A 3-D dynamic model for the anomalous topography and geoid over the south-east Indian Ridge
The anomalous sea-floor topography and geoid height over the Australian-Antarctic Discordance (AAD) are examined and attributed to dynamic mantle flow in this study. Because the subsidences of sea-floor depth and geoid with age exhibit forms of isostatic response of cooling from the surface, they ar...
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1995
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fthighwire:oai:open-archive.highwire.org:gji:121/1/1 2023-05-15T13:56:55+02:00 A 3-D dynamic model for the anomalous topography and geoid over the south-east Indian Ridge Kuo, Ban-Yuan Hung, Shu-Huei Chiao, Ling-Yun 1995-04-01 00:00:00.0 text/html http://gji.oxfordjournals.org/cgi/content/short/121/1/1 https://doi.org/10.1111/j.1365-246X.1995.tb03507.x en eng Oxford University Press http://gji.oxfordjournals.org/cgi/content/short/121/1/1 http://dx.doi.org/10.1111/j.1365-246X.1995.tb03507.x Copyright (C) 1995, Oxford University Press Articles TEXT 1995 fthighwire https://doi.org/10.1111/j.1365-246X.1995.tb03507.x 2012-11-23T22:11:40Z The anomalous sea-floor topography and geoid height over the Australian-Antarctic Discordance (AAD) are examined and attributed to dynamic mantle flow in this study. Because the subsidences of sea-floor depth and geoid with age exhibit forms of isostatic response of cooling from the surface, they are removed from the data to retain the dynamic components. In removing the cooling effect we allow for different subsidence rates for different spreading corridors. The reduction yields primarily north-south-trending lows crossing the AAD in both the residual topography and the residual geoid. Assuming that the mantle behaves viscously, the residual data were inverted to thermal perturbations in the assigned depth extents. The obtained thermal perturbations exhibit mainly east-west, or axis-parallel variation and indicate that along the 3000 km long ridge, the mantle beneath the AAD is about 150 and 50°C colder than average for perturbation layers confined within 100 and 300 km from the surface, respectively. As a result, the 3-D flow driven by the thermal anomaly is also predominantly east-west oriented with a major downwelling near the AAD and its aged mantle. To independently constrain these results, we derive a simple formula to estimate the mantle temperature beneath the ridge from the subsidence rates of topography and geoid for different corridors. This simple estimation yields a variation of about 200°C with the low near AAD and high at the segment to the east. The trend of variation is consistent with that from the dynamic modelling, and the magnitude is relatively high but favours the model in which the dynamic source is concentrated within the upper asthenosphere. The thermal anomaly could be, however, eliminated by lateral advection in the along-axis direction which is not considered in the inversion. The advection effect is estimated to cause a decay of the dynamic topography at a rate of the order of 0.005 km Myr−1, making the downwelling die out very slowly with age. The actual 3-D anomalous flow in the ... Text Antarc* Antarctic HighWire Press (Stanford University) Antarctic Indian Australian-Antarctic Discordance ENVELOPE(124.000,124.000,-49.000,-49.000) Long Ridge ENVELOPE(73.583,73.583,-53.100,-53.100) Geophysical Journal International 121 1 1 20 |
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Articles Kuo, Ban-Yuan Hung, Shu-Huei Chiao, Ling-Yun A 3-D dynamic model for the anomalous topography and geoid over the south-east Indian Ridge |
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Articles |
description |
The anomalous sea-floor topography and geoid height over the Australian-Antarctic Discordance (AAD) are examined and attributed to dynamic mantle flow in this study. Because the subsidences of sea-floor depth and geoid with age exhibit forms of isostatic response of cooling from the surface, they are removed from the data to retain the dynamic components. In removing the cooling effect we allow for different subsidence rates for different spreading corridors. The reduction yields primarily north-south-trending lows crossing the AAD in both the residual topography and the residual geoid. Assuming that the mantle behaves viscously, the residual data were inverted to thermal perturbations in the assigned depth extents. The obtained thermal perturbations exhibit mainly east-west, or axis-parallel variation and indicate that along the 3000 km long ridge, the mantle beneath the AAD is about 150 and 50°C colder than average for perturbation layers confined within 100 and 300 km from the surface, respectively. As a result, the 3-D flow driven by the thermal anomaly is also predominantly east-west oriented with a major downwelling near the AAD and its aged mantle. To independently constrain these results, we derive a simple formula to estimate the mantle temperature beneath the ridge from the subsidence rates of topography and geoid for different corridors. This simple estimation yields a variation of about 200°C with the low near AAD and high at the segment to the east. The trend of variation is consistent with that from the dynamic modelling, and the magnitude is relatively high but favours the model in which the dynamic source is concentrated within the upper asthenosphere. The thermal anomaly could be, however, eliminated by lateral advection in the along-axis direction which is not considered in the inversion. The advection effect is estimated to cause a decay of the dynamic topography at a rate of the order of 0.005 km Myr−1, making the downwelling die out very slowly with age. The actual 3-D anomalous flow in the ... |
format |
Text |
author |
Kuo, Ban-Yuan Hung, Shu-Huei Chiao, Ling-Yun |
author_facet |
Kuo, Ban-Yuan Hung, Shu-Huei Chiao, Ling-Yun |
author_sort |
Kuo, Ban-Yuan |
title |
A 3-D dynamic model for the anomalous topography and geoid over the south-east Indian Ridge |
title_short |
A 3-D dynamic model for the anomalous topography and geoid over the south-east Indian Ridge |
title_full |
A 3-D dynamic model for the anomalous topography and geoid over the south-east Indian Ridge |
title_fullStr |
A 3-D dynamic model for the anomalous topography and geoid over the south-east Indian Ridge |
title_full_unstemmed |
A 3-D dynamic model for the anomalous topography and geoid over the south-east Indian Ridge |
title_sort |
3-d dynamic model for the anomalous topography and geoid over the south-east indian ridge |
publisher |
Oxford University Press |
publishDate |
1995 |
url |
http://gji.oxfordjournals.org/cgi/content/short/121/1/1 https://doi.org/10.1111/j.1365-246X.1995.tb03507.x |
long_lat |
ENVELOPE(124.000,124.000,-49.000,-49.000) ENVELOPE(73.583,73.583,-53.100,-53.100) |
geographic |
Antarctic Indian Australian-Antarctic Discordance Long Ridge |
geographic_facet |
Antarctic Indian Australian-Antarctic Discordance Long Ridge |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_relation |
http://gji.oxfordjournals.org/cgi/content/short/121/1/1 http://dx.doi.org/10.1111/j.1365-246X.1995.tb03507.x |
op_rights |
Copyright (C) 1995, Oxford University Press |
op_doi |
https://doi.org/10.1111/j.1365-246X.1995.tb03507.x |
container_title |
Geophysical Journal International |
container_volume |
121 |
container_issue |
1 |
container_start_page |
1 |
op_container_end_page |
20 |
_version_ |
1766264519813758976 |