scholarly journals Precious- and base-metal deposits of the southern Abitibi greenstone belt, Superior Province, Ontario and Quebec: 14th Biennial Society for Geology Applied to Mineral Deposits meeting field trip guidebook

2017 ◽  
Author(s):  
P Mercier-Langevin ◽  
J Goutier ◽  
B Dubé
2013 ◽  
Vol 109 (1) ◽  
pp. 27-59 ◽  
Author(s):  
V. McNicoll ◽  
J. Goutier ◽  
B. Dube ◽  
P. Mercier-Langevin ◽  
P.-S. Ross ◽  
...  

1990 ◽  
Vol 27 (4) ◽  
pp. 582-589 ◽  
Author(s):  
S. L. Jackson ◽  
R. H. Sutcliffe

Published U–Pb geochronological, geological, and petrochemical data suggest that there are late Archean ensialic greenstone belts (GB) (Michipicoten GB and possibly the northern Abitibi GB), ensimatic greenstone belts (southern Abitibi GB and Batchawana GB), and possibly a transitional ensimatic–ensialic greenstone belt (Swayze GB) in the central Superior Province. This lateral crustal variability may preclude simple correlation of the Michipicoten GB and its substrata, as exposed in the Kapuskasing Uplift, with that of the southern Abitibi GB. Furthermore, this lateral variability may have determined the locus of the Kapuskasing Uplift. Therefore, although the Kapuskasing Uplift provides a useful general crustal model, alternative models of crustal structure and tectonics for the southern Abitibi GB warrant examination.Thrusting of a juvenile, ensimatic southern Abitibi GB over a terrane containing evolved crust is consistent with (i) the structural style of the southern Abitibi GB; (ii) juvenile southern Abitibi GB metavolcanic rocks intruded by rocks having an isotopically evolved, older component; and (iii) Proterozoic extension that preserved low-grade metavolcanic rocks within the down-dropped Cobalt Embayment, which is bounded by higher grade terranes to the east and west.


1980 ◽  
Vol 17 (9) ◽  
pp. 1292-1299 ◽  
Author(s):  
I. E. M. Smith

In well exposed, well developed greenstone belts of the Superior Province there is a clear progression from stratigraphically lower, geochemically primitive volcanic rock types (komatiites, tholeiites) to overlying geochemically evolved calc-alkaline volcanic rock types. In the western Blake River Group of the Abitibi Greenstone Belt the change from tholeiitic to calc-alkaline volcanics represents a geochemical discontinuity defined by an increase in incompatible elements and light/heavy rare-earth element fractionation in the overlying rocks. Quantitative modelling of the parameters of the discontinuity indicates that it can be explained by a change to very small amounts of melting of unmodified mantle lherzolite, although this is not a unique solution. In calc-alkaline suites showing high degrees of rare-earth element fractionation the calculated melt fraction required of unmodified mantle becomes unrealistically low and models involving a geochemically evolved source may have to be considered.


1992 ◽  
Vol 29 (11) ◽  
pp. 2429-2444 ◽  
Author(s):  
Keith Benn ◽  
Edward W. Sawyer ◽  
Jean-Luc Bouchez

The late Archean Opatica granitoid-gneiss belt is situated within the northern Abitibi Subprovince, along the northern margin of the Abitibi greenstone belt. Approximately 200 km of structural section was mapped along three traverses within the previously unstudied Opatica belt. The earliest preserved structures are penetrative foliations and stretching and mineral lineations recording regional ductile shearing (D1). Late-D1 deformation was concentrated into kilometre-scale ductile fault zones, typically with L > S tectonite fabrics. Two families of lineations are associated with D1, indicating shearing both parallel and transverse to the east-northeast trend of the belt. Lineations trending east-northeast or northwest–southeast tend to be dominant within domains separated by major fault zones. In light of the abundant evidence for early north–south compression documented throughout southern Superior Province, including the Abitibi greenstone belt, D1 is interpreted in terms of mid-crustal thrusting, probably resulting in considerable crustal thickening. Movement-sense indicators suggest that thrusting was dominantly southward vergent. D2 deformation resulted in the development of vertical, regional-scale dextral and sinistral transcurrent fault zones and open to tight upright horizontal folds of D1 fabrics. In the context of late Archean orogenesis in southern Superior Province, the tectonic histories of the Abitibi and Opatica belts should not be considered separately. The Opatica belt may correlate with the present-day mid-crustal levels of the Abitibi greenstone belt, and to crystalline complexes within the Abitibi belt. It is suggested that the Abitibi Subprovince should be viewed, at the regional scale, as a dominantly southward-vergent orogenic belt. This work demonstrates that structural study of granitoid-gneiss belts adjacent to greenstone belts can shed considerable light on the regional structure and structural evolution of late Archean terranes.


1975 ◽  
Vol 12 (12) ◽  
pp. 2080-2085 ◽  
Author(s):  
D. E. Vogel

Chloritoid- and kyanite-bearing acid metavolcanic rocks of the Abitibi Greenstone belt have acquired an aluminum surplus by weathering prior to metamorphism. The weathering increases from the top of the volcanic unit downwards, as shown by increasing values for both Niggli-t and the Zr/P ratio. The depositional environment of these rocks is postulated to be either shallow marine or terrestrial.


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