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Dr Lorna Linch

Lorna

Visiting Research Fellow

Email: l.d.linch@qmul.ac.uk
Telephone: (+44) (0)7533 946 738

Profile


Fig.1. Salient features of a typical continental shelf scour mark (modified from Woodworth-Lynas and Dowdeswell, 1994).

Research Interests

My research interests are in sedimentology and geomorphology; deformation of sediment (particularly glacial); Micromorphology; and Quaternary Environments. Examination of these fields is critical to the reconstruction of palaeoenvironments, which will allow better understanding of present and future environmental change including glacial dynamics.

My PhD research ‘Micromorphology of Iceberg Scour’ (NERC funded) focused on the macroscale and microscale deformation of iceberg scoured sediments. Icebergs plough through unconsolidated lake/sea sediments gouging out kilometre long grooves, hundreds of metres wide and tens of metres deep (Fig. 1). Although the surface morphology of iceberg scours is well documented, little is known about what scours look like in stratigraphic section, particularly where surface characteristics are absent (e.g. through deterioration or burial).

This research establishes a definitive set of diagnostic criteria for identifying iceberg scours in the Quaternary and pre-Quaternary rock record by macroscopically and microscopically (2D thin sections and Metripol Birefringence Imaging) examining sediment deformation below iceberg scours from 1) former Glacial Lake Agassiz (Manitoba, Canada) (Figs. 2 and 3); 2) Scarborough Bluffs (ancestral Lake Ontario, Canada); 3) the North Sea (Witch Ground Basin); and 4) Antarctica (Bellingshausen and Amundsen Seas). These specific sites ensured that sub-scour structure was examined and identified in both fine-grained, clay-rich sediment as well as in diamicton. In addition, suspected seasonal/perennial ice scoured lacustrine sediment was macroscopically and microscopically examined from Sweden (thin sections already in the Centre for Micromorphology, QMUL), which compares well to iceberg scoured sediment. Finally, a new method in micromorphology called ‘Metripol Birefringence Imaging’ was pioneered as part of this research as a valuable and innovative micromorphological tool in terms of identifying and quantifying (unistrial) plasmic fabric in unconsolidated sediment.

 

Fig.2. Aerial photograph of the area formerly occupied by Glacial Lake Agassiz near the town of Lorette, southeast Winnipeg, Manitoba, Canada. Light grey tracks are iceberg scours. Source: Department of Energy, Mines and Resources, Canada, 1988.

Fig. 3. Pit excavation through an iceberg scour in former Glacial Lake Agassiz in order to carry out micromorphological sampling. Backhoe bucket is c. 1.65 m in horizontal length. 

 

 

All research from this project will be particularly valuable for correctly reconstructing palaeoenvironmental information e.g. calving glacial margins, wind direction, extent of subglacial environment etc. and predicting future glacial dynamics. In addition, it may eventually aid structural engineering on Arctic shelves, which could be of great value to oil and gas companies given the anticipated increase in number, size and frequency of icebergs within areas of petroleum exploration and extraction as a result of climate change. The findings of this research are being prepared for publication in collaboration with Profs. Jaap van der Meer and John Menzies.

 
References:
Woodworth-Lynas, C. M. T. and Dowdeswell, J.A. (1994). Soft-sediment striated surfaces and massive diamicton facies produced by floating ice. In: Earth’s Glacial Record, eds. M. Deynoux, J. M. G. Miller, E. W. Domack. N. Eyles, I. J. Fairchild & G. M. Young, pp. 241–259. Cambridge University Press, Cambridge.

Research

Publications

Research Publications:

  • Linch, L. D., Meer van der, J. J. M. & Menzies, J. (2012) Micromorphology of iceberg scour in clays: Glacial Lake Agassiz, Manitoba, Canada. Quaternary Science Reviews 55, 125–144 (DOI: 10.1016/j.quascirev.2012.07.008).
  • Linch, L. D. & Meer van der, J. J. M. (2013) Metripol birefringence imaging of glaciotectonized and ice keel scoured sediment: identification of unistrial plasmic fabric. Boreas (DOI: 10.1111/j.1502-3885.2012.00290).
  • Linch, L. D. & Meer van der, J. J. M. (in review) Micromorphology of ice keel scour in glaciolacustrine pebbly, sandy mud and fine-grained sand: Scarborough Bluffs, Ontario, Canada. Sedimentology.
  • Linch, L. D., Meer van der, J. J. M., Hillenbrand, C-D., Smith, J. A., Graham, A. G. C., & Larter, R. D. (in prep). Micromorphological characterisation of iceberg scours in West Antarctic palaeo-ice stream troughs: implications for reconstructions of LGM ice-sheet extent.
  • Linch, L. D., Meer van der, J. J. M. & Graham, A. G. C. (in prep). Micromorphological characterisation of iceberg scours in the Witch Ground Basin, North Sea.
  • Linch, L. D., Phillips, E. R., Carr, S. J. & Meer van der, J. J. M. (in prep). Metripol birefringence imaging of metamorphic rock.
  • Carr, S. J., Meer van der, J. J. M., Linch, L. D., Hiemstra, J. F., & Rijsdjik, K. (in prep) Characterisation of sediment shear-strain deformation within natural and experimentally-deformed soft sediments using Metripol analysis.

Reports:

  • Linch, L. D. 2013: Glaciation of the Scottish Borders: The 13th Glacial Landsystems Working Group (GLWG), 26th-28th October 2012. Quaternary Newsletter.
  • Linch, L. D. 2010: Micromorphology of iceberg scour marks: clay mineralogy analysis. Quaternary Newsletter, 121, 48–51.
  • Linch, L. D. 2009: The micromorphology of iceberg scour marks.  International Association of Sedimentologists Postgraduate Award. http://www.iasnet.org/members/grantreports/lorna_linch.pdf
  • Linch, L. D. 2009: The University Centre in Svalbard, Course AG-322: Arctic Marine and Terrestrial Quaternary Stratigraphy. Geopherma, 105, 16–18.
  • Lane, C. & Linch, L. D. 2009: The Quaternary Research Association 7th Postgraduate International Symposium. Quaternary Newsletter, 118, 11–14.
  • Linch, L. D. 2008: A micromorphological investigation of deformation structures beneath iceberg scours. Quaternary Newsletter, 114, p 45.
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