Geology of the Jackson river catchment, Southern Westland.

Author:

Ransley, John Francis.

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Abstract:

Three major disparate terrains are juxtaposed giving a diversity in geology seldom found in the confines of a single study area. Pervasive deformation and physical remoteness have discouraged previous workers, and up to this stage, much of the local geology consisted of a pastiche of extrapolations. The Alpine and Livingstone Faults converge and produce heavily tectonised zones on the margins of the main blocks. A strongly deformed paragneiss unit of at least Devonian and probably Late PreCambrian age is recognised and named Cauldron Paragneiss. Metamorphism to sillimanite + K-feldspar grade, subsequent intrusive events and development of mylonitic fabric are detailed. The basal harzburgitic peridotite of the Dun Mountain Ophiolite Belt is truncated with the convergence of the two faults and a fault zone melange formed on the eastern margin. Emphasis is placed on the formation of podiform chromite deposits found in the area. The Biotite and garnet isograds within the Haast Schist are refined on the basis of field work as is a scheme for progressive multiphase deformation. A large recumbent antiformal structure, later coaxially re-folded is infered from mapping and mesofold vergence. Caples Group rocks are correlated as protolithic for the upper green-schist facies, quartzofeldspathic and mafic schists. A three-dimensional model is proposed combining many aspects of this work. A deep crustal structure with a major imbricate fan thrust system is envisaged and extrapolated on a regional scale.

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Thesis description:

142 p. : ill. (some col.), maps ; 30 cm.

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OU geology Identifier:

1983Ransley

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Location (WKT, WGS84):

POLYGON ((168.568254987000046 -44.167950091999955,168.565973369000062 -44.165457911999965,168.547797107000065 -44.14559507499996,168.530557419000047 -44.126740669999947,168.550017775000015 -44.117701908999948,168.578744049000079 -44.104348107999954,168.583822765000036 -44.101985796999941,168.593794875000071 -44.097346148999975,168.627495420000059 -44.081654367999931,168.628109020000124 -44.081368487999953,168.66454250400011 -44.06438286499997,168.66728614200008 -44.063102875999959,168.703281325000034 -44.046298606999983,168.711782395000114 -44.055706136999959,168.710838105000107 -44.068377075999933,168.708593740000083 -44.098469076999947,168.708547151000062 -44.099093359999983,168.706923538000069 -44.120840222999959,168.705892244000097 -44.134644375999983,168.704141504000063 -44.15806233099994,168.602977984000063 -44.205846134999945,168.592357499000059 -44.194261275999963,168.591147238000076 -44.192940792999934,168.575215190000108 -44.175551040999949,168.573566107000033 -44.173750360999975,168.568254987000046 -44.167950091999955))

Files

http://download.otagogeology.org.nz/temp/Abstracts/1983Ransley.pdf

Collection

Citation

Ransley, John Francis., “Geology of the Jackson river catchment, Southern Westland.,” Otago Geology Theses, accessed February 7, 2025, https://theses.otagogeology.org.nz/items/show/169.

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