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Origin and Emplacement Mechanisms of the Slieve Gullion Ring Dyke Complex, Ireland

Graham, H (2016) Origin and Emplacement Mechanisms of the Slieve Gullion Ring Dyke Complex, Ireland. Masters thesis, Liverpool John Moores University.

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Abstract

The purpose of this research was to study the rock units of the Slieve Gullion ring dyke complex, to determine their composition, structure and position within the stratigraphic sequence; as well as producing a model for the emplacement of these units. A combination of detailed field observations, mapping, rock sample collection and structural measurements were obtained at selected field sites around the ring dyke complex. In the laboratory, the rock samples obtained were prepared for thin section and geochemical analysis. When compared to previously published geochemical data, the results found here were generally in agreement. The geochemistry results obtained for the various rock units studied were also generally within the expected igneous rock categories on the IUGS classification graph. There are some exceptions to this however and it is suggested here that those rocks have undergone hydrothermal secondary alteration, which is supported by the presence of infilled fractures within the outcrops and evidence for the presence of hot fluids (tuffisites). The geochemistry data plots all of the rocks studied here (apart from the basalts) within the alkaline or high-k calc-alkaline series on the tectonic environment graph of Ewart (1982). This suggests a cratonic or continental rift environment which supports that this igneous complex is related to the opening of the Atlantic Ocean. The geochemistry results and observations of the thin sections for the rafts of basalt found within the Forkill Quarry both confirm that these outcrops are basalts. It was also found that the basalts were geochemically similar to the Antrim basalts and it is therefore suggested here that the Forkill Quarry basalts predate the formation of the ring dyke. Overall this research agrees with the traditional ring dyke emplacement model as proposed by Emeleus et al. (2012) due to the presence of multiple sharp contacts between the rock units as well as evidence of crushing and the presence of percolating hot fluids near to rock contacts.

Item Type: Thesis (Masters)
Uncontrolled Keywords: geology; ring dyke; intrusion; geochemistry; petrology; tertiary
Subjects: G Geography. Anthropology. Recreation > G Geography (General)
Divisions: Natural Sciences and Psychology
Date Deposited: 01 Nov 2016 13:15
Last Modified: 01 Nov 2016 13:15
Supervisors: Gonzalez, S and Power, S
URI: http://researchonline.ljmu.ac.uk/id/eprint/4678

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