Reprocessing and enhanced interpretation of the initial COCORP Southern Appalachians traverse

Cook, Frederick A.; Vasudevan, K.

doi:10.1016/j.tecto.2006.01.022

Cited by 58 publications

(75 citation statements)

References 13 publications

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“…4) correlates with a prominent set of reflections imaged in COCORP line 1 by Iverson and Smithson (1983) and Cook and Vasudevan (2006). One possible model, similar to the interpretation of Cook and Vasudevan (2006), is that the conversions mark the southeast-dipping boundary between more mafic arc rocks at depth within the Carolina terrane allochthon (hanging wall) and more felsic rocks of the Inner Piedmont (footwall). The overall geometry at depth would be similar to that of the contact between the Inner Piedmont and Blue Ridge along the Brevard fault zone .…”

Section: Discussionmentioning

confidence: 65%

“…1A and 4;Figs. DR4 and DR5) (McBride et al, 2005;Cook and Vasudevan, 2006). The switch in dominant polarity of the basement conversions between the Blue Ridge and Inner Piedmont is interpreted to result from low-Vs metasedimentary platform rocks, shearing along the detachment, or a combination thereof (e.g., Johnston and Christensen, 1992;Szymanski and Christensen, 1993).…”

Section: Seismic Discontinuities Beneath the Inner Piedmont And Carolmentioning

confidence: 99%

“…Strong reflectivity in the upper crust is interpreted as a thick section of deformed platform metasediments beneath the BR-IP that correlates with Cambrian-Ordovician carbonates and siliciclastic rocks in Valley and Ridge thrust sheets to the northwest . To the southeast, beneath the Carolina terrane, complex reflectivity patterns have been attributed to the continuation of passivemargin rocks (Cook and Vasudevan, 2006) or mylonitic shear zones (Iverson and Smithson, 1983). Improved resolution of velocity structure is needed to refine crustal models inferred from regional geology and reflection profiling.…”

Section: Introductionmentioning

confidence: 99%

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Constraining lithologic variability along the Alleghanian detachment in the southern Appalachians using passive-source seismology

Parker

Hawman

Fischer

et al. 2015

Geology

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Polarities and amplitudes of intracrustal P-SV conversions (P waves converted to vertically polarized shear waves) in receiver functions from the Southeastern Suture of the Appalachian Margin Experiment array and USArray Transportable Array provide new constraints on the origin of seismic reflectivity delineating the Alleghanian detachment in the southern Appalachians(eastern United States). Forward modeling of receiver functions is consistent with a 3.5-km-thick, high shear-wave velocity (Vs = 3.9 km/s) section of deformed Paleozoic platform metasedimentary rocks beneath the Blue Ridge at 3-6.5 km depth. In the Inner Piedmont, conversions from the top and base of a low-Vs zone (3.1 km/s) at depths of 5-9 km are interpreted as a package of metasedimentary rocks or a shear zone characterized by radial anisotropy. The detachment continues to the southeast beneath the Carolina terrane, where high-amplitude negative conversions at 10-13 km depth are consistent with arc rocks (Vs = 4.0 km/s) overlying sheared rocks with lower Vs (3.2 km/s). Southeast-dipping conversions at 5-10 km depth mark the boundary between the Inner Piedmont and Carolina terrane. This study demonstrates that relatively high-frequency receiver functions (up to ~3 Hz), though still lower in frequency than P-wave energy analyzed for reflection profiling (>20 Hz), can provide important links between surface geology and active-source experiments to better constrain models of crustal structure.

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Section: Discussionmentioning

confidence: 65%

Section: Seismic Discontinuities Beneath the Inner Piedmont And Carolmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Constraining lithologic variability along the Alleghanian detachment in the southern Appalachians using passive-source seismology

Parker

Hawman

Fischer

et al. 2015

Geology

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“…Subduction was predominantly NW-directed beneath LaurentiaeBaltica in the Canadian Appalachians (e.g., van Staal et al, 2009) and in the Variscan belt of Europe, where arc magmatism developed on the previously accreted peri-Gondwanan terranes (e.g., Mid-German Crystalline High; Kroner et al, 2007). However, the polarity of subduction was SE-directed beneath Gondwana in the U.S. Appalachian-Ouachita belt, where Laurentia forms the lower plate (e.g., Cook and Vasudevan, 2006). This would have required a major transform boundary in the southwestern Rheic Ocean, which Pe-Piper et al (2010) have suggested was located in the eastern Gulf of Maine based on plutonism linked to the slab tear.…”

Section: Ocean Closurementioning

confidence: 99%

“…High-grade metamorphism and associated magmatism occurred in the Late PennsylvanianeEarly Permian, but is limited in its extent and attributed to local crustal thickening (e.g., Snoke and Mosher, 1989). Conversely, in the southern Appalachian orogen and Ouachita belt, collision began in the late Mississippian and was essentially head-on, leading to the development of crustal-scale decollement structures and north-and west-vergent fold-thrust belts as thinned Laurentian continental crust was subducted beneath Gondwana (e.g., Cook and Vasudevan, 2006). In the orogenic hinterland exposed in the southern Appalachians, deformation was accompanied by dextral strike-slip tectonics, significant metamorphism and widespread latest Mississippiane Pennsylvanian magmatism attributed to crustal thickening (e.g., Hatcher, 2002).…”

Section: Terminal Collisionmentioning

confidence: 99%

A brief history of the Rheic Ocean

Nance

Gutiérrez-Alonso

Keppie

et al. 2012

Geoscience Frontiers

247

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The Rheic Ocean was one of the most important oceans of the Paleozoic Era. It lay between Laurentia and Gondwana from the Early Ordovician and closed to produce the vast OuachitaAlleghanian-Variscan orogen during the assembly of Pangea. Rifting began in the Cambrian as a continuation of Neoproterozoic orogenic activity and the ocean opened in the Early Ordovician with the separation of several Neoproterozoic arc terranes from the continental margin of northern Gondwana along the line of a former suture. The rapid rate of ocean opening suggests it was driven by slab pull in the outboard Iapetus Ocean. The ocean reached its greatest width with the closure of Iapetus and the accretion of the periGondwanan arc terranes to Laurentia in the Silurian. Ocean closure began in the Devonian and continued through the Mississippian as Gondwana sutured to Laurussia to form Pangea. The ocean consequently plays a dominant role in the Appalachian-Ouachita orogeny of North America, in the basement geology of

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Crustal velocity structure associated with the eastern Tennessee seismic zone: Vp and Vs images based upon local earthquake tomography

et al. 2014

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We present three-dimensional P and S wave velocity models for the active eastern Tennessee seismic zone (ETSZ) using arrival time data from more than 1000 local earthquakes. A nonlinear tomography method is used that involves sequential inversion for model and hypocenter parameters. We image several velocity anomalies that persist through most of the inversion volume. Some anomalies support the presence of known features such as an ancient rift zone in northern Tennessee. Other anomalies reveal the presence of basement features that can be correlated with regional gravity and magnetic anomalies. We image a narrow, NE-SW trending, steeply dipping zone of low velocities that extends to a depth of at least 24 km and is associated with the vertical projection of the prominent New York-Alabama magnetic lineament. The low-velocity zone may have an apparent dip to the SE at depths exceeding 15 km. The low-velocity zone is interpreted as a major basement fault juxtaposing Granite-Rhyolite basement to the NW from Grenville southern Appalachian basement to the SE. Relocated hypocenters align in near-vertical segments suggesting reactivation of a distributed zone of deformation associated with a major strike-slip fault. We suggest that the ETSZ represents reactivation of an ancient shear zone established during formation of the super continent Rodinia.

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Reprocessing and enhanced interpretation of the initial COCORP Southern Appalachians traverse

Cited by 58 publications

References 13 publications

Constraining lithologic variability along the Alleghanian detachment in the southern Appalachians using passive-source seismology

Constraining lithologic variability along the Alleghanian detachment in the southern Appalachians using passive-source seismology

A brief history of the Rheic Ocean

Crustal velocity structure associated with the eastern Tennessee seismic zone: Vp and Vs images based upon local earthquake tomography

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