4D evolution of segmented strike-slip fault systems: applications to NW Europe

Abstract

Scaled, physical sandbox modelling has been used to simulate the progressive deformation of segmented strike-slip fault systems at both releasing (pull-apart basins) and restraining oversteps ('pop-up' structures) developed in a weak sedimentary cover above rigid basement. Pull-apart basin evolution is characterized by the initial development of a spindle graben bounded by oblique-extensional faults that cross the 'basement' overstep, and subsequent lengthening of the basin as displacement on the master faults increases. The pull-apart basins are bounded by terraced oblique slip extensional sidewall fault systems that link the laterally offset principal displacement zones (PDZ). The sidewall faults show changes in kinematics from dominantly dip-slip extension in their central sections to oblique slip and strike-slip at either end where they merge with the PDZ. The pull-apart basin models are flat-bottomed in the centre of the basin and become asymmetric at either end where the sidewall fault systems join the PDZ. Cross-basin fault systems, which are characteristic of all models, cut the floor of the pull-apart basins and link the offset PDZs. Deformation above restraining offsets is characterized by the formation of rhombic to lozenge-shaped uplifts or 'pop-ups' -structures bounded by oblique-slip reverse faults that fan outwards from the PDZ. With increased displacement on the master faults the rhombic-uplifts grow in amplitude. The upper surfaces of the 'pop-up' structures are dissected by both synthetic and antithetic strike-and oblique-slip faults. Distinctive asymmetric positive flower structures characterize the lateral margins of the 'pop-up' structures.The analogue models are compared with natural examples of strike-slip pull-apart and 'pop-up' fault systems from NW Europe. The models show many strong similarities in structural geometry and stratal architectures with many natural examples, although it must be emphasized that similarities between structures of purely extensional origin (multiphase) and those associated with inversion do exist. Therefore, these analogue models of complex strike-slip structures may provide useful templates for seismic interpretation in petroleum basins provided there is a demonstrable link between strike-slip motion on basement structures and deformation in the cover.at Yale University on June 28, 2015 http://pgc.lyellcollection.org/ Downloaded from

Tectonics of strike-slip restraining and releasing bends

“…As seen in deeply eroded outcrop exposures or from subsurface geophysical surveys, double restraining bends and releasing bends commonly define positive and negative flower structures respectively, and strikeslip bends or 'duplexes' in plan view (Fig. 1;Lowell 1972;Sylvester & Smith 1976;ChristieBlick & Biddle 1985;Harding 1985;Woodcock & Fisher 1986;Dooley et al 1999), although considerable structural variation and complexity occurs (Barka & Gulen 1989;May et al 1993;Wood et al 1994;Waldron 2004;Barnes et al 2005;Decker et al 2005;Parsons et al 2005). Single bends commonly have horsetail splay fault geometries in plan view, with strike-slip displacements terminally accommodated by oblique-slip and dip-slip faulting (McClay & Bonora 1997).…”

Map of the 2010 Greendale Fault surface rupture, Canterbury, New Zealand: application to land use planning

“…From a kinematics perspective, the mapped surface rupture presents typical tectonic structures associated with transpressional strike-slip faulting (e.g., Schreurs & Colletta 1998;Dooley et al 1999). These features closely resemble those formed by sand box models (e.g., Dooley et al 1999) and other historic strike-slip surface ruptures (Petersen et al 2011).…”

Lough Neagh: the site of a Cenozoic pull-apart basin

“…It is well documented that the application of regional stresses oblique to fault trends gives rise to strike-slip reactivation (Lake & Karner 1987;Ziegler 1990;Bartholomew et al 1993;Dooley et al 1999). A complex regional system of wrench faults extends north of the From the Late Cretaceous, Laramide collision between Africa and Europe produced stresses that induced NW-SE compression and far-field dextral reactivation of favourably-oriented strike-slip faults such as the Sticklepath-Lustleigh fault system (Lake & Karner 1987;Ziegler 1990).…”

“…The formation of a pull-apart basin from right-stepping controlling faults can only occur when the movement on them is dextral. The initiation of the Lough Neagh pull-apart basin would have resulted in subsidence between the major en echelon controlling faults (Dooley et al 1999) an example of the episodic development of pull-apart basins (Mann et al 1983). In the Kish…”

“…The nature and mode of formation of pull-apart basins have been the subject of study by many workers, and examples have been described worldwide (for example, Aydin & Nur 1982;Mann et al 1983;Sylvester 1988;Bartholomew et al 1993;Oudmayer & de Jager 1993;Dooley et al 1999;Reijs & McClay 2003). Pull-aparts are generally defined as zones of extension produced at bends or step-overs in a strike-slip fault system.…”