Revisiting the Australian-Antarctic ocean-continent transition zone using petrological and geophysical characterization of exhumed subcontinental mantle

The final lithospheric breakup of the Australian‐Antarctic rift system remains controversial due to sparse geological constraints on the nature of the basement along the ocean‐continent transition (OCT) zones. We present new interpretations of multichannel seismic reflection transects and new petrol...

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Published in:Geochemistry, Geophysics, Geosystems
Main Authors: McCarthy, A, Falloon, TJ, Sauermilch, I, Whittaker, JM, Niida, K, Green, DH
Format: Article in Journal/Newspaper
Language:English
Published: Amer Geophysical Union 2020
Subjects:
Online Access:https://doi.org/10.1029/2020GC009040
http://ecite.utas.edu.au/139766
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spelling ftunivtasecite:oai:ecite.utas.edu.au:139766 2023-05-15T13:42:40+02:00 Revisiting the Australian-Antarctic ocean-continent transition zone using petrological and geophysical characterization of exhumed subcontinental mantle McCarthy, A Falloon, TJ Sauermilch, I Whittaker, JM Niida, K Green, DH 2020 application/pdf https://doi.org/10.1029/2020GC009040 http://ecite.utas.edu.au/139766 en eng Amer Geophysical Union http://ecite.utas.edu.au/139766/1/139766 - Revisiting the Australian‐Antarctic ocean‐continent transition zone using petrological and geophysical characterization of exhumed subcontinental mantle.pdf http://dx.doi.org/10.1029/2020GC009040 McCarthy, A and Falloon, TJ and Sauermilch, I and Whittaker, JM and Niida, K and Green, DH, Revisiting the Australian-Antarctic ocean-continent transition zone using petrological and geophysical characterization of exhumed subcontinental mantle, Geochemistry Geophysics Geosystems, 21, (7) Article e2020GC009040. ISSN 1525-2027 (2020) [Refereed Article] http://ecite.utas.edu.au/139766 Earth Sciences Geology Igneous and metamorphic petrology Refereed Article PeerReviewed 2020 ftunivtasecite https://doi.org/10.1029/2020GC009040 2022-08-29T22:18:01Z The final lithospheric breakup of the Australian‐Antarctic rift system remains controversial due to sparse geological constraints on the nature of the basement along the ocean‐continent transition (OCT) zones. We present new interpretations of multichannel seismic reflection transects and new petrological data of dredged mantle rocks along the East Antarctic margin (Seamount B, offshore Terre Adlie). By combining both data sets, we show that a 50100 km wide domain of cold and fertile subcontinental mantle was exhumed along the magma‐poor Antarctic margin. This study represents only the second locality, along with the Iberia‐Newfoundland margins, where the importance of exhumed mantle domains along OCTs can be clearly identified. The dredged peridotites preserve characteristics similar to mantle xenoliths found in syn‐ to post‐rift volcanism at the eastern end of the Australian margin (Victoria and Tasmania), indicating the exhumation of fertile subcontinental mantle during rifting between Australia and Antarctica. Seamount B represents the initial stages of exhumation of cold subcontinental lithosphere along an OCT during rifting. This thick mantle domain was likely affected by melt impregnation at high pressure (8 kbar), leading to the formation of plagioclase‐pyroxenites. The combination of continental rifted blocks, a wide domain of volcanic‐poor subcontinental mantle and (ultra‐) slow spreading is analogous to OCTs from the Jurassic Western Tethys and Iberia‐Newfoundland rifted margins. Additionally, evidence of melt stagnation at high pressure suggests that magmatism along the Australian‐Antarctic rifted margins was sufficient to form magnetic anomalies that can be used as isochrons despite their formation in lithosphere other than mature, steady‐state ocean crust. Article in Journal/Newspaper Antarc* Antarctic Antarctic Ocean Antarctica Newfoundland eCite UTAS (University of Tasmania) Antarctic Antarctic Ocean Geochemistry, Geophysics, Geosystems 21 7
institution Open Polar
collection eCite UTAS (University of Tasmania)
op_collection_id ftunivtasecite
language English
topic Earth Sciences
Geology
Igneous and metamorphic petrology
spellingShingle Earth Sciences
Geology
Igneous and metamorphic petrology
McCarthy, A
Falloon, TJ
Sauermilch, I
Whittaker, JM
Niida, K
Green, DH
Revisiting the Australian-Antarctic ocean-continent transition zone using petrological and geophysical characterization of exhumed subcontinental mantle
topic_facet Earth Sciences
Geology
Igneous and metamorphic petrology
description The final lithospheric breakup of the Australian‐Antarctic rift system remains controversial due to sparse geological constraints on the nature of the basement along the ocean‐continent transition (OCT) zones. We present new interpretations of multichannel seismic reflection transects and new petrological data of dredged mantle rocks along the East Antarctic margin (Seamount B, offshore Terre Adlie). By combining both data sets, we show that a 50100 km wide domain of cold and fertile subcontinental mantle was exhumed along the magma‐poor Antarctic margin. This study represents only the second locality, along with the Iberia‐Newfoundland margins, where the importance of exhumed mantle domains along OCTs can be clearly identified. The dredged peridotites preserve characteristics similar to mantle xenoliths found in syn‐ to post‐rift volcanism at the eastern end of the Australian margin (Victoria and Tasmania), indicating the exhumation of fertile subcontinental mantle during rifting between Australia and Antarctica. Seamount B represents the initial stages of exhumation of cold subcontinental lithosphere along an OCT during rifting. This thick mantle domain was likely affected by melt impregnation at high pressure (8 kbar), leading to the formation of plagioclase‐pyroxenites. The combination of continental rifted blocks, a wide domain of volcanic‐poor subcontinental mantle and (ultra‐) slow spreading is analogous to OCTs from the Jurassic Western Tethys and Iberia‐Newfoundland rifted margins. Additionally, evidence of melt stagnation at high pressure suggests that magmatism along the Australian‐Antarctic rifted margins was sufficient to form magnetic anomalies that can be used as isochrons despite their formation in lithosphere other than mature, steady‐state ocean crust.
format Article in Journal/Newspaper
author McCarthy, A
Falloon, TJ
Sauermilch, I
Whittaker, JM
Niida, K
Green, DH
author_facet McCarthy, A
Falloon, TJ
Sauermilch, I
Whittaker, JM
Niida, K
Green, DH
author_sort McCarthy, A
title Revisiting the Australian-Antarctic ocean-continent transition zone using petrological and geophysical characterization of exhumed subcontinental mantle
title_short Revisiting the Australian-Antarctic ocean-continent transition zone using petrological and geophysical characterization of exhumed subcontinental mantle
title_full Revisiting the Australian-Antarctic ocean-continent transition zone using petrological and geophysical characterization of exhumed subcontinental mantle
title_fullStr Revisiting the Australian-Antarctic ocean-continent transition zone using petrological and geophysical characterization of exhumed subcontinental mantle
title_full_unstemmed Revisiting the Australian-Antarctic ocean-continent transition zone using petrological and geophysical characterization of exhumed subcontinental mantle
title_sort revisiting the australian-antarctic ocean-continent transition zone using petrological and geophysical characterization of exhumed subcontinental mantle
publisher Amer Geophysical Union
publishDate 2020
url https://doi.org/10.1029/2020GC009040
http://ecite.utas.edu.au/139766
geographic Antarctic
Antarctic Ocean
geographic_facet Antarctic
Antarctic Ocean
genre Antarc*
Antarctic
Antarctic Ocean
Antarctica
Newfoundland
genre_facet Antarc*
Antarctic
Antarctic Ocean
Antarctica
Newfoundland
op_relation http://ecite.utas.edu.au/139766/1/139766 - Revisiting the Australian‐Antarctic ocean‐continent transition zone using petrological and geophysical characterization of exhumed subcontinental mantle.pdf
http://dx.doi.org/10.1029/2020GC009040
McCarthy, A and Falloon, TJ and Sauermilch, I and Whittaker, JM and Niida, K and Green, DH, Revisiting the Australian-Antarctic ocean-continent transition zone using petrological and geophysical characterization of exhumed subcontinental mantle, Geochemistry Geophysics Geosystems, 21, (7) Article e2020GC009040. ISSN 1525-2027 (2020) [Refereed Article]
http://ecite.utas.edu.au/139766
op_doi https://doi.org/10.1029/2020GC009040
container_title Geochemistry, Geophysics, Geosystems
container_volume 21
container_issue 7
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