000			02289nab a2200205 4500
005			20260520000244.0
008			260224s2010 xxu
245	0	0	_aNew insights into deformation mechanisms in the gravitationally driven Niger Delta deep-water fold and thrust belt
260			_a _b _csep. 2010
270			_a13/10/2010 ; 13/10/2010
300			_a24 p. ; 1401-1424
520			_aTranscripción del resumen del autor. We use two- and three-dimensional seismic reflection data from the deep-water Niger Delta fold and thrust belt to document evidence for two, discrete, postfaulting deformation mechanisms. An early phase of thrust-propagation folding is followed by folding caused by thickness changes within the basal shale detachment unit. The later phase of folding is caused by a lateral redistribution of the strata within the basal detachment unit. This example of late deformation occurred over a 4–5-m.y. period as a result of the displacement of approximately 590 km3 (370 mi3) of the underlying strata within the detachment unit. In another deformation event in the basal detachment unit, about 160 km3 (100 mi3) moved, laterally creating a synform in the overburden and parallel onlap fill, indicative of the relatively rapid creation of accommodation space. On the basis of seismic reflection data from the delta and a consideration of the volumes and rates of movement of sedimentary rock, we conclude that the poorly imaged succession commonly referred to as mobile shale cannot deform solely by ductile mechanisms as interpretations of shale tectonic provinces have commonly suggested but instead by brittle processes that involve thickening by thrust faulting and subseismic accommodation structures. Processes such as liquefaction, where a complete loss of shear strength is observed, had a minimal function. Therefore, the term "mobile shale" in this setting is widely exaggerated. An awareness of postfaulting deformation mechanisms will be important for the successful exploration of gravitationally driven fold and thrust belts.
581			_a9
773	0		_tAAPG Bulletin _g94
942			_cARTICULO
100	1		_aMaloney, Dominic _947075
100	1		_aDavies, Richard _926257
100	1		_aImber, Jonathan _947076
999			_c177385 _d177385