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TitleA review of the Late Cretaceous Little Nahanni Pegmatite Group and associated rare element mineralization in the Selwyn Basin area, Northwest Territories
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AuthorBarnes, E M; Groat, L A; Falck, H
SourceMineral and energy resource assessment of the Greater Nahanni Ecosystem under consideration for the expansion of the Nahanni National Park Reserve, Northwest Territories; by Wright, D F (ed.); Lemkow, D (ed.); Harris, J R (ed.); Geological Survey of Canada, Open File 5344, 2007 p. 191-202; 1 DVD, https://doi.org/10.4095/224554
Year2007
Documentopen file
Lang.English
MediaDVD
RelatedThis publication is contained in Wright, D F; Lemkow, D; Harris, J R; (2007). Mineral and energy resource assessment of the Greater Nahanni Ecosystem under consideration for the expansion of the Nahanni National Park Reserve, Northwest Territories, Geological Survey of Canada, Open File 5344
ProvinceNorthwest Territories
NTS105I/02
AreaNahanni National Park; Nahanni River; Logan Mountains
Lat/Long WENS-129.0000 -128.5000 62.2500 62.0000
Subjectsstructural geology; economic geology; geochronology; geochemistry; bedrock geology; igneous rocks; pegmatites; tantalum; niobium; tin; structural features; mineralization; mineral occurrences; Greater Nahanni Ecosystem; Little Nahanni Pegmatite Group; Selwyn Basin; Beauvoir Granite; sedimentary exhalative deposits; Mesozoic; Cretaceous
Illustrationstables; plots; stereonets; sketch maps
Viewing
Location
 
Natural Resources Canada Library - Ottawa (Earth Sciences)
 
Natural Resources Canada library - Calgary (Earth Sciences)
 
Geological Survey of Canada (Atlantic)
 
Natural Resources Canada library - Vancouver (Earth Sciences)
 
Natural Resources Canada library - Québec (Earth Sciences)
 
ProgramMineral and Energy Resource Assessment (MERA)
Released2007 11 19
AbstractThe Late Cretaceous Little Nahanni Pegmatite Group (LNPG) is composed of more than 200 subvertical, lithium-cesium-tantalum (LCT) pegmatites, occurring in an area of approximately 55 km2. The pegmatite group is hosted by Selwyn Basin offshelf facies of the Neoproterozoic to Lower Cambrian Hyland Group and is located between, and subparallel to, major regional northwest-trending structures, such as the March Fault and the Fork Anticline.

Since their discovery in 1961, these coarse-grained, mostly quartz, feldspar, and spodumene pegmatites have been investigated for economic concentrations of rare elements. Whole-rock geochemical analyses indicate granitic compositions and strong peraluminous signatures suggest an S-type affiliation. The depletion in rare earth element (REE) abundance, enrichment of Li, Ta, Cs, Sn, Rb, and Nb, and emplacement into low-pressure metamorphic rocks is typical of LCT pegmatites.

There are similarities between the LNPG dykes and the Greenbushes pegmatite, Australia, which is rich in Sn, Ta, Nb, and Li (Wengzynowski, 2002). However, even closer geochemical comparisons can be made with examples of European late-Variscan, post-orogenic mineralized plutons and pegmatites. One such example, the Beauvoir granite, is suggested as an analog for the plutonic source of the LNPG dykes. Comparison of the setting and ages obtained for the emplacement of the LNPG with this well studied Variscan granite suggests a period of post-orogenic collapse and extension during the late Cretaceous period in this region of the northern Cordillera.
GEOSCAN ID224554