Insights into glacial processes from micromorphology of silt-sized sediment
Silt-rich meltwater plume deposits (MPDs) analyzed from marine sediment cores have elucidated relationships that are clearly connected, yet difficult to constrain, between subglacial hydrology, ice-marginal landforms, and grounding-zone retreat patterns for several glacial catchments. Few attempts h...
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ftdoajarticles:oai:doaj.org/article:bd53423d9c394799b306a31afcd18926 2024-09-15T18:38:59+00:00 Insights into glacial processes from micromorphology of silt-sized sediment A. P. Lepp L. E. Miller J. B. Anderson M. O'Regan M. C. M. Winsborrow J. A. Smith C.-D. Hillenbrand J. S. Wellner L. O. Prothro E. A. Podolskiy 2024-05-01T00:00:00Z https://doi.org/10.5194/tc-18-2297-2024 https://doaj.org/article/bd53423d9c394799b306a31afcd18926 EN eng Copernicus Publications https://tc.copernicus.org/articles/18/2297/2024/tc-18-2297-2024.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-18-2297-2024 1994-0416 1994-0424 https://doaj.org/article/bd53423d9c394799b306a31afcd18926 The Cryosphere, Vol 18, Pp 2297-2319 (2024) Environmental sciences GE1-350 Geology QE1-996.5 article 2024 ftdoajarticles https://doi.org/10.5194/tc-18-2297-2024 2024-08-05T17:49:26Z Silt-rich meltwater plume deposits (MPDs) analyzed from marine sediment cores have elucidated relationships that are clearly connected, yet difficult to constrain, between subglacial hydrology, ice-marginal landforms, and grounding-zone retreat patterns for several glacial catchments. Few attempts have been made to infer details of subglacial hydrology, such as flow regime, geometry of drainage pathways, and mode(s) of sediment transport through time, from grain-scale characteristics of MPDs. Using sediment samples from MPD, till, and grounding-zone proximal diamicton collected offshore of six modern and relict glacial catchments in both hemispheres, we examine grain shape distributions and microtextures (collectively, grain micromorphology) of the silt fraction to explore whether grains are measurably altered from their subglacial sources via meltwater action. We find that 75 % of all imaged grains ( n = 9400) can be described by 25 % of the full range of measured shape morphometrics, indicating grain shape homogenization through widespread and efficient abrasive processes in subglacial environments. Although silt grains from MPDs exhibit edge rounding more often than silt grains from tills, grain surface textures indicative of fluvial transport (e.g., v-shaped percussions) occur in only a modest number of grains. Furthermore, MPD grain surfaces retain several textures consistent with transport beneath glacial ice (e.g., straight or arcuate steps, (sub)linear fractures) in comparable abundances to till grains. Significant grain shape alteration in MPDs compared to their till sources is observed in sediments from glacial regions where (1) high-magnitude, potentially catastrophic meltwater drainage events are inferred from marine sediment records and (2) submarine landforms suggest supraglacial melt contributed to the subglacial hydrological budget. This implies that quantifiable grain shape alteration in MPDs could reflect a combination of high-energy flow of subglacial meltwater, persistent sediment ... Article in Journal/Newspaper The Cryosphere Directory of Open Access Journals: DOAJ Articles The Cryosphere 18 5 2297 2319 |
institution |
Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 A. P. Lepp L. E. Miller J. B. Anderson M. O'Regan M. C. M. Winsborrow J. A. Smith C.-D. Hillenbrand J. S. Wellner L. O. Prothro E. A. Podolskiy Insights into glacial processes from micromorphology of silt-sized sediment |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
Silt-rich meltwater plume deposits (MPDs) analyzed from marine sediment cores have elucidated relationships that are clearly connected, yet difficult to constrain, between subglacial hydrology, ice-marginal landforms, and grounding-zone retreat patterns for several glacial catchments. Few attempts have been made to infer details of subglacial hydrology, such as flow regime, geometry of drainage pathways, and mode(s) of sediment transport through time, from grain-scale characteristics of MPDs. Using sediment samples from MPD, till, and grounding-zone proximal diamicton collected offshore of six modern and relict glacial catchments in both hemispheres, we examine grain shape distributions and microtextures (collectively, grain micromorphology) of the silt fraction to explore whether grains are measurably altered from their subglacial sources via meltwater action. We find that 75 % of all imaged grains ( n = 9400) can be described by 25 % of the full range of measured shape morphometrics, indicating grain shape homogenization through widespread and efficient abrasive processes in subglacial environments. Although silt grains from MPDs exhibit edge rounding more often than silt grains from tills, grain surface textures indicative of fluvial transport (e.g., v-shaped percussions) occur in only a modest number of grains. Furthermore, MPD grain surfaces retain several textures consistent with transport beneath glacial ice (e.g., straight or arcuate steps, (sub)linear fractures) in comparable abundances to till grains. Significant grain shape alteration in MPDs compared to their till sources is observed in sediments from glacial regions where (1) high-magnitude, potentially catastrophic meltwater drainage events are inferred from marine sediment records and (2) submarine landforms suggest supraglacial melt contributed to the subglacial hydrological budget. This implies that quantifiable grain shape alteration in MPDs could reflect a combination of high-energy flow of subglacial meltwater, persistent sediment ... |
format |
Article in Journal/Newspaper |
author |
A. P. Lepp L. E. Miller J. B. Anderson M. O'Regan M. C. M. Winsborrow J. A. Smith C.-D. Hillenbrand J. S. Wellner L. O. Prothro E. A. Podolskiy |
author_facet |
A. P. Lepp L. E. Miller J. B. Anderson M. O'Regan M. C. M. Winsborrow J. A. Smith C.-D. Hillenbrand J. S. Wellner L. O. Prothro E. A. Podolskiy |
author_sort |
A. P. Lepp |
title |
Insights into glacial processes from micromorphology of silt-sized sediment |
title_short |
Insights into glacial processes from micromorphology of silt-sized sediment |
title_full |
Insights into glacial processes from micromorphology of silt-sized sediment |
title_fullStr |
Insights into glacial processes from micromorphology of silt-sized sediment |
title_full_unstemmed |
Insights into glacial processes from micromorphology of silt-sized sediment |
title_sort |
insights into glacial processes from micromorphology of silt-sized sediment |
publisher |
Copernicus Publications |
publishDate |
2024 |
url |
https://doi.org/10.5194/tc-18-2297-2024 https://doaj.org/article/bd53423d9c394799b306a31afcd18926 |
genre |
The Cryosphere |
genre_facet |
The Cryosphere |
op_source |
The Cryosphere, Vol 18, Pp 2297-2319 (2024) |
op_relation |
https://tc.copernicus.org/articles/18/2297/2024/tc-18-2297-2024.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-18-2297-2024 1994-0416 1994-0424 https://doaj.org/article/bd53423d9c394799b306a31afcd18926 |
op_doi |
https://doi.org/10.5194/tc-18-2297-2024 |
container_title |
The Cryosphere |
container_volume |
18 |
container_issue |
5 |
container_start_page |
2297 |
op_container_end_page |
2319 |
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1810483378954174464 |