Formation of dome-in-dome structures: Results from experimental studies and comparison with natural examples. (January 2019)

• Record Type: Journal Article
• Authors: Zulauf, G.; Zulauf, J.; Thiessen, A.; Hattingen, E.
• Is Part Of: Journal of structural geology. Volume 118(2019)
• Page Start: 324
• Page End: 339
• Publication Date: 2019-01
• Subjects: Analogue modelling -- Dome-in-dome structure -- Dome-and-basin structure -- Rising diapir -- Constriction; Geology, Structural -- Periodicals; Géomorphologie structurale -- Périodiques; Geology, Structural; Periodicals; 551.805
• DOI: 10.1016/j.jsg.2018.11.008
• Languages: English
• ISSNs: 0191-8141

Abstract

Abstract: Dome-in-dome structures are frequent in salt provinces and in high-grade rocks of orogens. Their origin is only poorly understood. In the present study we have modelled dome-in-dome structures, which result from constrictional (radial) in-plane shortening of a competent layer embedded in a rising less competent matrix. Both the layer and the matrix consist of non-linear viscous plasticine, which display a viscosity contrast of 5. The deforming competent layer is characterized by (1) a striking downward drag along the margins, (2) a sample-scale first-order dome, and (3) numerous second-order domes and basins straddling the first-order dome. With increasing layer thickness and strain, the amplitude, A, arc-length, L, and wavelength, λ, of the second-order domes and basins increase. However, their growth rate is significantly smaller than that of non-rising domes and basins, which result from a bidirectional flow. This restricted growth of rising domes and basins is attributed to the simultaneous growth of the first-order dome, and explains, why hair-pin type folds – typical for non-rising domes and basins - are lacking, even at higher finite strain. Similar dome-in-dome structures like those produced in the present study have been described from deeper levels of salt and gneiss domes or from foliation triple points of interfering diapirs. Highlights: Dome-in-dome structures develop during in-plane constriction. Dome-in-dome structures occur in salt and gneiss domes. Rising dome-and-basin structures are growing on top of a single superior dome. Rising dome-and-basin structures do not develop a dominant wavelength. Rising dome-and-basin structures are characterized by a reduced growth rate.