Crustal Structure of the Northern Mississippi Embayment and a Comparison with other Continental Rift Zones

Mooney, Walter D.; Andrews, M.C.; Ginzburg, A.; Peters, D.A.; Hamilton, Rebecca

doi:10.1016/b978-0-444-42198-2.50025-0

Cited by 144 publications

(124 citation statements)

References 18 publications

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“…Alternatively the low-velocity zone might represent compositional variations across the rift, perhaps related to the magmatism during the Reelfoot rifting. But our results do not favor intrusive bodies in the lower crust because mafic intrusions typically cause high-velocity anomalies within rifts [Mooney et al, 1983]. These lead us to speculate that the anomaly is related to the deformational fabrics (weak zone).…”

Section: Discussionmentioning

confidence: 78%

“…Furthermore, because almost all local events in the NMSZ are too shallow to sample the lower crust, a sufficiently large dataset is needed to resolve the vertical trade-off of delay times. Previous refraction seismic profiles [Mooney et al, 1983;Catchings, 1999] suggest high-velocity intrusions at the bottom of the lower crust, but their interpreted intrusive bodies are broader than the rift zone or the scale of our lower crust image. [14] Teleseismic tomography inverts relative travel-time residuals and thus only shows relative velocity variations.…”

Section: Discussionmentioning

confidence: 99%

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Lithospheric velocity structure of the New Madrid Seismic Zone: A joint teleseismic and local P tomographic study

Zhang¹,

Sandvol²,

Liu³

2009

Geophysical Research Letters

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[1] The enigmatic seismicity in the New Madrid Seismic Zone (NMSZ) has been attributed to some abnormal lithospheric structure, including the presence of dense mafic intrusions and a low-viscosity lower crust. However, the area's detailed lithospheric structure remains unclear. Here we invert 2,056 teleseismic P and 12,226 local P first arrival times from a recent nine-year dataset to infer the lithospheric velocity structure beneath the NMSZ. Our results show that the seismically active zone is associated with a local, NE -SW trending low-velocity anomaly in the lower crust and upper mantle, instead of high-velocity intrusive bodies proposed in previous studies. The lowvelocity anomaly is on the edge of a high-velocity lithospheric block, consistent with the notion of stress concentration near rheological boundaries. This lithospheric weak zone may shift stress to the upper crust when loaded, thus leading to repeated shallow earthquakes.Citation: Zhang, Q., E. Sandvol, and M. Liu (2009), Lithospheric velocity structure of the New Madrid Seismic Zone: A joint teleseismic and local P tomographic study, Geophys. Res. Lett., 36, L11305,

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Section: Discussionmentioning

confidence: 78%

Section: Discussionmentioning

confidence: 99%

Lithospheric velocity structure of the New Madrid Seismic Zone: A joint teleseismic and local P tomographic study

Zhang¹,

Sandvol²,

Liu³

2009

Geophysical Research Letters

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“…It is associated with an ancient intraplate rift zone, commonly known as Reelfoot rift. On the basis of regional network data and seismic reflection surveys, Mooney et al (1983) proposed a five-layer crustal model for the region, which consists of a 14 km thick altered lower crust. Details of crustal layers, together with the relevant geothermal parameters (Mooney et al, 1983;Liu and Zoback, 1997;Bedle and Lee, 2006), are given in Table 1.…”

Section: New Madrid Seismic Zone (Usa)mentioning

confidence: 99%

“…On the basis of regional network data and seismic reflection surveys, Mooney et al (1983) proposed a five-layer crustal model for the region, which consists of a 14 km thick altered lower crust. Details of crustal layers, together with the relevant geothermal parameters (Mooney et al, 1983;Liu and Zoback, 1997;Bedle and Lee, 2006), are given in Table 1. In this zone, measured heat flow is about 60 mW m −2 and depth to the LAB is about 72 km, as obtained below the Reelfoot rift through tomographic study (Bedle and Lee, 2006).…”

Section: New Madrid Seismic Zone (Usa)mentioning

confidence: 99%

Predicting heat flow in the 2001 Bhuj earthquake (<i>M</i><sub>w</sub>=7.7) region of Kachchh (Western India), using an inverse recurrence method

Vedanti

Pandey

Srivastava

et al. 2011

Nonlin. Processes Geophys.

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Abstract. Terrestrial heat flow is considered an important parameter in studying the regional geotectonic and geodynamic evolutionary history of any region. However, its distribution is still very uneven. There is hardly any information available for many geodynamically important areas. In the present study, we provide a methodology to predict the surface heat flow in areas, where detailed seismic information such as depth to the lithosphere-asthenosphere boundary (LAB) and crustal structure is known. The tool was first tested in several geotectonic blocks around the world and then used to predict the surface heat flow for the 2001 Bhuj earthquake region of Kachchh, India, which has been seismically active since historical times and where aftershock activity is still continuing nine years after the 2001 main event. Surface heat flow for this region is estimated to be about 61.3 mW m −2 . Beneath this region, heat flow input from the mantle as well as the temperatures at the Moho are quite high at around 44 mW m −2 and 630 • C, respectively, possibly due to thermal restructuring of the underlying crust and mantle lithosphere. In absence of conventional data, the proposed tool may be used to estimate a first order heat flow in continental regions for geotectonic studies, as it is also unaffected by the subsurface climatic perturbations that percolate even up to 2000 m depth.

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“…Under this condition, the background horizontal stress field will concentrate shear stress in the weak (intersection) zone. The model of Stuart et al (1997) is based on seismic and gravity data that indicates that, in addition to widespread exposed or shallowly buried basalts, the NMSZ is underlain by a lense-shaped, high-density rift pillow Mooney et al, 1983) of dimension of about 10 4 km 3 within the lower crust (likely mantle melt intrusions in the deep crust) and centered on the locus of current seismic activity ( Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Sinking Mafic Body in a Reactivated Lower Crust: A Mechanism for Stress Concentration at the New Madrid Seismic Zone

Pollitz

Kellogg

Bürgmann

2001

Bulletin of the Seismological Society of America

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We propose a geodynamic model for stress concentration in the New Madrid seismic zone (NMSZ). The model postulates that a high-density (mafic) body situated in the deep crust directly beneath the most seismically active part of the NMSZ began sinking several thousands of years ago when the lower crust was suddenly weakened. Based on the fact that deformation rates in the NMSZ have accelerated over the past 9 k.y., we envision the source of this perturbation to be related to the last North American deglaciation. Excess mass of the mafic body exerts a downward pull on the elastic upper crust, leading to a cycle of primary thrust faulting with secondary strike-slip faulting, after which continued sinking of the mafic body reloads the upper crust and renews the process. This model is consistent with the youth of activity, the generation of a sequence of earthquakes, and the velocity evolution during interseismic periods, which depend upon the density contrast of the mafic body with respect to the surrounding crust, its volume, and the viscosity of the lower crust.

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Crustal Structure of the Northern Mississippi Embayment and a Comparison with other Continental Rift Zones

Cited by 144 publications

References 18 publications

Lithospheric velocity structure of the New Madrid Seismic Zone: A joint teleseismic and local P tomographic study

Lithospheric velocity structure of the New Madrid Seismic Zone: A joint teleseismic and local P tomographic study

Predicting heat flow in the 2001 Bhuj earthquake (<i>M</i><sub>w</sub>=7.7) region of Kachchh (Western India), using an inverse recurrence method

Sinking Mafic Body in a Reactivated Lower Crust: A Mechanism for Stress Concentration at the New Madrid Seismic Zone

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Crustal Structure of the Northern Mississippi Embayment and a Comparison with other Continental Rift Zones

Cited by 144 publications

References 18 publications

Lithospheric velocity structure of the New Madrid Seismic Zone: A joint teleseismic and local P tomographic study

Lithospheric velocity structure of the New Madrid Seismic Zone: A joint teleseismic and local P tomographic study

Predicting heat flow in the 2001 Bhuj earthquake (&lt;i&gt;M&lt;/i&gt;&lt;sub&gt;w&lt;/sub&gt;=7.7) region of Kachchh (Western India), using an inverse recurrence method

Sinking Mafic Body in a Reactivated Lower Crust: A Mechanism for Stress Concentration at the New Madrid Seismic Zone

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Product

Resources

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Predicting heat flow in the 2001 Bhuj earthquake (<i>M</i><sub>w</sub>=7.7) region of Kachchh (Western India), using an inverse recurrence method