Paleomagnetic evidence for low-latitude glaciation during deposition of the Neoproterozoic Rapitan Group, Mackenzie Mountains, N.W.T., Canada

1997 ◽  
Vol 34 (1) ◽  
pp. 34-49 ◽  
Author(s):  
John K. Park
Keyword(s):  
Hydrothermal Activity ◽  
Iron Formation ◽  
Low Latitude ◽  
Northern Canada ◽  
Mackenzie Mountains ◽  
Study Development

The rift-related Rapitan Group of the Mackenzie Mountains of northwestern Canada acquired several magnetizations due to pulses of hydrothermal activity. The first pulse, attributed to initiation of Rapitan rifting, produced a widespread overprint (P2) that may be reflected in the basal Mount Berg Formation. Two later pulses produced overprints similar to components found in an earlier study. Development of iron formation and hematite pigment in the overlying Sayunei Formation is attributed to the second pulse, represented by a paleopole (N = 10 sites; 334°E, 01°S; δp, δm = 4°, 9°) that coincides with poles of the Franklin igneous events of northern Canada. The Franklin episode, suggested on geological grounds to be coeval with Sayunei deposition, dates the Sayunei at ca. 725 Ma. This relation implies that rifting in Mackenzie Mountains could be related to rifting in northern Canada. A third pulse, reflected by a pole at 007°E, 16°N (N = 6 sites; δp, δm = 6°, 12°), is attributed to final rifting during deposition of the Shezal Formation at the top of the Rapitan. Overprints attributed to Sayunei and Shezal times indicate regional latitudes of 6 ± 4° and 4 ± 6° during the Sturtian glaciation. During Mount Berg time, the regional latitude could have exceeded 25°. All directions have been tilt corrected and some have been then rotated, based on comparisons with a P2 reference overprint.

scholarly journals Metallogenic Evolution of the Mackenzie and Eastern Selwyn Mountains of Canada’s Northern Cordillera, Northwest Territories: A Compilation and Review

2013 ◽  
Vol 40 (1) ◽  
Author(s):  
Luke Ootes ◽  
Sarah A. Gleeson ◽  
Elizabeth Turner ◽  
Kirsten Rasmussen ◽  
Steve Gordey ◽  
...  
Keyword(s):  
Northwest Territories ◽  
Hanging Wall ◽  
Gold Deposits ◽  
Mineral Deposit ◽  
Iron Formation ◽  
Low Grade ◽  
Base Metals ◽  
Geologic History ◽  
Coal Deposits ◽  
Mackenzie Mountains

The Mackenzie and eastern Selwyn Mountains, Northwest Territories, Canada, are the northeast expression of the Cordilleran orogen and have a geologic history that spans the last one billion years. The region has undergone a diverse tectonic evolution, which is reflected in an equally diverse collection of mineral deposits and prospects. More than 300 of these deposits and prospects have been documented in this area of the Northwest Territories and here they are categorized into mineral deposit types and their mode of formation evaluated and highlighted. Stratiform/stratabound Cu-Ag occurrences are hosted in the Neoproterozoic Coates Lake Group, generally preserved in the hanging wall of the Cretaceous Plateau fault, and define a belt through the central part of the Mackenzie Mountains. Low-grade phosphatic stratiform iron (47.5% Fe) occurs as iron formation in the Neoproterozoic Rapitan Group in the very northwest of the Mackenzie Mountains. Sedimentary exhalative Zn-Pb (± Ba) deposits are preserved in Cambrian through Devonian strata of the Selwyn Basin in the eastern Selwyn Mountains. Numerous carbonate-hosted Zn-Pb (± base-metals) occurrences are located in the Paleozoic strata of the Mackenzie Platform in the Mackenzie Mountains. Cretaceous felsic-intermediate plutons, which occur throughout the eastern Selwyn Mountains, are associated with tungsten skarn (proximal to intrusions), base-metal skarn (distal from intrusions), rare metals, semi-precious tourmaline related to pegmatites, and vein-hosted emeralds. Other resources of potential interest include coal deposits, placer gold, and possible Carlin-type gold deposits that have recently been identified farther west in the Yukon.SOMMAIRELes monts Mackenzie et ceux de la chaîne orientale de Selwyn, dans les Territoires du Nord-Ouest, au Canada, sont l'expression au nord-est de l'orogène de la Cordillère, et leur histoire géologique s’étale sur le dernier milliard d’années. La région a été l’hôte d’une évolution tectonique diversifiée, et cela se reflète par une suite tout aussi diversifiée de gisements minéraux et d’indices prometteurs. Plus de 300 de ces dépôts et indices prometteurs ont été documentées dans cette région des Territoires du Nord-Ouest, et le présent article ils sont classés en types de gîtes minéraux, et l’attention est portée sur leur mode de formation. Les gisements de Cu-Ag stratiformes ou stratoïdes sont encaissés dans le Groupe néoprotérozoïque de Coates Lake, et ils sont généralement préservés dans l'éponte supérieure de la faille du plateau crétacé, et ils forment une bande qui traverse la partie centrale des monts Mackenzie. Le fer se retrouve dans des gisements phosphatées stratiformes à faible teneur (47,5% Fe) qui provient de formations de fer dans le Groupe néoprotérozoïque de Rapitan situé dans la pointe nord-ouest des monts Mackenzie. Des gisements sédimentaires exhalatifs de Zn-Pb (± Ba) sont préservés dans des strates cambriennes à dévoniennes du bassin de Selwyn dans la portion est des monts Selwyn. De nombreux indices de Zn-Pb (± métaux communs) dans des roches carbonatées des strates paléozoïques de la plate-forme de Mackenzie, des monts Mackenzie. Des plutons felsiques intermédiaires crétacés, qui pointent tout au long de la chaîne est de Selwyn, sont associées à des skarns de tungstène (proximaux), à des skarns de métaux communs (distaux), à des concentrations de métaux rares, de tourmaline semi-précieuses liés aux pegmatites, et à des émeraudes filoniennes. Parmi d’autres ressources d'intérêt, on retrouve des gisements de charbon, d'or alluvionnaire, et d’éventuels gisements d'or de type Carlin qui ont été découverts récemment plus à l'ouest au Yukon.

Stromatolites of the late Archean Back River stratovolcano, Slave structural province, Northwest Territories, Canada

1998 ◽  
Vol 35 (3) ◽  
pp. 290-301 ◽  
Author(s):  
M B Lambert
Keyword(s):  
Volcanic Ash ◽  
Microbial Mats ◽  
Local Environment ◽  
Hydrothermal Activity ◽  
Iron Formation ◽  
Explosive Eruptions ◽  
Volcanic Complex ◽  
Banded Iron Formation ◽  
Seaward Side ◽  
Back River

Nine stromatolite localities in the Back River volcanic complex occur at the boundary between 2692 Ma felsic dome-flow complexes, marking the latest eruptions of this stratovolcano, and overlying turbiditic sedimentary rocks of the Beechy Lake Group, Yellowknife Supergroup. Stromatolites form lenses isolated within coarse volcanic breccia at margins of felsic dome-flow complexes, and 2 m thick bioherms that extend laterally for hundreds of metres. Thin units contain wavy laminae and open-spaced, linked mounds, which form thin encrustations on breccia blocks, or clusters of mounds with low synoptic relief. Thick successions comprise undulatory, flat laminated dolomite that contains wrinkled wavy laminae, pseudocolumnar forms, and locally elongate, low-relief mounds. These units typically contain millimetre-scale layers of fine volcanic ash at regular intervals, testifying periodic explosive eruptions during deposition of microbial mats. The stromatolites, which are identified by gross morphology and distinctive laminae, are all stratiform types. Carbonate units all occur on the seaward side of the volcanic dome-flow complexes that straddled the shoreline around the volcano. The stromatolites probably represent isolated microbial communities that may have developed around areas of fumarolic (or hydrothermal) activity associated with these domes. Stratigraphy seaward from the domes comprises carbonate-cemented dome-flanking breccia, stromatolitic and oolitic carbonate, pebbly rhyolite volcarenite, carbonaceous mudstones, banded iron formation, and turbidites. Thus the stromatolites mark a local environment where life flourished in an Archean sea that lapped onto active volcanic domes along the shallow flanks of an emergent stratovolcano.

Concentration of gold during retrograde metamorphism of Archean banded iron formations, Slave Province, Canada

1993 ◽  
Vol 30 (8) ◽  
pp. 1566-1581 ◽  
Author(s):  
R. Craig Ford ◽  
Norman A. Duke
Keyword(s):  
Hydrothermal Activity ◽  
Gold Deposits ◽  
Iron Formation ◽  
Banded Iron Formations ◽  
High Background ◽  
Multistage Processes ◽  
Slave Province ◽  
Sulphide Precipitation ◽  
Iron Formations ◽  
Gold Bearing

Gold-bearing iron formations are widely distributed within extensive metasedimentary terranes of the Archean Slave Province, situated in the northwestern Canadian Precambrian Shield. Mineralized iron formations occur within thick turbidite sequences overprinted by a protracted history of deformation, metamorphism, and plutonism. Economically significant gold prospects are specifically sited at structural culminations characterized by polyphase folding. Based on garnet–biotite geothermometry on the stable prograde metamorphic assemblage of enveloping metapelites, peak metamorphic conditions are approximated to be 570 °C and 4 kbar (1 kbar = 100 MPa). Diagnostic prograde mineralogy reveals that two facies of silicate iron formation are represented at the five gold occurrences investigated: (1) amphibolitic iron formation (AIF), characterized by quartz + grunerite + hornblende + pyrrhotite ± garnet ± graphite + ilmenite, and (2) pelitic iron formation (PIF), consisting of quartz + biotite + garnet + ilmenite ± grunerite ± hornblende. Textures reveal that grunerite crystallization preceded hornblende and garnet. Within AIF, banded pyrrhotite is in textural equilibrium with prograde metamorphic minerals. Retrograde hornblende, garnet, zoisite, apatite, carbonate, ferroactinolite, and gold-bearing sulphide minerals replace the prograde mineral assemblages on the margins of quartz veins that intensify at AIF fold hinges.It is hypothesized that the iron-formation-hosted gold deposits of the Slave Province are a result of multistage processes. Gold concentrated at high background levels within pyrrhotite-bearing AIF was remobilized during fluid migration into brittle AIF fold hinges in subsequent metamorphic and deformational events. Metamorphic fluid, ponded in fractured AIF hinge domains, caused retrogressive replacement, quartz veining, and gold-bearing sulphide precipitation during waning temperature. Although the mineralized hinge zones commonly display evidence of late chloritization, this alteration did not further affect gold distribution. The gold precipitated with destabilization of thio complexes due to sulphidation prior to low-temperature hydrothermal activity.

A Multistage Genetic Model for the Metamorphosed Mesoproterozoic Swartberg Base Metal Deposit, Aggeneys-Gamsberg Ore District, South Africa

2020 ◽  
Vol 115 (5) ◽  
pp. 1021-1054 ◽  
Author(s):  
Tarryn Kim Cawood ◽  
Abraham Rozendaal
Keyword(s):  
South Africa ◽  
Genetic Model ◽  
Close Association ◽  
Hydrothermal Activity ◽  
Iron Formation ◽  
Fine Grained ◽  
Clastic Sediments ◽  
Mineral Assemblages ◽  
Stage 1 ◽  
Ore District

Abstract The polymetamorphosed Swartberg Cu-Pb-Zn-Ag deposit in the Namaqua Metamorphic Province of South Africa is a major metal producer in the region, yet its genesis remains poorly understood. The deposit comprises several stratiform to stratabound units, namely the Lower Orebody and Dark Quartzite, the overlying Barite Unit, and the Upper Orebody, all of which are folded by an F2 isoclinal syncline and refolded by an open F3 synform. A discordant Garnet Quartzite unit surrounds the Upper Orebody in the F2 hinge, where it overprints the Lower Orebody and Barite Unit. The Lower Orebody comprises sulfidic, pelitic lenses with fine-grained pyrite, sphalerite, galena, and lesser pyrrhotite, hosted by sulfide-poor but magnetite- and barite-bearing siliceous rock. The overlying Barite Unit is poorly mineralized and grades from massive magnetite-barite close to the F2 hinge to distal laminated baritic schist and quartzite. The Dark Quartzite is the stratigraphic equivalent of the Lower Orebody and Barite Unit but comprises siliceous quartzite and schist, with lenses of conglomerate and minor Fe-Mn-Zn phases. The Upper Orebody displays rapid zonations from massive magnetite-rich iron formation in the F2 hinge, rich in coarse galena, pyrrhotite, and chalcopyrite, to sulfide-poor, magnetite-bearing schist and quartzite. The Garnet Quartzite is dominated by quartz and almandine garnet and mineralized with pyrite and chalcopyrite. Geochemical discriminant plots show that the Lower Orebody has a significant detrital component, whereas the Upper Orebody and Barite Unit are strongly zoned, with the greatest chemogenic component close to the F2 hinge. This corresponds to a deposit-scale metal zonation from the Cu-rich F2 hinge to more Pb- and then Zn-dominated areas. Mineral assemblages and paleoredox proxies suggest generally oxic conditions, with a more reduced signature close to the hinge and in the sulfidic Lower Orebody lenses. The Lower Orebody is interpreted as a mixed chemogenic-pelitic unit, with sulfides deposited on or near the seafloor during stage 1 hydrothermal activity. The sulfidic lenses formed from fine mud and clay deposited in quiet seafloor depressions, in which warm, dense, reducing, Pb-Zn-Ba–rich stage 1 brines accumulated, while the siliceous portions formed from higher-energy clastic sediments on aerated seafloor highs. The Barite Unit forms a baritic cap to the Lower Orebody, while the Dark Quartzite is their shallower-water equivalent. Thereafter, clastic sediment with lesser hydrothermal input was deposited during stage 2a exhalations, forming the poorly mineralized portions of the Upper Orebody. During stage 2b hydrothermal activity, hot Cu-Fe–rich fluids invaded part of the Upper Orebody, creating the highly chemogenic protolith to the well-mineralized, magnetite-rich portion. Associated hydrothermal alteration in a discordant subseafloor feeder zone created the Garnet Quartzite protolith. The F2 hinge thus corresponds closely to the original vent zone. Swartberg therefore resembles a deformed and metamorphosed Selwyn-type sedimentary exhalative deposit, with both proximal- (Upper Orebody, Garnet Quartzite) and distal-style (Lower Orebody) mineralization. The close association of these styles suggests that differences in the mineralizing fluids and depositional environment, rather than proximity to a vent, determine the deposit style.

Late Proterozoic stratigraphy, U–Pb zircon ages, and rift tectonics, Mackenzie Mountains, northwestern Canada

1989 ◽  
Vol 26 (9) ◽  
pp. 1784-1801 ◽  
Author(s):  
C. W. Jefferson ◽  
R. R. Parrish
Keyword(s):  
Climatic Change ◽  
Quartz Diorite ◽  
Iron Formation ◽  
Late Proterozoic ◽  
Windermere Supergroup ◽  
Lead Zinc ◽  
Mackenzie Mountains ◽  
Stratiform Copper Deposits ◽  
Fault Scarps ◽  
Red Bed

Stratigraphic evidence suggests sporadic rifting began during deposition of the mainly platformal Mackenzie Mountains Supergroup: minor magnetite iron-formation in shale basins, lead–zinc in karsted and brecciated carbonates, red-bed and evaporite wedges, and basalts at the top. In the unconformably overlying Coates Lake Group similar climates and definite rifting are recorded by thin orthoconglomerates with thick red-bed and evaporite wedges containing stratiform copper deposits in paleovalleys. Unconformably above this, basal Windermere Supergroup records major climatic change and more emphatic rifting, with thick orthoconglomerates next to fault scarps overlain by glaciomarine deposits with volcanics and hydrothermal iron-formation.A quartz diorite plug, here dated by the U–Pb zircon method at [Formula: see text], is bounded by faults but is contained in a thrust panel together with Mackenzie Mountains Supergroup and is chemically similar to diabase sills previously dated at 766–769 ± 27 Ma (Rb–Sr). A diatreme intruding Coates Lake Group contains clasts of granite and gneiss from inferred basement. U–Pb systematics from a granite clast indicate inherited zircons about 1.6 ± 0.25 Ga in age and crystallization between 1100 and 1175 Ma, a maximum age for Mackenzie Mountains Supergroup.

Air transport in northern Canada

Polar Record ◽  
1971 ◽  
Vol 15 (97) ◽  
pp. 495-498 ◽  
Author(s):  
Joe Courtney
Keyword(s):  
New Technology ◽  
Air Transport ◽  
Resource Potential ◽  
Northern Canada ◽  
Drilling Equipment ◽  
Pack Ice ◽  
Land Surveying ◽  
Mackenzie Mountains ◽  
Northern Alberta

Aviation is playing an increasingly important role in developing the resource potential of northern Canada. It is the most common means of supplying the oil rigs on Melville Island, the mining camps in the Mackenzie Mountains, and the meteorological stations on the pack ice. New technology has increased both capability and capacity. Pipe and drilling equipment can now be flown non-stop from southern Canada to airfields on the Queen Elizabeth Islands; helicopters able to carry two tons then distribute the equipment to well sites. Very rapid and precise land surveying can be conducted using the Bell Jet Ranger helicopter. Recently, a 16 640 km2 region of northern Alberta was surveyed in less than five days.

Geology and geochemistry of the Yuanjiacun banded iron formation in Shanxi Province, China: constraints on the genesis

2019 ◽  
Vol 156 (11) ◽  
pp. 1839-1862
Author(s):  
Yekai Men ◽  
Ende Wang ◽  
Jianfei Fu ◽  
Sanshi Jia ◽  
Xinwei You ◽  
...  
Keyword(s):  
Tectonic Setting ◽  
Hydrothermal Activity ◽  
Hydrothermal Fluids ◽  
Shanxi Province ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Margin Setting ◽  
Oxidation Reduction ◽  
Magnetite Quartzite ◽  
High Maturity

AbstractThe Yuanjiacun banded iron formation (BIF) is hosted in lower Proterozoic metamorphic strata, and its structures are dominated by bands or streaks. Based on their differences in mineral compositions, the iron ores can be subdivided into haematite quartzite, magnetite quartzite, stilpnomelane magnetite quartzite and stilpnomelane haematite quartzite. The geochemical characteristics of the surrounding rocks show that the protoliths consisted of argillaceous and arenaceous sedimentary rocks. The predominant provenance was a high-maturity felsic sedimentary terrane. The absence of syn-depositional igneous rocks and the tectonic setting discrimination diagrams indicate that the Yuanjiacun BIF formed in a passive continental margin setting. Negligible terrigenous materials were involved in the precipitation of the Yuanjiacun BIF. The precipitation of the Yuanjiacun BIF was predominantly controlled by the mixing of seawater and hydrothermal fluids. Its metallogenic material originated from the leaching of mafic oceanic crust by hydrothermal fluids. The observed Ce anomaly deficiency and heavy Fe isotope enrichment indicate that the Yuanjiacun BIF formed in an anoxic marine environment. In a redox-stratified palaeo-ocean, the Yuanjiacun BIF formed in reducing seawater below the oxidation–reduction transition zone. The Si and O isotope compositions of quartz suggest that the formation of the Yuanjiacun BIF was closely related to submarine hydrothermal activity. The Si and Fe erupted from the seafloor and precipitated by supersaturation and biological oxidation under anoxic conditions, respectively.

Early and Middle Proterozoic evolution of Yukon, Canada

2005 ◽  
Vol 42 (6) ◽  
pp. 1045-1071 ◽  
Author(s):  
Derek J Thorkelson ◽  
J Grant Abbott ◽  
James K Mortensen ◽  
Robert A Creaser ◽  
Michael E Villeneuve ◽  
...  
Keyword(s):  
Hydrothermal Activity ◽  
Igneous Rocks ◽  
Isotopic Data ◽  
Zircon Age ◽  
Depleted Mantle ◽  
Windermere Supergroup ◽  
Bear River ◽  
Mackenzie Mountains ◽  
Hydrothermal Event ◽  
Middle Proterozoic

This paper provides a comprehensive synthesis of virtually all units and events of Early and Middle Proterozoic age in the Yukon, spanning ~1 Ga. Early and Middle Proterozoic time was dominated by a series of extensional-basin-forming events punctuated by orogenesis, magmatism, and hydrothermal activity. Basinal deposits include the Wernecke Supergroup (>1.71 Ga), Pinguicula Group (~1.38 Ga), and Mackenzie Mountains Supergroup (1.00–0.78 Ga). Igneous rocks include the Bonnet Plume River Intrusions (1.71 Ga), Slab volcanics (≥1.6 Ga), Hart River sills and volcanics (1.38 Ga), and Bear River (Mackenzie) dykes (1.27 Ga). A voluminous hydrothermal event generated the widespread Wernecke breccias at 1.60 Ga. The Racklan orogeny deformed the Wernecke Supergroup prior to emplacement of the Wernecke Breccia. The Corn Creek orogeny deformed Mackenzie Mountains Supergroup and older rocks prior to deposition of the Windermere Supergroup (<0.78 Ga). Long intervals with scanty rock records extended for as much as 300 Ma and appear to represent periods of crustal stability and subaerial conditions. By the time of Windermere rifting (<0.78 Ga), the supracrust of northwestern Laurentia was a mature, largely denuded orogenic belt with a composite sedimentary–metamorphic–igneous character. New isotopic data include Nd depleted mantle model ages for the Wernecke Supergroup (2.28–2.69 Ga) and Wernecke Breccia (2.36–2.96 Ga), a U–Pb zircon age for a Hart River sill 1381.9+5.3-3.7 (Ma), detrital U–Pb zircon ages from the basal Pinguicula Group (1841–3078 Ma), detrital muscovite ages from the Mackenzie Mountains Supergroup (1037–2473 Ma), and muscovite 40Ar/39Ar cooling ages from the Wernecke Supergroup (788 ± 8 and 980 ± 4 Ma).

New cheirurinid trilobites from the lower Whittaker Formation (Ordovician), southern Mackenzie Mountains

1976 ◽  
Vol 13 (7) ◽  
pp. 947-959 ◽  
Author(s):  
Rolf Ludvigsen
Keyword(s):  
New Species ◽  
Late Ordovician ◽  
New Genera ◽  
Monotypic Genus ◽  
Northern Canada ◽  
Mackenzie Mountains ◽  
Anticosti Island ◽  
Early Late

Two new genera of cheirurinid trilobites are described from the lower Whittaker Formation (?Rocklandian to Edenian; late Middle and early Late Ordovician) of the southern Mackenzie Mountains. The monotypic genus, Whittakerites n. gen., is a probable descendant of Ceraurus and is presently known only from northern Canada. Borealaspis n. gen. is established for two species from northern Canada, one of which possibly occurs in northern Greenland, and includes B. numitor (Billings) from Anticosti Island. New species described are Whittakerites planatus, Borealaspis whittakerensis, and B. biformis.

Progress report on 21-cm observations at low latitude between longitudes (l 11) 0° and 66°

1967 ◽  
Vol 31 ◽  
pp. 177-179
Author(s):  
W. W. Shane
Keyword(s):  
Preliminary Report ◽  
Progress Report ◽  
Galactic Centre ◽  
Low Latitude ◽  
The Third ◽  
Introductory Lecture ◽  
Centre Region

In the course of several 21-cm observing programmes being carried out by the Leiden Observatory with the 25-meter telescope at Dwingeloo, a fairly complete, though inhomogeneous, survey of the regionl11= 0° to 66° at low galactic latitudes is becoming available. The essential data on this survey are presented in Table 1. Oort (1967) has given a preliminary report on the first and third investigations. The third is discussed briefly by Kerr in his introductory lecture on the galactic centre region (Paper 42). Burton (1966) has published provisional results of the fifth investigation, and I have discussed the sixth in Paper 19. All of the observations listed in the table have been completed, but we plan to extend investigation 3 to a much finer grid of positions.

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