Dr Mark Tarplee, BSc, PGCE, PhD
Honorary Research Assistant
School of Geography
Queen Mary, University of London
Mile End Road, London E1 4NS
Tel: 0044 (0)20 7882 2777
Fax: 0044 (0)20 7882 7479
E-mail: M.Tarplee@qmul.ac.uk
A brief history of Tarplee:
| 2007 | Post-doctoral Research Assistant, Department of Geography, Queen Mary. X-ray microtomography of geological materials. |
| 2002-2006 | PhD, subglacial sedimentology, Department of Geography, Queen Mary. |
| 1998-2001 | MPhil, glacial geomorphology (Part-time), University of Luton. Not completed due to closure of the Earth Sciences department |
| 1997-2002 | Large goods vehicle, C+E (38 tonne articulated truck) driver |
| 1995-1996 | Lecturer in Geography, Deeside College, Flintshire |
| 1994-1995 | P.G.C.E. (Further/Higher Education) University of Wales, Cardiff |
| 1988-1991 | B.Sc. (Hons) Science - Geology/Geography, University of Luton |
Research interests:
Research areas:
Subglacial Till – The ‘Upwardly Mobile’ Sediment?
1. View west from Pit 1 approximately 500m east of the Tynagh mine site (partially obscured behind the trees in the middle distance).
2. Pit 2 (with me for scale), approximately 2.75 km east of the Tynagh mine site.
3. The Geological Survey of Ireland drill rig and team auger sampling approximately 4.5 km east of the Tynagh mine site.
My primary research interests are sediment dispersal processes and dynamics within the subglacial environment, particularly associated with the deformation of soft sediment (till) proximal to the ice-bed interface. The nature and extent of subglacial till deformation is the subject of much conjecture and debate, its role in controlling ice-sheet dynamics (with the consequent effects on global climate) still ambiguous. Palaeoglaciated landscapes (areas from which formally much more extensive ice-sheets have retreated) offer an insight into what is a largely inaccessible contemporary environment.
Glacial erratic material is sediment of any size that has been transported and deposited beyond the margins of its source sub/outcrop, often forming definable three-dimensional lenses within till, referred to as erratic or dispersal plumes. The two-dimensional surface expression of these sediment assemblages is usually termed an erratic/dispersal train/fan. Subglacial erratic plumes can be viewed as lithologically, mineralogically and/or geochemically distinct tracers (similar to chemical/dye tracers used in hydrological studies) providing a unique insight into the sedimentological processes that occur within this environment. Additionally, material eroded and dispersed from mineral deposits located in palaeoglaciated areas produces a much larger target than the orebody itself, thereby increasing the chances of detecting the presence and exact location of the source, which is often obscured by overlying glacigenic sediments.
My PhD research involved three-dimensional, multi-scale geomorphological, sedimentological, geochemical and micromorphological analyses of a 93 km2 area around the Tynagh mineral deposit, south-east County Galway, Ireland (Figs. 1-3). The surface expression of the associated erratic assemblage has a ‘ribbon-type’ form (a common feature of erratic trains), but within the sediment package the morphology of the assemblage diverges significantly from that of other three-dimensionally mapped erratic plumes. The findings of this research, including an updated idealised model of an erratic plume, are being prepared for publication in collaboration with Professor Jaap J.M. van der Meer, with one paper ‘Glacial erratic assemblages: reliable indicators of palaeo-iceflow dynamics’ currently in review.
The research is part of a wider project on subglacial sedimentary processes and glacial geomorphology being undertaken by fellow members of the Environmental Change and Management Research Group [new window]. The Geological Survey of Ireland generously provided technical, equipment and field support for the research as well as permitting use of the Open File Databank for the Tynagh area. Aurum Exploration Ltd. also provided materials and invaluable advice. Innov-X UK generously provided an Innov-X Systems Alpha Analyzer Field Portable X-Ray Fluorescence analyser for the geochemical analyses.
Microtomography: X-ray vision of internal structure
4. Visualisation of the internal structure of a diamict from Antarctica, constructed from an X-ray microtomographic analysis of the sample. The densest portion of the sediment (clasts and matrix) is represented in green; voids are coloured red. The configuration of the prominent voids appears to be associated with (produced by?) the position of the adjacent clast (the obvious coherent feature at the top of the sample).
Computed tomography (CT scanning) has revolutionised materials science, providing insights into the composition and structure of objects (most notably humans) without the need for invasive/destructive analytical techniques. The acquisition of a Skyscan 1072 microtomograph, part of the Centre for Micromorphology, has provided me with the opportunity to apply this technique to a variety of geological samples, primarily subglacial in origin. Volumetric three-dimensional visualisations and analyses of some of the ‘type’ examples of subglacial sediment microstructures has permitted significant insights into their possible formative mechanisms (Fig. 4). This preliminary work is currently being prepared for publication and investigations are ongoing. The technique has also been applied to ostracods, in collaboration with Dr David Horne, and other geomaterials.
Geological materials, especially (glacial) diamicts that are often composed of materials of highly varied densities (the technique is based on detecting the density contrast of different materials), present specific challenges to the (micro)tomograph user. I have compiled information regarding how these problems may be mitigated and combined it with a set of protocols detailing how optimal quality scans and visualisations can be acquired using the Skyscan 1072, in collaboration with Mr Nick Corps, Skyscan Engineer, e2v scientific instruments. However, much of the information contained within the manual should also be relevant to the application of other tomographic equipment in the analysis of geological materials.
Other research projects
I have participated in a collaborative project between the Geological Survey of Canada and Alberta Geological Survey, mapping the surficial (glacial) deposits of northern Alberta. Micromorphological sampling of sediments located within the Bistcho Lake area (NTS 84M) map sheet, northwest of Zama City was conducted (Figs.5-7). It is hoped that microtomographic analyses can be used to assess the level of till microfabric development in a selection of the samples, in order to assist in reconstructing the nature and direction of ice flow across the area during the last glacial maximum. The findings of this research are currently being prepared for publication in collaboration with members of both surveys. During 2005 I attended course AG-321 - Arctic Terrestrial and Marine Quaternary Stratigraphy – Excursion, at the University of Norway in Svalbard (UNIS), in order to gain an insight into processes occurring within a modern glacial environment (Figs. 8-10). During the field excursion I acquired micromorphological samples from a variety of sedimentary environments. The results of the analyses will be prepared for publication, hopefully in collaboration with researchers based at UNIS, in the near future.
5. Aerial photo of Zama City viewed from the South.
6. One of the many oil wells scattered around the Zama City area.
7. An undisturbed sediment sample across the contact between two tills contained within a ‘Kubiena’ tin for thin section analysis, west of Zama City.
8. View north towards Longyearbyen from Sarkofagen, Spitsbergen.
9. The course group in discussions with Prof Jon Landvik (facing the camera), Linnédalen, Spitsbergen.
10. Me standing a few metres north of Nordenskiöldbreen, Spitsbergen.
Publications:
Protocol:
- Tarplee, M., Corps, N., 2008. Skyscan 1072 desktop X-ray microtomograph: sample scanning, reconstruction and visualisation (2D and 3D) protocols. Guidelines, notes, selected references and F.A.Q’s. Centre for Micromorphology, Department of Geography, Queen Mary, University of London. 31pp.
Thesis:
- Tarplee, M.F.V., 2006. Subglacial till – the ‘upwardly mobile’ sediment? Ph.D. Thesis, Queen Mary, University of London. 318pp.
Reports:
- Tarplee, M., 2006. Report on the use of an International Association of Sedimentologists Postgraduate Grant Scheme 2005 Award.
http://www.iasnet.org/members/grantreports/mark_tarplee.pdf - Tarplee, M., Sheehy, M., 2004. Report on the drilling project carried out in the vicinity of the Tynagh mineral deposit, southeast County Galway, 4th–14th May 2004. Geological Survey of Ireland Open-File report, Dublin, 31pp.
Examples of research funding:
Financial support for the PhD research and conference attendance has been provided in the form of grants from:
• Queen Mary, University of London Research Studentship
• Quaternary Research Association
• The International Association of Sedimentologists
• British Society for Geomorphology
• The Royal Society 20th International Geographical Congress Fund
• Department of Geography Postgraduate Research Fund
The Geological Survey of Canada and Alberta Geological Survey shared the fieldwork costs associated with my participation in the Bistcho Lake area surficial sediment mapping program.