Geoelectric structure of the Proterozoic Wopmay Orogen and adjacent terranes, Northwest Territories, Canada

2005 ◽  
Vol 42 (6) ◽  
pp. 955-981 ◽  
Author(s):  
Xianghong Wu ◽  
Ian J Ferguson ◽  
Alan G Jones
Keyword(s):  
Northwest Territories ◽  
Sedimentary Rocks ◽  
Lithospheric Structure ◽  
Uppermost Mantle ◽  
Slave Craton ◽  
Western Margin ◽  
Northern Canada ◽  
Magmatic Arc ◽  
Ductile Shearing

Magnetotelluric (MT) soundings were made along a transect in northern Canada crossing the Proterozoic Wopmay Orogen, Fort Simpson basin, and adjacent parts of the Slave craton and the Nahanni terrane. The results are used to define the geoelectric structure and constrain the crustal and lithospheric structure and evolution. Across the Wopmay Orogen, geoelectric strikes at crustal depths average N34°E and are interpreted to be related to transcurrent faulting that occurred during late distal collisions at the western margin of the orogen. Weak two-dimensionality in the Fort Simpson basin is interpreted to be due to the sedimentary rocks in the basin. At longer periods, geoelectric strikes across the Wopmay Orogen rotate from ∼N43°E at uppermost mantle penetration to ∼N62°E at a depth of 100 km. The uppermost mantle strikes are interpreted to be due to ductile shearing linked to the transcurrent faulting in the overlying crust. The deeper strikes may be caused by shearing at the base of the present-day lithosphere. Within the Wopmay Orogen, the MT results image a conductor at the margin of the Fort Simpson and Hottah terranes interpreted to be related to the collision of these terranes. Conductive crust beneath the western margin of the Great Bear magmatic arc suggests correlative rocks of the Coronation margin extend south of the Slave craton. Lastly, decreased resistivity in the Hottah terrane at mantle depths is interpreted to be caused by the introduction of graphitic or sulphidic rocks during subduction prior to the Hottah–Slave and Fort Simpson – Hottah collisions.

scholarly journals Volcanic, sedimentary, and deformation history of Winter Lake greenstone belt, Slave craton, Northwest Territories: preliminary results from the 2019 field season

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Valentin Alain ◽  
Michelle DeWolfe ◽  
Camille Partin ◽  
Bernadette Knox
Keyword(s):  
Northwest Territories ◽  
Greenstone Belt ◽  
Tectonic Setting ◽  
Sedimentary Rocks ◽  
Massive Sulfide ◽  
Geodynamic Evolution ◽  
Slave Craton ◽  
Metasedimentary Rocks ◽  
Bear Lake ◽  
Field Season

The Archean Winter Lake greenstone belt (WGB) in the Slave craton, located ~250 km northeast of Yellowknife in the Northwest Territories, has been underexplored relative to other supracrustal belts in the Slave craton, but shows potential for base-metal mineralization. It consists of lower greenschist to upper amphibolite grade mafic to felsic volcanic rocks and sedimentary rocks that are surrounded by ca. 3.3 to 2.9 Ga granitoids of the Central Slave Basement Complex (CSBC). The overall objective of this study is to better understand the origin and geodynamic evolution of the WGB and to evaluate its economic potential. The project will examine the tectonic setting of volcanic and sedimentary rocks of the WGB and their relationships to the CSBC granitoids. In 2019, three weeks were spent bedrock mapping near Newbigging Lake and one week near Big Bear Lake (at 1:5,000 and 1:10,000 scales, respectively) to generate a lithostratigraphic scheme for the southern WGB. This mapping evaluated the nature of contacts, previously interpreted as unconformities, between the CSBC, the ca. 2734-2924 Ma Central Slave Cover Group (CSCG) volcanic and sedimentary rocks, and post-volcanic sedimentary and granitoid rocks (Hrabi et al., 1995). Mapping near Big Bear Lake also allowed the examination of a previously mapped ~ 1.3-1.7 km wide rhyolite interpreted to be part of the ca. 3.3 Ga Newbigging Formation (Hrabi et al., 1995). Based on field observations, the formation does not include a rhyolite sensu stricto but rather a succession of weathered mafic to intermediate volcanic and intrusive rocks. This field season, the first of three, also led to the discovery of several semi-massive to massive sulfide showings within the mafic volcanic sequence, and the identification of sulfides (interpreted as remobilised) and multiple younging indicators within the younger conglomerate unit that are necessary for our lithostratigraphy study. Future U-Pb geochronological analysis of detrital zircon and Sm-Nd isotope geochemistry of metasedimentary rocks will enable us to determine their sources and age. Together with absolute timing of thermotectonic events, an Archean oceanic and continental crust geodynamic evolution model will be produced.  An additional goal of this study is to identify the ore-forming environment for the sulfide mineralization and to generate an ore-deposit model for the mineralisation observed in the WGB. References:Hrabi, H.B., Nelson, M.D., and Helmstaedt, H., 1995: Diverse metavolcanic sequences and late polymictic conglomerate-associated metasedimentary rocks in the Winter Lake supracrustal belt, Slave Province, Northwest Territories; in Current research 1995-E; Geological Survey of Canada, p. 137-148.

Petrography and provenance of the Marambio Group, Vega Island, Antarctica

1994 ◽  
Vol 6 (4) ◽  
pp. 517-527 ◽  
Author(s):  
Duncan Pirrie
Keyword(s):  
Late Cretaceous ◽  
Sedimentary Rocks ◽  
Clay Mineralogy ◽  
Minor Component ◽  
Source Area ◽  
Low Grade ◽  
Western Margin ◽  
Sediment Input ◽  
A Minor ◽  
Sandstone Petrography

Late Cretaceous sedimentary rocks assigned to the Santa Marta (Herbert Sound Member) and López de Bertodano (Cape Lamb and Sandwich Bluff members) formations of the Marambio Group, crop out on Cape Lamb, Vega Island. Although previous studies have recognized that these sedimentary rocks were derived from the northern Antarctic Peninsula region, the work presented here allows the provenance and palaeogeographical evolution of the region to be described in detail. On the basis of both sandstone petrography and clay mineralogy, the Herbert Sound and Cape Lamb members reflect sediment input from a low relief source area, with sand grade sediment sourced from low grade metasediments, and clay grade sediment ultimately derived from the weathering of an andesitic source area. In contrast, the Sandwich Bluff Member reflects a switch to a predominantly andesitic volcaniclastic source. However, this sediment was largely derived from older volcanic suites due to renewed source area uplift, with only a minor component from coeval volcanism. Regional uplift of both the arc terrane and the western margin of the James Ross Basin was likely during the Maastrichtian.

Constraints on the composition of the crust and uppermost mantle in northwestern Canada: Vp/Vs variations along Lithoprobe's SNorCLE transect

2005 ◽  
Vol 42 (6) ◽  
pp. 1205-1222 ◽  
Author(s):  
Gabriela Fernández-Viejo ◽  
Ron M Clowes ◽  
J Kim Welford
Keyword(s):  
Wave Velocity ◽  
Upper Mantle ◽  
Laboratory Data ◽  
High Ratio ◽  
P Wave ◽  
S Wave ◽  
Uppermost Mantle ◽  
Crust And Upper Mantle ◽  
Slave Craton ◽  
Crustal Composition

Shear-wave seismic data recorded along four profiles during the SNoRE 97 (1997 Slave – Northern Cordillera Refraction Experiment) refraction – wide-angle reflection experiment in northwestern Canada are analyzed to provide S-wave velocity (Vs) models. These are combined with previous P-wave velocity (Vp) models to produce cross sections of the ratio Vp/Vs for the crust and upper mantle. The Vp/Vs values are related to rock types through comparisons with published laboratory data. The Slave craton has low Vp/Vs values of 1.68–1.72, indicating a predominantly silicic crustal composition. Higher values (1.78) for the Great Bear and eastern Hottah domains of the Wopmay orogen imply a more mafic than average crustal composition. In the western Hottah and Fort Simpson arc, values of Vp/Vs drop to ∼1.69. These low values continue westward for 700 km into the Foreland and Omineca belts of the Cordillera, providing support for the interpretation from coincident seismic reflection studies that much of the crust from east of the Cordilleran deformation front to the Stikinia terrane of the Intermontane Belt consists of quartzose metasedimentary rocks. Stikinia shows values of 1.78–1.73, consistent with its derivation as a volcanic arc terrane. Upper mantle velocity and ratio values beneath the Slave craton indicate an ultramafic peridotitic composition. In the Wopmay orogen, the presence of low Vp/Vs ratios beneath the Hottah – Fort Simpson transition indicates the presence of pyroxenite in the upper mantle. Across the northern Cordillera, low Vp values and a moderate-to-high ratio in the uppermost mantle are consistent with the region's high heat flow and the possible presence of partial melt.

Chapter 10: Olympiada Gold Deposit, Yenisei Ridge, Russia

2020 ◽  
pp. 203-226
Author(s):  
A. M. Sazonov ◽  
K. V. Lobanov ◽  
E. A. Zvyagina ◽  
S. I. Leontiev ◽  
S. A. Silyanov ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Gold Mineralization ◽  
Sedimentary Rocks ◽  
Gold Deposits ◽  
Yenisei Ridge ◽  
Structural Factors ◽  
Tectonic Zone ◽  
Central Siberia ◽  
Western Margin ◽  
Clastic Sedimentary

Abstract The Olympiada deposit, containing >1,560 metric tons (t; 50 Moz) of gold at an average grade of 4 to 4.6 g/t Au, occurs in central Siberia, Russia. Over 30 years, the deposit produced more than 580 t of gold, including 200 t from oxidized ore grading 11.1 g/t. The deposit forms a 2-km-long, steeply dipping system, which is traced downdip for 1.7 km. It occurs in the Neoproterozoic orogen of the Yenisei Ridge at the western margin of the Siberian craton. This and other gold deposits in the district are controlled by the large, long-lived Tatarka-Ishimbino tectonic zone, marking a suture between terranes chiefly consisting of deformed Meso- to Neoproterozoic carbonate-clastic sedimentary rocks. The combination of lithologic and structural factors was critical for localization of gold mineralization associated with calcic and siliceous alteration accompanied by early arsenic and late antimony sulfides. As a result, very fine (10 μm) and high fineness (910–997) gold associates with diverse sulfides, especially arsenopyrite, and commonly contains mercury, similar to some characteristics of Carlin-type deposits. Geochronologic studies suggest that mineralization was formed during several stages between 817 and 660 Ma. The isotopic composition of Os and He, along with presence of anomalous Ni, Co, and Pt, points to a mantle mafic source, whereas isotopic composition of Pb and S suggest a contaminated crustal source, i.e., originating from a mix of mantle and crustal fluids.

Progress of mineral development in northern Canada

Polar Record ◽  
1965 ◽  
Vol 12 (81) ◽  
pp. 683-702
Author(s):  
Amil Dubnie ◽  
W. Keith Buck
Keyword(s):  
Northwest Territories ◽  
Direct Effect ◽  
Subject Matter ◽  
Northern Canada ◽  
The North ◽  
Mineral Development ◽  
The Subject ◽  
Small Parts

For the purpose of this paper, northern Canada comprises all the territory north of lat 60° N. Included in this area of approximately 1500000 square miles are all of Yukon and Northwest Territories and small parts of Quebec and Labrador. Although the area is clearly defined by latitude, the subject matter of this paper also takes into account those developments farther south which have a direct effect upon the north.

NOTES ON ORTHOPTEROID INSECTS FROM YUKON AND NORTHERN BRITISH COLUMBIA

1983 ◽  
Vol 115 (5) ◽  
pp. 567-568
Author(s):  
V. R. Vickery
Keyword(s):  
British Columbia ◽  
Northwest Territories ◽  
Published Data ◽  
Northern Canada ◽  
Additional Information ◽  
University Of British Columbia ◽  
Orthopteroid Insects ◽  
Research Institute

Some time ago I published data on orthopteroid insects from northern Canada and Alaska (Vickery 1967, 1969). Two species and one subspecies were described as new. Two of these taxa occur only in the Yukon and Northwest Territories.Since that time additional information has become available. During 1982 two lots of northern orthopteroid insects were received for identification. These were sent from the Spencer Museum, University of British Columbia and from Biosystematics Research Institute, Canada Agriculture, Ottawa. These are abbreviated in the following list as UBC and CNC, respectively. The UBC specimens were collected by S. G. Cannings, R. J. Cannings, C. S. Guppy, B. Gill, and G. G. E. Scudder mainly in 1980 and 1981. The CNC specimens were collected in 1981 by C. D. Dondale.

Modelling of dissolution–reprecipitation ion-exchange reactions for the development of flame perthite in a suite of sheared alkaline rocks: an example from Chimakurthy, Eastern Ghats, India

2014 ◽  
Vol 78 (5) ◽  
pp. 1301-1323 ◽  
Author(s):  
Sudip Bhattacharyya ◽  
P. Sengupta
Keyword(s):  
Ion Exchange ◽  
Alkali Feldspar ◽  
Eastern Ghats ◽  
Partial Replacement ◽  
Exchange Reactions ◽  
Complex Interplay ◽  
Differential Stress ◽  
Western Margin ◽  
Ductile Shearing ◽  
Chemical Evidence

AbstractA suite of sheared syenites occurring along the western margin of the Eastern Ghats Belt, India have developed extensive flame perthite in K-feldspar. Albite flames show large variation in size, shape and abundance. Field, petrographic and chemical evidence suggests complex interplay between differential stress, recycling of K-Na-Ca and supply of Na by infiltration for the development of flame perthite. Partial replacement of pyroxenes, plagioclase and alkali feldspar by amphibole, biotite, nepheline and calcite causes internal recycling of Na-Ca-K in a closed system. Representative compositions of the minerals are used to constrain the model dissolution–reprecipitation ion-exchange reactions involving Na and K either as reactants and/or as products. A substantial proportion of Na+ required for the development of the albite flames, originates from Na metasomatism accompanied by ductile shearing in the feldspathic rocks, providing an ideal open system wherein both the differential stress and Na+ are made available for the development of the flame perthites. This process probably augmented the replacement of K-feldspar grains by flame albite and the K+ released was carried away by the fluid or, possibly, augmented the biotite-forming reactions in the associated quartz-poor syenites and, hence, trigger the Na-K cycle in these rocks.

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