Development of the Australian‐Antarctic depth anomaly
The oceanic Australian‐Antarctic Discordance (AAD) contains two unusual features: (1) NS trendinganomalously deep bathymetries and (2) rough basement morphologies in young (<∼20 Ma) crust between120E and 128E. Models generally attribute AAD formation to underlying cold and/or depleted uppermantle...
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Online Access: | https://doi.org/10.1029/2010GC003276 http://ecite.utas.edu.au/84437 |
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ftunivtasecite:oai:ecite.utas.edu.au:84437 2023-05-15T14:02:31+02:00 Development of the Australian‐Antarctic depth anomaly Whittaker, J Muller, RD Gurnis, M 2010 application/pdf https://doi.org/10.1029/2010GC003276 http://ecite.utas.edu.au/84437 en eng American Geophysical Unoin http://ecite.utas.edu.au/84437/1/Whittaker_etal_AAD_G3_2010.pdf http://dx.doi.org/10.1029/2010GC003276 Whittaker, J and Muller, RD and Gurnis, M, Development of the Australian‐Antarctic depth anomaly, Geochemistry Geophysics Geosystems, 11, (11) pp. Q11006. ISSN 1525-2027 (2010) [Refereed Article] http://ecite.utas.edu.au/84437 Earth Sciences Geology Marine Geoscience Refereed Article PeerReviewed 2010 ftunivtasecite https://doi.org/10.1029/2010GC003276 2019-12-13T21:48:52Z The oceanic Australian‐Antarctic Discordance (AAD) contains two unusual features: (1) NS trendinganomalously deep bathymetries and (2) rough basement morphologies in young (<∼20 Ma) crust between120E and 128E. Models generally attribute AAD formation to underlying cold and/or depleted uppermantle, but no model adequately accounts for all the anomalous attributes. We quantify anomalous basementroughness and basement depths utilizing new seismic reflection data, in combination with all available geophysicaland geological observations. We find that the interaction of negative dynamic topography andcrustal thickness variations results in the observed complex patterns of residual basement depths. Downwelling,caused by a sinking Mesozoic slab, is the most likely cause of the broad NS trending residualdepth anomalies, while overprinting by westward flowing, buoyant Pacific mantle resulted in the distinctiveV‐shaped eastern boundary of the AAD. The particularly large residual depths proximal to the Australianand Antarctic margins may be due to negative dynamic topography combined with thinned oceanic crustcaused by ultraslow (<10 mm/yr) half‐spreading rates and sampling of depleted subduction wedge contaminatedmantle. Only oceanic basement aged <20 Ma is anomalously rough, a result of sampling of cool/depleted upper mantle material. Although oceanic crust older than 43 Ma may have sampled depleted mantle,the resulting oceanic basement is not anomalously rough likely because a melt volume controlledthreshold of accretion‐related roughness had already been reached due to ultraslow spreading rates. Ouranalysis reveals that the enigmatic roughness of the Diamantina Zone is mainly related to >45 spreadingobliquities. Article in Journal/Newspaper Antarc* Antarctic eCite UTAS (University of Tasmania) Antarctic Australian-Antarctic Discordance ENVELOPE(124.000,124.000,-49.000,-49.000) Pacific Geochemistry, Geophysics, Geosystems 11 11 n/a n/a |
institution |
Open Polar |
collection |
eCite UTAS (University of Tasmania) |
op_collection_id |
ftunivtasecite |
language |
English |
topic |
Earth Sciences Geology Marine Geoscience |
spellingShingle |
Earth Sciences Geology Marine Geoscience Whittaker, J Muller, RD Gurnis, M Development of the Australian‐Antarctic depth anomaly |
topic_facet |
Earth Sciences Geology Marine Geoscience |
description |
The oceanic Australian‐Antarctic Discordance (AAD) contains two unusual features: (1) NS trendinganomalously deep bathymetries and (2) rough basement morphologies in young (<∼20 Ma) crust between120E and 128E. Models generally attribute AAD formation to underlying cold and/or depleted uppermantle, but no model adequately accounts for all the anomalous attributes. We quantify anomalous basementroughness and basement depths utilizing new seismic reflection data, in combination with all available geophysicaland geological observations. We find that the interaction of negative dynamic topography andcrustal thickness variations results in the observed complex patterns of residual basement depths. Downwelling,caused by a sinking Mesozoic slab, is the most likely cause of the broad NS trending residualdepth anomalies, while overprinting by westward flowing, buoyant Pacific mantle resulted in the distinctiveV‐shaped eastern boundary of the AAD. The particularly large residual depths proximal to the Australianand Antarctic margins may be due to negative dynamic topography combined with thinned oceanic crustcaused by ultraslow (<10 mm/yr) half‐spreading rates and sampling of depleted subduction wedge contaminatedmantle. Only oceanic basement aged <20 Ma is anomalously rough, a result of sampling of cool/depleted upper mantle material. Although oceanic crust older than 43 Ma may have sampled depleted mantle,the resulting oceanic basement is not anomalously rough likely because a melt volume controlledthreshold of accretion‐related roughness had already been reached due to ultraslow spreading rates. Ouranalysis reveals that the enigmatic roughness of the Diamantina Zone is mainly related to >45 spreadingobliquities. |
format |
Article in Journal/Newspaper |
author |
Whittaker, J Muller, RD Gurnis, M |
author_facet |
Whittaker, J Muller, RD Gurnis, M |
author_sort |
Whittaker, J |
title |
Development of the Australian‐Antarctic depth anomaly |
title_short |
Development of the Australian‐Antarctic depth anomaly |
title_full |
Development of the Australian‐Antarctic depth anomaly |
title_fullStr |
Development of the Australian‐Antarctic depth anomaly |
title_full_unstemmed |
Development of the Australian‐Antarctic depth anomaly |
title_sort |
development of the australian‐antarctic depth anomaly |
publisher |
American Geophysical Unoin |
publishDate |
2010 |
url |
https://doi.org/10.1029/2010GC003276 http://ecite.utas.edu.au/84437 |
long_lat |
ENVELOPE(124.000,124.000,-49.000,-49.000) |
geographic |
Antarctic Australian-Antarctic Discordance Pacific |
geographic_facet |
Antarctic Australian-Antarctic Discordance Pacific |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_relation |
http://ecite.utas.edu.au/84437/1/Whittaker_etal_AAD_G3_2010.pdf http://dx.doi.org/10.1029/2010GC003276 Whittaker, J and Muller, RD and Gurnis, M, Development of the Australian‐Antarctic depth anomaly, Geochemistry Geophysics Geosystems, 11, (11) pp. Q11006. ISSN 1525-2027 (2010) [Refereed Article] http://ecite.utas.edu.au/84437 |
op_doi |
https://doi.org/10.1029/2010GC003276 |
container_title |
Geochemistry, Geophysics, Geosystems |
container_volume |
11 |
container_issue |
11 |
container_start_page |
n/a |
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n/a |
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1766272825101910016 |