Insights Into Intraplate Stresses and Geomorphology in the Southeastern United States

Murphy, Benjamin S.; Liu, Liang; Egbert, G. D.

doi:10.1029/2019gl083755

Cited by 11 publications

(11 citation statements)

References 65 publications

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“…With a resistivity contrast of three orders of magnitude, a small C 1 (e.g., 0.35) leads to a viscosity variation of only 1 order of magnitude, whereas C 1 = 2.0 results in a magnitude difference of six orders. The geodynamic study with crustal viscosity informed from magnetotelluric resistivity model shows a promising match with the observed surface stress (Murphy et al, 2019).…”

Section: Rheology Constraints From Conductivity Modelmentioning

confidence: 65%

Shaping the Surface Deformation of Central and South Tibetan Plateau: Insights From Magnetotelluric Array Data

et al. 2020

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The ongoing India-Asia collision since the Paleogene created the Tibetan Plateau, the most prominent elevated plateau on our planet. This convergence also contributed to the formation of two distinct types of active surface deformation of the plateau, namely, north-south trending normal fault systems and "conjugate" strike-slip fault systems. The tectonics and geodynamic mechanism(s) behind this curious combination are still unclear, despite numerous theories proposed over past decades. Here we present a new three-dimensional, lithospheric-scale, electrical conductivity model with unprecedented resolution of the central part of Tibetan Plateau derived from the SINOPROBE magnetotelluric array data set and discuss its inferences related to this question. Our model reveals contrasting conductivity structures corresponding to the surface deformation patterns, namely, highly conductive lower crustal anomalies beneath the graben systems in the Lhasa and Qiangtang terranes and moderately resistive crustal features in the strike-slip region near Bangong-Nujiang Suture Zone. With the help of experimentally calibrated constraints between conductivity and melt fraction, the conductivity model and the inferred lateral viscosity distribution together suggest a weak lower crust beneath the graben regions, compared to a stronger crustal rheology associated with the strike-slip zone. Here we expand the previously proposed "extensional extrusion" tectonic model in central Tibet to interpret our conductivity model and other geophysical/geodesic observations. The weak rheology under a N-S directed primary stress may have caused the east-west extension of the graben regions, which further aides the eastward extrusion of the conjugate strike-slip zone and eventually shapes the surface deformation of central Tibetan Plateau into its current, complex pattern. Plain Language Summary The collision between the Indian and Asian continents built the Tibetan Plateau, the highest plateau in the world. This active collision also formed distinctly different types of large-scale geological structures on the plateau surface. Among the most important features on the plateau, the origin of the N-S directed normal (or spreading) fault zones in two regions named Lhasa and Qiangtang, and the NW/SE directed slip fault zones between these two regions are still unclear. In order to understand the generation of those structures, we use a geophysical imaging method called magnetotellurics to measure the naturally occurring electromagnetic waves in the earth. We model and analyze these magnetotellurics data to obtain the deep structure beneath those surface structures, using sophisticated computer codes. We find that the two dominant but different types of those structures are most likely due to the different strengths of the deep crust. This strength difference can lead to a mechanical stress contrast, which further builds the distinctly different surface structures. These kinds of deep physical structure differences have not been detected for the area bef...

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Section: Rheology Constraints From Conductivity Modelmentioning

confidence: 65%

Shaping the Surface Deformation of Central and South Tibetan Plateau: Insights From Magnetotelluric Array Data

et al. 2020

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“…where  rr E is the predicted radial normal stress at the model surface and  c E is the crustal density. This approach of calculating surface topography follows recent studies (Flament et al, 2014;Murphy et al, 2019). The resulting surface elevation is implicit, whose effect on lithospheric stress should be similar to the traditional GPE calculation (e.g., Ghosh et al, 2013) and can be compared with true surface elevation as an additional validation.…”

Section: Calculation Of S Hmax and Surface Topographymentioning

confidence: 99%

“…In the tectonically active WUS, plate interactions (Flesch et al, 2000(Flesch et al, , 2007Humphreys & Coblentz, 2007), GPE gradients (Flesch et al, 2000(Flesch et al, , 2007Ghosh et al, 2013;Jones et al, 1996), and mantle convection (Becker et al, 2015) are all proposed to be important. In the tectonically stable EUS, proposed sources of stress include a dense lower crust (Levandowski et al, 2017), crustal thickness variations (Murphy et al, 2019), inhomogeneous lithosphere rheology (Zhan et al, 2016), large-scale mantle convection (Ghosh et al, 2019;Zoback & Zoback, 1980), and localized mantle downwelling (Forte et al, 2007). Furthermore, some studies (Lowry & Smith, 1995;Mooney et al, 2012) emphasize lateral variations in effective viscosity as the key reason for stress concentration along rheological boundaries as well as the observed continent-scale stress partitioning, which is reflected in the distribution of earthquakes.…”

Section: Review Of Previous Studies On the Origin Of Crustal Stressmentioning

confidence: 99%

“…In addition, the existence of weak zones within the lithosphere could accommodate and redistribute stresses generated by plate boundary interactions (Flesch et al., 2000; Ghosh & Holt, 2012; Ghosh et al., 2013). Besides lateral variations in lithospheric effective viscosity, radial variations in mantle and lithospheric viscosity also affect lithospheric stress partitioning (Bischoff & Flesch, 2019; Lithgow‐Bertelloni & Guynn, 2004; Murphy et al., 2019).…”

Section: Review Of Previous Studies On the Origin Of Crustal Stressmentioning

confidence: 99%

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Origin of Three‐Dimensional Crustal Stress Over the Conterminous United States

Cao

Liu

2021

JGR Solid Earth

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The state of stress in the Earth's crust is a fundamental physical property that controls crustal deformation ranging from seismicity to long-term tectonic evolution. Consequently, understanding the origin of stress in the crust is the key to understanding crustal deformation. There are multiple proposed sources for crustal stress, including lateral variations in gravitational potential energy (GPE; e.g., Flesch et al., 2001;Ghosh et al., 2006;Jones et al., 1996) and mantle flow, where the latter further breaks down to plate boundary interactions (e.g., Flesch et al., 2001) and basal tractions (e.g., Lithgow-Bertelloni & Guynn, 2004;Steinberger et al., 2001). However, the relative importance of these sources of stress for generating the observed stress field remains unclear. The North American plate provides an unprecedented opportunity to further understand the relative contributions of these different mechanisms given its well-studied geology, the recently updated crustal stress map, and increasing knowledge about its underlying mantle processes.Recent efforts to map the orientation of the maximum horizontal principal stress (S Hmax ) and relative magnitudes of the three principal stresses (Aφ parameter; Simpson, 1997

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“…It is also roughly compatible with the observed earthquake focal mechanisms although local contributions to geopotential stresses, including inherited ancient basement structures producing lithospheric density contrasts (Levandowski et al, 2016), may be important for localising seismicity and perhaps are even sufficient for inducing it. For example, Murphy et al (2019) recently ascribed seismicity in the southeastern United States (e.g. the 2011 Virginia earthquake) to be largely explicable by forces arising from crustal thickness variations in the region.…”

Section: North Americamentioning

confidence: 99%

Late Cretaceous-Cenozoic basin inversion and palaeostress fields in the North Atlantic-western Alpine-Tethys realm: Implications for intraplate tectonics

Stephenson

Schiffer

Peace

et al. 2020

Earth-Science Reviews

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Intraplate basin/structural inversion (indicating tectonic shortening) is a good marker of ("far-field") tectonic stress regime changes that are linked to plate geometries and interactions, a premise that is qualitatively well-established in the literature. There is also quantitative evidence that Late Cretaceous-Palaeocene inversion of sedimentary basins in north-central Europe was explicitly driven by an intraplate, relaxational response to forces developed during rapid reconfigurations of the Alpine-Tethys (Europe-Africa) convergent plate boundary. Although with a degree of temporal ambiguity, three main periods of intraplate tectonics (marked primarily by structural inversion in initially extensional sedimentary basins) are indicated in the North Atlantic-western Alpine-Tethys realm. These are in the Late Cretaceous-Palaeocene, the Eocene-Oligocene and the Miocene. Examples recording these periods are primarily interpreted seismic reflection profiles (of varying quality and resolution) from the published literature. Additional examples where seismic data are not present, but timing constraints are robust from other observations, have also been considered. The schematic distribution and orientation of the literature-compiled intraplate inversion structures are compared to the model palaeostress fields derived from Late Cretaceous-Palaeocene, Eocene-Oligocene and Miocene tectonic reconstructions of the North Atlantic-western Alpine-Tethys realm. The modelled palaeostress fields include geopotential effects from palaeobathymetry and palaeotopography of the Earth's surface as well as laterally variable lithosphere and crustal palaeothicknesses but do not include any component of the stress field produced by processes occurring at contiguous convergent plate margins. The former satisfactorily provides the background stress field of most of the Earth's plate interiors and it is inferred that the latter is paramount in producing "stress trauma" in the interior of plates resulting in permanent intraplate deformation such as basin inversion.

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Insights Into Intraplate Stresses and Geomorphology in the Southeastern United States

Cited by 11 publications

References 65 publications

Shaping the Surface Deformation of Central and South Tibetan Plateau: Insights From Magnetotelluric Array Data

Shaping the Surface Deformation of Central and South Tibetan Plateau: Insights From Magnetotelluric Array Data

Origin of Three‐Dimensional Crustal Stress Over the Conterminous United States

Late Cretaceous-Cenozoic basin inversion and palaeostress fields in the North Atlantic-western Alpine-Tethys realm: Implications for intraplate tectonics

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