Enceladus’ extreme heat flux as revealed by its relaxed craters
[1] Enceladus' cratered terrains contain large numbers of unusually shallow craters consistent with deformation by viscous relaxation of water ice under conditions of elevated heat flow. Here we use high-resolution topography to measure the relaxation fraction of craters on Enceladus far from t...
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ftciteseerx:oai:CiteSeerX.psu:10.1.1.1046.1332 2023-05-15T18:23:07+02:00 Enceladus’ extreme heat flux as revealed by its relaxed craters Michael T Bland Kelsi N Singer William B Mckinnon Paul M Schenk The Pennsylvania State University CiteSeerX Archives 2012 application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1046.1332 http://levee.wustl.edu/%7Embland/pubs/Bland_et_al_12.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1046.1332 http://levee.wustl.edu/%7Embland/pubs/Bland_et_al_12.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://levee.wustl.edu/%7Embland/pubs/Bland_et_al_12.pdf text 2012 ftciteseerx 2020-04-05T00:18:55Z [1] Enceladus' cratered terrains contain large numbers of unusually shallow craters consistent with deformation by viscous relaxation of water ice under conditions of elevated heat flow. Here we use high-resolution topography to measure the relaxation fraction of craters on Enceladus far from the active South Pole. We find that many craters are shallower than expected, with craters as small as 2 km in diameter having relaxation fractions in excess of 90%. These measurements are compared with numerical simulations of crater relaxation to constrain the minimum heat flux required to reproduce these observations. We find that Enceladus' nominal cold surface temperature (70 K) and low surface gravity strongly inhibit viscous relaxation. Under such conditions less than 3% relaxation occurs over 2 Ga even for relatively large craters (diameter 24 km) and high, constant heat fluxes (150 mW m À2 ). Greater viscous relaxation occurs if the effective temperature at the top of the lithosphere is greater than the surface temperature due to insulating regolith and/or plume material. Even for an effective temperature of 120 K, however, heat fluxes in excess of 150 mW m À2 are required to produce the degree of relaxation observed. Simulations of viscous relaxation of Enceladus' largest craters suggest that relaxation is best explained by a relatively short-lived period of intense heating that decayed quickly. We show that infilling of craters by plume material cannot explain the extremely shallow craters at equatorial and higher northern latitudes. Thus, like Enceladus' tectonic terrains, the cratered regions of Enceladus have experienced periods of extreme heat flux. Citation: Bland, M. T., K. N. Singer, W. B. McKinnon, and P. M. Schenk (2012), Enceladus' extreme heat flux as revealed by its relaxed craters, Geophys. Text South pole Unknown South Pole |
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[1] Enceladus' cratered terrains contain large numbers of unusually shallow craters consistent with deformation by viscous relaxation of water ice under conditions of elevated heat flow. Here we use high-resolution topography to measure the relaxation fraction of craters on Enceladus far from the active South Pole. We find that many craters are shallower than expected, with craters as small as 2 km in diameter having relaxation fractions in excess of 90%. These measurements are compared with numerical simulations of crater relaxation to constrain the minimum heat flux required to reproduce these observations. We find that Enceladus' nominal cold surface temperature (70 K) and low surface gravity strongly inhibit viscous relaxation. Under such conditions less than 3% relaxation occurs over 2 Ga even for relatively large craters (diameter 24 km) and high, constant heat fluxes (150 mW m À2 ). Greater viscous relaxation occurs if the effective temperature at the top of the lithosphere is greater than the surface temperature due to insulating regolith and/or plume material. Even for an effective temperature of 120 K, however, heat fluxes in excess of 150 mW m À2 are required to produce the degree of relaxation observed. Simulations of viscous relaxation of Enceladus' largest craters suggest that relaxation is best explained by a relatively short-lived period of intense heating that decayed quickly. We show that infilling of craters by plume material cannot explain the extremely shallow craters at equatorial and higher northern latitudes. Thus, like Enceladus' tectonic terrains, the cratered regions of Enceladus have experienced periods of extreme heat flux. Citation: Bland, M. T., K. N. Singer, W. B. McKinnon, and P. M. Schenk (2012), Enceladus' extreme heat flux as revealed by its relaxed craters, Geophys. |
author2 |
The Pennsylvania State University CiteSeerX Archives |
format |
Text |
author |
Michael T Bland Kelsi N Singer William B Mckinnon Paul M Schenk |
spellingShingle |
Michael T Bland Kelsi N Singer William B Mckinnon Paul M Schenk Enceladus’ extreme heat flux as revealed by its relaxed craters |
author_facet |
Michael T Bland Kelsi N Singer William B Mckinnon Paul M Schenk |
author_sort |
Michael T Bland |
title |
Enceladus’ extreme heat flux as revealed by its relaxed craters |
title_short |
Enceladus’ extreme heat flux as revealed by its relaxed craters |
title_full |
Enceladus’ extreme heat flux as revealed by its relaxed craters |
title_fullStr |
Enceladus’ extreme heat flux as revealed by its relaxed craters |
title_full_unstemmed |
Enceladus’ extreme heat flux as revealed by its relaxed craters |
title_sort |
enceladus’ extreme heat flux as revealed by its relaxed craters |
publishDate |
2012 |
url |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1046.1332 http://levee.wustl.edu/%7Embland/pubs/Bland_et_al_12.pdf |
geographic |
South Pole |
geographic_facet |
South Pole |
genre |
South pole |
genre_facet |
South pole |
op_source |
http://levee.wustl.edu/%7Embland/pubs/Bland_et_al_12.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1046.1332 http://levee.wustl.edu/%7Embland/pubs/Bland_et_al_12.pdf |
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Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
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1766202558470160384 |