Crustal structure of the Kapuskasing uplift from Lithoprobe Near‐vertical/wide‐angle seismic reflection data

Wu, Juntao; Mereu, R. F.

doi:10.1029/92jb01470

Cited by 22 publications

(8 citation statements)

References 27 publications

(15 reference statements)

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“…Similar sutures and subcrustal features were also inferred via reflection along the AG transect [ Calvert et al , 1995; Calvert and Ludden , 1999], though they have also been interpreted to represent lower crustal delamination [ Benn , 2006]. By contrast, the Kapuskasing Structural Zone does not exhibit Moho‐crossing reflections [ Wu and Mereu , 1992]. …”

Section: Previous Geophysical Studiesmentioning

confidence: 79%

Lithospheric variations across the Superior Province, Ontario, Canada: Evidence from tomography and shear wave splitting

et al. 2007

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[1] The Superior Province of the Canadian Shield is the largest contiguous region of the Archean crust. A combination of data from multiple experiments is used to obtain shear wave splitting parameters and a three-dimensional tomographic velocity model beneath a large portion of the Superior, corresponding approximately to the province of Ontario. Shear wave splits are obtained at 24 sites across the Superior, displaying strong (averaging 1.34 s) ENE-WSW splitting at stations west of 86°W and weaker (0.67 s) E-W splitting in the east. The fast direction is subparallel to both absolute plate motion and tectonic belt boundaries. The recovered tomographic velocity model shows a major boundary oriented NNW-SSE, separating high velocities in the western Superior (WS) from low velocities in the east and coinciding with the divide between weak and strong shear wave splits. Other features include a 200-km-thick low-velocity anomaly corresponding to the Nipigon Embayment, a 1.0-Ga failed-rift branch; and a linear low-velocity anomaly in the east, attributed to the Great Meteor hot spot track. The Nipigon anomaly, in the western portion of the model, is probably in situ, while the Great Meteor track is displaced from crustal features associated with the hot spot. We interpret this displacement as evidence that the eastern lithosphere has been deformed by basal drag, while the western lithosphere has remained stable, and propose that the east-west lithospheric boundary we have detected represents a change in mechanical properties, between stronger, higher velocity western material with consistent anisotropic fabric, and weaker eastern material with more variable fabric.

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Section: Previous Geophysical Studiesmentioning

confidence: 79%

Lithospheric variations across the Superior Province, Ontario, Canada: Evidence from tomography and shear wave splitting

et al. 2007

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“…As in most hard rock areas, refraction statics was an important 20 processing step (e.g. Wu and Mereu, 1992;Juhlin, 1995 allowing both more sub-horizontal and steeply dipping reflections to be imaged simultaneously (Fig. 4).…”

Section: Data Processingmentioning

confidence: 99%

Reflection seismic studies over the end-glacial Burträsk fault, Skellefteå, Sweden

Juhlin¹,

Lund²

2010

Preprint

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Reflection seismic data were acquired along a ca. 22 km long profile over the end-glacial Burträsk Fault with a nominal receiver and source spacing of 20 m. A steeply dipping reflection can be correlated to the Burträsk Fault, indicating that the fault dips at about 55° to the southeast near the surface. The reflection from the fault is rather poorly imaged, probably due to a jump in the fault and the crookedness of the seismic profile in the vicinity of the fault. A more pronounced steeply dipping reflection is observed about 4 km southeast of the Burträsk Fault. Based on its correlation with a topographic low at the surface this reflection is interpreted to originate from a fracture zone. There are no signs of large displacements along this fault as the glacial ice receded, but it may be active today. Other reflections on the processed seismic section may originate from changes in lithological variations in the supra-crustal rocks or from intrusions of more mafic rock. Constraints on the fault geometry provided by the reflection seismic data will help determine what stresses were required to activate the fault when the major rupture along it occurred

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“…Important processing steps included refraction statics, spectral whitening and dip moveout (DMO). Good refraction statics are critical for successful processing of this type of data [e.g., Wu and Mereu , 1992; Juhlin , 1995]. The approximate depth scale shown in the unmigrated sections in this paper is based on an average velocity of 5850 m/s.…”

Section: Data Processingmentioning

confidence: 99%

Gently dipping fracture zones in Paleoproterozoic metagranite, Sweden: Evidence from reflection seismic and cored borehole data and implications for the disposal of nuclear waste

Juhlin

Stephens

2006

J. Geophys. Res.

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[1] The Svecokarelian orogen in the coastal area north of Stockholm, central Sweden, is characterized by a complex deformation belt. In this belt, bedrock domains strike WNW-NW, dip steeply, and are affected by high ductile strain. These domains anastomose around tectonic lenses that are up to a few tens of kilometers in length and are a few kilometers wide. The bedrock within the lenses is folded and, in general, affected by lower ductile strain. Site investigations for the disposal of highly radioactive nuclear waste are presently in progress within one of these lenses. Approximately 16 km of high-resolution (10 m source and receiver spacing, 100 channels) seismic data were acquired in 2002 along five separate profiles (2 to 5 km in length) within this lens. In the southeast, reflection orientations are well determined where profiles cross one another. Here, there is a nearly one to one correlation of distinct reflections on the seismic sections with hydraulically conductive fracture zones in cored boreholes, indicating that these fracture zones control the reflectivity. However, smaller lenses of amphibolite within the fracture zones may enhance the reflectivity. The reflections dip gently to the SSE and SE, and the zones in the boreholes are dominated by fractures that show the same dip direction or are subhorizontal. A working hypothesis for the gently dipping fracture zones suggests that these structures formed as minor thrust faults during the later stages of the Svecokarelian orogeny. Mineral fillings and coatings along fractures in these zones indicate later reactivation. The current stress field, a high intensity of fractures in the zones at a high angle to s 3 , high in situ stresses in the bedrock, and rapid glacial unloading with the development of high differential stresses may explain the large volume of groundwater in these zones. The reflection seismic data, in combination with the verifying work presented in the cored borehole data, have steered the subsequent focus in geoscientific studies to the northwestern part of the candidate area.Citation: Juhlin, C., and M. B. Stephens (2006), Gently dipping fracture zones in Paleoproterozoic metagranite, Sweden: Evidence from reflection seismic and cored borehole data and implications for the disposal of nuclear waste,

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Crustal structure of the Kapuskasing uplift from Lithoprobe Near‐vertical/wide‐angle seismic reflection data

Cited by 22 publications

References 27 publications

Lithospheric variations across the Superior Province, Ontario, Canada: Evidence from tomography and shear wave splitting

Lithospheric variations across the Superior Province, Ontario, Canada: Evidence from tomography and shear wave splitting

Reflection seismic studies over the end-glacial Burträsk fault, Skellefteå, Sweden

Gently dipping fracture zones in Paleoproterozoic metagranite, Sweden: Evidence from reflection seismic and cored borehole data and implications for the disposal of nuclear waste

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