Rifts and Rifted Margins: A Review of Geodynamic Processes and Natural Hazards

Abstract

This review provides an introduction to the geodynamic processes that influence tectonic rift evolution and rifted margin architecture. With a strong focus on numerical modeling, I summarize classical and recent insights on rift evolution with differentiation between 2D and 3D concepts and models. One of the key processes during rift evolution is crust-mantle coupling, which controls not only the width of a rift system but also crustal hyperextension and the degree of final margin asymmetry. Accounting for 3D rift geometries allows investigating along-strike heterogeneities, rift segmentation and rift obliquity. Large amounts of sediments have accumulated at rifted margins, especially at the mouths of large rivers and former glaciers, providing important stratigraphic archives and georesources. Shifting the focus from the geological scale of continental extension to the human time scale, natural hazards are discussed regarding earthquakes and volcanic eruptions during active rifting. Finally, I review natural hazards due to passive margin seismicity as well as slope instabilities at heavily sedimented continental margins that have the potential to generate large landslide tsunamis.

Control of Pre‐rift Lithospheric Structure on the Architecture and Evolution of Continental Rifts: Insights From the Main Ethiopian Rift, East Africa

“…Continental rifts often have considerable along‐strike variations in architecture and magmatism. Variations in fault pattern and evolution may be the result of variations in pre‐existing lithospheric rheology, rift width, and extension rate and kinematics (e.g., Brune, ; Corti, ; Ebinger, ; Ziegler & Cloetingh, ). Along‐axis differences in magmatism are commonly explained by processes such as variable mantle potential temperature, heterogeneous anomalous volatile content in the asthenosphere, variable extension rate, or processes such as melt focusing at steep gradients of the lithosphere‐asthenosphere boundary (e.g., Keir et al, and references therein).…”

“…Along‐axis differences in magmatism are commonly explained by processes such as variable mantle potential temperature, heterogeneous anomalous volatile content in the asthenosphere, variable extension rate, or processes such as melt focusing at steep gradients of the lithosphere‐asthenosphere boundary (e.g., Keir et al, and references therein). Among these parameters, pre‐existing plate structure is expected to play a major role in controlling continental rift architecture, because variations in crustal and lithospheric vertical layering and strength and/or the presence of inherited heterogeneities may significantly influence the style and distribution of deformation at both local and regional scale (e.g., Brune, ; Corti, ; Sokoutis et al, ; Ziegler & Cloetingh, ). Continental rifting results from the application of extensional stresses to a predeformed, anisotropic lithosphere and, consequently, rift structures are not randomly distributed.…”

“…influence the style and distribution of deformation at both local and regional scale (e.g., Brune, 2016;Corti, 2012;Sokoutis et al, 2007;Ziegler & Cloetingh, 2004). Continental rifting results from the application of extensional stresses to a predeformed, anisotropic lithosphere and, consequently, rift structures are not randomly distributed.…”

Controls of inherited lithospheric heterogeneity on rift linkage: Numerical and analog models of interaction between the Kenyan and Ethiopian rifts across the Turkana depression

“…The evolution and architecture of continental rifts is controlled by the interaction among several parameters, including the rate of plate divergence, the thermal state of the lithosphere, and the presence and volumes of magmatic products [e.g., Ziegler and Cloetingh , ; Brune , ]. However, almost all continental rifts form in predeformed, and thus already structured, anisotropic lithosphere and reactivate preexisting weak zones, such as mobile belts, while avoiding stronger regions, such as cratons [e.g., Dunbar and Sawyer , ; Versfelt and Rosendahl , ].…”

Oblique rifting: the rule, not the exception

“…Note that this definition follows many previous studies (e.g. Fournier and Petit, 2007;Philippon et al, 2015;Brune, 2016;Zwaan and Schreurs, 2017;Ammann et al, 2017), but is opposite to the convention used in almost as many articles (e.g. Tron and Brun, 1991;Teyssier et al, 1995;Clifton and Schlische, 2001;Deng et al, 2018).…”