Micromorphological analysis of deformation structures

Ferguson, Amanda; van der Meer, Jaap J.M.; Phillips, Emrys. 2011 Micromorphological analysis of deformation structures. In: Phillips, E.; Lee, J.R.; Evans, H.M., (eds.) Glaciotectonics : field guide. Quaternary Research Association, 32-54. (QRA field guides).

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Micromorphology is increasingly being used by glaciologists and Quaternary geologists as a primary tool for the analysis of glacial sediments. This type of analysis, which utilises a standard petrological microscope (van der Meer, 1983; Carr, 2004; van der Meer and Menzies, 2011), can provide far greater detail of the depositional and deformation histories recorded by these sediments than can be obtained from macro‐scale studies alone. Published studies have used micromorphology to differentiate between diamictons deposited in different sedimentary environments (van der Meer, 1987; Harris, 1998; Lachniet et al., 1999, 2001; Carr et al., 2000; Carr, 2001; Menzies and Zaniewski, 2003; Carr et al., 2006; Phillips 2006; Menzies et al., 2006; Reinardy and Lukas, 2009; Kilfeather et al., 2010); as an aid to our understanding of the processes occurring beneath glaciers (Menzies and Maltman, 1992; van der Meer, 1997; Menzies et al., 1997; Khatwa and Tulaczyk, 2001; van der Meer et al., 2003; Roberts and Hart, 2005; Hiemstra et al., 2005; Baroni and Fasano, 2006; Larsen et al., 2006, 2007; Hart, 2007); unravelling the often complex deformation histories recorded by glacigenic sequences (van der Meer, 1993; Phillips and Auton, 2000; van der Wateren et al., 2000; Menzies, 2000; Phillips et al., 2007; Lee and Phillips, 2008; Denis et al., 2010); and investigating the role played by pressurised pore‐water/melt water during these deformation events (Hiemstra and van der Meer, 1997; Phillips and Merritt, 2008; van der Meer et al., 2009; Denis et al., 2010). The terminology used in these studies to describe the various micro‐textures observed in thin section typically follows that proposed by van der Meer (1987, 1993) and Menzies (2000). The recent development of a quantitative microstructural mapping method (Phillips et al., 2011) which utilises commercially available computer graphic software (e.g. Adobe Illustrator/CorelDraw) alongside these traditional methods, has the potential to further contribute to our understanding the processes occurring during the deformation of glacial sediments. During this process the relationships between successive generations of clast microfabrics and other microstructures (e.g. plasmic fabrics, turbate structures, folds, faults, shears…etc) are determined, allowing a detailed relative chronology of fabric development to be established, applying the terminology and approach typically used by structural geologists and metamorphic petrologists to unravel the often complex, polyphase deformation histories recorded by glacial deposits.

Item Type: Publication - Book Section
Programmes: BGS Programmes 2010 > Geology and Landscape (Scotland)
Date made live: 22 Dec 2011 14:05 +0 (UTC)

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