Basaltic traps and related intrusions, globally, host a variety of resources including aggregates (Mitchel, 2015), minerals (Lusty, 2017), geothermal (Campbell et al., 2016), and groundwater (Seneger et al., 2015; Babar and Muley, 2018). A detailed understanding of lava emplacement and stratigraphy can provide robust models to aid related resource management and sustainability. This project will focus on the stratigraphy and emplacement of the Antrim Lava Group, with implications and impacts that relate to the management and sustainability of related resources regionally and in similar geological settings worldwide.
During continental rifting that led to the opening of the North Atlantic ca. 56 Ma, the Antrim lavas erupted to form the basalt plateau in NE Ireland that includes the iconic Giant’s Causeway UNESCO World Heritage site. Much work to date has focused on the petrology and geochemistry of the Antrim Lavas, resulting in a sophisticated understanding of the genesis and evolution of the basalt magma (Gamble et al., 1999). However, relatively little is known about the internal stratigraphy and spatial heterogeneity of the lava sequence. This gap in knowledge inhibits exploration for potential resources such as aggregates, subsurface geothermal sources, platinum group elements, rare metals and groundwater (Robins et al., 2011). The excellent exposure of the lavas, alongside an extensive set of cores and geophysical data, provide an as yet untapped opportunity to generate a high resolution reconstruction of lava emplacement.
This project’s major work will involve analysis of 20 cores drilled across the plateau that penetrate the basalt sequence, plus 14 more logged boreholes (5 with geophysical logs), complemented by field sampling, collection and analysis of groundwater data, geological logging and mapping, augmented by a suite of laboratory analyses and subsequent modelling. In addition to stratigraphic analysis based on textural, petrological and geochemical characteristics (chemostratigraphy), the project will use magnetic analyses to aid stratigraphic interpretation (critically anisotropy of magnetic susceptibility (AMS) and palaeomagnetism). This will enable development of the most detailed model for the stratigraphy and emplacement of the Antrim lavas to date, improving our understanding of the volcanism that accompanied the rifting of the N. Atlantic, and generating one of the most detailed datasets worldwide that can be used to explore how magma productivity and effusive eruption frequency vary during rifting on kiloyear timescales.
The main objectives are:
1. Establish basalt and interbasalt facies: Examination of core and detailed logging of texture, composition, colour, structures, sediments, zeolites, veins/joints, fractures, alteration, etc. This will be supported by magnetic analyses to establish magnetostratigraphy
2. Correlation of facies between cores: quantitative analysis of basalt texture and composition. This can be supported by fieldwork and by logging sections in quarries and coastal cliffs, utilising modern remote sensing and drone technology where applicable.
3. Generation of stratigraphic model: facies correlations will be used to establish a sequence and develop a 3D framework using MoveTM modelling software.
Dr Rob Raine, GSNI, provides access to core material at the GSNI Core Store in Belfast, and contributes stratigraphic analyses expertise. Professor Dougal Jerram specialises in volcanic stratigraphy and is a member of the Centre for Earth Evolution and Dynamics at the University of Oslo. MoveTM software is provided by Midland Valley Exploration, part of the Edinburgh-based consultancy Petex that develops modelling software in structural geology for the mineral and hydrocarbon exploration industries.
Please contact the project supervisors for further details:
Carl Stevenson: [email protected]
Sebastian Watt: [email protected]
Babar, M. and Muley, R.B., 2018. Investigation of Sub-surface Geology through Integrated Approach of Geological and Geophysical Studies in the Part of South-eastern Maharashtra, India. American Journal of Water Resources, 6(3), pp.123-136. Cooper, M. R., Walsh, J. J., van Dam, C. L., Young, M. E., Earls, G., Anderson, H. & Walker A. (in prep). Palaeogene Alpine tectonics and Icelandic plume-related magmatism and deformation in Ireland.
Campbell, S.A., Mielke, P. and Götz, A.E., 2016. Geothermal energy from the Main Karoo Basin? New insights from borehole KWV-1 (Eastern Cape, South Africa). Geothermal Energy, 4(1), p.9.
Lusty, P., 2016, October. 8. Critical metals for high-technology applications: mineral exploration potential in the north of Ireland. Royal Irish Academy.
Mitchell, W. I., Meighan, I. G., Cooper, M. R., Ture, M. D., Ellam, R. M., Noble, S. R., Knox, R. W. O’B., Hards, V. L., McGinn, C. & Walker, G. P. L. (deceased) 2010. A Palaeogene, Pre-Flood Basalts Supervolcano in Co. Antrim?: Evidence from the ‘Clay with Flints.’ IGRM abstract volume, p. 52-53.
Mitchell, C., 2015. Construction aggregates: evaluation and specification. http://nora.nerc.ac.uk/id/eprint/510909
Gamble, J. A., Wysoczanski, R. J. & Meighan, I. G. 1999. Constraints on the age of the British Tertiary Volcanic Province from ion microprobe U-Pb (SHRIMP) ages for acid igneous rocks from Northern Ireland. J. Geol. Soc. Lond. 156, 291-299 (1999).
Robins, N.S., McConvey, P.J. and McLorinan, D., 2011. Groundwater flow in the Antrim Lava group and Ulster White Limestone formation, Northern Ireland. Quarterly Journal of Engineering Geology and Hydrogeology, 44(1), pp.63-73.
Senger, K., Buckley, S.J., Chevallier, L., Fagereng, Å., Galland, O., Kurz, T.H., Ogata, K., Planke, S. and Tveranger, J., 2015. Fracturing of doleritic intrusions and associated contact zones: Implications for fluid flow in volcanic basins. Journal of African Earth Sciences, 102, pp.70-85.