Paleomagnetism of the Wintering Lake pluton and the Early Proterozoic tectonic motion of the Superior Boundary Zone, Manitoba

2006 ◽  
Vol 43 (7) ◽  
pp. 1071-1083
Author(s):  
M J Harris ◽  
D TA Symons ◽  
W H Blackburn ◽  
A Turek ◽  
D C Peck
Keyword(s):  
Coarse Grained ◽  
Boundary Zone ◽  
Polar Wander ◽  
Early Proterozoic ◽  
Apparent Polar Wander Path ◽  
Paleomagnetic Study ◽  
Paleomagnetic Result ◽  
Tectonic Motion ◽  
Host Rocks ◽  
Superior Craton

This Lithoprobe-funded paleomagnetic study of the Early Proterozoic Wintering Lake granitoid body supports tectonic models that suggest continental accretion of the Trans-Hudson Orogen with the Superior Craton occurred at ~1822 Ma. Thermal demagnetization data for the granitoid specimens suggest that the magnetic remanence carriers are coarse-grained magnetite or titanomagnetite, and saturation isothermal remanence tests suggest that the magnetite is mostly multidomain. Six of seven paleomagnetic contact tests were negative, indicating that the host rocks have been remagnetized and that the granitoid body may have been partially remagnetized near its margins. Acceptable site mean remanence directions for 20 of 21 granitic sites yield a paleopole at 46.8°N, 102.2°W (with semi-axes of the 95% ellipse of confidence about the paleopole of dp = 11° and dm = 11°). The paleopole fits on the extrapolated apparent polar wander path (APWP) for the Superior craton at ~1822 Ma, which is the interpreted emplacement age of the pluton close to the peak of the Trans-Hudson orogeny. This is the first well-constrained paleomagnetic result from the Superior Province that provides direct evidence from concordant paleopoles for the Early Proterozoic accretion of the orogen to the craton. Further, the paleomagnetic results from the pluton's host rocks, along with other recent results from the Superior Boundary Zone, fill in a gap in the APWP for the craton between ~1780 and ~1720 Ma. The Superior path is now shown to form a hairpin as the craton moves from mid to polar paleolatitudes from ~1880 to ~1830 Ma, suffers a stillstand from ~1830 to ~1770 Ma during the peak of the Trans-Hudson orogeny, returns to mid-paleolatitudes from ~1770 to ~1740 Ma, and then moves on to subequatorial paleolatitudes by ~1720 Ma.

Paleomagnetism of the Lawrenceton Formation volcanic rocks, Silurian Botwood Group, Change Islands, Newfoundland

1989 ◽  
Vol 26 (2) ◽  
pp. 296-304 ◽  
Author(s):  
Julie E. Gales ◽  
Ben A. van der Pluijm ◽  
Rob Van der Voo
Keyword(s):  
North American ◽  
Volcanic Rocks ◽  
Mobile Belt ◽  
Structural Mapping ◽  
Polar Wander ◽  
The North ◽  
Apparent Polar Wander Path ◽  
Paleomagnetic Study ◽  
North American Craton

Paleomagnetic sampling of the Lawrenceton Formation of the Silurian Botwood Group in northeastern Newfoundland was combined with detailed structural mapping of the area in order to determine the deformation history and make adequate structural corrections to the paleomagnetic data.Structural analysis indicates that the Lawrenceton Formation experienced at least two folding events: (i) a regional northeast–southwest-trending, Siluro-Devonian folding episode that produced a well-developed axial-plane cleavage; and (ii) an episode of local north-trending folding. Bedding – regional cleavage relationships indicate that the latter event is older than the regional folding.Thermal demagnetization of the Lawrenceton Formation yielded univectorial southerly and shallow directions (in situ). A fold test on an early mesoscale fold indicates that the magnetization of the Botwood postdates this folding event. However, our results, combined with an earlier paleomagnetic study of nearby Lawrenceton Formation rocks, demonstrate that the magnetization predates the regional folding. Therefore, we conclude that the magnetization occurred subsequent to the local folding but prior to the period of regional folding.While a tectonic origin for local folding cannot be entirely excluded, the subaerial nature of these volcanics, the isolated occurrence of these folds, and the absence of similar north-trending folds in other areas of eastern Notre Dame Bay suggest a syndepositional origin. Consequently, the magnetization may be nearly primary. Our study yields a characteristic direction of D = 175°, I = +43°, with a paleopole (16°N, 131 °E) that plots near the mid-Silurian track of the North American apparent polar wander path. This result is consistent with an early origin for the magnetization and supports the notion that the Central Mobile Belt of Newfoundland was adjacent to the North American craton, in its present-day position, since the Silurian.

A paleomagnetic study of the lava flows within the Copper Harbor Conglomerate, Michigan: new results and implications

1994 ◽  
Vol 31 (2) ◽  
pp. 369-380 ◽  
Author(s):  
J. F. Diehl ◽  
T. D. Haig
Keyword(s):  
High Temperature ◽  
Entire Range ◽  
Lava Flows ◽  
Polar Wander ◽  
Lake Shore ◽  
Apparent Polar Wander Path ◽  
Paleomagnetic Pole ◽  
Complete Section ◽  
Paleomagnetic Study ◽  
Petrographic Analyses

New paleomagnetic data have been obtained from the interbedded lava flows within the Copper Harbor Conglomerate on Michigan's Keweenaw Peninsula. Previous paleomagnetic studies of these lava flows, known collectively as the Lake Shore Traps, have produced contradictory results. To investigate the cause of these conflicting results, 30 sites encompassing the most complete section of lava flows possible were collected and analyzed.Well-defined characteristic directions of magnetization were isolated using either alternating-field or thermal demagnetization or a combination of both. These directions of magnetization are interpreted as primary magnetizations acquired during the original cooling of the lavas. Hysteresis, thermomagnetic, and petrographic analyses suggest the carrier of magnetization is a pseudo-single-domain, titanium-poor magnetite that has undergone some high-temperature oxidation.Site means determined from the 30 lava flows define three distinct directional clusters. Each cluster of directions corresponds to a different stratigraphic package of lava flows with the Copper Harbor Conglomerate. Between-site dispersion for each stratigraphic package or unit is much less than the expected value for Keweenawan-age rocks. Therefore, we suggest that most of the lava flows in each unit were extruded rapidly and that within an individual stratigraphic unit, paleosecular variation has not been adequately sampled. This explains why previous studies on the Lake Shore Traps have produced such different results; each study did not sample the entire range of directions possible in these lava flows.The paleomagnetic pole calculated from the 30 site-mean virtual geomagnetic poles is located at 22.2°N, 180.8°E (k = 35.0; A95 = 6.5°). The new Copper Harbor pole is now located in the appropriate chronological position with respect to the underlying Portage Lake Volcanics and the overlying Nonesuch Shale on the Keweenawan apparent polar wander path. The similarity of our Copper Harbor pole to that of the Portage Lake Volcanics reinforces the idea that the Copper Harbor Conglomerate is more closely related in time to the Portage Lake Volcanics than to the Nonesuch Shale.

Malley diabase dykes of the Slave craton, Canadian Shield: U–Pb age, paleomagnetism, and implications for continental reconstructions in the early Paleoproterozoic1Geological Survey of Canada Contribution 20110114.

2012 ◽  
Vol 49 (2) ◽  
pp. 435-454 ◽  
Author(s):  
Kenneth L. Buchan ◽  
Anthony N. LeCheminant ◽  
Otto van Breemen
Keyword(s):  
Relative Orientation ◽  
Canadian Shield ◽  
Dyke Swarm ◽  
Slave Craton ◽  
Polar Wander ◽  
Thermal Demagnetization ◽  
Contact Test ◽  
Apparent Polar Wander Path ◽  
Close Proximity ◽  
Superior Craton

The NE-trending Malley dyke swarm, dated herein at 2231 ± 2 Ma (U–Pb baddeleyite), extends from the central Slave craton to the vicinity of the Kilohigok basin, and may continue farther to the northeast as the geochemically similar Brichta dyke swarm, having been offset sinistrally along the prominent Bathurst fault. It carries a characteristic high unblocking temperature paleomagnetic component of single polarity directed up SE (mean direction: D = 138.3°, I = –53.8°), with corresponding paleopole at 50.8°S, 50.0°W. Lower unblocking temperature components, in some cases directed down SE, similar to ca 1.75 Ga post-Hudsonian overprints, are easily removed using combined alternating field (AF) thermal demagnetization, but difficult to remove using AF cleaning alone. The characteristic remanence has not been demonstrated primary, but is significantly older than 2.03 Ga, the age of Lac de Gras dykes, based on a baked contact test at a Lac de Gras – Malley dyke intersection. In addition, an E- to ESE-trending dyke carries a down WNW remanence, typical of 2.19 Ga Dogrib dykes near Yellowknife, suggesting that regional overprinting has not affected the study area since Dogrib emplacement, and that the Malley remanence was acquired at or shortly after Malley emplacement. Comparing Malley and Lac de Gras paleopoles with the 2.22–2.00 Ga Superior craton apparent polar wander path indicates that the two cratons were (i) not in their present relative orientation at 2.23 or 2.03 Ga, and (ii) likely not drifting in close proximity to one another as parts of a single (super)continent throughout the 2.23–2.03 Ga interval.

Indication for counterclockwise declination deviation in the Cretaceous of the North Paris Basin

2004 ◽  
Vol 175 (3) ◽  
pp. 249-255
Author(s):  
Emó Márton ◽  
László Csontos ◽  
Jean-Louis Mansy ◽  
Françoise Bergerat
Keyword(s):  
Late Cretaceous ◽  
Late Eocene ◽  
Angular Deviation ◽  
Paris Basin ◽  
Polar Wander ◽  
The North ◽  
Apparent Polar Wander Path ◽  
Paleomagnetic Result ◽  
Angle Of Deviation ◽  
Paleomagnetic Direction

Abstract Paleomagnetic sampling was carried out in Mesozoic exposures of Northwest France and Southeast Belgium. Cretaceous localities in Hainaut, Boulonnais and Normandie yielded statistically well defined paleomagnetic directions. These localities fall into two groups. Hainaut and Boulonnais are characterized by declinations suggesting 30° counterclockwise (CCW) angular deviation of declination with respect to the present North, while Normandie exhibits moderate (12°) clockwise (CW) angular deviation with respect to the present North. In Normandie, we also observed occasionally very weak signals of a CCW deviated component, which, however, could not be treated statistically. Fold test suggests that both groups of samples were remagnetized during deformation. The overall mean paleomagnetic declination of the first group is westernly, that of the second group practically coincides with post-Eocene European reference directions, From assessing structural inversion and relevant paleostress-directions in Normandie, remagnetization may be connected to tectonic inversion in late Eocene-Oligocene times. While the statistically meaningful paleomagnetic result for the second group fit the synthetic stable European apparent polar wander path (APWP) at about 30 Ma, the overall mean paleomagnetic direction of the first group (based on 5 localities, representing 42 samples) defines a pole which is significantly offset from it, at any time following the deposition of the studied sediments. One explanation of this offset could be intraplate rotation on a small (Brabant Massif) scale. However, the angle of deviation in declination seems to be too large for a tectonic solution. Furthermore the data obtained from the Paleozoic do not show such declination deviation. It seems, therefore, that we need to increase considerably the direct stable European paleomagnetic database for the late Cretaceous-Tertiary, in order to further improve the late Cretaceous-Paleogene segment of the European APWP.

Paleomagnetism of Archean granites and Matachewan dikes in the Wawa Subprovince, Ontario: reevaluation of the Archean apparent polar wander path

1990 ◽  
Vol 27 (8) ◽  
pp. 1031-1039 ◽  
Author(s):  
T. A. Vandall ◽  
D. T. A. Symons
Keyword(s):  
Single Component ◽  
Superior Province ◽  
Polar Wander ◽  
Early Proterozoic ◽  
Dike Swarm ◽  
The North ◽  
Apparent Polar Wander Path ◽  
Quartz Monzonite ◽  
Greenstone Belts ◽  
Tectonic Rotation

Paleomagnetic measurements have been completed on 400 specimens from dated Archean granites and Matachewan dikes in the Michipicoten and Gamitagama greenstone belts in the western Wawa Subprovince of the Superior Province, Ontario. Detailed alternating-field and thermal step demagnetization analyses were used to isolate stable remanence directions. A single-component remanence was isolated within three adjacent dated granitic plutons on the eastern margin of the Michipicoten belt, including the Hawk Lake trondhjemite, the Southern external granite, and the Eastern external granite (HSE). The maximum possible age for this remanence is constrained by the intrusion of the last pluton at 2694 Ma. The corresponding HSE paleopole is located at 10°W, 41°S (dp = 8°, dm = 13°). A second paleopole, NB, is derived from the Northern external granite and the Baldhead River quartz monzonite, which give U–Pb zircon ages of 2662 and 2668 Ma, respectively. Their single-component remanence defines a paleopole on the Archean apparent polar wander path (APWP) at 15°E, 27°S (dp = 8°, dm = 13°), with a maximum possible age of 2.66 Ga. A third paleopole, GD, is derived from the north-northwest-trending Gamitagama diabase dikes and yields a position of 57°E, 41°N (dp = 7°, dm = 14°), which agrees with poles determined by other workers from the 2454 Ma Matachewan dike swarm. The GD pole, along with previously determined Matachewan dike poles, demonstrates that a tectonically stable craton has existed since intrusion of this extensive dike swarm, and it improves the precision of the 2454 Ma Matachewan pole on the APWP. These poles, when compared with coeval poles from the eastern side of the Kapuskasing Structural Zone in the Superior Province, imply no tectonic rotation or translation between the Wawa and Abitibi subprovinces along this Early Proterozoic structure.

Pliocene–Pleistocene genesis for the Murray Brook and Heath Steele Au–Ag gossan ore deposits, New Brunswick, from paleomagnetism

1996 ◽  
Vol 33 (1) ◽  
pp. 1-11 ◽  
Author(s):  
D. T. A. Symons ◽  
M. T. Lewchuk ◽  
D. R. Boyle
Keyword(s):  
New Brunswick ◽  
Ore Deposits ◽  
Age Dating ◽  
Rotational Axis ◽  
Polar Wander ◽  
The Past ◽  
The North ◽  
Apparent Polar Wander Path ◽  
Last Glaciation ◽  
Host Rocks

Several Au–Ag gossans occur over massive sulphide deposits in the Ordovician Tetagouche Group near Bathurst, New Brunswick. The Murray Brook and Heath Steele B zone goethite gossans were about 45 and 15 m thick, respectively, prior to mining. They contain no minerals suitable for radiometric age dating. Geologically they must be younger than the Devonian Acadian orogeny and older than the last glaciation. Paleomagnetic methods were used to analyse specimens from 29 sites, mostly from ore on the pit walls. Host rocks and sulphide mineralization retain characteristic remanent magnetization directions in magnetite and pyrrhotite with a variety of directions that include possible Devonian overprints. Fertile and barren gossan specimens at 21 sites retain antiparallel normal and reversed A characteristic remanence components in goethite and (or) hematite. The A direction is D = 357.7°, I = 61.7 °(α95 = 4.5°, k = 31). Its pole of 134.2°E, 85.2°N (dp = 5.4°, dm = 7.0°) falls on the North American apparent polar wander path and circumscribes the Earth's present rotational axis, indicating that the gossans formed during the Pliocene–Pleistocene. Examination of the site locations in the pits, along with the remanence polarity of their goethite and hematite A components, suggests the gossans formed during Chrons 1 and 2 only, or in the past 2.3 ± 0.3 Ma.

Preliminary Proterozoic apparent polar wander paths for the South China Block and their tectonic implications

1998 ◽  
Vol 35 (3) ◽  
pp. 302-320 ◽  
Author(s):  
Huimin Zhang
Keyword(s):  
South China ◽  
North China ◽  
Eastern China ◽  
North China Block ◽  
Polar Wander ◽  
Late Proterozoic ◽  
The North ◽  
Apparent Polar Wander Path ◽  
Paleomagnetic Study ◽  
Middle Proterozoic

Results of a regional paleomagnetic study of Precambrian rocks in central-east China are summarized and interpreted. The study is a partial outcome of a geoscience transect incorporating three terranes, namely the Yangzi, Jiangnan, and Huaxia blocks. Paleomagnetic poles derived from a range of metamorphic, igneous, and sedimentary rocks define a northeast to southwest swath crossing the present Pacific Ocean and interpreted to embrace Early to Late Proterozoic times. All three terranes define segments of the same swath and correlate with a similar apparent polar wander path previously defined from the North China Block. The results imply that the constituent blocks of eastern China formed a united block during Early to Middle Proterozoic times. Later relatively large fragmentation is confirmed by Late Proterozoic apparent polar wander path records of the North China and South China Blocks.

Broad-scale Proterozoic deformation of the central Superior Province revealed by paleomagnetism of the 2.45 Ga Matachewan dyke swarm

1991 ◽  
Vol 28 (11) ◽  
pp. 1780-1796 ◽  
Author(s):  
M. P. Bates ◽  
H. C. Halls
Keyword(s):  
Large Scale ◽  
Dyke Swarm ◽  
Superior Province ◽  
Polar Wander ◽  
The North ◽  
Paleomagnetic Study ◽  
Secondary Feature ◽  
Dual Polarity ◽  
Host Rocks ◽  
Broad Scale

An extensive paleomagnetic study of the 2.45 Ga Matachewan dyke swarm of the North American Superior Province suggests that the interior of an Archean shield can undergo broad-scale distortion as a result of later (Proterozoic) orogenic activity around the craton margins. Data collected from over 300 sites, of which 137 are reported here for the first time, reveal that the dykes contain a dual-polarity primary remanence that varies across the swarm in both inclination and declination. These regional variations are statistically significant at the 95% confidence level, and cannot be attributed to remagnetization or to magnetic anisotropy. Inclination variation is probably due to real or apparent polar wander during the emplacement of the swarm, and may in part explain the declination variation as well. However, for dykes within and northwest of the Kapuskasing Structural Zone (KSZ) a positive correlation is found between regionally averaged values of declination and dyke trend. Here the dykes appear to have suffered differential rotations about vertical axes of up to 40° since emplacement. The Matachewan swarm radiates northwards from a broad focus situated approximately in northern Lake Huron but the trend of the western half of the swarm follows a broad Z-shaped pattern where it crosses the KSZ. Our data suggest that this changing trend is a secondary feature and that the western dykes, like their eastern counterparts, originally had a more uniform trend. This large-scale distortion of the western Matachewan swarm and Archean host rocks within and north of the KSZ is probably the result of broad-scale deformation during the Trans-Hudson Orogeny at about 1.95 Ga, coeval with uplift along the KSZ.

A regional paleomagnetic study of Archean rocks from the Superior Geotraverse area, northwestern Ontario

1979 ◽  
Vol 16 (10) ◽  
pp. 1906-1919 ◽  
Author(s):  
David J. Dunlop
Keyword(s):  
Reliable Determination ◽  
Polar Wander ◽  
Apparent Polar Wander Path ◽  
Northwestern Ontario ◽  
Paleomagnetic Study ◽  
Igneous Activity ◽  
Greenstone Belts ◽  
Mafic Intrusives ◽  
Iron Formations ◽  
East West

Preliminary paleomagnetic data are reported for Archean metavolcanics, felsic and mafic intrusives, gneisses, and iron formations from the Quetico, Shebandowan, and Wabigoon belts in the western Superior Structural Province. Eleven of the 23 formations sampled have been studied in detail using stepwise alternating-field demagnetization and, in some cases, thermal demagnetization. Two characteristic components of magnetization are revealed. One is widespread in occurrence and reasonably well grouped (D = 4.5°, I = + 55.7°, k = 17.9, α95 = 5.4°, N = 40 samples for the Shelley Lake granite for example). It is a regional magnetic overprint due to the Kenoran orogeny, acquired, according to the position of its paleopole (71.7°E, 77.3°N, δp = 5.5°, δm = 8 °for the Shelley Lake granite) on the Laurentian apparent polar wander path and to independent radiometric evidence, about −2600 Ma. The second magnetic component is spotty in occurrence, more prevalent in the Wabigoon belt than elsewhere, and everywhere rather scattered. The only fully reliable determination is D = 66.0°, I = −5.1 °(k = 10.2, α95 = 15°, N = 11 samples) for the Wabigoon gabbro. The corresponding paleopole is either 17.8°E, 13.1°N (δp = 7.5°, δm = 15°) falling at about −2800 Ma on the apparent polar wander path or the antipole of this direction, dating between −1350 and −1250 Ma. The younger date, implying a late ProterQzoic metamorphic event in the region, is more likely than the older age, which would require that the magnetization be primary or a pre-Kenoran overprint. The metamorphism seems to have occurred too early to have been caused by igneous activity ca. 1100 Ma in the nearby Keweenawan basin. About −2600 Ma, the region was in its present orientation, but at a latitude of 20 to 35°N and probably drifting northward. About −1250 Ma, the region was equatorial but rotated 90°, so that presently east–west trending greenstone belts were north–south. It is possible, but un-proven, that a paleoocean existed between the Wabigoon subprovince and the other belts about −1250 Ma, the Wabigoon region having since moved > 500 km westward (present-day direction) to its present location.

scholarly journals Rotation of the Philippine Sea plate inferred from paleomagnetism of oriented cores taken with an ROV-based coring apparatus

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Toshitsugu Yamazaki ◽  
Shun Chiyonobu ◽  
Osamu Ishizuka ◽  
Fumisato Tajima ◽  
Naoki Uto ◽  
...  
Keyword(s):  
Plate Motion ◽  
Philippine Sea Plate ◽  
Late Oligocene ◽  
Clockwise Rotation ◽  
Polar Wander ◽  
Philippine Sea ◽  
Apparent Polar Wander Path ◽  
Paleomagnetic Study ◽  
History Of ◽  
The Mean

AbstractReconstructing the history of Philippine Sea (PHS) plate motion is important for better understanding of the tectonics of the surrounding plates. It is generally considered that the PHS plate migrated northward since Eocene, but its rotation has not been constrained well; some reconstructions incorporated a large clockwise rotation but others did not. This is mainly because the difficulty of collecting oriented rocks from the mostly submerged PHS plate hindered establishing an apparent polar wander path. In this study, we conducted a paleomagnetic study of oriented cores taken using an ROV-based coring apparatus from the Hyuga Seamount on the northern part of the Kyushu-Palau Ridge, a remnant arc in the stable interior of the PHS plate. Stepwise thermal and alternating-field demagnetizations were applied to specimens taken successively from two ~ 30 cm long limestone cores of middle to late Oligocene age, and characteristic remanent magnetization directions could be isolated. Declination and inclination of D = 51.5° and I = 39.8°, respectively, were obtained as the mean of the two cores. The easterly-deflected declination means ~ 50° clockwise rotation of the PHS plate since middle to late Oligocene. In addition, ~ 5° latitudinal change of the site is estimated from the mean inclination. The result implies that the Kyushu-Palau Ridge was located to the southwest of the present position in middle to late Oligocene, and that PHS plate rotation as well as the Shikoku and Parece Vela Basin spreading contributed to the eastward migration of the Izu-Ogasawara (Bonin) Arc to the current position.

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