Paleomagnetic results from the upper Keweenawan Chequamegon Sandstone: implications for red bed diagenesis and Late Precambrian apparent polar wander of North America

1983 ◽  
Vol 20 (1) ◽  
pp. 105-112 ◽  
Author(s):  
Chad McCabe ◽  
Rob Van der Voo
Keyword(s):  
North America ◽  
High Latitude ◽  
North Pole ◽  
End Points ◽  
Polar Wander ◽  
Late Precambrian ◽  
Red Bed

Two components of magnetization have been isolated from Chequamegon Sandstone samples using chemical demagnetization. A characteristic magnetization resides in magnetite of detrital origin. The pole calculated from this magnetization is 12.3°S, 177.7°E (K = 111.5, A95 = 4.6°). This pole lies with other poles of late Keweenawan age and is very close to the Jacobsville Sandstone poles. A secondary magnetization resides in authigenic hematite and yields a pole close to the present north pole. This high-latitude pole is known from an earlier study of the Chequamegon and has been used as evidence for the Hadrynian APW track. However, most if not all of the high-latitude poles that define the Hadrynian track are secondary and undated. Our preferred alternative to the Hadrynian track is that the high-latitude poles are recent remagnetizations and that the antipodal equatorial poles that mark its end points represent field reversals.

Palaeomagnetic evidence for Proterozoic continental development

1981 ◽  
Vol 301 (1461) ◽  
pp. 265-277 ◽  
Keyword(s):  
North America ◽  
High Latitude ◽  
Baltic Shield ◽  
Continental Drift ◽  
Polar Wander ◽  
Late Proterozoic ◽  
Apparent Polar Wander Path ◽  
Orogenic Uplift ◽  
The Baltic ◽  
Opening And Closing

The palaeomagnetic record of continental drift during the Proterozoic is reasonably complete for North America (including Greenland and the Baltic Shield), less complete for Africa and Australia, and fragmentary elsewhere. Palaeomagnetic poles of similar age from different cratons or structural provinces of any one continent tend to fall on a common apparent polar wander path (a.p.w.p.), indicating no major (> 1000 km) intercratonic movements. On this evidence, Proterozoic orogens and mobile belts are essentially ensialic in origin. However, the palaeomagnetic record has systematic gaps. In highly metamorphosed orogens (amphibolite grade and above), remagnetization dating from post-orogenic uplift and cooling is pervasive. Collisional and ensialic orogenesis cannot then be distinguished. Palaeopoles from different continents do not follow a common a.p.w.p. They record large relative rotations and palaeolatitude shifts. A recurrent pattern appears in the late Proterozoic drift of North America. At approximately 200 Ma intervals (at about 1250, 1050, 850 and 600 Ma B.P .), the continent returned to the same orientation and (equatorial) latitudes from various rotations and high-latitude excursions. Lacking detailed a.p.w.ps. from other continents, it is not possible to say if these motions represent Wilson cycles of ocean opening and closing in the Phanerozoic style, but they do require minimum drift rates of 50—60 mm/a, comparable to the most rapid present-day plate velocities.

The Influence of Earth Movements on Climate

1935 ◽  
Vol 72 (2) ◽  
pp. 64-73
Author(s):  
R. G. Lewis
Keyword(s):  
North America ◽  
North Pole ◽  
Warm Climate ◽  
Medium Intensity ◽  
Classical Work ◽  
Gulf Of Bothnia ◽  
The Alps

In the early days of the study of glaciation the problem appeared to be a simple one: we are used to an ice-bound North Pole, and it was natural to assume that the boundary for some reason spread southwards to cover Scandinavia, Scotland, and even some of England. When it was further learnt that North America showed signs of extensive glaciation, this news fell naturally into place and scientists began to form hypotheses to account for a worldwide refrigeration. Quite soon, however, investigators in the countries concerned began to disagree as to the phases, and even the number, of glaciations: the centre of dispersal of the Scandinavian ice was found to be near the head of the Gulf of Bothnia; English geologists were inclined to favour only one glaciation, with certain retreats and advances; Boule would allow three glaciations, while Penck and Bruckner in their classical work on the Alps proved four in their region; Günz, Mindel, Riss, and Würm (with a short climatic improvement at the maximum); followed by the Bühl advance, Gschnitz Stadium and Daun readvance. But these Alpine phases cannot be followed into Italy. Gortani says (1): “Among us, too, Penck had disciples; and we, too, sought all means of adapting his system to the observed facts. But all attempts are vain because (a) nowhere are Günzian moraines to be found; (b) nowhere are to be found traces of more than one true interglacial with a warm climate and (c) the last two advances of the glaciers, where they have left separable traces, show themselves as two principal phases of one glaciation of medium intensity.”

A Discussion on global tectonics in Proterozoic times - Palaeomagnetic evidence for a Proterozoic super-continent

1976 ◽  
Vol 280 (1298) ◽  
pp. 469-490 ◽  
Keyword(s):  
North American ◽  
Mantle Convection ◽  
Great Circle ◽  
Prominent Feature ◽  
Time Data ◽  
Polar Wander ◽  
Late Precambrian ◽  
Palaeomagnetic Data ◽  
The Baltic ◽  
Global Tectonics

The Precambrian apparent polar wander (a.p.w.) curve for Africa is now defined in a general way from ca . 2700 million years (Ma) to Palaeozoic times, and is compared here with palaeomagnetic results from other Precambrian regions. Loops present in the African and North American a.p.w. curves between 2000 and 1000 Ma can be matched in size and shape, and when superimposed show that the AfroArabian and North American regions were in continuity at this time. Data from other Gondwanaland continents are reviewed and seem to be consistent with the SmithHallam reconstruction to ca . 2100 Ma for South America, to ca . 1800 Ma for India, and possibly for Australia back to ca . 2100 Ma. The a.p.w. curve from the Baltic and Ukrainian Shields can be matched with that from Africa and North America such that there was crustal continuity prior to 1000 Ma with the Gothide and Grenville mobile belts in great-circle alignment. The limited palaeomagnetic data from the Siberian Shield do not allow it to be placed uniquely with respect to the other land masses but are consistent with a position in juxtaposition with the Baltic-Ukrainian Shields such that massive anorthosites and ca . 1000 Ma mobile belts are in alignment with those from elsewhere. The palaeomagnetic evidence is consistent with a model in which the bulk of the Precambrian shields were aggregated together as a single super-continent during much of Proterozoic times, the most prominent feature of which is a great circle alignment of massive anorthosites (2250-1000 Ma) along a belt which also became a concentrated zone of igneous intrusion by rapakivi granites and alkaline intrusions, and culminated in generation of long linear mobile belts at 1150 ± 200 Ma and thick graben sedimentation. The predominance of this feature during much of the Proterozoic suggests that a simple mantle convection system pertained during this time. The proposed super-continent is not greatly different in form from the later shortlived super-continent Pangaea, formation of which may have involved relatively minor redistribution of the sialic regions in late Precambrian (probably post-800 Ma) and Palaeozoic times.

Recent development of Arctic air routes

Polar Record ◽  
1962 ◽  
Vol 11 (72) ◽  
pp. 261-264
Author(s):  
John Grierson
Keyword(s):  
North America ◽  
Long Range ◽  
North Pole ◽  
The Real ◽  
The North ◽  
The World ◽  
North Polar ◽  
The One ◽  
Over The Top

Since Andrée's magnificent failure to fly to the North Pole in a balloon in 1897, two great epochs have been marked in polar aviation. The first was the epoch of adventure, lasting nearly 60 years, which attracted to its ranks such men as Roald Amundsen, Lincoln Ellsworth, Umberto Nobile, Richard Byrd, Charles Lindbergh, Gino Watkins and the real father of Arctic aviation, Hubert Wilkins. Many others added their quota of experience until enough was known, and the technique of long-range polar flying had developed sufficiently far, for a regular air line to start operations across the North Polar Basin. That was on 15 November 1954 when Scandinavian Airways System (SAS) opened the first air route over the top of the world, from Europe to North America. This heralded the second epoch—the one of consolidation, and the purpose of this article is to describe very briefly the course of developments during these last seven and a half years.

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