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

Paper Link : https://www.sciencedirect.com/science/article/pii/S0012821X18302073

Received: 19 December 2017

Accepted: 8 April 2018

Published: 17 April 2018

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 paleoextension 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.

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

  • Department of Earth, Environmental and Planetary Sciences, Rice University, MS-126 Main Street, 77005, Houston, TX, USA.
  • Lamont-Doherty Earth Observatory, Columbia University, 61 Route 9W, PO Box 1000, 10964-8000, Palisades, NY, USA.
  • School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
  • National Oceanography Centre Southampton, University of Southampton, Southampton, S014 3ZH, United Kingdom.
  • BP America Inc., 501 WestLake Park Blvd., 23.126C, 77079, Houston, TX, USA.
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