How sharp is the sharp Archean Moho? Example from eastern Superior Province

Levin, Vadim; VanTongeren, J. A.; Servali, A.

doi:10.1002/2016gl067729

Cited by 24 publications

(28 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Tests have proved that a 5% change in the average V p or V p / V s ratio relative to the selected velocity model may account for ~3 km uncertainties in the Moho depth for the CCP stacking of P‐RFs (Caldwell et al, ). On the other hand, the vertical resolution of receiver function can be determined by half of the wavelength of the S wave (Levin et al, ). The dominant periods of the P‐RFs and S‐RFs in our study are 1 s and 4 s, respectively, corresponding to maximum vertical resolutions at the Moho of 2 km for Ps and 8 km for Sp conversions assuming a lower crustal V s of 4.0 km/s.…”

Section: Methodsmentioning

confidence: 99%

Detailed Configuration of the Underthrusting Indian Lithosphere Beneath Western Tibet Revealed by Receiver Function Images

Zhao

Yuan

et al. 2017

JGR Solid Earth

View full text Add to dashboard Cite

We analyze the teleseismic waveform data recorded by 42 temporary stations from the Y2 and ANTILOPE‐1 arrays using the P and S receiver function techniques to investigate the lithospheric structure beneath western Tibet. The Moho is reliably identified as a prominent feature at depths of 55–82 km in the stacked traces and in depth migrated images. It has a concave shape and reaches the deepest location at about 80 km north of the Indus‐Yarlung suture (IYS). An intracrustal discontinuity is observed at ~55 km depth below the southern Lhasa terrane, which could represent the upper border of the eclogitized underthrusting Indian lower crust. Underthrusting of the Indian crust has been widely observed beneath the Lhasa terrane and correlates well with the Bouguer gravity low, suggesting that the gravity anomalies in the Lhasa terrane are induced by topography of the Moho. At ~20 km depth, a midcrustal low‐velocity zone (LVZ) is observed beneath the Tethyan Himalaya and southern Lhasa terrane, suggesting a layer of partial melts that decouples the thrust/fold deformation of the upper crust from the shortening and underthrusting in the lower crust. The Sp conversions at the lithosphere‐asthenosphere boundary (LAB) can be recognized at depths of 130–200 km, showing that the Indian lithospheric mantle is underthrusting with a ramp‐flat shape beneath southern Tibet and probably is detached from the lower crust immediately under the IYS. Our observations reconstruct the configuration of the underthrusting Indian lithosphere and indicate significant along strike variations.

show abstract

Section: Methodsmentioning

confidence: 99%

Detailed Configuration of the Underthrusting Indian Lithosphere Beneath Western Tibet Revealed by Receiver Function Images

Zhao

Yuan

et al. 2017

JGR Solid Earth

View full text Add to dashboard Cite

show abstract

“…The maximum frequency at which the pulse size stops decreasing is ~1.75 Hz for all stations; this result is typical of Moho signals over the entire network. These frequencies correspond to shear wavelengths of ~2.1 km, resulting in a maximum vertical extent over which seismic properties change at the Moho of ~1–2 km [ Levin et al ., ], thus indicating a seismically sharp Moho.…”

Section: Receiver Functionsmentioning

confidence: 99%

Architecture of the crust and uppermost mantle in the northern Canadian Cordillera from receiver functions

et al. 2017

View full text Add to dashboard Cite

The northern Canadian Cordillera (NCC) is an active orogenic belt in northwestern Canada characterized by deformed autochtonous and allochtonous structures that were emplaced in successive episodes of convergence since the Late Cretaceous. Seismicity and crustal deformation are concentrated along corridors located far (>200 to ~800 km) from the convergent plate margin. Proposed geodynamic models require information on crust and mantle structure and strain history, which are poorly constrained. We calculate receiver functions using 66 broadband seismic stations within and around the NCC and process them to estimate Moho depth and P‐to‐S velocity ratio (Vp/Vs) of the Cordilleran crust. We also perform a harmonic decomposition to determine the anisotropy of the subsurface layers. From these results, we construct simple seismic velocity models at selected stations and simulate receiver function data to constrain crust and uppermost mantle structure and anisotropy. Our results indicate a relatively flat and sharp Moho at 32 ± 2 km depth and crustal Vp/Vs of 1.75 ± 0.05. Seismic anisotropy is pervasive in the upper crust and within a thin (~10–15 km thick) sub‐Moho layer. The modeled plunging slow axis of hexagonal symmetry of the upper crustal anisotropic layer may reflect the presence of fractures or mica‐rich mylonites. The subhorizontal fast axis of hexagonal anisotropy within the sub‐Moho layer is generally consistent with the SE‐NW orientation of large‐scale tectonic structures. These results allow us to revise the geodynamic models proposed to explain active deformation within the NCC.

show abstract

“…Hz. Most locations in the Superior Province show similar results, yielding estimates of the Moho width not exceeding 1.5 km (Levin et al, 2016). One exception is the area just north of the GF.…”

Section: Moho Widthmentioning

confidence: 65%

“…Based on a subset of the data used here, Levin et al (2016) noted that all stations within the Superior Craton display uniformly sharp (<1.5 km vertical thickness) Moho transitions regardless of the age of the tectonic terrane or the surface lithology.…”

Section: Variability Of Moho Widthmentioning

confidence: 86%

See 1 more Smart Citation

Crust-mantle boundary in eastern North America, from the (oldest) craton to the (youngest) rift

Levin¹,

Servali²,

VanTongeren³

et al.

Geological Society of America Special Papers

Self Cite

View full text Add to dashboard Cite

The North American continent consists of a set of Archean cratons, Proterozoic orogenic belts and a sequence of Phanerozoic accreted terranes. We present an ~1250 km long seismological profile that crosses the Superior craton, Grenville province, and Appalachian domains, with the goal of documenting the thickness, internal properties and the nature of the lower boundary of the North American crust using uniform procedures for data selection, preparation and analysis to ensure compatibility of the constraints we derive. Crustal properties show systematic differences between the three major tectonic domains. 2 The Archean Superior Province is characterized by thin crust, sharp Moho and low values of Vp/Vs ratio. The Proterozoic Grenville Province has some crustal thickness variation, near-uniform values of Vp/Vs, and consistently small values of Moho width. Of the three tectonic domains in the region the Grenville Province has the thickest crust. Vp/Vs ratios are systematically higher than in the Superior Province. Within the Paleozoic Appalachian Orogen all parameters (crustal thickness, Moho width, Vp/Vs ratio) vary broadly over distances of 100 km or less, both across the strike and along it. Internal tectonic boundaries of the Appalachians do not appear to have clear signatures in crustal properties. Of the three major tectonic boundaries crossed by our transect, two have clear manifestations in the crustal structure. The Grenville Front is associated with a change in crustal thickness and crustal composition (as reflected in Vp/Vs ratios). The Norumbega Fault Zone is at the apex of the regional thinning of the Appalachian crust. The Appalachian Front is not associated with a major change in crustal properties, rather it coincides with a zone of complex structure resulting from prior tectonic episodes, and thus presents a clear example of tectonic inheritance over successive Wilson Cycles.

show abstract

How sharp is the sharp Archean Moho? Example from eastern Superior Province

Cited by 24 publications

References 45 publications

Detailed Configuration of the Underthrusting Indian Lithosphere Beneath Western Tibet Revealed by Receiver Function Images

Detailed Configuration of the Underthrusting Indian Lithosphere Beneath Western Tibet Revealed by Receiver Function Images

Architecture of the crust and uppermost mantle in the northern Canadian Cordillera from receiver functions

Crust-mantle boundary in eastern North America, from the (oldest) craton to the (youngest) rift

Contact Info

Product

Resources

About