Microstructures in subglacial and proglacial sediments: understanding faults,folds and fabrics,and the influence of water on the style of deformation |
| |
| Institution: | 1. Geological Survey of Finland, FI-02150, Espoo, Finland;2. Posiva Oy, FI-27160, Eurajoki, Finland;3. Swedish Nuclear Fuel and Waste Management Company, Box 3091, SE-16903, Solna, Sweden;4. Department of Earth Sciences, Uppsala University, SE-75236, Uppsala, Sweden;1. Indiana University Purdue University Indianapolis, Dept. of Earth Sciences, Indianapolis, IN, USA;2. University of Vermont, Dept. of Geology, Burlington, VT, USA;3. NASA Goddard Space Flight Center, Greenbelt, MD, USA;1. Geological Survey of Norway, P.O. Box 6315 Sluppen, NO-7491 Trondheim, Norway;2. Norwegian University of Science and Technology, Museum of Natural History and Archaeology, NO-7491 Trondheim, Norway;3. Norwegian University of Science and Technology, Department of Geography, NO-7491 Trondheim, Norway;4. The University Centre in Svalbard, P.O. Box 156, NO-9171 Longyearbyen, Norway;5. Institute of Limnology, Russian Academy of Sciences, Sevastyanova Str. 9, St. Petersburg 196105, Russia;6. Department of Physical Geography & Environment, Alexander Herzen State, Pedagogical University, St. Petersburg 191186, Moika 48, Russia;1. US Geological Survey, New Mexico Water Science Center, 6700 Edith Blvd., NE, USA;2. Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA;3. School of Geosciences, University of Edinburgh, Drummond Street, Edinburgh, EH10 4ET, United Kingdom;4. School of Geographical Sciences, University of Bristol, Bristol, United Kingdom;5. Department of Geography and Sustainable Development, University of St. Andrews, St. Andrews, KY16 9AL, United Kingdom |
| |
| Abstract: | Macroscopic field and micromorphological studies have been carried out on subglacially and proglacially deformed glacigenic sequences at a number of sites throughout Scotland, UK. Examination of microstructures (folds, faults, hydrofractures, plasmic fabrics) aided understanding of the deformation histories preserved in the sediments, but a similar range of structures were developed in both Subglacial and Proglacial settings. Discrimination between Subglacial and Proglacial deformation was only possible when micromorphological data was used in conjunction with larger-scale field observations. Variations in lithology and water content were controlling factors influencing the style and apparent intensity of deformation recorded. Changes in pore-water content and pressure during deformation can lead to liquefaction and hydrofracturing, with early-formed structures locally controlling the pattern of water escape. Liquefaction can also lead to homogenisation of the sediments and the destruction of earlier deformation structures, even at relatively low strains. Beds or zones of liquefied sand and silt may form highly ‘lubricated’ detachments within the sediment pile, resulting in a marked reduction in the amount of shear transmitted to underlying units. A multidisciplinary approach, involving sedimentological, geomorphological, stratigraphical and structural field observations, combined with micromorphological analysis, is recommended to confidently unravel the glacitectonic history and depositional environment of most deformed glacigenic sedimentary sequences. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
