Structural interpretation of the Midcontinent Rift in eastern Lake Superior from seismic reflection and potential-field studies

1994 ◽  
Vol 31 (4) ◽  
pp. 619-628 ◽  
Author(s):  
John Mariano ◽  
William J. Hinze
Keyword(s):  
Potential Field ◽  
Seismic Reflection ◽  
Gravity Data ◽  
Lake Superior ◽  
Field Studies ◽  
Continuous Section ◽  
Midcontinent Rift ◽  
Seismic Reflection Data ◽  
Potential Field Data ◽  
Reflection Data

Integrated interpretations of potential-field and GLIMPCE and industry seismic reflection data in eastern Lake Superior reveal the structural and stratigraphic complexity of the Midcontinent Rift in this region. Projection of the Keweenaw fault into southeastern Lake Superior suggested by early potential-field studies is confirmed by seismic reflection data. Analysis of seismic data in conjunction with aeromagnetic anomalies and regional gravity data also reveals a continuous section of basalt in the footwall of the Keweenaw fault. The lateral dimensions of this section vary along the strike of the rift from the center of the basin towards the southern flank. Spatially extensive anticlinal and synclinal features, reverse faults and related drag folds imaged by the reflection and enhanced potential-field data attest to the influence of a late-stage compressional event in this region. East-northeast trending gradients and displacements associated with observed potential-field anomalies and fault traces mapped at the surface also indicate a degree of accommodation perpendicular to the strike of the rift. These trends parallel the prevalent tectonic grain in the adjacent Archean basement rocks, perhaps suggesting that structures within the rift were in part controlled by preexisting crustal features.

Inversion of the Proterozoic Wernecke basin during tectonic development of the Racklan Orogen, northwest Canada

1994 ◽  
Vol 31 (3) ◽  
pp. 447-457 ◽  
Author(s):  
Marlene Dredge Mitchelmore ◽  
Frederick A. Cook
Keyword(s):  
Seismic Reflection ◽  
Sedimentary Rocks ◽  
Drill Hole ◽  
Seismic Reflection Data ◽  
Potential Field Data ◽  
Eastern Front ◽  
Reflection Data ◽  
Tectonic Development ◽  
Mackenzie Mountains ◽  
Middle Proterozoic

New deep seismic reflection data coupled with regional stratigraphic correlations, drill-hole information, and potential field data are interpreted to provide images of Middle Proterozoic Wernecke Supergroup (meta-)sedimentary layers that were uplifted during tectonic development of the ca. 0.9–1.3 Ga Racklan Orogen in Canada's western Northwest Territories. The reflection data are located at the eastern front of the Mackenzie Mountains portion of the Canadian Cordillera and on the western flank of the Fort Simpson structural trend that is a prominent Proterozoic structure in the subsurface throughout the region. Along three parallel profiles, layers that are correlated with thick Wernecke Supergroup sedimentary rocks produce prominent reflections between about 3.0 and 9.0 s (about 7.5 and 23 km) that were arched prior to deposition of younger Proterozoic (probably Mackenzie Mountains Supergroup) and Phanerozoic sedimentary rocks. The strata are considered to be Wernecke basin sedimentary rocks that were uplifted during deformation associated with the development of the Racklan Orogen.

scholarly journals Integrated geophysical analysis provides an alternate interpretation of the northern margin of the North American Midcontinent Rift System, Central Lake Superior

2020 ◽  
Vol 8 (4) ◽  
pp. SS63-SS85
Author(s):  
V. J. S. Grauch ◽  
Eric D. Anderson ◽  
Samuel J. Heller ◽  
Esther K. Stewart ◽  
Laurel G. Woodruff
Keyword(s):  
Great Lakes ◽  
Seismic Reflection ◽  
Lake Superior ◽  
Rift System ◽  
Reverse Fault ◽  
Midcontinent Rift ◽  
Seismic Reflection Data ◽  
Northern Margin ◽  
Midcontinent Rift System ◽  
Alternate Model

The Midcontinent Rift System (MRS) is a 1.1 Ga sequence of voluminous basaltic eruptions and multiple intrusions followed by widespread sedimentation that extends across the Midcontinent and northern Great Lakes region of North America. Previous workers have commonly used seismic-reflection data (Great Lakes International Multidisciplinary Program on Crustal Evolution [GLIMPCE] line A) to demonstrate that the northern rift margin in central Lake Superior developed as a normal growth fault that was structurally inverted to a reverse fault during a compressional event after rifting had ended. A prominent, curvilinear aeromagnetic anomaly that extends from Isle Royale, Michigan, to Superior Shoal in central Lake Superior, Ontario (the IR-SS anomaly), is commonly presented as a manifestation of this reverse fault. We have integrated multidisciplinary geophysical analyses (seismic-reflection, seismic-refraction, aeromagnetic, and gravity), physical-property information (density, magnetic susceptibility and remanence, and compressional-wave velocity), and geologic concepts to develop an alternate interpretation of the rift margin along GLIMPCE line A, where it intersects the IR-SS anomaly. Our new model indicates that a normal fault is the dominant structure at the northern rift margin along line A, contrary to the original rift-margin paradigm, which asserts that compressional structures are the dominant features preserved today. Integral to this alternate model is a newly interpreted, prerift sedimentary basin intruded by sills in northern Lake Superior. Our alternate model of the northern rift margin has implications for interpreting the style, scale, and timing of extension, rift-related intrusion, and compression during development of the MRS.

Gravity modelling along a Lithoprobe seismic traverse, northern Grenville Province, western Quebec

1997 ◽  
Vol 34 (2) ◽  
pp. 127-134 ◽  
Author(s):  
Hamid Telmat ◽  
Caroline N. Antonuk ◽  
Jean-Claude Mareschal
Keyword(s):  
Lower Crust ◽  
Seismic Reflection ◽  
Gravity Data ◽  
Regional Scale ◽  
Gravity Anomalies ◽  
Gravity Modelling ◽  
Grenville Province ◽  
Seismic Reflection Data ◽  
Mafic Intrusions ◽  
Reflection Data

High-precision gravity data were collected along Lithoprobe seismic reflection lines in the northern part of the Grenville Province, in western Quebec. An interpretation is presented for line 52, which starts some 60 km southeast of the Grenville Front, traverses the parautochthonous Reservoir Dozois Terrane including the allochthonous slice of the Réservoir Cabonga Terrane, and ends near the town of Mont-Laurier, in the allochthonous Mont-Laurier Terrane. On the regional scale, the Bouguer gravity anomaly is consistent with the interpretation of the seismic reflection data. It supports crustal thinning southward of the Grenville Front, under the Cabonga allochthon. This thinning may be related to postorogenic extension. The gravity modelling shows dramatic thinning of the lower crust and suggests that extension was accommodated by extrusion of the lower crust. The gravity modelling also requires a steep boundary between the Réservoir Cabonga and the Réservoir Dozois terranes extending to ~ 15 km. The geometry of the Baskatong ramp derived from gravity data is also consistent with the seismic interpretation. This supports the suggestion that the Baskatong ramp is a major discontinuity along which Proterozoic terranes were accreted. In the Réservoir Cabonga Terrane in the northern part of the profile, the residual gravity anomalies (short wavelength variations) are related to outcropping mafic intrusions. Modelling of these anomalies complements the seismic reflection data, which did not image the base of the intrusions. The interpretation calls for three small distinct gabbroic bodies that extend no deeper than 3 km. The total volume of the intrusions is ~ 3000 km3.

The style of transverse faulting in the Dead Sea basin from seismic reflection data: The Amazyahu fault

2006 ◽  
Vol 55 (3) ◽  
pp. 129-139 ◽  
Author(s):  
Avihu Ginzburg ◽  
Moshe Reshef ◽  
Zvi Ben-Avraham ◽  
Uri Schattner
Keyword(s):  
Seismic Reflection ◽  
Dead Sea ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Dead Sea Basin ◽  
The Dead
Sign in / Sign up

Export Citation Format

Share Document