The Australian-Antarctic Mantle Anomaly as the principal cause of the Australian-Antarctic Discordance

We present evidence for the existence of an Australian-Antarctic Mantle Anomaly (AAMA) that trends northwest-southeast (NW-SE) through the Australian-Antarctic Discordance (AAD) on the Southeast Indian Ridge (SEIR), is confined to the upper 120 km of the mantle beneath the AAD, and dips shallowly to...

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Main Authors: M. H. Ritzwoller, N. M. Shapiro, G. M. Leahy
Other Authors: The Pennsylvania State University CiteSeerX Archives
Format: Text
Language:English
Published: 2002
Subjects:
Online Access:http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.399.8351
http://ciei.colorado.edu/geophysics/pubs/mhrpubs/pubs/2002/15.pdf
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spelling ftciteseerx:oai:CiteSeerX.psu:10.1.1.399.8351 2023-05-15T13:59:39+02:00 The Australian-Antarctic Mantle Anomaly as the principal cause of the Australian-Antarctic Discordance M. H. Ritzwoller N. M. Shapiro G. M. Leahy The Pennsylvania State University CiteSeerX Archives 2002 application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.399.8351 http://ciei.colorado.edu/geophysics/pubs/mhrpubs/pubs/2002/15.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.399.8351 http://ciei.colorado.edu/geophysics/pubs/mhrpubs/pubs/2002/15.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://ciei.colorado.edu/geophysics/pubs/mhrpubs/pubs/2002/15.pdf text 2002 ftciteseerx 2016-09-25T00:13:40Z We present evidence for the existence of an Australian-Antarctic Mantle Anomaly (AAMA) that trends northwest-southeast (NW-SE) through the Australian-Antarctic Discordance (AAD) on the Southeast Indian Ridge (SEIR), is confined to the upper 120 km of the mantle beneath the AAD, and dips shallowly to the west so that it extends to a depth of about 150 km west of the AAD. Average temperatures within the AAMA are depressed about 100 C relative to surrounding lithosphere and suggest very rapid cooling of newly formed lithosphere at the AAD to an effective thermal age between 20- 30 Ma. A convective down-welling beneath the AAD is not consistent with the confinement of the AAMA in the uppermost mantle. In substantial agreement with the model of Gurnis et al. (1998), we argue that the AAMA is the suspended remnant of a slab that subducted at the Gondwanaland-Pacific convergent margin more than 100 Ma ago, foundered in the deeper mantle, and then ascended into the shallow mantle within the past 30 Ma cutting any ties to deeper roots. The stability of the AAMA and its poor correlation with residual topography and gravity imply that it is approximately neutrally buoyant. The thermally induced density Text Antarc* Antarctic Unknown Antarctic Australian-Antarctic Discordance ENVELOPE(124.000,124.000,-49.000,-49.000) Indian Pacific Southeast Indian Ridge ENVELOPE(110.000,110.000,-50.000,-50.000)
institution Open Polar
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language English
description We present evidence for the existence of an Australian-Antarctic Mantle Anomaly (AAMA) that trends northwest-southeast (NW-SE) through the Australian-Antarctic Discordance (AAD) on the Southeast Indian Ridge (SEIR), is confined to the upper 120 km of the mantle beneath the AAD, and dips shallowly to the west so that it extends to a depth of about 150 km west of the AAD. Average temperatures within the AAMA are depressed about 100 C relative to surrounding lithosphere and suggest very rapid cooling of newly formed lithosphere at the AAD to an effective thermal age between 20- 30 Ma. A convective down-welling beneath the AAD is not consistent with the confinement of the AAMA in the uppermost mantle. In substantial agreement with the model of Gurnis et al. (1998), we argue that the AAMA is the suspended remnant of a slab that subducted at the Gondwanaland-Pacific convergent margin more than 100 Ma ago, foundered in the deeper mantle, and then ascended into the shallow mantle within the past 30 Ma cutting any ties to deeper roots. The stability of the AAMA and its poor correlation with residual topography and gravity imply that it is approximately neutrally buoyant. The thermally induced density
author2 The Pennsylvania State University CiteSeerX Archives
format Text
author M. H. Ritzwoller
N. M. Shapiro
G. M. Leahy
spellingShingle M. H. Ritzwoller
N. M. Shapiro
G. M. Leahy
The Australian-Antarctic Mantle Anomaly as the principal cause of the Australian-Antarctic Discordance
author_facet M. H. Ritzwoller
N. M. Shapiro
G. M. Leahy
author_sort M. H. Ritzwoller
title The Australian-Antarctic Mantle Anomaly as the principal cause of the Australian-Antarctic Discordance
title_short The Australian-Antarctic Mantle Anomaly as the principal cause of the Australian-Antarctic Discordance
title_full The Australian-Antarctic Mantle Anomaly as the principal cause of the Australian-Antarctic Discordance
title_fullStr The Australian-Antarctic Mantle Anomaly as the principal cause of the Australian-Antarctic Discordance
title_full_unstemmed The Australian-Antarctic Mantle Anomaly as the principal cause of the Australian-Antarctic Discordance
title_sort australian-antarctic mantle anomaly as the principal cause of the australian-antarctic discordance
publishDate 2002
url http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.399.8351
http://ciei.colorado.edu/geophysics/pubs/mhrpubs/pubs/2002/15.pdf
long_lat ENVELOPE(124.000,124.000,-49.000,-49.000)
ENVELOPE(110.000,110.000,-50.000,-50.000)
geographic Antarctic
Australian-Antarctic Discordance
Indian
Pacific
Southeast Indian Ridge
geographic_facet Antarctic
Australian-Antarctic Discordance
Indian
Pacific
Southeast Indian Ridge
genre Antarc*
Antarctic
genre_facet Antarc*
Antarctic
op_source http://ciei.colorado.edu/geophysics/pubs/mhrpubs/pubs/2002/15.pdf
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http://ciei.colorado.edu/geophysics/pubs/mhrpubs/pubs/2002/15.pdf
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