Archean wrench fault tectonics and structural evolution of the Blake River Group, Abitibi Belt, Quebec

1984 ◽  
Vol 21 (9) ◽  
pp. 1024-1032 ◽  
Author(s):  
Claude Hubert ◽  
Pierre Trudel ◽  
Léopold Gélinas
Keyword(s):  
Volcanic Rocks ◽  
Structural Evolution ◽  
Shear Zones ◽  
Lateral Movement ◽  
Alpine Fault ◽  
San Andreas ◽  
Fault Tectonics ◽  
Tectonic System ◽  
Wrench Fault ◽  
East West

Structural analysis of the Blake River Group volcanic rocks in the Rouyn–Noranda region shows the formations to be distributed largely in Z shapes, resulting from the interference of two early fold systems oriented west-northwest–east-southeast and east–west, respectively. The first of these two fold systems is probably related to the shortening associated with left-lateral movement along the two major fractures in the region, namely the Porcupine–Destor and Larder Lake – Cadillac faults. The second system appears to be the result of north–south compression perpendicular to the two major fractures.The two major faults, the first system of early folding, the normal and reverse faults, and the minor dextral and sinistral strike-slip faults that have been observed in the Blake River Group rocks can all be integrated into one tectonic system, that of wrench fault tectonics. The orientations of the principal structures recognized in the Abitibi Belt (major shear zones, folding, and faulting) suggest that the deformation mechanism for the rocks in the belt could be a large lateral movement controlled by megashears similar to those observed at present on the California coast (San Andreas Fault), in New Zealand (Alpine Fault), and in Sumatra (Semangko Fault).

The geology and structure of the mid-crustal Wawa gneiss domain: a key to understanding tectonic variation with depth and time in the late Archean Abitibi–Wawa orogen

1994 ◽  
Vol 31 (7) ◽  
pp. 1064-1080 ◽  
Author(s):  
D. E. Moser
Keyword(s):  
Structural Evolution ◽  
Shear Zones ◽  
Fault Reactivation ◽  
Upper Crust ◽  
Middle Crust ◽  
Tectonic Events ◽  
Granulite Metamorphism ◽  
Stage 1 ◽  
Structural Levels ◽  
East West

The amphibolite-facies central Wawa gneiss domain (CWGD) preserves structures that developed at the mid-crustal level of the ca. 2.7 Ga Abitibi–Wawa orogen in the southern Superior Province. The relative ages of these domainal structures are documented and brackets on their absolute ages established using existing U–Pb age data. Correlation of tectonic events within the CWGD, and comparison of these events with the evolution of other structural levels of the orogen, has led to subdivision of orogenesis into five stages. During stage 1 (2700–2680 Ma), 2.9 and 2.7 Ga rocks were tightly folded and (or) thrusted at all crustal levels in at least one thick-skinned compression event. During stage 2 (2680–2670 Ma), folding and thrusting of Timiskaming-age sediments at high levels of the orogen was thin-skinned and had no effect on CWGD gneisses. During stage 3 (2670–2660 Ma), while the upper crust was relatively stable, a 1 km thick package of volcanics and sediments, the Borden Lake belt, was underthrust northwards to depths of 30 km and in-folded with orthogneiss of the CWGD. During stage 4 (2660–2637 Ma), coeval east–west extension and granulite metamorphism of the middle crust produced gently dipping shear zones that overprinted earlier fold structures in the CWGD and lower structural levels of the orogen. This took place with minimal effect on the upper crust. Stage 5 (2630–2580 Ma) marks a period of east–west shortening and (or) fault reactivation in the Kapuskasing uplift and upper-crustal greenstone belts that allowed penetration of deep-crustal metamorphic fluids into the latter. In general, analysis of the structural evolution of the CWGD indicates that deformation and metamorphism in the middle crust of the Abitibi–Wawa orogen outlasted that at upper-crustal levels, resulting in the generally shallower dips of planar fabrics in the deeper structural levels of the Kapuskasing uplift crustal cross section.

Structural evolution of the eastern Amisk collage, Trans-Hudson Orogen, Manitoba

1999 ◽  
Vol 36 (2) ◽  
pp. 251-273 ◽  
Author(s):  
James J Ryan ◽  
Paul F Williams
Keyword(s):  
Structural Evolution ◽  
Shear Zones ◽  
Detailed Structural Analysis ◽  
Vertical Extension ◽  
Deformational History ◽  
Flin Flon ◽  
Mountain Belts ◽  
Geochemical Studies ◽  
Early Late ◽  
East West

Deformation recorded in the Amisk collage in the central part of the Paleoproterozoic Flin Flon Belt (southeastern Trans-Hudson Orogen) is divided into pre-, early, late, and post-Hudsonian orogeny, distinguished by significant changes in metamorphic conditions and the orientation of structures. Detailed structural analysis, petrography, and high-precision geochronology, combined with previous mapping and geochemical studies, indicate a structural history spanning 180 Ma in the Amisk collage, and the database provides an excellent opportunity to study the structural evolution of Precambrian greenstone belts. Accretion of the 1.92-1.88 Ga tectono-stratigraphic assemblages in the Amisk collage began prior to 1.868 Ga. The deformational history records six generations of ductile structures (F1-F6), followed by development of brittle-ductile and brittle structures (F7), which may have continued as late as 1.690 Ga, during exhumation of the collage. The steep, generally north-northeast macroscopic structural grain is dominated by two regional foliations (S2 and S5), and contrasts strongly with the less steeply inclined, east-west grain in the adjacent Kisseynew Domain. Maximum displacements between tectono-stratigraphic assemblages occurred along early rather than late shear zones. Vertical extension was important in post-D1 deformations, even in the later stages. Postorogenic, low-angle extensional features that are common to many mountain belts appear to be absent, possibly indicating that erosion was the dominant unroofing mechanism.

Mafic igneous rocks and mineralisation in the Palaeoproterozoic Ketilidian orogen, South-East Greenland: project SUPRASYD 1996

1997 ◽  
pp. 66-74
Author(s):  
Henrik Stendal ◽  
Wulf Mueller ◽  
Nicolai Birkedal ◽  
Esben I. Hansen ◽  
Claus Østergaard
Keyword(s):  
Mineral Exploration ◽  
Volcanic Rocks ◽  
Shear Zones ◽  
Field Work ◽  
Igneous Rocks ◽  
Border Zone ◽  
The South ◽  
East Greenland ◽  
North West ◽  
Arc Setting

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Stendal, H., Mueller, W., Birkedal, N., Hansen, E. I., & Østergaard, C. (1997). Mafic igneous rocks and mineralisation in the Palaeoproterozoic Ketilidian orogen, South-East Greenland: project SUPRASYD 1996. Geology of Greenland Survey Bulletin, 176, 66-74. https://doi.org/10.34194/ggub.v176.5064 _______________ The multidisciplinary SUPRASYD project (1992–96) focused on a regional investigation of the Palaeoproterozoic Ketilidian orogenic belt which crosses the southern tip of Greenland. Apart from a broad range of geological and structural studies (Nielsen et al., 1993; Garde & Schønwandt, 1994, 1995; Garde et al., 1997), the project included a mineral resource evaluation of the supracrustal sequences associated with the Ketilidian orogen (e.g. Mosher, 1995). The Ketilidian orogen of southern Greenland can be divided from north-west to south-east into: (1) a border zone in which the crystalline rocks of the Archaean craton are unconformably overlain by Ketilidian supracrustal rocks; (2) a major polyphase pluton, referred to as the Julianehåb batholith; and (3) extensive areas of Ketilidian supracrustal rocks, divided into psammitic and pelitic rocks with subordinate interstratified mafic volcanic rocks (Fig. 1). The Julianehåb batholith is viewed as emplaced in a magmatic arc setting; the supracrustal sequences south of the batholith have been interpreted as either (1) deposited in an intra-arc and fore-arc basin (Chadwick & Garde, 1996), or (2) deposited in a back-arc or intra-arc setting (Stendal & Swager, 1995; Swager, 1995). Both possibilities are plausible and infer subduction-related processes. Regional compilations of geological, geochemical and geophysical data for southern Greenland have been presented by Thorning et al. (1994). Mosher (1995) has recently reviewed the mineral exploration potential of the region. The commercial company Nunaoil A/S has been engaged in gold prospecting in South Greenland since 1990 (e.g. Gowen et al., 1993). A principal goal of the SUPRASYD project was to test the mineral potential of the Ketilidian supracrustal sequences and define the gold potential in the shear zones in the Julianehåb batholith. Previous work has substantiated a gold potential in amphibolitic rocks in the south-west coastal areas (Gowen et al., 1993.), and in the amphibolitic rocks of the Kutseq area (Swager et al., 1995). Field work in 1996 was focused on prospective gold-bearing sites in mafic rocks in South-East Greenland. Three M.Sc. students mapped showings under the supervision of the H. S., while an area on the south side of Kangerluluk fjord was mapped by H. S. and W. M. (Fig. 4).

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