| Title | On the Statherian-Calymmian palaeogeography of northwestern Laurentia |
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| Author | Rainbird, R H ;
Davis, W J |
| Source | Journal of the Geological Society vol. 179, issue 5, 2022 p. 1-20, https://doi.org/10.1144/jgs2022-062 |
| Image |  |
| Year | 2022 |
| Alt Series | Natural Resources Canada, Contribution Series 20220491 |
| Publisher | The Geological Society of London |
| Document | serial |
| Lang. | English |
| Media | paper; digital; on-line |
| File format | pdf |
| Province | Nunavut; Northwest Territories |
| NTS | 66; 76; 86; 67; 77; 87 |
| Area | Hornby Bay; Amendsen; Elu |
| Lat/Long WENS | -120.0000 -100.0000 70.0000 65.0000 |
| Subjects | general geology; stratigraphy; sedimentology; geochronology; tectonostratigraphic zones; depositional environment; paleogeography; Laurentia; Hornby Bay Basin; Paleozoic; Proterozoic |
| Illustrations | location maps; stratigraphic columns; tables; diagrams |
| Program | GEM2: Geo-mapping for Energy and Minerals Mackenzie Corridor, Coppermine River Transect |
| Released | 2022 09 05 |
| Abstract | The c. 1.75 to 1.27 Ga Hornby Bay intracontinental basin, exposed in northwestern Canada, NE of Great Bear Lake, includes the Big Bear, Mountain Lake and Dismal Lakes groups. The Big Bear group
comprises mainly immature clastic rocks deposited by high-energy rivers in restricted fault-bounded basins formed during the late-stage assembly of supercontinent Nuna. Detrital zircon analysis of the Big Bear group suggests provenance from a
combination of local sources including recycling of sedimentary rocks, which were originally derived from sources further east, such as the Thelon orogen. The overlying Mountain Lake group was deposited by westerly flowing rivers over a much broader
region, with less evidence for syndepositional faulting, suggesting thermal subsidence. It displays provenance via recycling of strata from the proximal Coronation Supergroup and the more distal and correlative Goulburn Supergroup of Kilohigok Basin.
Following tectonic uplift and erosion, basal clastic rocks of the Dismal Lakes Group were deposited in fluvial and then shallow-marine to paralic environments. Detrital zircon from these strata displays prominent late Archean peaks demonstrating
provenance from adjacent rocks of the Slave craton and recycling of the Mountain Lake group. Detrital zircon geochronology of sandstones from the Hornby Bay Basin supports stratigraphic correlation with the Wernecke Supergroup in the Wernecke
Mountains and the Muskwa assemblage, located further southward along the ancient western margin of Laurentia. Our data, along with Nd and C isotopes from corresponding shale and carbonate units, provide robust evidence for a palaeogeographical model
whereby these successions represent the terrestrial and marine components of a west-facing, passive-margin clastic wedge, considered the westward extension of an Amazon-scale, braided fluvial system that originated in the foreland of the Trans-Hudson
orogen, to the east. Elements of this system have been identified from inliers in northeastern Australia, which was attached to northwestern Laurentia prior to the break-up of supercontinent Nuna. |
| Summary | (Plain Language Summary, not published)
The Hornby Bay basin is exposed between Great Bear Lake and the Canada's northernmost mainland coast. Research there by the GSC in the late 2000s was
aimed at understanding the basin stratigraphy in relation to uranium mineralization, similar to work we have conducted in the Thelon Basin and well-known Athabasca Basin, host to the world's largest uranium deposits. This paper reports on U-Pb
isotope analysis of zircon from sandstones of the Big Bear group, which tell us the age of the grains and that they were derived from a combination of local sources including recycling of sedimentary rocks, which were originally derived from sources
several hundreds of kilometres to the east, such as the Thelon orogen. The overlying Mountain Lake group was deposited by westerly flowing rivers over a much broader region, and displays zircon provenance mainly via recycling of older sedimentary
rocks from, for example, the Goulburn Supergroup of Kilohigok Basin. Detrital zircon geochronology of sandstones from the Hornby Bay Basin supports stratigraphic correlation with similar-age rocks located in the northern Canadian Cordillera, such as
the Wernecke Supergroup in the Wernecke Mountains and the Muskwa assemblage, in the Muskwa Range, of northern British Columbia. Our data provide robust evidence for an ancient geographic reconstruction whereby these successions represent the westward
extension of an Amazon-scale, braided river system that originated from a huge mountain range, the Trans-Hudson orogen, to the east. |
| GEOSCAN ID | 331321 |
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