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

Louise Watremez, K. W. Helen Lau, Mladen R. Nedimovic and Keith E. Louden
Traveltime tomography of a dense wide-angle profile across Orphan Basin
Geophysics (May 2015) 80 (3): B69-B82

Abstract

We used first arrivals and Moho reflections from the 500-km-long Orphan Basin Wide-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.


ISSN: 0016-8033
EISSN: 1942-2156
Coden: GPYSA7
Serial Title: Geophysics
Serial Volume: 80
Serial Issue: 3
Title: Traveltime tomography of a dense wide-angle profile across Orphan Basin
Affiliation: University of Southampton, National Oceanography Centre, Southampton, United Kingdom
Pages: B69-B82
Published: 201505
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 47
Accession Number: 2015-058159
Categories: Applied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch map
N47°00'00" - N50°30'00", W50°00'00" - W44°00'00"
Secondary Affiliation: Dalhousie University, CAN, Canada
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 201526
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