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

C. Nur Schuba, Gary G. Gray, Julia K. Morgan, Dale S. Sawyer, Donna J. Shillington, Tim J. Reston, Jonathan M. Bull, Brian E. Jordan

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)232-238
Number of pages7
JournalEarth and Planetary Science Letters
Volume492
DOIs
StatePublished - Jun 15 2018
Externally publishedYes

Keywords

  • Galicia margin
  • continent–ocean transition zone
  • detachment faults
  • fault rock production
  • fault surface morphology
  • rifting

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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