Modeling the role of erosion in diapir development in contractional settings

Centrifuge modelling of deformation of a multi-layered sequence over a ductile substrate: 1. Style and 4D geometry of active cover folds during layer-parallel shortening

“…foreland-propagating folds) occurred in all our models similar to numerical models of Stockmal et al (2007). This also appears to be the case in centrifuge models of Sans and Koyi (2001), although is not discussed by these authors. In comparison, whilst foreland propagation occurred in one of the models involving lateral compression of a thick sequence of ductile layers above a décollement zone at 1g by Blay et al (1977), folds developed diachronously in different parts of their models, and widely spaced individual folds developed from furthest to the advancing end wall to progressively closer to the moving end wall (i.e.…”

“…Differences to previous centrifuge studies Apart from centrifuge models by Dennis and Häll (1978), Koyi (1988), and Sans and Koyi (2001) active buckle detachment-related folding above a (relatively) thick ductile substrate without contemporaneous faulting in either the basal or cover sequence has received little attention.…”

“…As explained by Sans and Koyi (2001), the density inversion was not sufficient to overcome the shear strength of the modelling clay and silicone layers of the cover sequence and no faults, boudins, or fractures developed in the cover sequence to focus diapiric rise of the PDMS. Flow of the ductile substrate during subsequent stages of differential erosion of our models is discussed in a subsequent paper.…”

“…Centrifuge models that include the investigation of differences in layer thickness on fold geometry over a thin ductile layer during shortening are presented in Aydemir (1998); however, these models are extremely simple and the ductile basal layer is relatively thin; these models are more applicable to upper crustal deformation at the local scale (which was their intended purpose). Our centrifuge modelling goes beyond experiments at normal laboratory conditions by Bucher (1956) and centrifuge models of Dennis and Häll (1978), Koyi (1988) and Sans and Koyi (2001) in studying the effects of a ductile substrate and the role of a low-viscosity and density detachment horizon for part of some models in 4D. Our models differ significantly from Koyi (1988) and Sans and Koyi (2001) in that they do not address the process of diapirism and diapir-fold interaction as, apart from the PDMS layer used in part of some models described below, the thick ductile substrate and cover sequence are of similar density, achieved by using lower-density modelling clay mixes than in previous research.…”

“…Our centrifuge modelling goes beyond experiments at normal laboratory conditions by Bucher (1956) and centrifuge models of Dennis and Häll (1978), Koyi (1988) and Sans and Koyi (2001) in studying the effects of a ductile substrate and the role of a low-viscosity and density detachment horizon for part of some models in 4D. Our models differ significantly from Koyi (1988) and Sans and Koyi (2001) in that they do not address the process of diapirism and diapir-fold interaction as, apart from the PDMS layer used in part of some models described below, the thick ductile substrate and cover sequence are of similar density, achieved by using lower-density modelling clay mixes than in previous research. Tomodensitometry (''CT scanning'') techniques used in some of our models provide for the first time an exceptional view of the progressive development of structures in 3D.…”