Proterozoic paleocurrents and depositional history of the East Arm fold belt, Great Slave Lake, Northwest Territories

1969 ◽  
Vol 6 (3) ◽  
pp. 441-462 ◽  
Author(s):  
Paul Hoffman
Keyword(s):  
Volcanic Rocks ◽  
Canadian Shield ◽  
Stratigraphic Correlation ◽  
Fold Belt ◽  
Axial Zone ◽  
Depositional History ◽  
Great Slave Lake ◽  
History Of ◽  
Three Stages ◽  
Fault Scarps

Nearly 40 000 ft (~12 190 m) of unmetamorphosed Aphebian (and possibly lowermost Helikian) sedimentary and volcanic rocks are exposed in the East Arm of Great Slave Lake. This sequence is an erosional remnant of an Appalachian-type geosynclinal complex with a NNW depositional strike. Integrated paleocurrent, stratigraphic, and sedimentological analysis reveals three stages in the depositional history of the complex: (1) a double transgressive, pre-orogenic miogeosyncline, which received sediment from a distant cratonic source to the ENE and which becomes thicker and more eugeosynclinal to the WSW; (2) a regressive, syn-orogenic exogeosyncline (clastic wedge), which received sediment from rapidly uplifted tectonic lands to the WSW; and (3) a continental, post-orogenic taphrogeosyncline (down-faulted intermontaine trough), which received sediment locally from block-fault scarps within the East Arm area.Facies predictions based on this model provide criteria for establishing stratigraphic correlation and contiguity between the East Arm and other Aphebian sequences in the northwestern Canadian Shield. The prevailing depositional strike is roughly perpendicular to the tectonic strike of the East Arm Fold Belt, and it should not therefore be assumed that depositional strike parallels tectonic strike in other belts. The Bear Province may have been the site of the orogenically active axial zone of the geosyncline, but that part of the Churchill Province near the East Arm remained passive until the final post-orogenic stage of sedimentation and may therefore be of epeirogenic origin.

Rb–Sr geochronology and metamorphic history of Proterozoic to early Archean rocks north of the Cape Smith Fold Belt, Quebec

1987 ◽  
Vol 24 (4) ◽  
pp. 813-825 ◽  
Author(s):  
Ronald Doig
Keyword(s):  
Volcanic Rocks ◽  
Granitic Rocks ◽  
Iron Formation ◽  
Fold Belt ◽  
Metasedimentary Rocks ◽  
Metamorphic History ◽  
The North ◽  
Basement Rocks ◽  
History Of ◽  
Wide Zone

The Churchill Province north of the Proterozoic Cape Smith volcanic fold belt of Quebec may be divided into two parts. The first is a broad antiform of migmatitic gneisses (Deception gneisses) extending north from the fold belt ~50 km to Sugluk Inlet. The second is a 20 km wide zone of high-grade metasedimentary rocks northwest of Sugluk Inlet. The Deception gneisses yield Rb–Sr isochron ages of 2600–2900 Ma and initial ratios of 0.701–0.703, showing that they are Archean basement to the Cape Smith Belt. The evidence that the basement rocks have been isoclinally refolded in the Proterozoic is clear at the contact with the fold belt. However, the gneisses also contain ubiquitous synclinal keels of metasiltstone with minor metapelite and marble that give isochron ages less than 2150 Ma. These ages, combined with low initial ratios of 0.7036, show that they are not part of the basement, as the average 87Sr/86Sr ratio for the basement rocks was about 0.718 at that time.The rocks west of Sugluk Inlet consist mainly of quartzo-feldspathic sediments, quartzites, para-amphibolites, marbles, and some pelite and iron formation. In contrast to the Proterozoic sediments in the Deception gneisses, these rocks yield dates of 3000–3200 Ma, with high initial ratios of 0.707–0.714. These initial ratios point to an age (or a provenance) much greater than that of the Archean Deception gneisses. The rocks of the Sugluk terrain are intruded by highly deformed sills of granitic rocks with ages of about 1830 Ma, demonstrating again the extent and severity of the Proterozoic overprint. The eastern margin of this possibly early Archean Sugluk block is a discontinuity in age, lithology, and geophysical character that could be a suture between two Archean cratons. It is not known if such a suturing event is of Archean age, or if it is related to the deformation of the Cape Smith Fold Belt.Models of evolution incorporating both the Cape Smith Belt and the Archean rocks to the north need to account for the internal structure of the fold belt, the continental affinity of many of the volcanic rocks, the continuity of basement around the eastern end of the belt, and the increase in metamorphism through the northern part of the belt into a broad area to the north. The Cape Smith volcanic rocks may have been extruded along a continental rift, parallel to a continental margin at Sugluk. Continental collison at Sugluk would have thrust the older and higher grade Sugluk rocks over the Deception gneisses, produced the broad Deception antiform, and displaced the Cape Smith rocks to the south in a series of north-dipping thrust slices.

Paleomagnetic evidence for the extent of Mackenzie igneous events

1969 ◽  
Vol 6 (4) ◽  
pp. 679-688 ◽  
Author(s):  
W. F. Fahrig ◽  
D. L. Jones
Keyword(s):  
Volcanic Rocks ◽  
Pole Position ◽  
Canadian Shield ◽  
Paleomagnetic Data ◽  
Paleomagnetic Pole ◽  
Great Slave Lake ◽  
The Mean ◽  
Coppermine River ◽  
Age Determinations ◽  
Middle Proterozoic

North-northwesterly striking Mackenzie diabase dikes of middle-Proterozoic (Helikian) age are profuse in the western part of the Canadian Shield. Published paleomagnetic data on dikes of this trend in Mackenzie District, on the Muskox Intrusion, the Coppermine River volcanic rocks, and the Sudbury dikes suggest that they are all products of closely related igneous events. This paper presents paleomagnetic data that suggest that the intrusion of extensive diabase sheets in the East Arm of Great Slave Lake, and of dikes as far to the northeast as Melville Peninsula and as far to the southeast as Manitoba, were also parts of these events. The mean paleomagnetic pole position for the Mackenzie dikes and for related intrusive and extrusive rocks is [Formula: see text], 171 °W with [Formula: see text]. Radioactive age determinations, some of which are unpublished, indicate an age of about 1200 m.y. for the formation of these rocks. It is suggested that for convenience all of these apparently related intrusive and extrusive igneous episodes be referred to as Mackenzie igneous events.

Correlation of Major Aphebian Rock Units in the Northeastern Canadian Shield

1972 ◽  
Vol 9 (12) ◽  
pp. 1650-1669 ◽  
Author(s):  
G. D. Jackson ◽  
F. C. Taylor
Keyword(s):  
Regional Metamorphism ◽  
Volcanic Rocks ◽  
Structural Data ◽  
Granulite Facies ◽  
Canadian Shield ◽  
Shelf Zone ◽  
Fold Belt ◽  
Entire Area ◽  
Fold Belts ◽  
Basic Volcanic

Several groups of Aphebian layered rocks in the northeastern Canadian Shield have been correlated because of lithologic and stratigraphic similarities and alignment of groups and structural trends. Most of these layered rocks lie in three distinct fold belts which from south to north have been named the Dorset, Foxe, and the Committee Fold Belts.The widespread occurrence of Aphebian outliers between the fold belts indicates that Aphebian strata probably originally covered the entire area from the Circum–Ungava Geosyncline or Fold Belt east to the Dorset Fold Belt and north to the Committee Fold Belt. The name Baffin Geosyncline is proposed for this depositional zone. Aphebian layered rocks in the two last-named fold belts were probably deposited in marginal mio-eugeosynclinal zones of the main geosyncline and are mainly meta-shale, meta-graywacke, and metamorphosed basic volcanic rocks and associated basic and ultrabasic intrusions. The Aphebian rocks of the Dorset and Foxe Fold Belts were deposited in the central shelf zone of the Baffin Geosyncline and are mainly meta-shale, meta-graywacke, rusty quartz-rich gneiss, marble, and quartzite.The Aphebian layered rocks have been intruded by large granitic plutons and have been metamorphosed to amphibolite and granulite facies of regional metamorphism. Age determinations and structural data indicate that a mid-Aphebian orogeny affected much of the northern part of this region 2000–2200 m.y. ago, and that the whole region was strongly affected by the Hudsonian orogeny.

Nikolay Sieber in the history of prerevolutionary Russian economic thought

2018 ◽  
pp. 95-110
Author(s):  
L. D. Shirokorad
Keyword(s):  
Economic Theory ◽  
Political Economy ◽  
Organic Synthesis ◽  
Marginal Utility ◽  
Economic Thought ◽  
History Of ◽  
Three Stages

This article shows how representatives of various theoretical currents in economics at different times in history interpreted the efforts of Nikolay Sieber in defending and developing Marxian economic theory and assessed his legacy and role in forming the Marxist school in Russian political economy. The article defines three stages in this process: publication of Sieber’s work dedicated to the analysis of the first volume of Marx’s Das Kapital and criticism of it by Russian opponents of Marxian economic theory; assessment of Sieber’s work by the narodniks, “Legal Marxists”, Georgiy Plekhanov, and Vladimir Lenin; the decline in interest in Sieber in light of the growing tendency towards an “organic synthesis” of the theory of marginal utility and the Marxist social viewpoint.

Structural and depositional history of East Timor

2018 ◽  
Author(s):  
T.A. Reed
Keyword(s):  
East Timor ◽  
Depositional History ◽  
History Of

Frontiers of Visibility

Transfers ◽  
2013 ◽  
Vol 3 (2) ◽  
pp. 24-46 ◽  
Author(s):  
Franziska Torma
Keyword(s):  
Twentieth Century ◽  
Current Understanding ◽  
Machine Age ◽  
History Of ◽  
Three Stages ◽  
The 1950S ◽  
The 1960S ◽  
Popular Images ◽  
Cinematic Technology

This article deals with the history of underwater film and the role that increased mobility plays in the exploration of nature. Drawing on research on the exploration of the ocean, it analyzes the production of popular images of the sea. The entry of humans into the depths of the oceans in the twentieth century did not revitalize myths of mermaids but rather retold oceanic myths in a modern fashion. Three stages stand out in this evolution of diving mobility. In the 1920s and 1930s, scenes of divers walking under water were the dominant motif. From the 1940s to the 1960s, use of autonomous diving equipment led to a modern incarnation of the “mermen“ myth. From the 1950s to the 1970s, cinematic technology was able to create visions of entire oceanic ecosystems. Underwater films contributed to the period of machine-age exploration in a very particular way: they made virtual voyages of the ocean possible and thus helped to shape the current understanding of the oceans as part of Planet Earth.

CLIMATIC AND DEPOSITIONAL HISTORY OF THE LOWER PALEOCENE UPPER NACIMIENTO FORMATION, SAN JUAN BASIN, NEW MEXICO

2016 ◽  
Author(s):  
Caitlin E. Leslie ◽  
◽  
Ross Secord ◽  
Daniel J. Peppe ◽  
Stacy Atchley ◽  
...  
Keyword(s):  
New Mexico ◽  
San Juan ◽  
Depositional History ◽  
San Juan Basin ◽  
History Of
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