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Distribution of recent volcanism and the morphology of seamounts and ridges in the GLIMPSE study area: Implications for the lithospheric cracking hypothesis for the origin of intraplate, non–hot spot volcanic chains

Distribution of recent volcanism and the morphology of seamounts and ridges in the GLIMPSE study area: Implications for the lithospheric cracking hypothesis for the origin of intraplate, non–hot spot volcanic chains
Distribution of recent volcanism and the morphology of seamounts and ridges in the GLIMPSE study area: Implications for the lithospheric cracking hypothesis for the origin of intraplate, non–hot spot volcanic chains
Lithospheric cracking by remotely applied stresses or thermoelastic stresses has been suggested to be the mechanism responsible for the formation of intraplate volcanic ridges in the Pacific that clearly do not form above fixed hot spots. As part of the Gravity Lineations Intraplate Melting Petrology and Seismic Expedition (GLIMPSE) project designed to investigate the origin of these features, we have mapped two volcanic chains that are actively forming to the west of the East Pacific Rise using multibeam echo sounding and side-scan sonar. Side-scan sonar reveals the distribution of rough seafloor corresponding to recent, unsedimented lava flows. In the Hotu Matua volcanic complex, recent flows and volcanic edifices are distributed over a region 450 km long and up to 65 km wide, with an apparent, irregular age progression from older flows in the west to younger in the east. The 550-km-long Southern Cross Seamount/Sojourn Ridge/Brown Ridge chain appears to have been recently active only at its eastern end near the East Pacific Rise. A third region of recent flows is found 120 km north of Southern Cross Seamount in seafloor approximately 9 Myr old. No indication of lithospheric extension in the form of faulting or graben formation paralleling the trend of the volcanic chains is found in the vicinity of recent flows or anywhere else in the study area. Thermoelastic cracking could be a factor in the formation of a few small, very narrow volcanic ridges, but most of the volcanic activity is broadly distributed in wide swaths with no indication of formation along narrow cracks. The Sojourn and Brown chains appear to begin as distributed zones of small seamounts that later develop into segmented ridges, perhaps under the influence of membrane stresses from self-loading. We suggest that the linear volcanic chains are created by moving melting anomalies in the asthenosphere and that lithospheric cracking plays at most a secondary role.

0148-0227
B11407
Forsyth, Donald W.
9a82b182-42c0-4799-acf9-bf513c11ea0f
Harmon, Nicholas
10d11a16-b8b0-4132-9354-652e72d8e830
Scheirer, Daniel S.
83d76280-51fc-41d3-b8ca-614eb25ad384
Duncan, Robert A.
69abf2b2-4f0b-4c39-9bde-463563ab8050
Forsyth, Donald W.
9a82b182-42c0-4799-acf9-bf513c11ea0f
Harmon, Nicholas
10d11a16-b8b0-4132-9354-652e72d8e830
Scheirer, Daniel S.
83d76280-51fc-41d3-b8ca-614eb25ad384
Duncan, Robert A.
69abf2b2-4f0b-4c39-9bde-463563ab8050

Forsyth, Donald W., Harmon, Nicholas, Scheirer, Daniel S. and Duncan, Robert A. (2006) Distribution of recent volcanism and the morphology of seamounts and ridges in the GLIMPSE study area: Implications for the lithospheric cracking hypothesis for the origin of intraplate, non–hot spot volcanic chains. Journal of Geophysical Research, 111, B11407. (doi:10.1029/2005JB004075).

Record type: Article

Abstract

Lithospheric cracking by remotely applied stresses or thermoelastic stresses has been suggested to be the mechanism responsible for the formation of intraplate volcanic ridges in the Pacific that clearly do not form above fixed hot spots. As part of the Gravity Lineations Intraplate Melting Petrology and Seismic Expedition (GLIMPSE) project designed to investigate the origin of these features, we have mapped two volcanic chains that are actively forming to the west of the East Pacific Rise using multibeam echo sounding and side-scan sonar. Side-scan sonar reveals the distribution of rough seafloor corresponding to recent, unsedimented lava flows. In the Hotu Matua volcanic complex, recent flows and volcanic edifices are distributed over a region 450 km long and up to 65 km wide, with an apparent, irregular age progression from older flows in the west to younger in the east. The 550-km-long Southern Cross Seamount/Sojourn Ridge/Brown Ridge chain appears to have been recently active only at its eastern end near the East Pacific Rise. A third region of recent flows is found 120 km north of Southern Cross Seamount in seafloor approximately 9 Myr old. No indication of lithospheric extension in the form of faulting or graben formation paralleling the trend of the volcanic chains is found in the vicinity of recent flows or anywhere else in the study area. Thermoelastic cracking could be a factor in the formation of a few small, very narrow volcanic ridges, but most of the volcanic activity is broadly distributed in wide swaths with no indication of formation along narrow cracks. The Sojourn and Brown chains appear to begin as distributed zones of small seamounts that later develop into segmented ridges, perhaps under the influence of membrane stresses from self-loading. We suggest that the linear volcanic chains are created by moving melting anomalies in the asthenosphere and that lithospheric cracking plays at most a secondary role.

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Published date: 25 November 2006

Identifiers

Local EPrints ID: 66063
URI: http://eprints.soton.ac.uk/id/eprint/66063
ISSN: 0148-0227
PURE UUID: 2bad4b4a-acb9-45db-97f2-ce2aaf78784a
ORCID for Nicholas Harmon: ORCID iD orcid.org/0000-0002-0731-768X

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Date deposited: 27 Apr 2009
Last modified: 14 Mar 2024 02:55

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Author: Donald W. Forsyth
Author: Nicholas Harmon ORCID iD
Author: Daniel S. Scheirer
Author: Robert A. Duncan

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