Incremental slip history of a thrust: diverse transport directions and internal folding of the Utrillas thrust sheet (NE Iberian Chain, Spain)
J. L. Simón, C. L. Liesa, 2011. "Incremental slip history of a thrust: diverse transport directions and internal folding of the Utrillas thrust sheet (NE Iberian Chain, Spain)", Kinematic Evolution and Structural Styles of Fold-and-Thrust Belts, J. Poblet, R. J. Lisle
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A kinematical model for the Utrillas thrust is proposed, including reconstruction of the incremental slip history, progressive internal deformation and tectono-sedimentary relationships at the Montalbán (foreland) and Aliaga (piggy-back) Tertiary basins. A 3D geometrical model of the main thrust surface, defined by ramps oriented NE–SW, east–west, NW–SE and north–south, is reconstructed from cross-sections. Besides, the thrust sheet is internally deformed by two main, frequently superposed fold sets, trending NW–SE to NNW–SSE (earlier) and east–west (later), respectively. A total ‘arrow’ (finite horizontal displacement) of about 5.9 km towards N032°E is estimated by means of schematic, plan-view retrodeformation of the distinctly oriented ramps making its front. Orientation and cross-cut relationships of mesoscopic kinematical indicators at the thrust front provide a scenario of successive transport directions towards the ENE, NNE and north, which is consistent with the progressive development of internal folding, as well as with the evolution of intraplate compressive stress fields through Tertiary times.