Tectonic Evolution and Midplate Volcanism in the South Pacific
Changes in morphology of the Marquesas Fracture Zone are correlated with small changes in Pacific-Farallon relative motion. The simple flexural signal of a locked fracture zone may be obscured by tectonic effects, and there is no evidence for the release of shear stress on the fracture zone by verti...
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ftdtic:ADA376670 2023-05-15T15:33:57+02:00 Tectonic Evolution and Midplate Volcanism in the South Pacific Jordahl, Kelsey A. MASSACHUSETTS INST OF TECH CAMBRIDGE 1999-02 text/html http://www.dtic.mil/docs/citations/ADA376670 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA376670 en eng http://www.dtic.mil/docs/citations/ADA376670 APPROVED FOR PUBLIC RELEASE DTIC AND NTIS Physical and Dynamic Oceanography Geology Geochemistry and Mineralogy *BATHYMETRY *TECTONICS *VOLCANISM THESES SEISMIC DATA ARCHIPELAGOES SOUTH PACIFIC OCEAN FLEXURAL MOAT ARCHIPELAGIC APRON Text 1999 ftdtic 2016-02-20T04:46:04Z Changes in morphology of the Marquesas Fracture Zone are correlated with small changes in Pacific-Farallon relative motion. The simple flexural signal of a locked fracture zone may be obscured by tectonic effects, and there is no evidence for the release of shear stress on the fracture zone by vertical slip after leaving the active transform. One such small change in plate motion is documented in the Southern Austral Island region of the South Pacific. A twelve degree clockwise change in Pacific-Farallon relative motion occurred around fifty million years ago. This Eocene change in spreading direction and rate is locally constrained with observations of magnetic anomalies and spreading fabric orientation. At the southeastern end of the Cook-Austral Island chain, multiple episodes of volcanism have left a diverse population of seamounts. Volume estimates from geophysical data and modeling show that one-half to two-thirds of the volcanic material is over thirty million years old, while the remainder is less than five million years old. Seismic and bathymetric data imply the presence of abyssal basalt flows in the flexural moat of the Austral Islands, probably associated with Austral Islands volcanism, which may contribute a significant amount of material to the archipelagic apron. Sponsored in part by Grant NSF-OCE94-15930. Text Austral Island Defense Technical Information Center: DTIC Technical Reports database Austral Austral Island ENVELOPE(110.650,110.650,-66.500,-66.500) Pacific |
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Open Polar |
collection |
Defense Technical Information Center: DTIC Technical Reports database |
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ftdtic |
language |
English |
topic |
Physical and Dynamic Oceanography Geology Geochemistry and Mineralogy *BATHYMETRY *TECTONICS *VOLCANISM THESES SEISMIC DATA ARCHIPELAGOES SOUTH PACIFIC OCEAN FLEXURAL MOAT ARCHIPELAGIC APRON |
spellingShingle |
Physical and Dynamic Oceanography Geology Geochemistry and Mineralogy *BATHYMETRY *TECTONICS *VOLCANISM THESES SEISMIC DATA ARCHIPELAGOES SOUTH PACIFIC OCEAN FLEXURAL MOAT ARCHIPELAGIC APRON Jordahl, Kelsey A. Tectonic Evolution and Midplate Volcanism in the South Pacific |
topic_facet |
Physical and Dynamic Oceanography Geology Geochemistry and Mineralogy *BATHYMETRY *TECTONICS *VOLCANISM THESES SEISMIC DATA ARCHIPELAGOES SOUTH PACIFIC OCEAN FLEXURAL MOAT ARCHIPELAGIC APRON |
description |
Changes in morphology of the Marquesas Fracture Zone are correlated with small changes in Pacific-Farallon relative motion. The simple flexural signal of a locked fracture zone may be obscured by tectonic effects, and there is no evidence for the release of shear stress on the fracture zone by vertical slip after leaving the active transform. One such small change in plate motion is documented in the Southern Austral Island region of the South Pacific. A twelve degree clockwise change in Pacific-Farallon relative motion occurred around fifty million years ago. This Eocene change in spreading direction and rate is locally constrained with observations of magnetic anomalies and spreading fabric orientation. At the southeastern end of the Cook-Austral Island chain, multiple episodes of volcanism have left a diverse population of seamounts. Volume estimates from geophysical data and modeling show that one-half to two-thirds of the volcanic material is over thirty million years old, while the remainder is less than five million years old. Seismic and bathymetric data imply the presence of abyssal basalt flows in the flexural moat of the Austral Islands, probably associated with Austral Islands volcanism, which may contribute a significant amount of material to the archipelagic apron. Sponsored in part by Grant NSF-OCE94-15930. |
author2 |
MASSACHUSETTS INST OF TECH CAMBRIDGE |
format |
Text |
author |
Jordahl, Kelsey A. |
author_facet |
Jordahl, Kelsey A. |
author_sort |
Jordahl, Kelsey A. |
title |
Tectonic Evolution and Midplate Volcanism in the South Pacific |
title_short |
Tectonic Evolution and Midplate Volcanism in the South Pacific |
title_full |
Tectonic Evolution and Midplate Volcanism in the South Pacific |
title_fullStr |
Tectonic Evolution and Midplate Volcanism in the South Pacific |
title_full_unstemmed |
Tectonic Evolution and Midplate Volcanism in the South Pacific |
title_sort |
tectonic evolution and midplate volcanism in the south pacific |
publishDate |
1999 |
url |
http://www.dtic.mil/docs/citations/ADA376670 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA376670 |
long_lat |
ENVELOPE(110.650,110.650,-66.500,-66.500) |
geographic |
Austral Austral Island Pacific |
geographic_facet |
Austral Austral Island Pacific |
genre |
Austral Island |
genre_facet |
Austral Island |
op_source |
DTIC AND NTIS |
op_relation |
http://www.dtic.mil/docs/citations/ADA376670 |
op_rights |
APPROVED FOR PUBLIC RELEASE |
_version_ |
1766364527535849472 |