Objective
The limited temperature and heat flow data available for the Republic of Ireland were confined mainly to that part of the country underlain by the Carboniferous Limestone. This work extends the measurements to the main Irish granites for which heat flow data was entirely absent. When studying granites heat production data is also required, and the project involves geochemical measurements on both core and surface samples. In addition, temperature and heat flow measurements are also being made in nongranitic areas in order to enhance the earlierdataset.
4 sites were selected, 2 in the Galway Granite, and 1 each in the Leinster and Barnesmore (Donegal) Granites. Physical and chamical property measurements were made on surface and core samples and heat flow measurements were made in the boreholes. Preliminary results gave the following heat flow and heat production values for the 4 boreholes. Galway Granite: 77mWm{- 2} and 7uWm{-3}; 65mWm{-2} and 4uWm{-3}. Leinster Granite: 80mWm{-2} and 2uWm{-3}. Barnesmore Granite: 85mWm{-2} and 5uWm{- 3}.
All the heat flow results are provisional. None of the boreholes have yet had a second visit, and the calculations and corrections will be subject to refinement. Nevertheless the general level of the values will be unlikely to change substantially and a number of trends are already apparent.
The granite heat flow values are all higher than the values in adjacent nongranite areas. The heat production potential of the granites has a clear influence on the heat flow. But the heat production heat flow relationships are not consistent. The Leinster granite shows low surface heat production with high heat flow, whilst the substantially higher heat production in the Galway Granite does not seem to be accompanied by an equivalently higher heat flow. The depth distribution of heat production on a scale length of km must be very different in the 2 granites. Similar discrepancies have shown themselves in the United Kingdom granites a nd it will be important to study the underlying geochemical aspects in detail. The large geochemical data set acquired during the course of this project will be crucial.
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CSC - Cost-sharing contractsCoordinator
90 GALWAY
Ireland