History of the discovery of diamondiferous kimberlites in the Northwest Territories, Canada

2019 ◽  
Keyword(s):  
Northwest Territories ◽  
History Of

Early Tertiary thermotectonic history of the northern Yukon and adjacent Northwest Territories, Arctic Canada

1997 ◽  
Vol 34 (10) ◽  
pp. 1366-1378 ◽  
Author(s):  
Paul B. O'Sullivan ◽  
Larry S. Lane
Keyword(s):  
Northwest Territories ◽  
Fission Track ◽  
Middle Eocene ◽  
Geothermal Gradient ◽  
Crystalline Rock ◽  
Early Eocene ◽  
Channel Formation ◽  
Rapid Cooling ◽  
Early Tertiary ◽  
History Of

Apatite fission-track data from 16 sedimentary and crystalline rock samples indicate rapid regional Early Eocene denudation within the onshore Beaufort–Mackenzie region of northwestern Canada. Rocks exposed in the area of the Big Fish River, Northwest Territories, cooled rapidly from paleotemperatures of >80–110 °C to <6 0°C at ca. 56 ± 2 Ma, probably in response to kilometre-scale denudation associated with regional structuring. The data suggest the region experienced a geothermal gradient of ~28 °C/km prior to rapid cooling, with ~2.7 km of section having been removed from the top of the exposed section in the Moose Channel Formation and ~3.8 km from the top of the exposed Cuesta Creek Member. Farther to the west, rocks exposed in the headwaters of the Blow River in the Barn Mountains, Yukon Territories, were exposed to paleotemperatures above 110 °C in the Late Paleocene prior to rapid cooling from these elevated paleotemperatures due to kilometre-scale denudation at ca. 56 ± 2 Ma. Exposure of these samples at the surface today requires that a minimum of ~3.8 km of denudation occurred since they began cooling below ~110 °C. The apatite analyses indicate that rocks exposed in the northern Yukon and Northwest Territories experienced rapid cooling during the Early Eocene in response to kilometre-scale denudation, associated with early Tertiary folding and thrusting in the northern Cordillera. Early Eocene cooling–uplift ages for onshore sections are slightly older than the Middle Eocene ages previously documented for the adjacent offshore foldbelt and suggest that the deformation progressed toward the foreland of the foldbelt through time.

Geology and petrochemistry of lower Aphebian (2.4–2.0 Ga) alkaline plutonic and hypabyssal rocks in the East Arm of Great Slave Lake, Northwest Territories

1979 ◽  
Vol 16 (1) ◽  
pp. 60-72 ◽  
Author(s):  
J. P. N. Badham
Keyword(s):  
Northwest Territories ◽  
Field Data ◽  
Easter Island ◽  
Chemical Data ◽  
Lower Proterozoic ◽  
Great Slave Lake ◽  
Data Support ◽  
Igneous Complexes ◽  
Igneous Activity ◽  
History Of

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.

A Study of Seismic Risk near Pipeline Corridors in Northwestern Canada and Eastern Alaska

1974 ◽  
Vol 11 (1) ◽  
pp. 147-164 ◽  
Author(s):  
A. E. Stevens ◽  
W. G. Milne
Keyword(s):  
Northwest Territories ◽  
Seismic Risk ◽  
Yukon Territory ◽  
Red River ◽  
Contour Maps ◽  
History Of ◽  
Strain Release ◽  
Fort Mcpherson ◽  
Risk Parameters ◽  
Large Earthquakes

Seismic risk in the Yukon Territory and adjacent areas of the western Northwest Territories and eastern Alaska is evaluated from locations and magnitudes of earthquakes in northern Canada and Alaska from 1899 to 1970. Contour maps illustrate strain release and also predicted accelerations on firm soil for return periods of 30, 50, and 100 years. Calculated values of these risk parameters may vary by a factor of two or more from actual values due to the short earthquake history of the region studied, uncertainties in location and magnitude of past large earthquakes, lack of measured ground accelerations in the regions, and the unknown modifying influence of soil and subsoil materials.Seismic risk may be significant for parts of the Mackenzie Valley pipeline corridor in the vicinity of Fort McPherson between mile 700 (east of Arctic Red River, Northwest Territories) and mile 850 (east of Old Crow, Yukon Territory).

A Paleoenvironmental Study Tracking Eutrophication, Mining Pollution, and Climate Change in Niven Lake, the First Sewage Lagoon of Yellowknife (Northwest Territories) + Supplementary Appendix 1 (See Article Tools)

ARCTIC ◽  
2018 ◽  
Vol 71 (2) ◽  
Author(s):  
Emily M. Stewart ◽  
Kathryn E. Hargan ◽  
Branaavan Sivarajah ◽  
Linda E. Kimpe ◽  
Jules M. Blais ◽  
...  
Keyword(s):  
Northwest Territories ◽  
Fecal Contamination ◽  
Phosphorus Loading ◽  
Disposal Site ◽  
Diagnostic Ratios ◽  
Wastewater Disposal ◽  
Recent Climate ◽  
Sewage Contamination ◽  
History Of ◽  
The City

Niven Lake was the first wastewater disposal site for the City of Yellowknife (Northwest Territories, Canada), receiving domestic sewage for more than 30 years. Here, we used a high-resolution sediment core to track past sewage inputs to Niven Lake by comparing changes in sedimentary sterols and three diagnostic ratios for human fecal contamination, as well as biological assemblages and overall lake production, with the known history of sewage inputs to the lake from 1948 to 1981. Coprostanol, often considered the best indicator of human fecal contamination, increased by ~8% between depths of 7.5 cm and 5 cm (~1950 to 1981) and was more reliable in tracking sewage contamination than diagnostic sterol ratios. Muted responses in subfossil diatom and chironomid assemblages were noted during the time of sewage inputs, and similar responses have been reported in other eutrophic Arctic sites, as well as in many macrophyte-dominated shallow lakes in general. More marked shifts in diatoms and chironomids occurred a decade after the end of sewage inputs, in the 1990s, a time that closely aligned with the warmest years on record for Yellowknife. This post–sewage era response was indicative of anoxia and possibly of positive feedback from internal phosphorus loading. The response may have been facilitated by recent climate warming, resulting in a lagging recovery from eutrophication. Changes in the diatoms and chironomids of Niven Lake were also indicative of metal pollution, suggesting that the lake has experienced the compounding effects of arsenic contamination from nearby gold mining.

CrypticOnchocercaspecies infecting North American cervids, with implications for the evolutionary history of host associations inOnchocerca

Parasitology ◽  
2012 ◽  
Vol 140 (10) ◽  
pp. 1201-1210 ◽  
Author(s):  
QUINN S. McFREDERICK ◽  
TAMARA S. HASELKORN ◽  
GUILHERME G. VEROCAI ◽  
JOHN JAENIKE
Keyword(s):  
New York ◽  
North America ◽  
Northwest Territories ◽  
Dna Sequence ◽  
Evolutionary History ◽  
Upstate New York ◽  
Zoonotic Infections ◽  
Limited Sampling ◽  
History Of ◽  
New Hosts

SUMMARYParasites in the genusOnchocercainfect humans, ruminants, camels, horses, suids, and canids, with effects ranging from relatively benign to debilitating. In North America,Onchocerca cervipedisis the sole species known to infect cervids, while at least 5Onchocercaspecies infect Eurasian cervids. In this study, we report the discovery of a cervid-parasitizingOnchocercaonly distantly related toO. cervipedis. To reconstruct the phylogenetic history of the genusOnchocerca, we used newly acquired DNA sequence fromO. cervipedis(from moose in Northwest Territories, Canada) and from the newly discovered species (from white-tailed deer in upstate New York), as well as previously published sequences. Ancestral host reconstructions suggest that host switches have been common throughout the evolutionary history ofOnchocerca, and that bovid- and cervid-parasitizing species have been particularly important sources of descendant species. North America cervids might therefore serve as a source forOnchocercainvasions into new hosts. Given the high density of deer populations, the potential for zoonotic infections may also exist. Our discovery of a newOnchocercaspecies with relatively limited sampling suggests that the diversity ofOnchocercaassociated with cervids in North America may be greater than previously thought, and surveys utilizing molecules and morphology are necessary.

scholarly journals Deformation history of the Black Bay Fault and associated mineralization, Northwest Territories

2017 ◽  
Author(s):  
D Jamison ◽  
P Acosta-Góngora ◽  
B K Knox ◽  
S J Pehrsson ◽  
S Lin
Keyword(s):  
Northwest Territories ◽  
Deformation History ◽  
History Of
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