New insights from magnetic data on the regional structure and geometry of the southwest Thelon Basin, Northwest Territories, Canada

2015 ◽  
Author(s):  
V. Tschirhart ◽  
S. Pehrsson
Keyword(s):  
Northwest Territories ◽  
Magnetic Data ◽  
Regional Structure ◽  
Thelon Basin

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

1989 ◽  
Vol 26 (5) ◽  
pp. 867-880 ◽  
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.

scholarly journals Previously unrecognized regional structure of the Coastal Belt of the Franciscan Complex, northern California, revealed by magnetic data

Geosphere ◽  
2013 ◽  
Vol 9 (6) ◽  
pp. 1514-1529 ◽  
Author(s):  
V.E. Langenheim ◽  
R.C. Jachens ◽  
C.M. Wentworth ◽  
R.J. McLaughlin
Keyword(s):  
Magnetic Data ◽  
Northern California ◽  
Regional Structure ◽  
Franciscan Complex ◽  
Coastal Belt

New insights from geophysical data on the regional structure and geometry of the southwest Thelon Basin and its basement, Northwest Territories, Canada

Geophysics ◽  
2016 ◽  
Vol 81 (5) ◽  
pp. B167-B178 ◽  
Author(s):  
Victoria Tschirhart ◽  
Sally J. Pehrsson
Keyword(s):  
Northwest Territories ◽  
Fault System ◽  
Precambrian Geology ◽  
Thelon Basin ◽  
The North ◽  
Gravity And Magnetic ◽  
Magnetic Signatures ◽  
Frontier Region ◽  
Geologic Map ◽  
Active Exploration

Detailed analysis of gravity and aeromagnetic data covering the southwest Thelon Basin, Northwest Territories, Canada, has provided insight into basement geology that has significance to exploration for uranium and possibly other economic metals in a remote frontier region. Interpretation of basement geology has been constrained by the calibration of gravity and magnetic signatures with Precambrian geology adjacent to the basin and sparse seismic data within the basin, creating the first basement geologic map of the southwest Thelon Basin. The basement to the overlying sedimentary units is dominated by magnetic felsic and mafic bodies variably overlying and intruding the gneissic crystalline basement. Supracrustal belts located outside the basin margins are interpreted to continue below the basin fill. Major structures have been delineated geophysically including the Howard Lake Shear Zone and the Bathurst and McDonald fault systems. Northwest-trending structures forming part of the Bathurst fault system appear to control the unconformity surface morphology and the location of basin depocenters. The geologic interpretations are corroborated by joint gravity and magnetic modeling of profiles that reveal the deepest part of the Thelon Basin reaches depths of [Formula: see text] in an area of subdued magnetic and gravimetric response to the north. The basin is a focus of active exploration for uranium, and we have found that areas along the south and eastern margins underlain by U-rich granitoid rocks may have significant potential where intersected by reactivated faults.

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