Diverse metavolcanic sequences and late polymictic conglomerate-associated metasedimentary rocks in the Winter Lake supracrustal belt, Slave Province, Northwest Territories

Metagreywackes, which lie stratigraphically above metavolcanics fringing a granitic complex (part basement), exhibit late Archean multiphase fold structures. F1 folds are large linear depressions and anticlinal culminations trending partly concordant with margins of the granitic complex. Open to isoclinal F2 folds vary and curve in trend. Though usually near upright, some F2 folds are overturned away from the complex and others towards F1 depressions. F3 folds are small-scale structures not present in most outcrops, but throughout a large region they are accompanied by a steep S3 axial-plane schistosity striking NW to N.Original orientations of an S2 schistosity, axial planar to F2 folds, are preserved as inclusion trails in biotite porphyroblasts. Angular deflections from the trails show that regional horizontal flattening across the S3 schistosity formed the F3 folds and tightened curved trends of F2 folds. Estimates of strain from the fabrics indicate no increase near the complex.As for folds in other Archean terrains, F1 and F2 folds could have developed mainly as gravity structures during diapiric uprise of a granitic basement. In contrast, the F3 structures may reflect horizontal movements of early crustal plates.

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Geology of the northern half of the Winter Lake supracrustal belt, Slave Province, Northwest Territories

10.4095/193809 ◽

1994 ◽

Cited By ~ 1

Author(s):

R B Hrabi ◽

J W Grant ◽

A Berclaz ◽

D Duquette ◽

M E Villeneuve

Keyword(s):

Northwest Territories ◽

Slave Province ◽

Northern Half ◽

Supracrustal Belt

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Geology of the Winter Lake supracrustal belt, Central Slave Province, District of Mackenzie, Northwest Territories

10.4095/134234 ◽

1993 ◽

Author(s):

R B Hrabi ◽

J W Grant ◽

P D Godin ◽

H Helmstaedt ◽

J E King

Keyword(s):

Northwest Territories ◽

Slave Province ◽

Supracrustal Belt

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Deformational history of an Archean fold belt, eastern Point Lake area, Slave Structural Province, N.W.T.

Canadian Journal of Earth Sciences ◽

10.1139/e89-009 ◽

1989 ◽

Vol 26 (1) ◽

pp. 106-118 ◽

Cited By ~ 4

Author(s):

J. E. King ◽

H. Helmstaedt

Keyword(s):

Lake Area ◽

Metasedimentary Rocks ◽

Thermal Peak ◽

Strain Pattern ◽

Slave Province ◽

Deformational History ◽

Supracrustal Belt ◽

Two Generations ◽

History Of ◽

Granitoid Intrusions

Archean metasedimentary rocks in the eastern Point Lake area of the Slave Structural Province preserve a sequence of Archean structures consisting of two generations of folds (F1 and F2) with little associated penetrative cleavage and two subsequent generations of cleavage (S3 and S4) with little associated folding. Gneissic layering in the high-grade margin of the belt is composed of transposed bedding and the S3 cleavage. Folding occurred prior to the thermal peak of metamorphism, whereas the develoment of subsequent cleavages spanned the thermal peak. The regional orientation of the folds and cleavages appears to be independent of the emplacement of granitoid intrusions, although their orientation is modified adjacent to syn- to late tectonic plutons. The supracrustal belt is interpreted as being part of a pre- to early metamorphic, west-verging fold (thrust?) belt whose strain pattern has been modified by post-folding, synmetamorphic shortening, and syn- to post-tectonic plutons. This deformation sequence is similar to those described in other supracrustal belts of the Slave Province and supports the concept that the Slave Province has undergone regional, horizontally directed compression before and during intrusion of large amounts of granitoids.

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