Tectonic Significance Of The Akaitcho Group, Wopmay Oreogen, Northwest Territories, Canada

Easton, R. M. (1982) Tectonic Significance Of The Akaitcho Group, Wopmay Oreogen, Northwest Territories, Canada. Doctoral (PhD) thesis, Memorial University of Newfoundland.

[img] [English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version
Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.

Download (21Mb)
  • [img] [English] PDF - Accepted Version
    Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.
    (Original Version)

Abstract

The early Proterozoic Akaitcho Group consists of 6 to 8 km of metasedimentary and metavolcanic rocks located in the central metamorphic core zone of the Wopmay, Orogen (Bear Province). In the northern part of the orogen, the following generalized stratigraphic sequence has been recognized: 1) a lower mainly basaltic sequence, 2) 1-2 km of arkosic turbidites intruded by sills of rhyolite porphyry, 3) basalt and rhyolite volcanic complexes, and 4) 1 to 2 km of pelite and tuffaceous sedimentary rocks, locally, intruded by gabbro sills. The Akaitcho Group is conformably overlain by the Odjick Formation, part of an inferred passive-continental margin sequence (the Epworth Group). -- Two types of chondrite-normalized REE patterns are present in the Akaitcho Group basalts: a sloping pattern similar to recent continental tholeiites, and a flat pattern similar to type II ocean tholeiites. The basalt geochemistry in the Akaitcho Group evolves from older, evolved continental tholeiites, through continental tholeiites, to younger oceanic tholeiites. The Akaitcho Group rhyolites are probably crustally-derived. REE patterns of the Akaitcho Group sedimentary rocks indicate that the arkosic turbidites were derived from a granodiorite source terrane (i.e. average continental crust), whereas the upper pelites were derived from a volcanic source terrane similar to the Akaticho Group volcanic complexes and a granodiorite source terrane. -- Bimodal volcanism (subalkaline basalt and rhyolite) in association with continent-derived sediments, the temporal evolution of the basalt geochemistry, and the similarity of the Akaitcho Group to recent rift sequences indicate that the Akaitcho Group was deposited in a rift. The stratigraphic position of the Akaitcho Group beneath the Epworth Group suggests that the Akaitcho Group is related to continental break-up along the western Slave Craton about 1.9 Ga. Zircon dates from central Wopmay Orogen indicate that sea-floor spreading associated with continental break-up was short-lived.

Item Type: Thesis (Doctoral (PhD))
URI: http://research.library.mun.ca/id/eprint/6710
Item ID: 6710
Additional Information: Bibliography: leaves 337-368.
Department(s): Science, Faculty of > Earth Sciences
Date: 1982
Date Type: Submission
Geographic Location: Canada--Northwest Territories--Great Bear Lake Region
Library of Congress Subject Heading: Geology, Stratigraphic--Precambrian; Geology--Northwest Territories--Great Bear Lake region

Actions (login required)

View Item View Item

Downloads

Downloads per month over the past year

View more statistics