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TitleBack River Volcanic Complex: an Archean stratovolcano, Nunavut-Northwest Territories
AuthorLambert, M B
SourceGeological Survey of Canada, Bulletin no. 581, 2005, 83 pages; 1 CD-ROM,
PublisherNatural Resources Canada
MapsPublication contains 1 map
Map Info.geological, bedrock geology and structural features, 1:50,000
Mediapaper; CD-ROM; digital; on-line
RelatedThis publication contains the following publications
File formatreadme / lisez-moi
File formatpdf (Adobe® Acrobat® Reader® v. 5.1 is included / est fourni)
ProvinceNorthwest Territories; Nunavut
NTS76B/12; 76B/13; 76B/16; 76C/01; 76C/04; 76C/09
AreaBack River
Lat/Long WENS-108.5000 -107.5000 65.2000 64.6667
Subjectsigneous and metamorphic petrology; stratigraphy; structural geology; economic geology; geochemistry; geophysics; Archean; lithology; bedrock geology; igneous rocks; volcanic rocks; plutonic rocks; rhyolites; basalts; andesites; tuffs; granites; sedimentary rocks; carbonates; stromatolites; dykes; sills; gabbros; petrography; structural features; deformation; folds; faults; metamorphism; mineral occurrences; magnetic surveys; total field magnetics; Back River Volcanic Complex; Slave Province; Back Group; Innerring Sequence; Thlewycho Sequence; Beechey Lake Group; Boucher-Regan Sequence; petrochemistry; Precambrian; Proterozoic
Illustrationssketch maps; photographs; stratigraphic sections; cross-sections
LinksMap in this survey - Carte de la même étude
LinksMetadata - Métadonnées
Released2005 10 01
AbstractThe Back River volcanic complex is a deformed Archean composite stratovolcano that evolved in a depositional basin in the northeastern Slave Province. Its diverse stratigraphy developed through three cycles of mafic (or intermediate) to felsic volcanism, each ending with eruption of large rhyolite to dacite dome-flow complexes from numerous centres around the volcano, followed by erosion and mass wasting from the volcanic edifice to produce extensive clastic fans and debris-avalanche deposits.

The oldest rocks in the volcanic complex are calc-alkaline andesitic lavas and ash-flow tuffs that represent the upper subaerial parts of the earliest cycle of volcanism. This cycle ended with cauldron subsidence, ring-fracture intrusion, and effusion of rhyolite domes. The second eruptive cycle involved a highly variable series of eruptions that deposited andesitic lava flows and intermittent pyroclastic and epiclastic units, to interlayered dacitic and andesitic lavas and tuffs overlain by voluminous, nonwelded, ash-flow tuffs. The last volcanic cycle marks a change to tholeiitic magmatism with the eruption mainly of basalt and andesite pillowed lavas on the submerged northern flanks of the stratovolcano.

Stromatolites developed along the margins of active lava domes that straddled the shoreline around the emergent stratovolcano. Iron-formation units mark the close of volcanism.

Three generations of folding deformed the volcanic complex and the surrounding metaturbidite units. Disharmonic folding produced tightly folded metasedimentary rocks between or against more open, folded volcanic sequences. The large dome in the southern part of the map area formed by superposition of regional strain on the core volcanic edifice.