Syndepositional Faults in
Mass-Transport Deposits: Seals or Conduits to Fluid Flow?
Dykstra, Mason1, Benjamin
Kneller2, Katerina Garyfalou2
(1) University of California, Santa Barbara, CA (2) University of Aberdeen,
Aberdeen, United Kingdom
Mass-transport deposits are typically
thought of as fairly homogenous deposits with a consistency similar to wet
cement, and are often thought of as seals. Extensive research on mass-transport
processes demonstrates, however, that many mass-transport deposits are composed
of internally undeformed coherent blocks as well as
homogeneous zones, and everything in between (e.g. Locat
and Mienert, 2003; Kneller
and Dykstra, 2004). Within mass-transport deposits therefore, strain is
accommodated in numerous ways, including by penetrative deformation of the
sediment involved, as well as the development of discrete ‘faults'
(semi-brittle to brittle discontinuities). The purpose of this contribution is
to examine the properties of faults in mass-transport deposits, and how these properties
determine the behavior of fluids in the system. Mass-transport related faults
include normal, reverse, and strike-slip type faults, many of which often
accommodate multiple phases and polarities of motion along them. They fall into
three categories with regards to conducting fluids: coarse-sediment filled,
fine-sediment filled, and welded faults. The eventual behavior of any given
fault as regards fluid flow depends on the type of fill of the fault zone, and
any diagenetic overprint that may result in a loss of
permeability in the fault fill. We present here end-member examples of fault
fills from outcrop data collected in numerous locations, and discuss the
implications of these fills to fluid flow and sealing.
Locat, J.
and J. Mienert, Eds. (2003). Submarine
Mass Movements and Their Consequences.
Kneller, B.
and M. Dykstra (2004). The Internal Structure and External Morphology of Submarine
Landslides: A Causative Link. In: AGU Annual Meeting,
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California