Preliminary Geological Assessment of the Northern Edge of Ultimi Lobe, Mars South Polar Layered Deposits
We have examined the local base of the south polar layered deposits (SPLD) exposed in the bounding scarp near 72°–74°S, 215°–230°W where there is a clear unconformable contact with older units. Sections of layering up to a kilometer thick were examined along the bounding scarp, permitting an...
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ftcaltechauth:oai:authors.library.caltech.edu:b8mc8-32y13 2024-06-23T07:56:20+00:00 Preliminary Geological Assessment of the Northern Edge of Ultimi Lobe, Mars South Polar Layered Deposits Murray, Bruce Koutnik, Michelle Byrne, Shane Soderblom, Laurence Herkenhoff, Kenneth Tanaka, Kenneth L. 2001-11 https://doi.org/10.1006/icar.2001.6657 unknown Elsevier https://doi.org/10.1006/icar.2001.6657 oai:authors.library.caltech.edu:b8mc8-32y13 eprintid:42966 resolverid:CaltechAUTHORS:20131211-152152382 info:eu-repo/semantics/closedAccess Other Icarus, 154(1), 80-97, (2001-11) 2nd International Conference on Mars Polar Science and Exploration, Reykjavik, Iceland, Aug. 21-25, 2000 Mars surface geological processes info:eu-repo/semantics/article 2001 ftcaltechauth https://doi.org/10.1006/icar.2001.6657 2024-06-12T03:10:27Z We have examined the local base of the south polar layered deposits (SPLD) exposed in the bounding scarp near 72°–74°S, 215°–230°W where there is a clear unconformable contact with older units. Sections of layering up to a kilometer thick were examined along the bounding scarp, permitting an estimate of the thinnest individual layers yet reported in the SPLD. Rhythmic layering is also present locally, suggesting a similarly rhythmic variation in environmental conditions and a recorded climate signal at least in some SPLD strata. Locally, angular unconformities may be present, as has been reported for the north polar layered deposits (NPLD) and may likewise imply intervals of subaerial erosion in the SPLD. The outcropping layers display a broad range of weathering styles and may reflect more diverse conditions of depositions, erosion, and diagenesis than might have been expected from simple aeolian depostion modulated only by astronomically driven climatic fluctuations. An unexpected finding of our study is the presence of locally abundant small pits close to the bounding scarp. These quasi-circular, negative, rimless features probably originated as impact craters and were modified to varying degrees by local endogenic processes, as well as locally variable blanketing. A nominal exposure age for the most heavily cratered region in our study area is about 2 million years, and the crater statistics appear consistent with those for the overall SPLD, although there are large uncertainties in the absolute ages implied by the crater size–frequency statistics, as in all martian crater ages. Another new finding is the presence of mass wasting features along the steepest portion of the retreating bounding scarp as well as a number of examples of brittle fracture, consistent with large-scale slumping along the bounding scarp and probably also ancient basal sliding. Both subhorizontal and high angle faults appear to be exposed in the bounding scarp, but the dips of the faults are poorly constrained. These ... Article in Journal/Newspaper Polar Science Caltech Authors (California Institute of Technology) Icarus 154 1 80 97 |
institution |
Open Polar |
collection |
Caltech Authors (California Institute of Technology) |
op_collection_id |
ftcaltechauth |
language |
unknown |
topic |
Mars surface geological processes |
spellingShingle |
Mars surface geological processes Murray, Bruce Koutnik, Michelle Byrne, Shane Soderblom, Laurence Herkenhoff, Kenneth Tanaka, Kenneth L. Preliminary Geological Assessment of the Northern Edge of Ultimi Lobe, Mars South Polar Layered Deposits |
topic_facet |
Mars surface geological processes |
description |
We have examined the local base of the south polar layered deposits (SPLD) exposed in the bounding scarp near 72°–74°S, 215°–230°W where there is a clear unconformable contact with older units. Sections of layering up to a kilometer thick were examined along the bounding scarp, permitting an estimate of the thinnest individual layers yet reported in the SPLD. Rhythmic layering is also present locally, suggesting a similarly rhythmic variation in environmental conditions and a recorded climate signal at least in some SPLD strata. Locally, angular unconformities may be present, as has been reported for the north polar layered deposits (NPLD) and may likewise imply intervals of subaerial erosion in the SPLD. The outcropping layers display a broad range of weathering styles and may reflect more diverse conditions of depositions, erosion, and diagenesis than might have been expected from simple aeolian depostion modulated only by astronomically driven climatic fluctuations. An unexpected finding of our study is the presence of locally abundant small pits close to the bounding scarp. These quasi-circular, negative, rimless features probably originated as impact craters and were modified to varying degrees by local endogenic processes, as well as locally variable blanketing. A nominal exposure age for the most heavily cratered region in our study area is about 2 million years, and the crater statistics appear consistent with those for the overall SPLD, although there are large uncertainties in the absolute ages implied by the crater size–frequency statistics, as in all martian crater ages. Another new finding is the presence of mass wasting features along the steepest portion of the retreating bounding scarp as well as a number of examples of brittle fracture, consistent with large-scale slumping along the bounding scarp and probably also ancient basal sliding. Both subhorizontal and high angle faults appear to be exposed in the bounding scarp, but the dips of the faults are poorly constrained. These ... |
format |
Article in Journal/Newspaper |
author |
Murray, Bruce Koutnik, Michelle Byrne, Shane Soderblom, Laurence Herkenhoff, Kenneth Tanaka, Kenneth L. |
author_facet |
Murray, Bruce Koutnik, Michelle Byrne, Shane Soderblom, Laurence Herkenhoff, Kenneth Tanaka, Kenneth L. |
author_sort |
Murray, Bruce |
title |
Preliminary Geological Assessment of the Northern Edge of Ultimi Lobe, Mars South Polar Layered Deposits |
title_short |
Preliminary Geological Assessment of the Northern Edge of Ultimi Lobe, Mars South Polar Layered Deposits |
title_full |
Preliminary Geological Assessment of the Northern Edge of Ultimi Lobe, Mars South Polar Layered Deposits |
title_fullStr |
Preliminary Geological Assessment of the Northern Edge of Ultimi Lobe, Mars South Polar Layered Deposits |
title_full_unstemmed |
Preliminary Geological Assessment of the Northern Edge of Ultimi Lobe, Mars South Polar Layered Deposits |
title_sort |
preliminary geological assessment of the northern edge of ultimi lobe, mars south polar layered deposits |
publisher |
Elsevier |
publishDate |
2001 |
url |
https://doi.org/10.1006/icar.2001.6657 |
genre |
Polar Science |
genre_facet |
Polar Science |
op_source |
Icarus, 154(1), 80-97, (2001-11) 2nd International Conference on Mars Polar Science and Exploration, Reykjavik, Iceland, Aug. 21-25, 2000 |
op_relation |
https://doi.org/10.1006/icar.2001.6657 oai:authors.library.caltech.edu:b8mc8-32y13 eprintid:42966 resolverid:CaltechAUTHORS:20131211-152152382 |
op_rights |
info:eu-repo/semantics/closedAccess Other |
op_doi |
https://doi.org/10.1006/icar.2001.6657 |
container_title |
Icarus |
container_volume |
154 |
container_issue |
1 |
container_start_page |
80 |
op_container_end_page |
97 |
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1802649347066691584 |