Deciphering archives of magmatic, tectonic and hydrothermal events throughout emplacement and crystallisation of igneous intrusions
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Date
2025-12-31
Authors
Latimer, Benjamin
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University College Cork
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Abstract
Igneous intrusions play a crucial role within magma plumbing systems, acting as sites of magma storage and evolution. Alongside their role in feeding volcanic eruptions, they provide an important source of heat within the crust, driving the circulation of hydrothermal fluids required to form economic ore deposits and geothermal resources. Therefore, there is a socio-economic importance to better constrain how igneous intrusions form and their interactions with the surrounding crust.
Throughout formation, intrusions are exposed to internal and external stress regimes, with internal stress is sourced from processes intrinsic to the formation of magma chambers. In contrast, external stress is derived from other crustal processes such as tectonic deformation. The interplay between these stress regimes controls the architecture and features that form within an intrusion, providing an archive of the palaeostresses with which it has interacted throughout crystallisation. This strain archive from intrusions has been shown to offer a unique record of external and internal events, giving insight into magmatic processes and the tectonic framework active during and after magma emplacement.
While representing a powerful tool which can be applied to gain insight into crustal events, the record of strain within igneous intrusions is flawed by several issues. In this thesis, the Fanad Pluton, NW Ireland is used as test site to address three of these issues. The results of this thesis demonstrate:
1. Magmatic enclaves can archive multiple internal fabrics, providing a unique insight into magmatic fabric development within their surrounding host intrusion and its origin from magmatic or tectonic processes.
2. Igneous intrusions preserve a highly sensitive and temporal record of strain when archives from magmatic, submagmatic and subsolidus features are compared.
3. Utilising a multi-disciplinary magnetic-hyperspectral approach, a robust characterisation of the distribution and intensity of hydrothermal alterationcan be performed. This characterisation can then be used to evaluate the significance of magnetic fabrics in relation to magmatic, tectonic and hydrothermal fluid transport processes.
With these issues no longer outstanding, future studies should be able to identify a more comprehensive record of strain from igneous intrusions as it relates to magmatic, tectonic and hydrothermal alteration processes.
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Keywords
Structural geology , Igneous petrology , Hydrothermal processes , Rock magnetism
Citation
Latimer, B. 2025. Deciphering archives of magmatic, tectonic and hydrothermal events throughout emplacement and crystallisation of igneous intrusions. PhD Thesis, University College Cork.