Clay petrology of Mesozoic to recent sediments of central western North Island, New Zealand
type: CreativeWork
description: NOTE: Missing pages 177-78 and 181-82. Clay mineral, bulk mineral and chemical data for Mesozoic to Recent onshore sediments and Recent western shelf surficial sediments from central Western North Island are presented with the aim of determining the significance of areal and stratigraphic variations in clay mineral distributions. Sample analysis procedures using mainly X-ray diffractometry have been determined that are relatively simple, rapid and applicable to this wide variety of sediment types. Clay mineral analysis was carried out on the <2μ size fraction of all samples, and on the <1μ, 2-4μ, 4-8μ and 8-16μ size fractions of selected samples to compensate for any mineralogic bias imposed through the selection of the traditional <2μ fraction. The predominance in the same samples of illite and chlorite in coarser fractions but of montmorillonite and kaolinite in finer fractions emphasises that the geologic interpretation of clay mineral distributions in sediments may be significantly influenced by the grain size fraction chosen for analysis. Clay mineral mounts prepared using dropper-on-glass slide and smear-on-glass slide techniques gave identical qualitative and similar quantitative results so that the former simpler technique was used. Mesozoic to Recent sediments in Hamilton, Taranaki and Wanganui Districts contain varying amounts of kaolinite, illite, montmorillonite, chlorite and mixed-layer clay minerals. Clay mineral assemblages of mudstones, limestones or concretions, represent best those assemblages existing at the time of sediment deposition; clay minerals in sandstones are prone to diagenetic alteration because of their generally greater porosity. The clay mineralogy of Mesozoic to Pleistocene sediments bears the imprint of a complex set of factors, including provenance, climate, tectonism, depositional environment and diagenesis. The illite, chlorite and mixed-layer clay mineral suite of Mesozoic sediments is consistent with derivation from an igneous…
abstract: NOTE: Missing pages 177-78 and 181-82. Clay mineral, bulk mineral and chemical data for Mesozoic to Recent onshore sediments and Recent western shelf surficial sediments from central Western North Island are presented with the aim of determining the significance of areal and stratigraphic variations in clay mineral distributions. Sample analysis procedures using mainly X-ray diffractometry have been determined that are relatively simple, rapid and applicable to this wide variety of sediment types. Clay mineral analysis was carried out on the <2μ size fraction of all samples, and on the <1μ, 2-4μ, 4-8μ and 8-16μ size fractions of selected samples to compensate for any mineralogic bias imposed through the selection of the traditional <2μ fraction. The predominance in the same samples of illite and chlorite in coarser fractions but of montmorillonite and kaolinite in finer fractions emphasises that the geologic interpretation of clay mineral distributions in sediments may be significantly influenced by the grain size fraction chosen for analysis. Clay mineral mounts prepared using dropper-on-glass slide and smear-on-glass slide techniques gave identical qualitative and similar quantitative results so that the former simpler technique was used. Mesozoic to Recent sediments in Hamilton, Taranaki and Wanganui Districts contain varying amounts of kaolinite, illite, montmorillonite, chlorite and mixed-layer clay minerals. Clay mineral assemblages of mudstones, limestones or concretions, represent best those assemblages existing at the time of sediment deposition; clay minerals in sandstones are prone to diagenetic alteration because of their generally greater porosity. The clay mineralogy of Mesozoic to Pleistocene sediments bears the imprint of a complex set of factors, including provenance, climate, tectonism, depositional environment and diagenesis. The illite, chlorite and mixed-layer clay mineral suite of Mesozoic sediments is consistent with derivation from an igneous…
author: Hume, Terry M.
license: https://researchcommons.waikato.ac.nz/bitstreams/4a2faf3e-83e9-45a2-9b83-684f3be01c6d/download
date published: 1978
date modified: 2026-07-24T05:57:18Z
provider: University Waikato
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: The University of Waikato