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Investigating an igneous dyke swarm using applied field magnetics

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posted on 2024-10-02, 03:05 authored by Stephanie Grace Hawkins

A dyke swarm near Oberon in central-western New South Wales has been investigated using magnetics to determine its relationship to the Permian-Cretaceous rifting of eastern Australia. Rifting that allowed the extensional rift basin (Sydney Basin) to deposit unconformably on top of the Lachlan Fold Belt. The dyke swarm intrudes all phases of the Tarana Granite, which is adjacent to the 325Ma Bathurst Granite. Intruding the Tarana Granite is the Evan’s Crown Granite, dated at 312Ma, which provides a 20 million year bracket in which the dykes formed. This research uses magnetic modelling of the Oberon dyke swarm from aeromagnetic and ground magnetometer data to better understand the subsurface structure of the dykes. Magnetic modelling shows that bodies composed of groups of thin (~4-8m thick), vertically dipping tabular bodies successfully fit the anomalies. The modelling is accompanied by analysis of thin sections from the Fish River area within the Tarana Granite which identified the dykes as mafic, dominated by plagioclase, pyroxene and magnetite. This study has determined that the dyke swarm is likely related to both the Carboniferous Granites and the rifting that occurred in Bathurst-Oberon area of the Lachlan Fold Belt.

History

Table of Contents

1. Introduction -- 2. Methods -- 3. Results -- 4. Discussion -- 5. Conclusion -- References

Awarding Institution

Macquarie University

Degree Type

Thesis MRes

Degree

Master of Research

Department, Centre or School

Department of Earth and Planetary Sciences

Year of Award

2019

Principal Supervisor

Mark Lackie

Rights

Copyright: The Author Copyright disclaimer: https://www.mq.edu.au/copyright-disclaimer

Language

English

Extent

57 pages

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