Influence of pre-existing salt diapirs on 3D folding patterns

Structural evolution of salt-influenced fold-and-thrust belts: A synthesis and new insights from basins containing isolated salt diapirs

“…Nilsen et al, 1995;Callot et al, 2007;Dooley et al, 2009). The key point here is that to maintain kinematic compatibility, thrusts, folds or a combination of both must nucleate at the diapir before propagating out into the adjacent sedimentary rocks (Fig 3b) (Koyi, 1988;Nilsen et al, 1995;Baldschuhn et al, 2001;Rowan et al, 2001;Gottschalk et al, 2004;Letouzey and Sherkati, 2004;Rowan et al, 2004;Callot et al, 2007;Jackson et al, 2008;Fernandez and Kaus, 2014). In particular, faults commonly nucleate on the hinterland side of the diapir and subsequently propagate into the surrounding sedimentary rocks.…”

“…In areas prone to buckling, anticlines typically nucleate at, and propagate away from, each of the diapirs (e.g. Fernandez and Kaus, 2014). Anticlines develop rather than synclines as arched (i.e.…”

“…Anticlines develop rather than synclines as arched (i.e. anticlinal) diapir roofs are amplified by buckling (Callot et al, 2007(Callot et al, , 2012Jahani et al, 2009;Fernandez and Kaus, 2014;Jackson and Hudec, 2017). In contrast, where faulting predominates, thrust, transpressional and tear faults (frontal ramps, oblique ramps and lateral ramps, respectively) generally nucleate at, and propagate outward from each of the squeezed diapirs ( Fig.…”

“…Note that an exception occurs when precursor diapirs are closely-spaced in the shortening direction, in this case diapirs may be located in the limbs of folds or in synclines (e.g. Rowan, 2003;Jahani et al, 2009;Callot et al 2012;Fernandez and Kaus, 2014). A similar process to the development of the anticlinal fold chain occurs in fault-prone settings.…”

Anatomy and evolution of the Astoin diapiric complex, sub-Alpine fold-and-thrust belt (France)

“…If early salt structures (diapirs or walls, and associated sedimentary structures such as minibasins, hooks, wedges, and megaflaps) formed before the compression, the mechanical architecture of the sedimentary pile and its evolution during shortening will be considerably modified. At the small scale, early salt structures influence the internal structure of the growing compressional belt by (1) accommodating shortening through squeezing (as in the Flinders range in Australia or the La Popa basin in Mexico) (Rowan and Vendeville 2006;Callot et al 2007Callot et al , 2012, (2) controlling distribution and style of folding (as in the Zagros fold-and-thrust belt in Iran) (Jahani et al 2009;Callot et al 2012;Fernandez and Kaus 2014), (3) controlling the fault geometry inside the orogenic wedge, thrusts using preferentially weak salt structures to reach shallower levels (as in the SW French Alps or the Northern Calcareous Alps in the Austrian part of the Alpine orogen) Graham et al 2012;Granado et al 2019;Célini et al 2020) and (4) being reactivated and resulting in syn-compressional salt tectonics, such as in the Sivas basin in Turkey (Ringenbach et al 2013;Callot et al 2014;Kergaravat et al 2016;Legeay et al 2018Legeay et al , 2019.…”