Compositional Dependence of Potassium-Argon Ages and Hydrogren and Oxygen Stable Isotopes in Hornblendes From Connemara, Western Ireland

Jappy, Trevor George (1998) Compositional Dependence of Potassium-Argon Ages and Hydrogren and Oxygen Stable Isotopes in Hornblendes From Connemara, Western Ireland. PhD thesis, University of Glasgow.

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Abstract

The work of this thesis set out to investigate the relationship between K-Ar age, hydrogen isotope values, oxygen isotope values and mineral composition in samples collected from the Dalradian rocks of the Connemara region of western Ireland. Previous studies by Elias et al. (1988) and Miller et al. (1991) found no evidence for a connection between hornblende K-Ar ages and compositions on hornblendes ranging from ~490Ma to ~390Ma. The hornblendes are believed to have cooled through their 40Ar* closure temperature between 490Ma and 463Ma (Cliff et al., 1994; Friedrich et al., 1997), therefore the younger ages are not explainable by conventional understanding of 40Ar* loss. Miller et al. (1991) found a relationship of increasing hornblende 5D values (from -750/00 to -610/00) with decreasing age and excess water contents in hornblendes. This was interpreted as being due to the hornblende being infiltrated by a retrogressive, convecting meteoric fluid (RGF) at sub-40Ar* closure temperatures (~275

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: B E Leake
Keywords: Geology, Geochemistry
Date of Award: 1998
Depositing User: Enlighten Team
Unique ID: glathesis:1998-75407
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 Nov 2019 20:13
Last Modified: 19 Nov 2019 20:13
URI: https://theses.gla.ac.uk/id/eprint/75407

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