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A low-angle detachment fault revealed: three-dimensional images of the S-reflector fault zone along the Galicia passive margin

A low-angle detachment fault revealed: three-dimensional images of the S-reflector fault zone along the Galicia passive margin
A low-angle detachment fault revealed: three-dimensional images of the S-reflector fault zone along the Galicia passive margin
A new 3-D seismic reflection volume over the Galicia margin continent–ocean transition zone provides an unprecedented view of the prominent S-reflector detachment fault that underlies the outer part of the margin. This volume images the fault's structure from breakaway to termination. The filtered time-structure map of the S-reflector shows coherent corrugations parallel to the expected paleo-extension directions with an average azimuth of 107°. These corrugations maintain their orientations, wavelengths and amplitudes where overlying faults sole into the S-reflector, suggesting that the parts of the detachment fault containing multiple crustal blocks may have slipped as discrete units during its late stages. Another interface above the S-reflector, here named S′, is identified and interpreted as the upper boundary of the fault zone associated with the detachment fault. This layer, named the S-interval, thickens by tens of meters from SE to NW in the direction of transport. Localized thick accumulations also occur near overlying fault intersections, suggesting either non-uniform fault rock production, or redistribution of fault rock during slip. These observations have important implications for understanding how detachment faults form and evolve over time. 3-D seismic reflection imaging has enabled unique insights into fault slip history, fault rock production and redistribution.
0012-821X
232-238
Schuba, C. Nur
47898ae9-065b-49f3-b881-34c45b66a1ec
Gray, Gary G.
403acd31-28ad-4c2e-8fdd-8d35ff2f73b6
Morgan, Julia K.
af0f28ff-1eb0-4376-9e2d-341c548c35d2
Sawyer, Dale S.
9b2521e0-3bf5-425f-b057-995621975728
Shillington, Donna J.
7d553e6e-9f56-471a-88be-5736f7f9c826
Reston, Tim J.
6a6f7b70-726a-4cda-b104-12296ac7318b
Bull, Jonathan M.
974037fd-544b-458f-98cc-ce8eca89e3c8
Jordan, Brian E.
87694bf3-bacf-4f86-b059-e7767e1ee763
Schuba, C. Nur
47898ae9-065b-49f3-b881-34c45b66a1ec
Gray, Gary G.
403acd31-28ad-4c2e-8fdd-8d35ff2f73b6
Morgan, Julia K.
af0f28ff-1eb0-4376-9e2d-341c548c35d2
Sawyer, Dale S.
9b2521e0-3bf5-425f-b057-995621975728
Shillington, Donna J.
7d553e6e-9f56-471a-88be-5736f7f9c826
Reston, Tim J.
6a6f7b70-726a-4cda-b104-12296ac7318b
Bull, Jonathan M.
974037fd-544b-458f-98cc-ce8eca89e3c8
Jordan, Brian E.
87694bf3-bacf-4f86-b059-e7767e1ee763

Schuba, C. Nur, Gray, Gary G., Morgan, Julia K., Sawyer, Dale S., Shillington, Donna J., Reston, Tim J., Bull, Jonathan M. and Jordan, Brian E. (2018) A low-angle detachment fault revealed: three-dimensional images of the S-reflector fault zone along the Galicia passive margin. Earth and Planetary Science Letters, 492, 232-238. (doi:10.1016/j.epsl.2018.04.012).

Record type: Article

Abstract

A new 3-D seismic reflection volume over the Galicia margin continent–ocean transition zone provides an unprecedented view of the prominent S-reflector detachment fault that underlies the outer part of the margin. This volume images the fault's structure from breakaway to termination. The filtered time-structure map of the S-reflector shows coherent corrugations parallel to the expected paleo-extension directions with an average azimuth of 107°. These corrugations maintain their orientations, wavelengths and amplitudes where overlying faults sole into the S-reflector, suggesting that the parts of the detachment fault containing multiple crustal blocks may have slipped as discrete units during its late stages. Another interface above the S-reflector, here named S′, is identified and interpreted as the upper boundary of the fault zone associated with the detachment fault. This layer, named the S-interval, thickens by tens of meters from SE to NW in the direction of transport. Localized thick accumulations also occur near overlying fault intersections, suggesting either non-uniform fault rock production, or redistribution of fault rock during slip. These observations have important implications for understanding how detachment faults form and evolve over time. 3-D seismic reflection imaging has enabled unique insights into fault slip history, fault rock production and redistribution.

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Schuba_et_al_S_reflector_manuscript_april11 - Accepted Manuscript
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Accepted/In Press date: 8 April 2018
e-pub ahead of print date: 17 April 2018
Published date: 15 June 2018

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Local EPrints ID: 420022
URI: http://eprints.soton.ac.uk/id/eprint/420022
ISSN: 0012-821X
PURE UUID: 3a803abe-bc89-4987-bc20-8abd61642e64

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Date deposited: 25 Apr 2018 16:30
Last modified: 07 Oct 2020 06:28

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