scholarly journals Frozen subduction in Canada's Northwest Territories: Lithoprobe deep lithospheric reflection profiling of the western Canadian Shield

Tectonics ◽  
1999 ◽  
Vol 18 (1) ◽  
pp. 1-24 ◽  
Author(s):  
Frederick A. Cook ◽  
Arie J. van der Velden ◽  
Kevin W. Hall ◽  
Brian J. Roberts
Keyword(s):  
Northwest Territories ◽  
Canadian Shield

Provenance of Paleozoic sedimentary rocks in the Canadian Cordilleran miogeocline: a Nd isotopic study

1997 ◽  
Vol 34 (12) ◽  
pp. 1603-1618 ◽  
Author(s):  
Carmala N. Garzione ◽  
P. Jonathan Patchett ◽  
Gerald M. Ross ◽  
JoAnne Nelson
Keyword(s):  
British Columbia ◽  
Northwest Territories ◽  
Middle Devonian ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Canadian Shield ◽  
Isotopic Study ◽  
Middle Ordovician ◽  
Southern Alberta ◽  
T Values

Nd isotopes and trace elements in sedimentary rocks of the Yukon, the Northwest Territories, and northern British Columbia are used to examine the source of sediments in the Canadian Cordilleran miogeocline. Previous Nd isotope studies in southern Alberta demonstrated that strata of Neoproterozoic to Late Ordovician age were derived from Archean and Proterozoic Canadian Shield sources, whereas by the Late Devonian, a shift of 6 εNd units to younger crustal sources (εNd (T) = −6 to −9) had occurred. In this study, we found that the shift to younger crustal Nd isotopic signatures in the Yukon and Northwest Territories occurred much earlier than in southern Alberta. Cambrian and older strata have εNd(T) values of −10.0 to −21.1, consistent with derivation from Canadian Shield sources. Lower Ordovician through Permian strata in the Yukon and Northwest Territories, including the Innuitian-derived Imperial Assemblage, have εNd(T) values of −5 to −11.4. In northern British Columbia, the shift to a younger source reflects a wider range of εNd(T) values, from -−8.7 to −14.6 in Middle Ordovician through Middle Devonian strata, suggesting continued input from Canadian Shield sources. By the Middle Devonian, a complete shift to younger crustal signatures (εNd(T) = −5.9 to −10.5) had occurred in northern British Columbia. Several sources for the more juvenile sediments include (1) a mixture of locally erupted volcanic rocks with Canadian Shield sources, (2) a Grenville source, and (3) an Innuitian source. We propose that Ordovician to Lower Devonian strata were derived from a mixture of locally erupted, juvenile volcanics and pre-Cambrian Canadian Shield sources, and post-Middle Devonian strata were sourced from the Innuitian orogen in the Canadian Arctic.

A comparison of the receiver structure beneath stations of the Canadian National Seismograph Network

1995 ◽  
Vol 32 (7) ◽  
pp. 938-951 ◽  
Author(s):  
John F. Cassidy
Keyword(s):  
Northwest Territories ◽  
Upper Mantle ◽  
Velocity Structure ◽  
Receiver Functions ◽  
Canadian Shield ◽  
Low Velocity ◽  
Low Velocity Zone ◽  
Appalachian Orogen ◽  
Seismograph Network ◽  
Velocity Zone

Three-component broadband data from the recently deployed Canadian National Seismograph Network provide a new opportunity to examine the structure of the crust and upper mantle beneath the Canadian landmass. Receiver function analysis is an ideal method to use with this data set, as it can provide constraints on the S-velocity structure beneath each station of this seismograph network. This analysis method is particularly useful in that it provides site-specific information (i.e., within 5–15 km of the station), low-velocity layers can be identified, and it is possible to examine structure to upper mantle depths. In this study, receiver functions were computed for each of the 19 stations that made up the seismograph network in June 1994. Five stations, sampling a variety of tectonic environments, including the Appalachian Orogen, the Canadian Shield, the Western Canadian Sedimentary Basin, and the Cascadia subduction zone, were chosen for detailed modelling. The results presented here are the first estimates of the S-velocity structure beneath these five stations. For those stations where comparisons can be made with seismic reflection and refraction results, there is excellent agreement. In eastern Canada, simple receiver functions and clear Moho Ps conversions at most stations indicate a relatively transparent crust and a Moho depth of 40–45 km. In northwestern Canada, Moho Ps phases indicate a crustal thickness of 33–38 km. Beneath Inuvik, Northwest Territories, the Moho is interpreted as two velocity steps separated in depth by 5 km, and an upper mantle low-velocity zone is near 47 km depth. In western Canada, the data indicate a mid-crustal low-velocity zone beneath Edmonton. The Moho of the subducting Juan de Fuca plate is interpreted at 52 km depth beneath southern Vancouver Island. Several stations exhibiting complex receiver functions warrant further study. They include stations at Schefferville, Quebec, in the Canadian Shield; Deer Lake, Newfoundland, on the boundary of the Grenville Province and the Appalachian Orogen; and Yellowknife, Northwest Territories, at the intersection of the Churchill and Slave provinces and the Western Plains.

Paleomagnetism of the Western Channel Diabase and Associated Rocks, Northwest Territories

1972 ◽  
Vol 9 (8) ◽  
pp. 960-971 ◽  
Author(s):  
E. Irving ◽  
J. A. Donaldson ◽  
J. K. Park
Keyword(s):  
Northwest Territories ◽  
Remanent Magnetization ◽  
Opposite Sign ◽  
Canadian Shield ◽  
Peak Amplitude ◽  
Preliminary Results ◽  
Late Precambrian ◽  
General Region

The stable remanent magnetization of the Western Channel diabase (1325–1785 m.y.) determined at 35 sites has a mean direction of 356, −50 (α95 = 6°) and a corresponding pole at 9 °N, 115 °W (A95 = 6°). Studies of rocks bordering the diabase show that this magnetization was acquired at the time of initial cooling. Preliminary results from older sediments, diabase, and porphyry (1770 m.y.) give directions of opposite sign, with corresponding poles in the same general region. These results, and others recently published, allow the path of apparent polar wandering, relative to the Canadian Shield, to be constructed in a preliminary fashion for the middle and earlier Proterozoic. This path, together with that previously obtained by other workers for the late Precambrian, suggests that during the Proterozoic the pole moved through two cycles of a roughly sinusoidal path with a peak-to-peak amplitude of about 90° of arc and a period of several hundred million years.

scholarly journals Canada Close Up: Northwest Territories by R. Eagen

2016 ◽  
Vol 6 (2) ◽  
Author(s):  
No name BCR
Keyword(s):  
First Nations ◽  
Northwest Territories ◽  
Canadian Shield ◽  
Birch Bark ◽  
Southwest Part

Eagen, Rachel. Canada Close Up: Northwest Territories. Toronto: Scholastic Canada, 2010. Print. The first people to live in what is now the Northwest Territories arrived about 10,000 years ago in the southwest part of the Canadian Shield. It explains about the usage of birch bark and what they made from it. It talks about the northern lights and how many colours you can see in the Northwest Territories. It has content and it shows you the First Nations and the taiga and the barren islands. I like this book as a good example. I rate this book as a 4 out of 5. Recommended: 4 out of 5 stars Reviewer: no nameI like games because they are fun. I like walking my dog because it is healthy. I enjoy reading because it is educational and I can learn new things. Space is cool because you learn about galaxies and planets. Sports are fun because you can learn new things and get better at it.

scholarly journals A New Record of Deepwater Sculpin, Myoxocephalus thompsonii, in Northeastern Alberta

2006 ◽  
Vol 120 (4) ◽  
pp. 480
Author(s):  
M. Steinhilber ◽  
D. A. Neely
Keyword(s):  
Northwest Territories ◽  
New Record ◽  
Canadian Shield ◽  
Gill Nets ◽  
Northeastern Alberta ◽  
Northern Alberta

We present the first documented records of Deepwater Sculpin, Myoxocephalus thompsonii, from northern Alberta, and the second record for the province. Three specimens of Deepwater Sculpin were taken in gill nets set at 17 to 20 m depth in Colin Lake, Alberta, on 15 September 2001. Colin Lake, located in the Canadian Shield region of northeastern Alberta about 125 km northeast of Fort Chipewyan, drains into Lake Athabasca via the Colin River. The only other known Alberta population of Deepwater Sculpin inhabits Upper Waterton Lake in the southwestern corner of the province. This record is approximately 300 km SSE of the nearest verified record in the Northwest Territories and 400 km NW of the nearest verified record in Saskatchewan.

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