Investigating glacial sediment provenance in Northern Ireland using principal component analysis of Tellus soil geochemical data

• Main Authors: Scheib, A.J., Dunlop, P., Cooper, M.R.
• Other Authors: Young, M.E.
• Format: Report
• Language: English
• Published: British Geological Survey 2010
• Subjects: Earth Sciences; Ice Sheet
• Online Access: http://nora.nerc.ac.uk/id/eprint/11914/; https://nora.nerc.ac.uk/id/eprint/11914/1/OR10017.pdf

This report describes results of a preliminary study using Tellus soil geochemical baseline data to investigate the character and spatial variation of glacial deposits located north and south of the Armoy Moraine which marks the limit of two different ice flow events in north Northern Ireland. The first part of the report introduces the study area and describes the regional glacial geomorphology and soil geochemical and geological data The second part of this report discusses the multivariate analysis used to interrogate the soil geochemical data with the aims of a) establishing element associations for the different glacial deposits, b) ascribing these geochemical signatures to potential source bedrock and, as a result of these c) reconstructing ice flow trajectories. This preliminary study has established that there are distinct geochemical variations in soils derived over glacigenic sediments and related landforms in the area north and south of the Armoy Moraine, which supports the case that they have been formed by ice flowing from different directions. . Indicator elements for soils formed north of the Armoy Moraine in the area glaciated by an ice advance made by the Scottish ice sheet, that flowed onshore and created the Armoy Moraine, are rare earth elements (REE) Ce and La, as well as Nb As, Th and Rb. Soils south of the Armoy Moraine that formed over glacial sediments and landforms that were generated by ice flowing northwards out of the Lough Neagh basin are dominated by the geochemistry of major oxides and base metals. Key indicator elements are Co, Ni, V, Fe2O3, MgO and Cr, which tie them to basalts of the Antrim Lava Group of the Antrim plateau. This study shows that geochemical baseline data is an an important tool for investigating glacial sediments and geomorphological features formed by glacial ice advances and offers real potential to help unravel former ice sheet histories.