The crustal structure of the Chatham Rise and Chatham Terrace – A key region for understanding the separation of Zealandia from Antarctica
The submarine continental Chatham Rise extends up 1500 km east of New Zealand’s South Island as part of the continent Zealandia. During the Cretaceous it underwent a twofold tectonic history: 1) At ~100 Ma, the long ongoing subduction of the Proto-Pacific plate at the eastern Gondwana margin abruptl...
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ftawi:oai:epic.awi.de:48276 2023-05-15T13:45:21+02:00 The crustal structure of the Chatham Rise and Chatham Terrace – A key region for understanding the separation of Zealandia from Antarctica Riefstahl, Florian Gohl, Karsten Davy, Bryan Mortimer, Nicholas Jolis, Ester 2018-06-17 https://epic.awi.de/id/eprint/48276/ https://hdl.handle.net/10013/epic.86d6f98b-4b3f-4114-a6de-a06bfeb9127e unknown Riefstahl, F. , Gohl, K. orcid:0000-0002-9558-2116 , Davy, B. , Mortimer, N. and Jolis, E. (2018) The crustal structure of the Chatham Rise and Chatham Terrace – A key region for understanding the separation of Zealandia from Antarctica , SEISMIX2018, Krakow, Poland, 17 June 2018 - 21 June 2018 . hdl:10013/epic.86d6f98b-4b3f-4114-a6de-a06bfeb9127e EPIC3SEISMIX2018, Krakow, Poland, 2018-06-17-2018-06-21 Conference notRev 2018 ftawi 2021-12-24T15:44:14Z The submarine continental Chatham Rise extends up 1500 km east of New Zealand’s South Island as part of the continent Zealandia. During the Cretaceous it underwent a twofold tectonic history: 1) At ~100 Ma, the long ongoing subduction of the Proto-Pacific plate at the eastern Gondwana margin abruptly ceased as the Hikurangi Plateau collided with the subduction trench. 2) At least since ~94 Ma after cessation of the subduction, the compressional regime was replaced by continental rifting as evident by the oldest known terrestrial graben sandstones on the Chatham Islands, development of metamorphic core complexes on the South Island and changing geochemical constraints (I-type to A-type granites) in western Marie Byrd Land, Antarctica. Little is known about the geodynamic processes that accompany the rifting as well as the nature, characteristics and extent of continental thinning at the southern margin of the Chatham Rise. We examine two deep crustal seismic refraction/wide-angle reflection lines crossing the southern margin of the Chatham Rise and adjacent Chatham Terrace, and a third deep crustal seismic profile at the southeasternmost part of the Chatham Rise. Modelling of P-wave velocities indicate variable thicknesses for the part of the Chatham Rise close to Chatham Island (~24 km), west of Wishbone Ridge (< 22 km), east of Wishbone Ridge (18 – 12 km), and the easternmost part (only up to ~13 km). While thicker parts of Chatham Rise are probably underlain by the subducted Hikurangi Plateau, the thinner parts of the crust are strongly affected by normal faulting. As part of the southern Chatham Rise margin, the elevated Chatham Terrace shows a crustal thickness between 10 and 7 km. On the Chatham Terrace, P-wave velocities exceeding 7 km/s at the crustal base probably related to magmatic underplating. Our results indicate that the Chatham Terrace has continental affinities as evident from graben structures obvious in the seismic reflection data and from continental-affinity rocks dredged from the Stuttgart Seamount. We suggest that magma-poor continental rifting led to the formation of the Chatham Terrace, Bounty Trough, Canterbury Basin as well as the metamorphic core complex exhumation in the Dunstin Range onshore New Zealand’s South Island until ~84 Ma. Highly asymmetric westward propagation of the Pacific-Bellingshausen spreading ridge led to a magmatic overprint and formation of the Chatham Terrace seamounts, separation of the Bollons Seamount from the Bounty Platform and the breakup of the Chatham Rise and Campbell Plateau from Antarctica proceeded. Conference Object Antarc* Antarctica Marie Byrd Land Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) Bollons Seamount ENVELOPE(-176.500,-176.500,-49.833,-49.833) Bounty Trough ENVELOPE(178.070,178.070,-45.499,-45.499) Byrd Campbell Plateau ENVELOPE(171.000,171.000,-50.667,-50.667) Marie Byrd Land ENVELOPE(-130.000,-130.000,-78.000,-78.000) Pacific Wishbone Ridge ENVELOPE(-166.933,-166.933,-84.933,-84.933) |
institution |
Open Polar |
collection |
Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
op_collection_id |
ftawi |
language |
unknown |
description |
The submarine continental Chatham Rise extends up 1500 km east of New Zealand’s South Island as part of the continent Zealandia. During the Cretaceous it underwent a twofold tectonic history: 1) At ~100 Ma, the long ongoing subduction of the Proto-Pacific plate at the eastern Gondwana margin abruptly ceased as the Hikurangi Plateau collided with the subduction trench. 2) At least since ~94 Ma after cessation of the subduction, the compressional regime was replaced by continental rifting as evident by the oldest known terrestrial graben sandstones on the Chatham Islands, development of metamorphic core complexes on the South Island and changing geochemical constraints (I-type to A-type granites) in western Marie Byrd Land, Antarctica. Little is known about the geodynamic processes that accompany the rifting as well as the nature, characteristics and extent of continental thinning at the southern margin of the Chatham Rise. We examine two deep crustal seismic refraction/wide-angle reflection lines crossing the southern margin of the Chatham Rise and adjacent Chatham Terrace, and a third deep crustal seismic profile at the southeasternmost part of the Chatham Rise. Modelling of P-wave velocities indicate variable thicknesses for the part of the Chatham Rise close to Chatham Island (~24 km), west of Wishbone Ridge (< 22 km), east of Wishbone Ridge (18 – 12 km), and the easternmost part (only up to ~13 km). While thicker parts of Chatham Rise are probably underlain by the subducted Hikurangi Plateau, the thinner parts of the crust are strongly affected by normal faulting. As part of the southern Chatham Rise margin, the elevated Chatham Terrace shows a crustal thickness between 10 and 7 km. On the Chatham Terrace, P-wave velocities exceeding 7 km/s at the crustal base probably related to magmatic underplating. Our results indicate that the Chatham Terrace has continental affinities as evident from graben structures obvious in the seismic reflection data and from continental-affinity rocks dredged from the Stuttgart Seamount. We suggest that magma-poor continental rifting led to the formation of the Chatham Terrace, Bounty Trough, Canterbury Basin as well as the metamorphic core complex exhumation in the Dunstin Range onshore New Zealand’s South Island until ~84 Ma. Highly asymmetric westward propagation of the Pacific-Bellingshausen spreading ridge led to a magmatic overprint and formation of the Chatham Terrace seamounts, separation of the Bollons Seamount from the Bounty Platform and the breakup of the Chatham Rise and Campbell Plateau from Antarctica proceeded. |
format |
Conference Object |
author |
Riefstahl, Florian Gohl, Karsten Davy, Bryan Mortimer, Nicholas Jolis, Ester |
spellingShingle |
Riefstahl, Florian Gohl, Karsten Davy, Bryan Mortimer, Nicholas Jolis, Ester The crustal structure of the Chatham Rise and Chatham Terrace – A key region for understanding the separation of Zealandia from Antarctica |
author_facet |
Riefstahl, Florian Gohl, Karsten Davy, Bryan Mortimer, Nicholas Jolis, Ester |
author_sort |
Riefstahl, Florian |
title |
The crustal structure of the Chatham Rise and Chatham Terrace – A key region for understanding the separation of Zealandia from Antarctica |
title_short |
The crustal structure of the Chatham Rise and Chatham Terrace – A key region for understanding the separation of Zealandia from Antarctica |
title_full |
The crustal structure of the Chatham Rise and Chatham Terrace – A key region for understanding the separation of Zealandia from Antarctica |
title_fullStr |
The crustal structure of the Chatham Rise and Chatham Terrace – A key region for understanding the separation of Zealandia from Antarctica |
title_full_unstemmed |
The crustal structure of the Chatham Rise and Chatham Terrace – A key region for understanding the separation of Zealandia from Antarctica |
title_sort |
crustal structure of the chatham rise and chatham terrace – a key region for understanding the separation of zealandia from antarctica |
publishDate |
2018 |
url |
https://epic.awi.de/id/eprint/48276/ https://hdl.handle.net/10013/epic.86d6f98b-4b3f-4114-a6de-a06bfeb9127e |
long_lat |
ENVELOPE(-176.500,-176.500,-49.833,-49.833) ENVELOPE(178.070,178.070,-45.499,-45.499) ENVELOPE(171.000,171.000,-50.667,-50.667) ENVELOPE(-130.000,-130.000,-78.000,-78.000) ENVELOPE(-166.933,-166.933,-84.933,-84.933) |
geographic |
Bollons Seamount Bounty Trough Byrd Campbell Plateau Marie Byrd Land Pacific Wishbone Ridge |
geographic_facet |
Bollons Seamount Bounty Trough Byrd Campbell Plateau Marie Byrd Land Pacific Wishbone Ridge |
genre |
Antarc* Antarctica Marie Byrd Land |
genre_facet |
Antarc* Antarctica Marie Byrd Land |
op_source |
EPIC3SEISMIX2018, Krakow, Poland, 2018-06-17-2018-06-21 |
op_relation |
Riefstahl, F. , Gohl, K. orcid:0000-0002-9558-2116 , Davy, B. , Mortimer, N. and Jolis, E. (2018) The crustal structure of the Chatham Rise and Chatham Terrace – A key region for understanding the separation of Zealandia from Antarctica , SEISMIX2018, Krakow, Poland, 17 June 2018 - 21 June 2018 . hdl:10013/epic.86d6f98b-4b3f-4114-a6de-a06bfeb9127e |
_version_ |
1766221387255513088 |