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Traveltime tomography of a dense wide-angle profile across Orphan Basin

Traveltime tomography of a dense wide-angle profile across Orphan Basin
Traveltime tomography of a dense wide-angle profile across Orphan Basin

We used first arrivals and Moho reflections from the 500- km-long Orphan BasinWide-Angle Velocity Experiment (OBWAVE) profile with 3-5-km instrument spacing to construct a traveltime tomography section and to delineate the Moho discontinuity across the Orphan Basin. The Orphan Basin is a failed rift located offshore Newfoundland, Canada, showing thinned continental crust over an unusually wide region. We observed (1) a zone of extreme crustal thinning (<7-km-thick crust) with no evidence for mantle serpentinization, (2) basement morphology exhibiting tilted blocks linked to the crustal thinning, and (3) a thicker central crustal segment that is probably related to prerift structural inheritance. Comparison with the adjacent Jeanne d'Arc Basin to the southeast suggested the presence of a decoupling zone between the two basins accommodating the difference in extension rates. There was a good correlation between the tomographic velocities and the reflection structure derived from a coincident seismic reflection profile except in an area in which the reflection seismic data suggested the presence of a deep sedimentary basin. The velocity model computed in this work indicated that this area consists of prerift basement rather than Jurassic or older sediments. Tomographic models computed by varying the density of the recording instrument array gave insight into the relationship among the target size, the instrument spacing needed to resolve it, and the velocity model uncertainty. These results may help guide the design of future wide-angle reflection and refraction surveys across rifted structures.

0016-8033
B69-B82
Watremez, Louise
bce54c70-b287-4c80-966b-5096a29bc93a
Helen Lau, K.W.
6a4985b3-5f07-4b1a-b6d5-4fc8d02897a3
Nedimovic, Mladen R.
6f6b7996-eeda-4d43-be54-fcccc82ae7ff
Louden, Keith E.
b818fc43-6f0c-4cbd-99d1-3c60db40e9e8
Watremez, Louise
bce54c70-b287-4c80-966b-5096a29bc93a
Helen Lau, K.W.
6a4985b3-5f07-4b1a-b6d5-4fc8d02897a3
Nedimovic, Mladen R.
6f6b7996-eeda-4d43-be54-fcccc82ae7ff
Louden, Keith E.
b818fc43-6f0c-4cbd-99d1-3c60db40e9e8

Watremez, Louise, Helen Lau, K.W., Nedimovic, Mladen R. and Louden, Keith E. (2019) Traveltime tomography of a dense wide-angle profile across Orphan Basin. Geophysics, 80 (3), B69-B82. (doi:10.1190/geo2014-0377.1).

Record type: Article

Abstract

We used first arrivals and Moho reflections from the 500- km-long Orphan BasinWide-Angle Velocity Experiment (OBWAVE) profile with 3-5-km instrument spacing to construct a traveltime tomography section and to delineate the Moho discontinuity across the Orphan Basin. The Orphan Basin is a failed rift located offshore Newfoundland, Canada, showing thinned continental crust over an unusually wide region. We observed (1) a zone of extreme crustal thinning (<7-km-thick crust) with no evidence for mantle serpentinization, (2) basement morphology exhibiting tilted blocks linked to the crustal thinning, and (3) a thicker central crustal segment that is probably related to prerift structural inheritance. Comparison with the adjacent Jeanne d'Arc Basin to the southeast suggested the presence of a decoupling zone between the two basins accommodating the difference in extension rates. There was a good correlation between the tomographic velocities and the reflection structure derived from a coincident seismic reflection profile except in an area in which the reflection seismic data suggested the presence of a deep sedimentary basin. The velocity model computed in this work indicated that this area consists of prerift basement rather than Jurassic or older sediments. Tomographic models computed by varying the density of the recording instrument array gave insight into the relationship among the target size, the instrument spacing needed to resolve it, and the velocity model uncertainty. These results may help guide the design of future wide-angle reflection and refraction surveys across rifted structures.

Full text not available from this repository.

More information

Accepted/In Press date: 27 January 2015
e-pub ahead of print date: 3 April 2015
Published date: May 2019

Identifiers

Local EPrints ID: 430121
URI: http://eprints.soton.ac.uk/id/eprint/430121
ISSN: 0016-8033
PURE UUID: 9bfcef6a-e08b-4ba1-a36f-df6fb30322e7

Catalogue record

Date deposited: 12 Apr 2019 16:30
Last modified: 12 Apr 2019 16:30

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