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The oceanic crustal structure at the extinct, slow to ultraslow Labrador Sea spreading center

The oceanic crustal structure at the extinct, slow to ultraslow Labrador Sea spreading center
The oceanic crustal structure at the extinct, slow to ultraslow Labrador Sea spreading center
Two seismic refraction lines were acquired along and across the extinct Labrador Sea spreading center during the Seismic Investigations off Greenland, Newfoundland and Labrador 2009 cruise. We derived two P?wave velocity models using both forward modeling (RAYINVR) and traveltime tomography inversion (Tomo2D) with good ray coverage down to the mantle. Slow-spreading Paleocene oceanic crust has a thickness of 5?km, while the Eocene crust created by ultraslow spreading is as thin as 3.5?km. The upper crustal velocity is affected by fracturation due to a dominant tectonic extension during the waning stage of spreading, with a velocity drop of 0.5 to 1?km/s when compared to Paleocene upper crustal velocities (5.2–6.0?km/s). The overall crustal structure is similar to active ultraslow-spreading centers like the Mohns Ridge or the South West Indian Ridge with lower crustal velocities of 6.0–7.0?km/s. An oceanic core complex is imaged on a 50?km long segment of the ridge perpendicular line with serpentinized peridotites (7.3–7.9?km/s) found 1.5?km below the basement. The second, ridge-parallel line also shows extremely thin crust in the extinct axial valley, where 8?km/s mantle velocity is imaged just 1.5?km below the basement. This thin crust is interpreted as crust formed by ultraslow spreading, which was thinned by tectonic extension.
spreading ridges, Labrador Sea, refraction seismics, oceanic core complex, ultraslow spreading, Monte Carlo analysis
5249-5272
Delescluse, Matthias
54e1642b-965b-46a4-a87e-10174c21cba9
Funck, Thomas
568a1ce0-7de6-42b7-8f68-bb891fd44653
Dehler, Sonya A.
2f80549f-71ef-4659-b396-acb8aa234f06
Louden, Keith E.
b818fc43-6f0c-4cbd-99d1-3c60db40e9e8
Watremez, Louise
bce54c70-b287-4c80-966b-5096a29bc93a
Delescluse, Matthias
54e1642b-965b-46a4-a87e-10174c21cba9
Funck, Thomas
568a1ce0-7de6-42b7-8f68-bb891fd44653
Dehler, Sonya A.
2f80549f-71ef-4659-b396-acb8aa234f06
Louden, Keith E.
b818fc43-6f0c-4cbd-99d1-3c60db40e9e8
Watremez, Louise
bce54c70-b287-4c80-966b-5096a29bc93a

Delescluse, Matthias, Funck, Thomas, Dehler, Sonya A., Louden, Keith E. and Watremez, Louise (2015) The oceanic crustal structure at the extinct, slow to ultraslow Labrador Sea spreading center. Journal of Geophysical Research: Solid Earth, 120 (7), 5249-5272. (doi:10.1002/2014JB011739).

Record type: Article

Abstract

Two seismic refraction lines were acquired along and across the extinct Labrador Sea spreading center during the Seismic Investigations off Greenland, Newfoundland and Labrador 2009 cruise. We derived two P?wave velocity models using both forward modeling (RAYINVR) and traveltime tomography inversion (Tomo2D) with good ray coverage down to the mantle. Slow-spreading Paleocene oceanic crust has a thickness of 5?km, while the Eocene crust created by ultraslow spreading is as thin as 3.5?km. The upper crustal velocity is affected by fracturation due to a dominant tectonic extension during the waning stage of spreading, with a velocity drop of 0.5 to 1?km/s when compared to Paleocene upper crustal velocities (5.2–6.0?km/s). The overall crustal structure is similar to active ultraslow-spreading centers like the Mohns Ridge or the South West Indian Ridge with lower crustal velocities of 6.0–7.0?km/s. An oceanic core complex is imaged on a 50?km long segment of the ridge perpendicular line with serpentinized peridotites (7.3–7.9?km/s) found 1.5?km below the basement. The second, ridge-parallel line also shows extremely thin crust in the extinct axial valley, where 8?km/s mantle velocity is imaged just 1.5?km below the basement. This thin crust is interpreted as crust formed by ultraslow spreading, which was thinned by tectonic extension.

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e-pub ahead of print date: 6 July 2015
Published date: July 2015
Keywords: spreading ridges, Labrador Sea, refraction seismics, oceanic core complex, ultraslow spreading, Monte Carlo analysis
Organisations: Geology & Geophysics

Identifiers

Local EPrints ID: 379470
URI: http://eprints.soton.ac.uk/id/eprint/379470
PURE UUID: 2f544771-1497-4591-9660-4a44f623c939

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Date deposited: 21 Jul 2015 13:39
Last modified: 14 Mar 2024 20:42

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Contributors

Author: Matthias Delescluse
Author: Thomas Funck
Author: Sonya A. Dehler
Author: Keith E. Louden
Author: Louise Watremez

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