A study of anisotropy of magnetic susceptibility’s effectiveness in understanding palaeoflow systematics in shale basins

Galvin, Matthew (2017) A study of anisotropy of magnetic susceptibility’s effectiveness in understanding palaeoflow systematics in shale basins. Masters thesis, UNSPECIFIED.

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Abstract

Understanding sedimentary transport mechanisms in shale-prone basins can be difficult, but anisotropy of magnetic susceptibility (AMS) has the sensitivity and ease of use to be widely applicable. Three distinct shale basins were selected, the turbidite Ainsa Basin, the shelfedge of the Welsh Borderlands and the hemiplegic Marcellus Shales within the Appalachian Basin. These were chosen to assess the strengths and limitation of AMS as a palaeoflow indicator, focusing mainly on the Ainsa Basin as it has a well characterised palaeoflow and geographically confined depositional model that spans a very short period. This project explored the viability of using Baas et al., (2007) description of the petrofabric’s AMS as a means to establish delivery mechanism. The Ainsa System showed two modes of AMS, one that was aligned with the flow direction and a transverse fabric normal to flow direction. Each site was examined for its minerology; hysteresis tests were performed to observe if the source of magnetic susceptibility was from ferrimagnetic or paramagnetic minerals and to infer if the AMS reflected a grain or crystalline fabric. In the Ainsa case study, the samples had a greater percentage of ferrimagnetic contribution so isothermal remanent magnetism (IRM) and anhysteretic remanent magnetisation (ARM) acquisition was used to determine the ferrimagnetic minerology. The sites were examined for the tectonic impact on the AMS which was largely minimal.

Item Type:
Thesis (Masters)
ID Code:
85729
Deposited By:
Deposited On:
29 Mar 2017 09:16
Refereed?:
No
Published?:
Published
Last Modified:
19 Sep 2020 07:38