Weathering of granite in Antarctica, II: thermal stress at the grain scale
Granular disintegration has long been recognized and referred to in weathering texts from all environments, including the Antarctic. Despite this universal identification and referral, few to no data exist regarding thermal conditions at this scale and causative mechanisms remain little more than co...
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Online Access: | http://hdl.handle.net/11383/1674330 https://doi.org/10.1002/esp.1617 |
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ftuninsubriairis:oai:irinsubria.uninsubria.it:11383/1674330 2024-04-14T08:03:38+00:00 Weathering of granite in Antarctica, II: thermal stress at the grain scale HALL K STRINI A. GUGLIELMIN, MAURO Hall, K Guglielmin, Mauro Strini, A. 2008 http://hdl.handle.net/11383/1674330 https://doi.org/10.1002/esp.1617 eng eng info:eu-repo/semantics/altIdentifier/wos/WOS:000254594100010 volume:33 firstpage:475 lastpage:493 journal:EARTH SURFACE PROCESSES AND LANDFORMS http://hdl.handle.net/11383/1674330 doi:10.1002/esp.1617 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-41549095476 info:eu-repo/semantics/closedAccess weathering granular disintegration temperature monitoring thermal stresse granite Antarctica info:eu-repo/semantics/article 2008 ftuninsubriairis https://doi.org/10.1002/esp.1617 2024-03-21T18:53:31Z Granular disintegration has long been recognized and referred to in weathering texts from all environments, including the Antarctic. Despite this universal identification and referral, few to no data exist regarding thermal conditions at this scale and causative mechanisms remain little more than conjecture. Here, as part of a larger weathering study, thermal data of individual grains (using infrared thermometry and ultra-fine thermocouples) composing a coarse granite, as well as the thermal gradients in the outer 10 cm (using thermistors), were collected from a north-facing exposure. Measurements were also made regarding the surface roughness of the rock. Based on recorded temperatures, the nature of the rock surface and the properties of the minerals, an argument is made for complex stress fields that lead to granular disintegration. Mineral to mineral temperature differences found to occur were, in part, due to the changing exposure to solar radiation through the day (and through seasons). Because the thermal conductivity and the coefficient of thermal expansion of quartz are not equal in all directions, coupled with the vagaries of heating, this leads to inter-granular stresses. Although fracture toughness increases with a decrease in temperature, it is suggested that the tensile forces resulting from falling temperatures are able to exceed this and produce granular disassociation. The lack of equality with respect to crystal axis of both thermal conductivity and expansion in quartz further exacerbates the propensity to failure. Grain size and porosity also influence the thermal stresses and may help explain why some grains are held in place despite disassociation near the surface. While the data presented here appear to beg more questions than providing answers, they do provide a basis for better, more detailed studies of this important weathering scale. Article in Journal/Newspaper Antarc* Antarctic Antarctica IRInSubria - Institutional Repository Insubria (Università degli Studi dell’Insubria) Antarctic The Antarctic Earth Surface Processes and Landforms 33 3 475 493 |
institution |
Open Polar |
collection |
IRInSubria - Institutional Repository Insubria (Università degli Studi dell’Insubria) |
op_collection_id |
ftuninsubriairis |
language |
English |
topic |
weathering granular disintegration temperature monitoring thermal stresse granite Antarctica |
spellingShingle |
weathering granular disintegration temperature monitoring thermal stresse granite Antarctica HALL K STRINI A. GUGLIELMIN, MAURO Weathering of granite in Antarctica, II: thermal stress at the grain scale |
topic_facet |
weathering granular disintegration temperature monitoring thermal stresse granite Antarctica |
description |
Granular disintegration has long been recognized and referred to in weathering texts from all environments, including the Antarctic. Despite this universal identification and referral, few to no data exist regarding thermal conditions at this scale and causative mechanisms remain little more than conjecture. Here, as part of a larger weathering study, thermal data of individual grains (using infrared thermometry and ultra-fine thermocouples) composing a coarse granite, as well as the thermal gradients in the outer 10 cm (using thermistors), were collected from a north-facing exposure. Measurements were also made regarding the surface roughness of the rock. Based on recorded temperatures, the nature of the rock surface and the properties of the minerals, an argument is made for complex stress fields that lead to granular disintegration. Mineral to mineral temperature differences found to occur were, in part, due to the changing exposure to solar radiation through the day (and through seasons). Because the thermal conductivity and the coefficient of thermal expansion of quartz are not equal in all directions, coupled with the vagaries of heating, this leads to inter-granular stresses. Although fracture toughness increases with a decrease in temperature, it is suggested that the tensile forces resulting from falling temperatures are able to exceed this and produce granular disassociation. The lack of equality with respect to crystal axis of both thermal conductivity and expansion in quartz further exacerbates the propensity to failure. Grain size and porosity also influence the thermal stresses and may help explain why some grains are held in place despite disassociation near the surface. While the data presented here appear to beg more questions than providing answers, they do provide a basis for better, more detailed studies of this important weathering scale. |
author2 |
Hall, K Guglielmin, Mauro Strini, A. |
format |
Article in Journal/Newspaper |
author |
HALL K STRINI A. GUGLIELMIN, MAURO |
author_facet |
HALL K STRINI A. GUGLIELMIN, MAURO |
author_sort |
HALL K |
title |
Weathering of granite in Antarctica, II: thermal stress at the grain scale |
title_short |
Weathering of granite in Antarctica, II: thermal stress at the grain scale |
title_full |
Weathering of granite in Antarctica, II: thermal stress at the grain scale |
title_fullStr |
Weathering of granite in Antarctica, II: thermal stress at the grain scale |
title_full_unstemmed |
Weathering of granite in Antarctica, II: thermal stress at the grain scale |
title_sort |
weathering of granite in antarctica, ii: thermal stress at the grain scale |
publishDate |
2008 |
url |
http://hdl.handle.net/11383/1674330 https://doi.org/10.1002/esp.1617 |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Antarc* Antarctic Antarctica |
genre_facet |
Antarc* Antarctic Antarctica |
op_relation |
info:eu-repo/semantics/altIdentifier/wos/WOS:000254594100010 volume:33 firstpage:475 lastpage:493 journal:EARTH SURFACE PROCESSES AND LANDFORMS http://hdl.handle.net/11383/1674330 doi:10.1002/esp.1617 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-41549095476 |
op_rights |
info:eu-repo/semantics/closedAccess |
op_doi |
https://doi.org/10.1002/esp.1617 |
container_title |
Earth Surface Processes and Landforms |
container_volume |
33 |
container_issue |
3 |
container_start_page |
475 |
op_container_end_page |
493 |
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1796299903789432832 |