Polymetallic unconformity-related uranium veins in lower Proterozoic Amer Group, Pelly Lake map area, northern Thelon Basin, Churchill Province, Northwest Territories

Two alkaline igneous complexes and three lines of diatreme breccias were emplaced in the East Arm of Great Slave Lake during the lower Proterozoic. Field relationships suggest that those rocks are broadly cogenetic and were emplaced about 2.1 Ga ago.One of the intrusions, the Easter Island dyke, was rotated subsequent to emplacement such that both top and bottom are now exposed. Field and petrographic data are indicative of progressive differentiation along (i.e., up) the dyke and are substantiated by chemical data. The differentiation history of the early gabbros of the Blachford Lake complex is similar. Late differentiates of both complexes closely resemble the igneous matrices of the breccias and petrographic and chemical data support the proposal of cogenesis and contemporaneity.The field data show that there was a period of significant faulting and concomitant alkaline igneous activity in the East Arm area in the lower Proterozoic.

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A potassic phreatomagmatic volcanic centre in the Thelon Basin (Northwest Territories): implications for diamond exploration

10.4095/202901 ◽

1995 ◽

Cited By ~ 2

Author(s):

T D Peterson

Keyword(s):

Northwest Territories ◽

Volcanic Centre ◽

Diamond Exploration ◽

Thelon Basin

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U–Pb, Pb–Pb, and K–Ar isotopic study and petrography of uraniferous phosphate-bearing rocks in the Thelon Formation, Dubawnt Group, Northwest Territories, Canada

Canadian Journal of Earth Sciences ◽

10.1139/e89-070 ◽

1989 ◽

Vol 26 (5) ◽

pp. 867-880 ◽

Cited By ~ 30

Author(s):

A. R. Miller ◽

G. L. Cumming ◽

D. Krstic

Keyword(s):

Northwest Territories ◽

Tectonic Setting ◽

Uranium Mineralization ◽

Isotopic Study ◽

Thelon Basin ◽

Wide Range ◽

Minimum Age ◽

Basal Conglomerate

The Thelon Formation, uppermost unit of the Dubawnt Group, overlies a regionally extensive paleoweathered zone developed on a wide range of lithochronological units including formations in the lower Dubawnt Group. Authigenic uraniferous phosphate minerals, fluorapatite and goyazite, cementing Thelon conglomerate–sandstone and filling fractures in the underlying paleoweathered zone, were dated in an attempt to better constrain the age of Thelon sedimentation and diagenesis. The oldest age, 1720 ± 6 Ma, derived from phosphate-cemented sediments, is interpreted as a minimum age for diagenesis and therefore brackets initial Thelon sedimentation between emplacement of fluorite-bearing granites at 1753 Ma and authigenic phosphate cementation at 1720 Ma. Additional ages of 1685 ± 4 and 1647 Ma are interpreted as remobilization or subsequent cementation events. K–Ar ages on illite, 1386 ± 37 and 1266 ± 31 Ma, from the paleoweathered zone and basal conglomerate, respectively, are significantly younger than ages derived from coexisting phosphate. These K–Ar ages record hydrothermal events that may be related to processes associated with unconformity-type uranium mineralization at approximately 1400–1300 Ma.Ages from the Thelon Basin permit geochronologic correlations with the Athabasca and Hornby basins, long correlated on the basis of similarities in sedimentation, stratigraphy, and tectonic setting.

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