Sedimentary and structural evidence for 2.7 Ga continental arc–oceanic-arc collision in the Savant–Sturgeon greenstone belt, western Superior Province, Canada

2006 ◽  
Vol 43 (7) ◽  
pp. 995-1030 ◽  
Author(s):  
M Sanborn-Barrie ◽  
T Skulski
Keyword(s):  
Continental Margin ◽  
Volcanic Rocks ◽  
Shear Zones ◽  
Iron Formation ◽  
Superior Province ◽  
Geophysical Surveys ◽  
Winnipeg River ◽  
Minimum Age ◽  
The Rich ◽  
Oceanic Rocks

The western Superior Province sustained rapid crustal growth in the interval 2.72–2.68 Ga through amalgamation of microcontinental crustal blocks and juvenile oceanic terranes. Recent field, isotopic, and geophysical surveys provide insight on the nature, timing, and scale of this accretionary growth. However, few places offer the rich tectono-stratigraphic and structural detail with which to establish accretion of oceanic and continental blocks as does the Savant–Sturgeon area. Here, 3.4–2.8 Ga continental crust of the Winnipeg River terrane is juxtaposed with 2.775–2.718 Ga juvenile oceanic rocks of the western Wabigoon terrane across a 2.85–2.75 Ga, southwest-facing, continental margin sequence. The continental margin was reactivated at ~2.715 Ga with the establishment of an arc, recorded by 2.715–2.70 Ga tonalite and associated intermediate volcanic rocks. This magmatic activity is interpreted to reflect north- and east-dipping subduction that led to consumption of a small tract of oceanic crust between the Winnipeg River and western Wabigoon terranes, ultimately leading to their amalgamation after 2.703 Ga. The telescoped fore arc also includes continental-derived turbiditic wacke, siltstone, and iron formation (Warclub assemblage) that are in tectonic contact with diverse oceanic rocks of the western Wabigoon terrane. Collision is bracketed between 2.703 Ga (the maximum age of marine fore arc deposits) and ~2.696 Ga (the minimum age of a late-tectonic pluton). Effects include thrust stacking and the development of shallow-plunging folds and bedding-parallel fabrics (D1), overprinted by steeply plunging inclined folds, steep foliations, and shear zones (D2). Collectively, these structures have penetratively reworked the suture between the ancient fore-arc and oceanic rocks in the Savant–Sturgeon area.

Stratigraphy, structure, and geochronology of the 3.0–2.7 Ga Wallace Lake greenstone belt, western Superior Province, southeast Manitoba, Canada

2006 ◽  
Vol 43 (7) ◽  
pp. 929-945 ◽  
Author(s):  
C Sasseville ◽  
K Y Tomlinson ◽  
A Hynes ◽  
V McNicoll
Keyword(s):  
Greenstone Belt ◽  
Volcanic Rocks ◽  
Crustal Contamination ◽  
Shear Zones ◽  
Iron Formation ◽  
Superior Province ◽  
Lake Winnipeg ◽  
The North ◽  
Southern Margin ◽  
Plume Magmatism

In western Superior province, the North Caribou terrane (NCT) constitutes a Mesoarchean proto-continent heavily overprinted by Neoarchean magmatism and deformation resulting from the western Superior Province accretion. Locally, along the southern margin of the NCT, Mesoarchean (~3.0 Ga) rift sequences are preserved. These sequences are of key importance to our understanding of the early tectonic evolution of continental crust. The Wallace Lake greenstone belt is located at the southern margin of the NCT and includes the Wallace Lake assemblage, the Big Island assemblage, the Siderock Lake assemblage, and the French Man Bay assemblage. The Wallace Lake assemblage exposes one of the best-preserved Mesoarchean rift sequences along the southern margin of the NCT. The volcano-sedimentary assemblage (3.0–2.92 Ga) exposes arkoses derived from the uplift of a tonalite basement in a subaqueous environment, capped by carbonate and iron formation. Mafic to ultramafic volcanic rocks exhibiting crustal contamination and derived from plume magmatism cap this rift sequence. The Wallace Lake assemblage exhibits D1 Mesoarchean deformation. The Big Island assemblage comprises mafic volcanic rocks of oceanic affinity that were docked to the Wallace Lake assemblage along northwest-trending D2 shear zones. The timing of volcanism and docking of the Big Island assemblage remain uncertain. The Siderock Lake and French Man Bay assemblages were deposited in strike-slip basins related to D3 and D4 stages of movement of the transcurrent Wanipigow fault (<2.709 Ga). Regionally, the Wallace Lake assemblage correlates with the Lewis–Story Rift assemblage observed in Lake Winnipeg, whereas the Big Island assemblage appears to correlate with the Black Island assemblage observed in the Lake Winnipeg area. Thus, the North Caribou terrane appears to preserve vestiges of a Mesoarchean rifted succession together with overlying Neoarchean allochthonous, juvenile, volcanic successions over a considerable distance along its present-day southern margin.

Geological evolution of the northwestern Superior Province: Clues from geology, kinematics, and geochronology in the Gods Lake Narrows area, Oxford–Stull terrane, Manitoba

2006 ◽  
Vol 43 (7) ◽  
pp. 749-765 ◽  
Author(s):  
S Lin ◽  
D W Davis ◽  
E Rotenberg ◽  
M T Corkery ◽  
A H Bailes
Keyword(s):  
Large Scale ◽  
Volcanic Rocks ◽  
Shear Zones ◽  
Superior Province ◽  
Continental Margins ◽  
The North ◽  
Geological Evolution ◽  
Southern Half ◽  
Andean Type ◽  
Tectonic Interpretation

The study of lithology, geochronology, and structure in the Oxford–Stull terrane, in particular in the Gods Lake Narrows area, has led to the recognition of three distinct supracrustal sequences: ~2.8–2.9 Ga volcanic rocks; a ~2720 Ma fault-bounded package of volcanics and sandstones; and ~2705 Ma conglomerate and alkaline volcanic rocks of the Oxford Lake Group. Detrital zircon as old as 3647 Ma is present in the Oxford Lake Group. An early generation of folding and shearing occurred prior to deposition of the Oxford Lake Group and was probably synchronous with emplace ment of 2721 Ma tonalite dykes. The second generation of deformation caused south-over-north thrusting of volcanic rocks over the Oxford Lake Group. The youngest fabric resulted from east-southeast-trending, dextral, south-over-north shearing. The youngest rock dated in the area is the 2668 ± 1 Ma Magill Lake pluton, which records crustal melting following deformation. The pattern of sedimentation and deformation in this area is similar to but slightly older than that found in the southern half of the Superior Province, which shows a southward-younging diachroneity. The south-dipping north-vergent shear zones observed in the area contrast with dominantly north-dipping south-vergent structures observed and interpreted south of the North Caribou superterrane (NCS). The limited size of the study area precludes any strongly based large-scale tectonic interpretation; however, data and observations from the Gods Lake Narrows area are most easily accommodated in a model where the NCS served as a nucleus onto which other terranes were accreted and both the northern and southern margins of the NCS were Andean-type continental margins with opposite subduction polarities.

The Kapuskasing uplift: a geological and geophysical synthesis

1994 ◽  
Vol 31 (7) ◽  
pp. 1256-1286 ◽  
Author(s):  
John A. Percival ◽  
Gordon F. West
Keyword(s):  
Greenstone Belt ◽  
Volcanic Rocks ◽  
Gravity Anomalies ◽  
Shear Zones ◽  
Local Deformation ◽  
Gold Deposition ◽  
Superior Province ◽  
Low Grade ◽  
Geophysical Investigation ◽  
Complex Deformation

Over the past decade, the Kapuskasing uplift has been the subject of intense geological and geophysical investigation as Lithoprobe's window on the deep-crustal structure of the Archean Superior Province. Enigmatic since its recognition as a positive gravity anomaly in 1950, the structure has been variably interpreted as a suture, rift, transcurrent shear zone, or intracratonic thrust. Diverse studies, including geochronology, geothermobarometry, and various geophysical probes, provide a comprehensive three-dimensional image of Archean (2.75–2.50 Ga) crustal evolution and Proterozoic (2.5–1.1 Ga) cooling and uplift. The data favour an interpretation of the structure as an intracratonic uplift related to Hudsonian collision.Eastward across the southern Kapuskasing uplift, erosion levels increase from < 10 km in the Michipicoten greenstone belt, through the Wawa gneiss domain (10–20 km), into granulites (20–30 km) of the Kapuskasing structural zone, juxtaposed against the low-grade Swayze greenstone belt along the Ivanhoe Lake fault zone. Most volcanic rocks in the greenstone belts erupted in the interval 2750–2700 Ma and were thrust, folded, and cut by late plutons and transcurrent faults before 2670 Ma. Wawa gneisses include major 2750–2660 and minor 2920 Ma tonalitic components, deformed in several events including prominent late subhorizontal extensional shear zones prior to 2645 Ma. Supracrustal rocks of the Kapuskasing zone have model Nd ages of 2750–2700 Ma, metamorphic zircon ages of 2696–2584 Ma, and titanite ages of 2600–2493 Ma, reflecting deposition, intrusion, complex deformation, recrystallization, and cooling during prolonged deep-crustal residence. Postorogenic unroofing rapidly cooled shallow (10–20 km) parts of the Superior Province, but metamorphism and local deformation continued in the ductile deep crust, overlapping the time of late gold deposition in shear zones in the shallow brittle regime.Elevation of granulites, expressed geophysically as positive gravity anomalies and a west-dipping zone of high refraction velocities, dates from a major episode of transpressive faulting. Analysis of deformation effects in Matachewan (2454 Ma), Biscotasing (2167 Ma), and Kapuskasing (2040 Ma) dykes, as well as the brittle nature of fault rocks and cooling patterns of granulites, constrains the time of uplift to ca, 1.9 Ga. Approximately 27 km of shortening was accommodated through brittle upper crustal thrusting and ductile growth of an 8 km thick root in the lower crust that has been maintained by relatively cool, strong mantle lithosphere. The present configuration of the uplift results from overall dextral displacement in which the block was broken and deformed by dextral, normal, and sinistral faults, and modified by later isostatic adjustment. Seismic reflection profiles display prominent northwest-dipping reflectors believed to image lithological contacts and ductile strain zones of Archean age; the indistinct reflection character of the Ivanhoe Lake fault is probably related to its brittle nature formed through brecciation and cataclasis at temperatures < 300 °C. The style and orientation of Proterozoic structures may have been influenced by the Archean crustal configuration.

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.

Pickle Lake revisited: New structural, geochronological and geochemical constraints on greenstone belt assembly, western Superior Province, Canada

2006 ◽  
Vol 43 (7) ◽  
pp. 821-847 ◽  
Author(s):  
M D Young ◽  
V McNicoll ◽  
H Helmstaedt ◽  
T Skulski ◽  
J A Percival
Keyword(s):  
Greenstone Belt ◽  
Volcanic Rocks ◽  
Tholeiitic Basalt ◽  
Pyroclastic Flows ◽  
Iron Formation ◽  
Geochemical Data ◽  
Superior Province ◽  
Isotopic Compositions ◽  
Isotopic Analyses ◽  
Two Samples

New field work, U–Pb ages, geochemical data, and Sm–Nd isotopic analyses have established the timing and determined the nature of volcanism, deformation, and tectonic assembly of the Pickle Lake greenstone belt in the Uchi subprovince of the western Superior Province of the Canadian Shield. The >2860 Ma Pickle Crow assemblage has been redefined to include the former Northern Pickle assemblage on the basis of stratigraphic continuity and similar volcanic geochemistry between the two units across a previously inferred fault contact. The Pickle Crow assemblage consists of tholeiitic basalt with thin, but laterally extensive, oxide-facies iron formation overlain by alkalic basalts and minor calc-alkaline andesites to dacites with primitive Nd isotopic compositions (εNd2.89 Ga = +2.1 to +2.4) suggestive of deposition in a sediment-starved oceanic basin. The ~2 km thick ~2836 Ma Kaminiskag assemblage (former Woman assemblage) consists of tholeiitic basalt interbedded with intermediate and rare felsic pyroclastic flows with primitive Nd isotopic compositions (εNd2.836 Ga = +2.4). Two samples of intermediate volcanic rocks interbedded with southeast-younging pillowed basalt, previously inferred to be part of the Pickle Crow assemblage, yielded U–Pb zircon ages of 2744 [Formula: see text] Ma and 2729 ± 3 Ma. These rocks are thus part of the younger Confederation assemblage, which consists of intercalated basalt and dacite (εNd2.74 Ga = +0.1 to +0.8) exhibiting diverse compositions probably reflecting eruption in a continental margin arc to back-arc setting. The contact between the Confederation and Kaminiskag assemblages is assumed to be a fault. The greenstone belt is intruded by late syn- to posttectonic plutons including the composite quartz dioritic to gabbroic July Falls stock with a new U–Pb zircon age of 2749 [Formula: see text] Ma, and the ~2741 to 2740 Ma trondhjemitic to granodioritic Ochig Lake pluton and Pickle Lake stock, as well as the ~2697 to 2716 Ma Hooker–Burkoski stock. The earliest recognized deformation (D1) is recorded by a local bedding-parallel foliation in the Pickle Crow assemblage. This foliation is truncated by the ~2735 Ma Albany quartz–feldspar porphyry dyke and is not recognized in the volcanic rocks of the Confederation assemblage. The early deformation event is attributed to overturning of the Pickle Crow assemblage prior to deposition of the ~2744 to 2729 Ma Confederation assemblage. Subsequent deformation and development of a regionally penetrative planar fabric (S2) postdates ~2729 Ma volcanism, pre-dates the intrusion of the ca. <2716 Ma Hooker–Burkoski stock and is host to gold mineralization.

Strike-slip juxtaposition of ca. 2.72 Ga juvenile arc and >2.98 Ga continent margin sequences and its implications for Archean terrane accretion, western Superior Province, Canada

2006 ◽  
Vol 43 (7) ◽  
pp. 895-927 ◽  
Author(s):  
J A Percival ◽  
V McNicoll ◽  
A H Bailes
Keyword(s):  
Strike Slip ◽  
Iron Formation ◽  
Superior Province ◽  
Arc Magmatism ◽  
Calc Alkaline ◽  
Lake Winnipeg ◽  
Red Lake ◽  
The North ◽  
Winnipeg River ◽  
Terrane Accretion

The North Caribou terrane of the western Superior Province attained continental thickness (~35 km) by 2997 Ma. It records a subsequent 300 million years history of continental fragmentation, arc magmatism, and terrane accretion. At Lake Winnipeg the ~2978 Ma Lewis–Storey quartzite–komatiite–iron formation assemblage marks Mesoarchean breakup. Unlike the relatively continuous 2980–2735 Ma stratigraphic record of the Red Lake and Birch–Uchi greenstone belts to the east, little of this interval is recorded at Lake Winnipeg. Rather, two belts of younger, juvenile rocks are tectonically juxtaposed: the Black Island assemblage of isotopically depleted, 2723 Ma basalt, and calc-alkaline andesite; and Rice Lake greenstone belt of basalt, calc-alkaline andesite, and dacite (2731–2729 Ma). Collectively these terranes represent a short-lived island-arc–back-arc system that docked with the southwestern North Caribou margin along a northwest-trending, dextral, transpressive, D1 suture. This zone is marked by the highly deformed coarse clastic Guano Island sequence (<2728 Ma) that contains detritus of North Caribou affinity and is interpreted as a strike-slip basin deposit. Younger clastic sequences, including the Hole River (<2708 Ma), San Antonio (<2705 Ma), and English River (<2704 Ma) assemblages, occur in east–west belts that may have been deposited during the terminal collision (D2, D3) between the North Caribou terrane and continental crust of the Winnipeg River terrane to the south. Several terrane docking events within a framework of north-dipping subduction and continental arc magmatism appear necessary to explain structural and stratigraphic relationships in the 2735–2700 Ma interval.

Structural features and some metallogenic patterns in the southern part of the Superior Province, Canada

1968 ◽  
Vol 5 (5) ◽  
pp. 1199-1208 ◽  
Author(s):  
J. Kalliokoski
Keyword(s):  
Volcanic Rocks ◽  
Metal Sulfide ◽  
Structural Features ◽  
Ore Deposits ◽  
Iron Formation ◽  
Superior Province ◽  
Metasedimentary Rocks ◽  
Sulfide Ore ◽  
Eastern Ontario ◽  
Broad Region

In the southern part of the Superior Province of the Canadian Shield the Quetico belt of metasedimentary rocks extends northeasterly from Minnesota, across the Kapuskasing zone of crustal rifting, to southeast of James Bay. The belt forms part of a broader northeasterly-trending orogenic zone, and truncates the more westerly fold trends in the lavas and sedimentary rocks of eastern Ontario and western Quebec. It is suggested that the Quetico trend is the younger, and that the Quetico belt demarcates the geographic limits of the Kenoran orogen.In western Quebec and eastern Ontario three granite-cored massifs are bounded on their northern flanks by curved, regional faults and synclinal belts of metasedimentary rocks. The most important of these, the Pontiac Massif, is associated with a corresponding sediment-filled depression on the west.A broad region extending easterly and northeasterly from Lake Superior can be distinguished from contiguous areas on the basis of the abundance and extent of belts of iron-formation, many of these associated with acid volcanic rocks. It is proposed that these rocks were formed either in a restricted period of time or in a restricted volcanic-sedimentary environment.Massive, stratabound, pyritic base-metal sulfide ore deposits are most abundant in pre-Quetico rocks. They do not seem to be related to the processes associated with the deposition of abundant iron-formation.

A new volcanic province: evidence from glacial erratics in western North Greenland

2000 ◽  
pp. 35-41 ◽  
Author(s):  
Peter R. Dawes ◽  
Bjørn Thomassen ◽  
T.I. Hauge Andersson
Keyword(s):  
Volcanic Rocks ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Common Component ◽  
Volcanic Province ◽  
North West ◽  
North East ◽  
The North ◽  
Surficial Deposits ◽  
North Greenland

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Dawes, P. R., Thomassen, B., & Andersson, T. H. (2000). A new volcanic province: evidence from glacial erratics in western North Greenland. Geology of Greenland Survey Bulletin, 186, 35-41. https://doi.org/10.34194/ggub.v186.5213 _______________ Mapping and regional geological studies in northern Greenland were carried out during the project Kane Basin 1999 (see Dawes et al. 2000, this volume). During ore geological studies in Washington Land by one of us (B.T.), finds of erratics of banded iron formation (BIF) directed special attention to the till, glaciofluvial and fluvial sediments. This led to the discovery that in certain parts of Daugaard-Jensen Land and Washington Land volcanic rocks form a common component of the surficial deposits, with particularly colourful, red porphyries catching the eye. The presence of BIF is interesting but not altogether unexpected since BIF erratics have been reported from southern Hall Land just to the north-east (Kelly & Bennike 1992) and such rocks crop out in the Precambrian shield of North-West Greenland to the south (Fig. 1; Dawes 1991). On the other hand, the presence of volcanic erratics was unexpected and stimulated the work reported on here.

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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