waikato
Degree
Supervisors
Rights
© 1970 Waikato Geological Society, The University of Waikato. All items in Research Commons are provided only to permit fair dealing for the purposes of research or private study. They are protected by copyright with all rights reserved unless otherwise indicated.