Coupling Crustal‐Scale Rift Architecture With Passive Margin Salt Tectonics: A Geodynamic Modeling Approach. Issue 11 (23rd November 2022)

• Record Type: Journal Article
• Authors: Pichel, Leonardo M.; Huismans, Ritske S.; Gawthorpe, Robert; Faleide, Jan Inge; Theunissen, Thomas
• Is Part Of: Journal of geophysical research. Volume 127:Issue 11(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-23
• Subjects: salt tectonics -- rifted margins -- rifting -- diapirism -- minibasins -- salt nappes; Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1029/2022JB025177
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: Continental rifted margins are often associated with widespread, thick evaporite (i.e., salt) deposits and pronounced salt tectonics. The majority of salt basins formed during the latest stages of rifting, prior to continental breakup. We use 2D thermo‐mechanical finite element modeling of lithospheric extension to investigate the interplay between rifted margin architecture, late syn‐rift salt deposition, and post‐rift salt tectonics. We focus on four different types of continental margins: (a) narrow, (b) intermediate, (c) wide, and (d) ultra‐wide margins. We evaluate the: (a) interplay between laterally variable syn‐rift extension, salt deposition and salt tectonics, (b) influence of syn‐rift basin architecture on post‐rift salt flow, (c) spatial and temporal distribution of salt‐related structural domains, and (d) contrasting styles of salt tectonics for different margin types. Narrow and intermediate margins form partially isolated salt basins associated with prominent base‐salt relief, limited translation but significant diapirism, and minibasin development. Wide and ultra‐wide margins form wide salt basins with subtle base‐salt relief that results in significant seaward salt expulsion and overburden translation. These wide margins demonstrate significant updip extension with the development of post‐rift normal faults and rollovers, mid‐margin translation associated with complex diapirism and downdip diapir shortening. All margins contain a distal salt nappe that varies in width and complexity. We also test the effect of different salt viscosities, relative post‐salt progradation rates, and pre‐salt sediment thicknesses. The results are comparable to several examples of salt‐bearing rifted margins and improve our understanding of their dynamics and on the controls on their salt tectonics variability. Plain Language Summary: Rifting of the continental lithosphere can lead to continental breakup and formation of continental margins, which are often associated with widespread, thick salt basins that deform in a ductile fashion and produce complex geological structures. Most of these basins formed during the latest stages of rifting, prior to continental breakup. We use 2D thermo‐mechanical numerical modeling of lithospheric extension to investigate the interplay between rifted margin architecture, late‐syn‐rift salt and post‐rift salt tectonics for four different types of margins: (a) narrow, (b) intermediate, (c) wide, and (d) ultra‐wide. We evaluate the interplay between syn‐rift extension, salt deposition and deformation, the influence of rift basin architecture on post‐rift salt flow, and the contrasting styles and magnitudes of salt deformation for different margin types. Narrow and intermediate margins form isolated salt sub‐basins associated with prominent relief, limited seaward translation but significant vertical salt flow. Wide and ultra‐wide margins form broad salt basins with subtle relief, significant seaward salt expulsion, updip extension, translation and downdip shortening. All margins contain a distal salt sheet advancing laterally over newly formed oceanic crust. The results can be directly compared to several examples of salt‐bearing rifted margins worldwide and provide an improved understanding of their dynamics. Key Points: We use geodynamic models of lithospheric extension to investigate post‐rift salt tectonics for different types of rifted margins Narrow margins form partially isolated salt sub‐basins associated with prominent relief, limited seaward translation but major diapirism Wide margins form large salt basins with low relief, major seaward salt expulsion, nappe advance, updip extension and downdip shortening