The Dynamics of Continental Breakup and Extension

Buck, W. Roger

doi:10.1016/b978-0-444-53802-4.00118-4

Cited by 17 publications

(11 citation statements)

References 266 publications

(264 reference statements)

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“…The SV and LT earthquake swarms themselves cover approximately 25% of the length of the geometric alignment. We propose that these processes indicate dike or fluid injection weakening and initiating rifting along the northern Sierra microplate [see Buck, 2007;Bialas et al, 2010]. The nearly identical vertical extent of each sequence (approximately 7 km up-dip) irrespective of their alignment, and the lack of lower crust seismicity, suggests a strong~7 km thick structure within the Moho-lower crustal transition zone.…”

Section: Tectonic Interpretationsmentioning

confidence: 99%

“…Generally, the strength of the lithosphere is greater than the tectonic forces required for rupture, termed the "tectonic force paradox" [Buck, 2004;see Karner et al, 2004;Buck, 2006Buck, , 2007. Buck [2006] has proposed that basaltic magmatism (e.g., dike emplacement) reduces the force necessary to rupture the lithosphere in order to proceed to rifting, for lithospheric thicknesses greater than~30 km.…”

Section: Introductionmentioning

confidence: 99%

“…Proposed mechanisms for rift initiation adopt a range of physical processes required to rupture the lithosphere [Buck, 2007]. Generally, the strength of the lithosphere is greater than the tectonic forces required for rupture, termed the "tectonic force paradox" [Buck, 2004;see Karner et al, 2004;Buck, 2006Buck, , 2007.…”

Section: Introductionmentioning

confidence: 99%

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Evidence for Moho‐lower crustal transition depth diking and rifting of the Sierra Nevada microplate

Smith

Kent

Seggern

et al. 2016

Geophysical Research Letters

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Lithospheric rifting most often initiates in continental extensional settings where “breaking of a plate” may or may not progress to sea floor spreading. Generally, the strength of the lithosphere is greater than the tectonic forces required for rupture (i.e., the “tectonic force paradox”), and it has been proposed that rifting requires basaltic magmatism (e.g., dike emplacement) to reduce the strength and cause failure, except for the case of a thin lithosphere (<30 km thick). Here we isolate two very similar and unprecedented observations of Moho‐lower crustal transition dike or fluid injection earthquake swarms under southern Sierra Valley (SV: 2011–2012) and North Lake Tahoe (LT: 2003–2004), California. These planar distributions of seismicity can be interpreted to define the end points, and cover ~25% of the length, of an implied ~56 km long structure, each striking N45°W and dipping ~50°NE. A single event at ~30 km depth that locates on the implied dipping feature between the two swarms is further evidence for a single Moho‐transition depth structure. We propose that basaltic or fluid emplacement at or near Moho depths weakens the upper mantle lid, facilitating lithospheric rupture of the Sierra Microplate. Similar to the LT sequence, the SV event is also associated with increased upper crustal seismicity. An 27 October 2011, Mw 4.7 earthquake occurred directly above the deep SV sequence at the base of the upper crustal seismogenic zone (~15 km depth).

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Section: Tectonic Interpretationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evidence for Moho‐lower crustal transition depth diking and rifting of the Sierra Nevada microplate

Smith

Kent

Seggern

et al. 2016

Geophysical Research Letters

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“…The reason for this behaviour has been deduced by means of analytical modelling suggesting that plastic yielding takes place at less tectonic force when the relative plate velocity is oblique to the rift trend (Brune et al, 2012) exerting additional control on rift strength that is otherwise governed by thermo-rheological properties, strain localisation and inherited weaknesses (Burov, 2015;Buck, 2015;Brune, 2018). As a consequence, during rift competition, oblique rifting should 25 prevail over orthogonal rifting if all other rift parameters are similar.…”

Section: Discussionmentioning

confidence: 99%

Oblique rifting: the rule, not the exception

Brune¹,

Williams²,

Müller³

2018

Preprint

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Abstract. Movements of tectonic plates often induce oblique deformation at divergent plate boundaries. This is in striking contrast with traditional conceptual models of rifting and rifted margin formation, which often assume 2D deformation 10 where the rift velocity is oriented perpendicular to the plate boundary. Here we quantify the validity of this assumption by analysing the kinematics of major continent-scale rift systems in a global plate tectonic reconstruction from the onset of Pangea breakup until present-day. We evaluate rift obliquity by joint examination of relative extension velocity and local rift trend using the script-based plate reconstruction software pyGPlates. Our results show that the global mean rift obliquity amounts to 34° with a standard deviation of 24°, using the convention that the angle of obliquity is spanned by extension 15 direction and rift trend normal. We find that more than ~70% of all rift segments exceeded an obliquity of 20° demonstrating that oblique rifting should be considered the rule, not the exception. In many cases, rift obliquity and extension velocity increase during rift evolution (e.g. Australia-Antarctica, Gulf of California, South Atlantic, India-Antarctica), which suggests an underlying geodynamic correlation via obliquity-dependent rift strength. Oblique rifting produces 3D stress and strain fields that cannot be accounted for in simplified 2D plane strain analysis. We therefore highlight the importance of 3D 20 approaches in modelling, surveying, and interpretation of most rift segments on Earth where oblique rifting is the dominant mode of deformation.

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“…In such systems, the organisation of normal faults may result in the formation of quasi-symmetrical halfgrabens with changing kinematics along their strike, where the localisation of deformation is often controlled by the inherited rheology of continental plates (e.g., van Wijk et al, 2008;Corti, 2009). Extension may also be associated with tens of kilometres of exhumation in the footwall of asymmetric detachments or low-angle normal faults, where kilometres-size (half-) grabens become gradually tilted by the continuation of deformation (e.g., Angelier and Colletta, 1983;Buck, 1991;Tirel et al, 2008;Buck, 2015). Depositional space in such basins is created by the subsidence of hanging-walls during successive events of normal faulting or may be cancelled by the relative uplift of footwalls associated with flexural effects or active rifting mechanics (e.g., Ziegler and Cloetingh, 2004).…”

Section: Extensional Basinsmentioning

confidence: 99%

Multi-Scale Depositional Successions in Tectonic Settings

Maţenco

Haq

2020

Preprint

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Observations in sedimentary basins affected by deformation show that the fault-induced depositional accommodation, at various spatial and temporal scales, is closely linked to basin kinematics. The tectonically-driven sediment infill displays the history of deepening and shoaling facies that are controlled by the activation of faults and changes in their offset rates. Simply stated, this results in shifting sedimentary facies towards the source area or towards the basin centre in response to increasing or decreasing depositional space. We propose a first-principle conceptual model for tectonic successions, controlled by the balance between the rates of creation of depositional space and sediment supply. These sediment bodies are bounded by succession boundaries and comprise sourceward or basinward shifting facies tracts that are separated at a point of reversal. Due to the relatively steep slopes associated with the evolution of faults, changes in sediment supply rates and mass-wasting are common in these systems and may complicate the normal rhythm of the shifting facies tracts. Once tectonic quiescence is achieved, and if the basin is connected to the open ocean, eurybatic or eustatic base level changes may take over and play a greater role in sedimentary rhythm and cyclicity. We illustrate the efficacy of the new concept with a review of examples from extensional, contractional and strike-slip basins. We show that the basic tectonic succession model is applicable at all temporal and spatial scales and whether the tectonics cause subsidence or uplift, and in all types of tectonic settings that determine the evolution of sedimentary basins.

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The Dynamics of Continental Breakup and Extension

Cited by 17 publications

References 266 publications

Evidence for Moho‐lower crustal transition depth diking and rifting of the Sierra Nevada microplate

Evidence for Moho‐lower crustal transition depth diking and rifting of the Sierra Nevada microplate

Oblique rifting: the rule, not the exception

Multi-Scale Depositional Successions in Tectonic Settings

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