Discrete element modelling of the influence of cover strength on basement-involved fault-propagation folding

Abstract A discrete element model is used to investigate the influence of sedimentary cover strength on the development of basement-involved fault-propagation folds. We find that uniformly weak cover best promotes the development of classical, trishear-like fault-related folds showing marked anticlinal thinning and synclinal thickening, with cover dips increasing downwards towards the fault tip. Uniformly strong cover results in more rounded fold forms with only minor hinge thickening/thinning and significant basement fault-propagation into the sedimentary cover. Heterogeneous, layered, cover sequences with marked differences in strength promote the development of more complex and variable fold forms, with a close juxtaposition of brittle and macroscopically ductile features, which diverge from the predictions of simple kinematic models. In these structures the upper layers are often poor indicators of deeper structure. In addition, we find that in layered cover sequences fault-propagation into the cover is a complex process and is strongly buffered by the weaker cover units.

[1]  S. Mitra,et al.  Experimental (clay) models of inversion structures , 1994 .

[2]  J. Suppe,et al.  Out-of-plane motion of a thrust sheet during along-strike propagation of a thrust ramp: a distinct-element approach , 2002 .

[3]  P. Cundall,et al.  A discrete numerical model for granular assemblies , 1979 .

[4]  C. Mariotti,et al.  Numerical study of rock and concrete behaviour by discrete element modelling , 2000 .

[5]  Sophie-Adélaïde Magnier,et al.  Numerical modeling of a highly explosive source in an elastic-brittle rock mass , 1996 .

[6]  Jean-Pierre Bardet,et al.  The Structure of Shear Bands in Idealized Granular Materials , 1992 .

[7]  Jean Braun,et al.  Dynamical Lagrangian Remeshing (DLR): A new algorithm for solving large strain deformation problems and its application to fault-propagation folding , 1994 .

[8]  E. Rutter.  On the nomenclature of mode of failure transitions in rocks , 1986 .

[9]  Alan T. Zehnder,et al.  Velocity field for the trishear model , 2000 .

[10]  M. Oda,et al.  Micro-Deformation Mechanism of Shear Banding Process Based on Modified Distinct Element Method , 1999 .

[11]  Peter Mora,et al.  Simulation of the Micro-physics of Rocks Using LSMearth , 2002 .

[12]  Gary Douglas Couples,et al.  Kinematics of experimental forced folds and their relevance to cross-section balancing , 1994 .

[13]  Alan T. Zehnder,et al.  Mechanical models of fault propagation folds and comparison to the trishear kinematic model , 2003 .

[14]  D. Stearns.  Faulting and forced folding in the Rocky Mountains foreland , 1978 .

[15]  J. Vergés,et al.  Progressive evolution of a fault-related fold pair from growth strata geometries, Sant Llorenç de Morunys, SE Pyrenees , 1997 .

[16]  D. Pollard,et al.  A new conceptual fold-fracture model including prefolding joints, based on the Emigrant Gap anticline, Wyoming , 2004 .

[17]  W. Narr,et al.  Kinematics of basement-involved compressive structures , 1994 .

[18]  Peter Mora,et al.  a Lattice Solid Model for the Nonlinear Dynamics of Earthquakes , 1993 .

[19]  Arvid M. Johnson,et al.  Mechanical analysis of the geometry of forced-folds , 2002 .

[20]  J. Suppe,et al.  Influence of Growth Strata on the Evolution of Fault-related Folds— Distinct-element Models , 2004 .

[21]  Arvid M. Johnson,et al.  Mechanical models of trishear-like folds , 2002 .

[22]  Zeshan Ismat,et al.  Folding by cataclastic flow: evolution of controlling factors during deformation , 2005 .

[23]  Fujiu Ke,et al.  Numerical Simulation of Rock Failure and Earthquake Process on Mesoscopic Scale , 2000 .

[24]  J. Shaw,et al.  Estimation of fault propagation distance from fold shape: Implications for earthquake hazard assessment , 2000 .

[25]  P. Mora,et al.  Numerical simulation of faults and shear zones , 1994 .

[26]  Lluís Cabrera,et al.  Time lag of syntectonic sedimentation across an alluvial basin: theory and example from the Ebro Basin, Spain , 2004 .

[27]  Matthew R. Kuhn,et al.  Structured deformation in granular materials , 1999 .

[28]  Peter Mora,et al.  Simulation of the frictional stick-slip instability , 1994 .

[29]  Stuart Hardy,et al.  Discrete‐element modelling of extensional fault‐propagation folding above rigid basement fault blocks , 2004 .

[30]  Raymond C. Fletcher,et al.  A rheological model for fractured rock , 1998 .

[31]  Eric A. Erslev,et al.  Trishear fault-propagation folding , 1991 .

[32]  Z. T. Bieniawski,et al.  Rock mechanics design in mining and tunneling , 1984 .

[33]  Richard W. Allmendinger,et al.  Inverse and forward numerical modeling of trishear fault‐propagation folds , 1998 .

[34]  L. Strayer,et al.  Numerical modeling of fold initiation at thrust ramps , 1997 .

[35]  Christopher J. Bean,et al.  Numerical simulation of seismic waves using a discrete particle scheme , 2000 .

[36]  David D. Pollard,et al.  Distinct element modeling of deformation bands in sandstone , 1995 .

[37]  S. Hardy,et al.  Numerical modeling of trishear fault propagation folding , 1997 .

[38]  R. Groshong,et al.  Trishear kinematic modeling of extensional fault-propagation folding , 2006 .

[39]  John R. Underhill,et al.  Fault-propagation folding in extensional settings: Examples of structural style and synrift sedimentary response from the Suez rift, Sinai, Egypt (vol 112, pg 1877, 2000) , 2000 .

[40]  D. Muir Wood,et al.  Localisation and bifurcation theory for soils and rocks , 1998 .

[41]  Jon E. Olson,et al.  Experimental models of extensional forced folds , 1990 .

[42]  David D. Pollard,et al.  Distinct element modeling of structures formed in sedimentary overburden by extensional reactivation of basement normal faults , 1992 .

[43]  Stuart Hardy,et al.  Discrete element modelling of contractional fault-propagation folding above rigid basement fault blocks , 2003 .

[44]  D. R. Scott,et al.  Seismicity and stress rotation in a granular model of the brittle crust , 1996, Nature.

[45]  R. C. Fletcher,et al.  Mathematical block-motion model for deformation of a layer above a buried fault of arbitrary dip and sense of slip , 1995 .

[46]  V. Mount,et al.  Foreland Basement-Involved Structures , 1998 .

[47]  Peter Mora,et al.  A random lattice solid model for simulation of fault zone dynamics and fracture processes , 2001 .

[48]  A. Bump.  Reactivation, trishear modeling, and folded basement in Laramide uplifts: Implications for the origins of intra-continental faults , 2003 .

[49]  John R. Underhill,et al.  Linked sequence stratigraphic and structural evolution of propagating normal faults , 1997 .

[50]  Shearer,et al.  An elusive blind-thrust fault beneath metropolitan los angeles , 1999, Science.

[51]  E. T. Brown,et al.  Analytical and computational methods in engineering rock mechanics , 1987 .

[52]  Stuart Hardy,et al.  Kinematic modelling of extensional fault-propagation folding , 1999 .

[53]  Kyle R. Mayborn,et al.  Multiple geometries and modes of fault-propagation folding in the Canadian thrust belt , 1997 .

[54]  J. Banavar,et al.  Computer Simulation of Liquids , 1988 .