Architecture of rifted continental margins and break-up evolution: insights from the South Atlantic, North Atlantic and Red Sea–Gulf of Aden conjugate margins

Mohriak, Webster Ueipass; Leroy, Sylvie

doi:10.1144/sp369.17

Cited by 62 publications

(42 citation statements)

References 137 publications

(138 reference statements)

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“…They also feature wide areas of highly thinned, so-called hyperextended crust with a thickness of less than 10 km, where crust and mantle deformation appears to be tightly coupled Mohn et al, 2014]. Well-studied examples of magma-poor margins comprise the Iberia-Newfoundland conjugates [Hopper et al, 2004;Reston, 2007;Ranero and Perez-Gussinye, 2010;Sutra and Manatschal, 2012], the Central South Atlantic segment [Contrucci et al, 2004;Aslanian et al, 2009;Mohriak and Leroy, 2012], the Australian North West Shelf [Karner and Driscoll, 1999], the eastern Gulf of Aden and the South China Sea [Zhou and Yao, 2009;Franke, 2013].…”

Section: Magma-poor and Magma Rich End-membersmentioning

confidence: 99%

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

Brune¹

2017

Preprint

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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.

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Section: Magma-poor and Magma Rich End-membersmentioning

confidence: 99%

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

Brune¹

2017

Preprint

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“…The evaporites themselves have variable age estimates ranging from as early as 124 Ma to as late as 110 Ma (Davison, 2007;Karner & Gamboa, 2007;Mohriak & LeRoy, 2013;Quirk et al, 2013), so were either pre-or post-breakup depending on the interpretation. Thus, the salt was deposited either in a single depocenter that was subsequently separated into the Brazilian and African basins (e.g.…”

Section: South Atlanticmentioning

confidence: 99%

Passive‐margin salt basins: hyperextension, evaporite deposition, and salt tectonics

Rowan

2014

Basin Research

158

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Passive-margin salt basins are classified as prerift, syn-stretching, syn-thinning, and syn-exhumation. Prerift salt, such as the Triassic Keuper in the Western Pyrenees, undergoes thick-skinned extension, first decoupled and then coupled, along with its substrate and cover. The base salt develops significant relief, is attenuated on the largest faults, and ends up distributed across the entire margin. Syn-stretching salt, such as along the Iberian and Newfoundland margins, is deposited during early rifting and is thus concentrated in proximal areas with variable thickness and extent, with decoupled and coupled thick-skinned deformation dominant. Syn-thinning salt, such as in the northern Red Sea, is also deposited during extension, with the base salt unconformably above proximal stretching faults but offset by distal thinning faults. Both thick-skinned and gravity-driven thinskinned deformation occur, with the latter strongly influenced by the ramp-flat geometry of the base salt. Syn-exhumation salt, such as in the Gulf of Mexico and South Atlantic salt basins, is deposited as part of the sag basin with broad distribution and a generally unfaulted base. Conjugate syn-exhumation salt basins are originally contiguous, form partly over exhumed mantle on magma-poor margin segments, and are commonly flanked by magma-rich segments with volcanic highs (seawarddipping reflectors) that isolate the salt basin from marine water. Salt tectonics is characterized by gravitational failure of the salt and overburden, with proximal extension and distal contraction, and the development of allochthonous salt that includes frontal nappes that advance over newly formed oceanic crust.

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“…The load is applied atop very thin crust (Mohriak et al, 2010;Assumpção et al, 2011;Zalán et al, 2011;Mohriak & Leroy, 2012). A diffuse belt of seismicity occurs near or beyond the Cretaceous hinge line (Fig.…”

Section: The Model Abroadmentioning

confidence: 99%

Some remarks on the earthquakes of Fennoscandia: A conceptual seismological model drawn from the perspective of hyperextension

Redfield¹,

Osmundsen²

2015

NJG

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To a first order, patterns of Fennoscandia's seismicity reflect the benchmark domain boundaries of its Mesozoic rifted margin. Three distinct belts of earthquakes strike sub-parallel to the generalized line of breakup. The outermost seismic belt (SB1) marks the Taper Break (TB), or the zone of flexural coupling/decoupling between the distal (seaward) and proximal/necking (landward) domains. A coastal belt (SB2) follows the Innermost Limit of Extension, defined as the onset of 39 km-thick crystalline continental crust. An interior belt (SB3) follows the Hinterland Break in Slope, or the landward limit of the Scandinavian rifted margin. Between each belt, large portions of the necking, proximal, and hinterland domains are seismically quiescent. Evaluation of the 'Cumulative Seismic Moment' (CSM w ) per unit area indicates that the release of seismic energy is asymmetric. Although some of Fennoscandia's largest seismic events occur in the dominantly Proterozoic to Archean lithosphere of the eastern craton, 80% of Fennoscandian CSM w maps to the domain boundaries of the western rifted margin. CSM w energy tends to be highest at the TB and decreases system atically towards the continental interior.As proposed by many previous studies, a first-order spatial correlation between Scandinavia's offshore earthquake belt and voluminous, geo logically rapid, sedimentary loading during the Neogene period is evident. However, the presence of thinned, faulted crystalline basement is also a very important factor behind Scandinavia's offshore seismicity. Where the Neogene deposits are at their thickest the underlying crust is dominantly oceanic; CSM w is lower per unit area there than where lesser Plio-Pleistocene loading impacts continental crust that was fully prepared by Mesozoic necking and hyperextension. CSM w data suggest that the 'strength' of the TB and the continental margin's distal domain is significantly less than that of relatively young (ca. 54 Ma) oceanic lithosphere. Our data imply that ridge push does not contribute significantly to Fennoscandia's seismicity. Rather, we find that thin-plate bending stresses stemming from offshore depositional loading conspire with unbuttressed Gravitational Potential Energy (GPE), onshore erosion, and post-glacial isostatic rebound to generate Fennoscandia's earthquakes.We present a conceptual seismological model for Fennoscadia that is consistent with modern hypotheses of extended margin evolution, including post-breakup reactivation by footwall uplift in regions adjacent to sharp crustal taper. Illustrated by simple concepts of elastic thin-plate theory, the model honors our conclusion that Fennoscandian seismicity is principally the product of locally derived stress fields and that far field stress from the oceanic domain is unlikely to penetrate deeply into a hyperextended continental margin. It predicts the locations of the observed seismic belts and seismic gaps with the mathematics of thin-plate bending. It describes how the outer seismic belt will remain localized in the...

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Architecture of rifted continental margins and break-up evolution: insights from the South Atlantic, North Atlantic and Red Sea–Gulf of Aden conjugate margins

Cited by 62 publications

References 137 publications

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

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

Passive‐margin salt basins: hyperextension, evaporite deposition, and salt tectonics

Some remarks on the earthquakes of Fennoscandia: A conceptual seismological model drawn from the perspective of hyperextension

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