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.

A reinterpretation of the Archaean stratigraphy south of Nkandla, southern Kaapvaal Craton, South Africa: Geophysical and stratigraphic constraints on a sheared granitoid-greenstone remnant

2021 ◽  
Author(s):  
N. Hicks ◽  
D.J.C. Gold
Keyword(s):  
South Africa ◽  
Greenstone Belt ◽  
Shear Zones ◽  
Kaapvaal Craton ◽  
Iron Formation ◽  
Sedimentary Sequences ◽  
The North ◽  
Southeastern Margin ◽  
Domain 3 ◽  
Volcanic Succession

Abstract A new lithostratigraphic framework based upon a review of historic data, field mapping and remote sensing, including aerial photography, high-resolution airborne aeromagnetic and radiometric data, is proposed for the Archaean geology along the southeastern margin of the Kaapvaal Craton, South Africa. A synthesis of new and existing data reveals that previously accepted lithostratigraphic schemes require complete revision, with reinterpretations identifying multiple major shear zones and previously unidentified granitoid successions along the margin of the craton. In this new lithostratigraphic framework, lithologies of the Southern Syncline previously correlated with the Nsuze Group of the Pongola Supergroup, are redefined as greenstone lithologies associated with the Ilangwe Greenstone Belt. The geology of the Nkandla region can be subdivided into five distinct geophysical domains including: (i) an extension of the Ilangwe Greenstone Belt, (Domain 1) which is subdivided into; a lower volcanic succession, the Thathe Formation, comprising pillow and amygdaloidal volcanics; the adjoining Sabiza Formation, comprising pillow volcanics exposed in the southeast of the study area; the volcano-sedimentary Mtshwili Formation, which overlies the Thathe and Sabiza formations, consisting of quartz (sericite) schist, phyllite, metavolcanics and iron formation; the Nomangci Formation, which occurs as a region of highly deformed quartz-kyanite-sericite schists, and the Simbagwezi Formation, which comprises maroon to green phyllites and schists in the north of the study area. (ii) granitoids of the Impisi Granitoid Suite (Domain 2) which border the greenstone succession to the north, intruding the Nomangci and Simbagwezi formations. (iii) a southern complex of sheared granitoids termed the Umgabhi Granitoid Suite (Domain 3), which intrudes the Thathe, Sabiza and Mtshwili formations. (iv) The two remaining domains, comprise the Mesoproterozoic Mfongosi and Ntingwe Groups (Domain 4) and Mesoarchaean volcano-sedimentary sequences of the Pongola Supergroup (Domain 5).

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.

Contrasts in the response to dextral transpression across the Quetico–Wawa subprovince boundary in northeastern Minnesota

1990 ◽  
Vol 27 (11) ◽  
pp. 1521-1535 ◽  
Author(s):  
Robert L. Bauer ◽  
Matthew E. Bidwell
Keyword(s):  
Shear Strain ◽  
Greenstone Belt ◽  
Shear Zones ◽  
Iron Formation ◽  
Stress Regime ◽  
Regional Stress ◽  
Early Stages ◽  
Southern Margin ◽  
Deformation Regime ◽  
Dextral Shear

Folds and shear zones in the central and western Vermilion district greenstone belt (Wawa Subprovince) are consistent with deformation in a regime of regional dextral transpression. However, the shear strain associated with this deformation regime is only locally evident in the schist and migmatite of the adjacent southeastern Vermilion Granitic Complex (VGC) (Quetico Subprovince). We suggest that differential partitioning of shear and flattening strains between the two terranes was controlled by the lower ductility, higher competency contrast, and steeper dip of orogen-parallel rock units in the Vermilion district compared with the variably oriented rocks in the adjacent VGC. Contact strains adjacent to plutonic bodies played a greater role in the development of complex fold geometries in the VGC.In the central Vermilion district, northwest-directed subhorizontal shortening produced easterly striking zones of brittle-ductile dextral shear and northeast-trending en echelon folds. The en echelon folds with curvilinear axial traces formed in the greenstone and local iron formation layers. These units were steepened during folding and early stages of deformation and acted as rigid competent units during subsequent shearing. The shear zones were concentrated in units of tuff and graywacke between the more rigid, steeply dipping greenstone units.In the adjacent southeastern VGC, the same regional stress regime resulted primarily in folding with only rare indications of ductile dextral shear. The transpression event produced westerly trending F2 folds along the southern margin of the VGC. However, the F2 folds have more varied orientations along the margins of syntectonic to late-tectonic granitic plutons and were locally refolded by easterly trending F3 folds during continued northwest-directed shortening.

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.

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.

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.

Rubidium–strontium ages from the Oxford Lake – Knee Lake greenstone belt, northern Manitoba

1980 ◽  
Vol 17 (5) ◽  
pp. 560-568 ◽  
Author(s):  
G. S. Clark ◽  
S.-P. Cheung
Keyword(s):  
Greenstone Belt ◽  
Volcanic Rocks ◽  
Superior Province ◽  
Granitic Intrusion ◽  
Greenstone Belts ◽  
Archean Greenstone Belts

Rb–Sr whole-rock ages have been determined for rocks from the Oxford Lake – Knee Lake – Gods Lake greenstone belt, in the Superior Province of northeastern Manitoba.The age of the Magill Lake Pluton is 2455 ± 35 Ma (λ87Rb = 1.42 × 10−11 yr−1), with an initial 87Sr/86Sr ratio of 0.7078 ± 0.0043. This granitic stock intrudes the Oxford Lake Group, so it is post-tectonic and probably related to the second, weaker stage of metamorphism.The age of the Bayly Lake Pluton is 2424 ± 74 Ma, with an initial 87Sr/86Sr ratio of 0.7029 ± 0.0001. This granodioritic batholith complex does not intrude the Oxford Lake Group. It is syn-tectonic and metamorphosed.The age of volcanic rocks of the Hayes River Group, from Goose Lake (30 km south of Gods Lake Narrows), is 2680 ± 125 Ma, with an initial 87Sr/86Sr ratio of 0.7014 ± 0.0009.The age for the Magill Lake and Bayly Lake Plutons can be interpreted as the minimum ages of granitic intrusion in the area.The age for the Hayes River Group volcanic rocks is consistent with Rb–Sr ages of volcanic rocks from other Archean greenstone belts within the northwestern Superior Province.

A structural reappraisal of the Beardmore–Geraldton Belt at the southern boundary of the Wabigoon subprovince, Ontario, and implications for gold mineralization

2004 ◽  
Vol 41 (2) ◽  
pp. 217-235 ◽  
Author(s):  
Bruno Lafrance ◽  
Jerry C DeWolfe ◽  
Greg M Stott
Keyword(s):  
Gold Mineralization ◽  
Shear Zones ◽  
Axial Plane ◽  
Superior Province ◽  
Southern Boundary ◽  
Gold Mines ◽  
Southern Margin ◽  
Ore Zones

The Beardmore–Geraldton Belt occurs along the southern margin of the Archean Wabigoon subprovince, Superior Province, Ontario. The belt consists of shear-bounded interleaved metasedimentary and metavolcanic units. The units were imbricated from 2696 to 2691 Ma during D1 thrusting and accretion of the Wabigoon, Quetico, and Wawa subprovinces. Post-accretion D2 deformation produced regional F2 folds that transposed lithological units parallel to the axial plane S2 cleavage of the folds. During D3 deformation, the folds were overprinted by a regional S3 cleavage oriented anticlockwise of F2 axial planes, and lithological contacts and S2 cleavage were reactivated as planes of shear within dextral regional shear zones that generally conform to the trend of the belt. D3 is a regional dextral transpression event that also affected the Quetico and Wawa subprovinces, south of the Beardmore–Geraldton Belt. Gold mineralization at the Leitch and MacLeod-Cockshutt mines, the two richest past-producing gold mines in the Beardmore–Geraldton Belt, is associated with D3 shear zones and folds, overprinting regional F2 folds. The plunge of the ore zones is parallel to F3 fold axes and to the intersection of D3 shear zones with F2 and F3 folds.

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