Regional deformations and emplacement of granitoid plutons in the Hackett River greenstone belt, Slave Province, Northwest Territories

1979 ◽  
Vol 16 (6) ◽  
pp. 1187-1195 ◽  
Author(s):  
W. K. Fyson ◽  
R. A. Frith
Keyword(s):  
Late Stage ◽  
Greenstone Belt ◽  
Metamorphic Rocks ◽  
Second Phase ◽  
Lower Grade ◽  
Granitoid Rock ◽  
Regional Deformation ◽  
Slave Province ◽  
Regional Strain ◽  
Domal Structure

Regional foliations resulting from two main phases of deformation within the Archean Hackett River greenstone belt are generally steeply inclined, except near some granitoid plutons where one or both structures are shallow dipping. Inclinations decrease near the plutons with little deviation in regional strike. Near other plutons all structures are steep; in some cases steep second phase foliation passes into the granitoid rock. It is suggested that the shallow dips reflect modifications of regional strain induced solely by those plutons that were rising during the phases of regional deformation. From changes in the structural arrangement along the belt it can be inferred that plutons rose into higher grade metamorphic rocks earlier than into lower grade rocks.A domal structure in basal gneiss could have formed during a late stage of the second deformation. Shallow dipping foliation within the gneiss may, however, reflect not only strain modification during regional deformation and buoyant uplift, but also the initial configuration of an infrastructure.

Geology and mineral occurrences of the southern part of High Lake Greenstone Belt, Slave Province, Northwest Territories

1993 ◽  
Author(s):  
J R Henderson ◽  
M N Henderson ◽  
J A Kerswill ◽  
Z Arias ◽  
D Lemkow ◽  
...  
Keyword(s):  
Northwest Territories ◽  
Greenstone Belt ◽  
Slave Province

THE ATHABASCA VALLEY ERRATICS TRAIN, ALBERTA AND PLEISTOCENE ICE MOVEMENTS ACROSS THE CONTINENTAL DIVIDE

1967 ◽  
Vol 4 (4) ◽  
pp. 625-632 ◽  
Author(s):  
M. A. Roed ◽  
E. W. Mountjoy ◽  
N. W. Rutter
Keyword(s):  
British Columbia ◽  
Rocky Mountains ◽  
Late Stage ◽  
National Park ◽  
Rocky Mountain ◽  
Metamorphic Rocks ◽  
Jasper National Park ◽  
Continental Divide ◽  
Park Area

The Athabasca Valley Erratics Train contains a variety of low- to medium- grade metamorphic rocks, the most abundant of which is talcose schist, with lesser amounts of garnet schist and biotite–quartz schist. This erratics train occurs in and west of the Athabasca Valley west of Edson, Alberta. It is probably a late stage deposit of the same glacier that carried and deposited the Erratics Train, Foothills of Alberta. The metamorphic erratics were incorporated into a glacier that originated in the northern part of the Monashee Mountains and Premier Range of British Columbia. This ice movement is also recorded by numerous U-shaped valleys, which extend across the Continental Divide. Thus, during a brief period in late(?) Wisconsin time, the Cordilleran ice in the Rocky Mountains of the Jasper National Park area was partly derived from west of the Continental Divide and the Rocky Mountain Trench. These data agree with the inferred ice movements shown on the 1958 Glacial Map of Canada.

Deformation across the western Quetico subprovince and adjacent boundarl regions in Minnesota

1992 ◽  
Vol 29 (10) ◽  
pp. 2087-2103 ◽  
Author(s):  
Robert L. Bauer ◽  
Peter J. Hudleston ◽  
David L. Southwick
Keyword(s):  
Shear Zones ◽  
Lower Grade ◽  
Seine River ◽  
Complex Deformation ◽  
Metasedimentary Rocks ◽  
Regional Deformation ◽  
Oblique Convergence ◽  
Deformation Features ◽  
Ductile Shear ◽  
East West

North- to northwest-directed crustal shortening across the western Quetico subprovince and its boundary regions produced a complex deformation sequence within the Quetico belt and resulted in concentrated zones of dextral ductile shear in the boundary regions within the adjacent greenstone–granite terranes. In this paper, we review and introduce new data on the regional deformation features and their geometries and discuss the history of generation of these features. We attribute the deformation sequence to differential partitioning of shortening and shear strains during dextral transpression associated with oblique convergence and accretion along the southern margin of the Superior Province.The turbiditic wacke in the western Quetico subprovince, now typically amphibolite-facies schist and migmatite, underwent an early deformation stage that included recumbent folding (F1) and the generation of an S1 bedding-parallel foliation. This event is most evident along the northern and southern boundaries of the subprovince, but it is also recognized in the lower grade metasedimentary rocks in the adjacent Wawa and Wabigoon subprovinces. In these subprovinces, F1 folding may have been associated with higher level thrusting and allochthonous emplacement of greenstone units. Despite our F1 designation of this event, it it unlikely that this deformation was synchronous across the subprovinces.Widespread upright folding of the overturned limbs of F1 folds produced moderately to gently plunging F2 folds with east–west-trending axial planes. F, folds, with an associated L, stretching lineation subparallel to fold hinges, are well developed along the southern and northern margins of the Quetico subprovince and in the metasediments of the adjacent Wawa subprovince. During this event, ductile dextral shear was concentrated in steeply dipping east–west-trending shear zones in the Wawa subprovince and in the region of the Rainy Lake – Seine River fault along the Quetico–Wabigoon subprovince boundary. In the northern Wawa subprovince, shear was strongly concentrated in relatively incompetent, steeply dipping metasedimentary and tuffaceous units interlayered with more competent greenstone units. Concentrated zones of ductile shear are not evident within the Quetico subprovince away from its boundary regions. However, emplacement of syntectonic plutons in the central Quetico reoriented F2 folds which were then refolded by large regional F3 folds during continued regional shortening.

U–Pb ages for late magmatism and regional deformation in the Shebandowan Belt, Superior Province, Canada

1986 ◽  
Vol 23 (8) ◽  
pp. 1075-1082 ◽  
Author(s):  
F. Corfu ◽  
G. M. Stott
Keyword(s):  
Volcanic Rock ◽  
Greenstone Belt ◽  
Volcanic Rocks ◽  
Superior Province ◽  
Tectonic Regime ◽  
Fault Systems ◽  
Regional Deformation ◽  
Minimum Age ◽  
Deformation Event ◽  
Type Sequence

Five precise U–Pb zircon (and titanite) ages from different lithologic units of the Shebandowan greenstone belt in the western Wawa Subprovince of the Superior Province put tight constraints on the time of late Archean magmatism and of two major deformation events.A porphyry sill from the older supracrustal sequence has an age of 2733 ± 3 Ma. Another porphyritic rock, a trondhjemite occurring as a clast in a conglomerate of the unconformably overlying Timiskaming-type supracrustal sequence, formed 2704 ± 2 Ma ago and defines a maximum age for the deposition of the Timiskaming-type sequence. An alkalic volcanic rock from this sequence has been directly dated at [Formula: see text], in accord with the above constraint and with another probable maximum age of deposition given by the date of 2696 ± 2 Ma for the Shebandowan Lake Pluton. A first deformation event (D1) was related to a predominantly vertical tectonic regime and occurred during or before intrusion of the Shebandowan Lake Pluton at 2696 ± 2 Ma. The second deformation event (D2) was caused by northwesterly-directed compression and occurred after [Formula: see text] ago, the age of the Timiskaming-type volcanic rocks. A minimum age for the D2 deformation event, which also affected the adjacent Quetico metasedimentary belt and was probably related to the development of major transcurrent fault systems throughout the Superior Province, is provided by an age of [Formula: see text] for the undeformed, late-kinematic Burchell Lake Pluton.

scholarly journals New Insights into Long-Term Aseismic Deformation and Regional Strain Rates from GNSS Data Inversion: The Case of the Pollino and Castrovillari Faults

2020 ◽  
Vol 12 (18) ◽  
pp. 2921
Author(s):  
Gabriele Cambiotti ◽  
Mimmo Palano ◽  
Barbara Orecchio ◽  
Anna Maria Marotta ◽  
Riccardo Barzaghi ◽  
...  
Keyword(s):  
Strain Rate ◽  
Strike Slip ◽  
Deformation Pattern ◽  
Fault Creep ◽  
Slip Mechanism ◽  
Regional Deformation ◽  
Regional Strain ◽  
Geodetic Strain Rate ◽  
Gnss Velocities

We present a novel inverse method for discriminating regional deformation and long-term fault creep by inversion of GNSS velocities observed at the spatial scale of intraplate faults by exploiting the different spatial signatures of these two mechanisms. In doing so our method provides a refined estimate of the upper bound of the strain accumulation process. As case study, we apply this method to a six year GNSS campaign (2003–2008) set up in the southern portion of the Pollino Range over the Castrovillari and Pollino faults. We show that regional deformation alone cannot explain the observed deformation pattern and implies high geodetic strain rate, with a WSW-ENE extension of 86±41×10−9/yr. Allowing for the possibility of fault creep, the modelling of GNSS velocities is consistent with their uncertainties and they are mainly explained by a shallow creep over the Pollino fault, with a normal/strike-slip mechanism up to 5 mm/yr. The regional strain rate decrease by about 70 percent and is characterized by WNW-ESE extension of 24±28×10−9/yr. The large uncertainties affecting our estimate of regional strain rate do not allow infering whether the tectonic regime of the area is extensional or strike-slip, although the latter is slightly more likely.

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