Comparisons between macro‐ and microfabrics in a pebble‐rich, sandy till deposited by the Cordilleran Ice Sheet
It is standard practice to measure particle fabrics in glacial studies to infer palaeo‐ice flow directions and processes of till formation but few studies examine the relationships between particle fabrics at different (i.e. the macro‐ and micro‐) scales. This knowledge is critical to inform the uti...
Published in: | Boreas |
---|---|
Main Authors: | , , |
Other Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Wiley
2015
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1111/bor.12120 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fbor.12120 https://onlinelibrary.wiley.com/doi/pdf/10.1111/bor.12120 |
id |
crwiley:10.1111/bor.12120 |
---|---|
record_format |
openpolar |
spelling |
crwiley:10.1111/bor.12120 2024-06-02T08:08:15+00:00 Comparisons between macro‐ and microfabrics in a pebble‐rich, sandy till deposited by the Cordilleran Ice Sheet Neudorf, Christina M. Brennand, Tracy A. Lian, Olav B. Natural Sciences and Engineering Research Council (NSERC) of Canada Geological Society of America NSERC Discovery 2015 http://dx.doi.org/10.1111/bor.12120 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fbor.12120 https://onlinelibrary.wiley.com/doi/pdf/10.1111/bor.12120 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Boreas volume 44, issue 3, page 483-501 ISSN 0300-9483 1502-3885 journal-article 2015 crwiley https://doi.org/10.1111/bor.12120 2024-05-03T11:48:40Z It is standard practice to measure particle fabrics in glacial studies to infer palaeo‐ice flow directions and processes of till formation but few studies examine the relationships between particle fabrics at different (i.e. the macro‐ and micro‐) scales. This knowledge is critical to inform the utility of the methods and limitations of the associated interpretations. Micro‐ (sand grain) and macro‐ (pebble) fabrics of pebble‐rich, sandy subglacial till (Kamloops Lake till) deposited by the Cordilleran Ice Sheet, south‐central British Columbia, were compared to assess their similarities and differences, and therefore their utility for understanding subglacial processes. Before comparisons were made, the data were tested for robustness by assessing various controls (e.g. sampling face orientation, number of particles measured, statistical variation resulting from sampling effects, particle shape, size and concentration) on particle fabrics. A new method of microfabric analysis was applied that involves the identification and delineation of distinct clusters of similarly orientated sand grains in order to compare them with macrofabrics and inferred ice‐flow directions. The results show that microfabrics, on their own, are an unreliable indicator of ice‐flow direction in Kamloops Lake till in the study area and should not be used as a substitute for macrofabric data, as they probably record late‐stage microscale strain patterns and pore‐water flow in addition to till deposition and deformation by overriding ice. We suspect that this would also be the case for coarse‐grained till elsewhere. Our findings suggest that till microfabric interpretations should always be made after assessing corresponding macrofabric data alongside sedimentological and structural observations. Article in Journal/Newspaper Ice Sheet Wiley Online Library Boreas 44 3 483 501 |
institution |
Open Polar |
collection |
Wiley Online Library |
op_collection_id |
crwiley |
language |
English |
description |
It is standard practice to measure particle fabrics in glacial studies to infer palaeo‐ice flow directions and processes of till formation but few studies examine the relationships between particle fabrics at different (i.e. the macro‐ and micro‐) scales. This knowledge is critical to inform the utility of the methods and limitations of the associated interpretations. Micro‐ (sand grain) and macro‐ (pebble) fabrics of pebble‐rich, sandy subglacial till (Kamloops Lake till) deposited by the Cordilleran Ice Sheet, south‐central British Columbia, were compared to assess their similarities and differences, and therefore their utility for understanding subglacial processes. Before comparisons were made, the data were tested for robustness by assessing various controls (e.g. sampling face orientation, number of particles measured, statistical variation resulting from sampling effects, particle shape, size and concentration) on particle fabrics. A new method of microfabric analysis was applied that involves the identification and delineation of distinct clusters of similarly orientated sand grains in order to compare them with macrofabrics and inferred ice‐flow directions. The results show that microfabrics, on their own, are an unreliable indicator of ice‐flow direction in Kamloops Lake till in the study area and should not be used as a substitute for macrofabric data, as they probably record late‐stage microscale strain patterns and pore‐water flow in addition to till deposition and deformation by overriding ice. We suspect that this would also be the case for coarse‐grained till elsewhere. Our findings suggest that till microfabric interpretations should always be made after assessing corresponding macrofabric data alongside sedimentological and structural observations. |
author2 |
Natural Sciences and Engineering Research Council (NSERC) of Canada Geological Society of America NSERC Discovery |
format |
Article in Journal/Newspaper |
author |
Neudorf, Christina M. Brennand, Tracy A. Lian, Olav B. |
spellingShingle |
Neudorf, Christina M. Brennand, Tracy A. Lian, Olav B. Comparisons between macro‐ and microfabrics in a pebble‐rich, sandy till deposited by the Cordilleran Ice Sheet |
author_facet |
Neudorf, Christina M. Brennand, Tracy A. Lian, Olav B. |
author_sort |
Neudorf, Christina M. |
title |
Comparisons between macro‐ and microfabrics in a pebble‐rich, sandy till deposited by the Cordilleran Ice Sheet |
title_short |
Comparisons between macro‐ and microfabrics in a pebble‐rich, sandy till deposited by the Cordilleran Ice Sheet |
title_full |
Comparisons between macro‐ and microfabrics in a pebble‐rich, sandy till deposited by the Cordilleran Ice Sheet |
title_fullStr |
Comparisons between macro‐ and microfabrics in a pebble‐rich, sandy till deposited by the Cordilleran Ice Sheet |
title_full_unstemmed |
Comparisons between macro‐ and microfabrics in a pebble‐rich, sandy till deposited by the Cordilleran Ice Sheet |
title_sort |
comparisons between macro‐ and microfabrics in a pebble‐rich, sandy till deposited by the cordilleran ice sheet |
publisher |
Wiley |
publishDate |
2015 |
url |
http://dx.doi.org/10.1111/bor.12120 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fbor.12120 https://onlinelibrary.wiley.com/doi/pdf/10.1111/bor.12120 |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Boreas volume 44, issue 3, page 483-501 ISSN 0300-9483 1502-3885 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/bor.12120 |
container_title |
Boreas |
container_volume |
44 |
container_issue |
3 |
container_start_page |
483 |
op_container_end_page |
501 |
_version_ |
1800753457415585792 |