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TitleParentage of Archean basement within a Paleoproterozoic orogen and implications for on-craton diamond preservation: Slave craton and Wopmay orogen, northwest Canada
AuthorOotes, L; Jackson, V A; Davis, W J; Bennett, V; Smar, L; Cousens, B
SourceCanadian Journal of Earth Sciences vol. 54, no. 2, 2017 p. 203-232,
Alt SeriesEarth Sciences Sector, Contribution Series 20160164
PublisherNRC Press
Mediapaper; on-line; digital
File formatpdf
ProvinceNorthwest Territories; Nunavut
NTS75; 76; 85; 86
AreaSlave craton; Wopmay Orogen
Lat/Long WENS-120.0000 -104.0000 68.0000 60.0000
Subjectsgeneral geology; geochemistry; geochronology; igneous and metamorphic petrology; structural geology; tectonics; Archean; bedrock geology; lead uranium ratios; uranium lead dates; uranium lead dating; zircon; orogenies; orogenesis; deformation; craton; plutons; kimberlites; plutonic rocks; metamorphism; Proterozoic
Illustrationslocation maps; geological sketch maps; cross-sections, structural; photographs; geochemical charts; geological time charts; tables; graphs
ProgramUranium Ore Systems, Targeted Geoscience Initiative (TGI-4)
AbstractThe Wopmay orogen is a Paleoproterozoic accretionary belt preserved to the west of the Archean Slave craton, northwest Canada. Reworked Archean crystalline basement occurs in the orogen, and new bedrock mapping, U-Pb geochronology, and Sm-Nd isotopic data further substantiate a Slave craton parentage for this basement. Detrital zircon results from unconformably overlying Paleoproterozoic supracrustal rocks also support a Slave craton provenance. Rifting of the Slave margin began at ca. 2.02 Ga with a second rift phase constrained between ca. 1.92 and 1.89 Ga, resulting in thermal weakening of the Archean basement and allowing subsequent penetrative deformation during the Calderian orogeny (ca. 1.88-1.85 Ga). The boundary between the western Slave craton and the reworked Archean basement in the southern Wopmay orogen is interpreted as the rifted cratonic margin, which later acted as a rigid backstop during compressional deformation. Age-isotopic characteristics of plutonic phases track the extent and evolution of these processes that left penetratively deformed Archean basement, Paleoproterozoic cover, and plutons in the west, and “rigid” Archean Slave craton to the east. Diamond-bearing kimberlite occurs across the central and eastern parts of the Slave craton, but kimberlite (diamond bearing or not) has not been documented west of 114°W. It is proposed that while the crust of the western Slave craton escaped thermal weakening, the mantle did not and was moved out of the diamond stability field. The Paleoproterozoic extension-convergence cycle preserved in the Wopmay orogen provides a reasonable explanation as to why the western Slave craton appears to be diamond sterile.
Summary(Plain Language Summary, not published)
This paper examines the regional extent of the western boundary of the Slave geological province in northwestern Canada. The Slave province is a resource-rich geological region and Canada's dominant diamond producer. Understanding its regional extent is important to the resource potential for the area. This study confirms that rocks of the Slave province occur within the adjacent Wopmay orogen, as far west as the Wopmay fault zone. The Slave rocks were affected by thermal processes related to rifting of the Slave province two billion years ago, as well as during the continental collision that formed the Wopmay mountain belt. This history is different from areas of the province with established high diamond potential, which may help explain why few diamond exploration successes are documented in this region.