Paleomagnetism and U–Pb geochronology of the Lac de Gras diabase dyke swarm, Slave Province, Canada: implications for relative drift of Slave and Superior provinces in the PaleoproterozoicGeological Survey of Canada Contribution 20080350.

2009 ◽  
Vol 46 (5) ◽  
pp. 361-379 ◽  
Author(s):  
Kenneth L. Buchan ◽  
Anthony N. LeCheminant ◽  
Otto van Breemen
Keyword(s):  
Magnetic Polarity ◽  
Canadian Shield ◽  
Dyke Swarm ◽  
Superior Province ◽  
Igneous Complex ◽  
Contact Test ◽  
Slave Province ◽  
Formed Part ◽  
Dyke Swarms

Lac de Gras diabase dykes trend north to NNE across the central Slave Province of the Canadian Shield. U–Pb baddeleyite ages of 2023 ± 2 and 2027 ± 4 Ma are interpreted as dyke emplacement ages. These ages are similar to that of the Booth River igneous complex, exposed along the margins of Kilohigok Basin near the northern end of the dyke swarm. Ten paleomagnetic sites (from four to six dykes) yield a mean paleopole at 11.8°N, 92.1°W (dm = 8.4°, dp = 6.0°). A positive baked contact test where a Lac de Gras dyke crosscuts a NE-trending Malley dyke demonstrates that this pole is primary. It represents the first key Paleoproterozoic pole from the Slave Province and, hence, the first Paleoproterozoic Slave pole suitable for reconstructing paleocontinents. Although a direct comparison is not available with precisely dated paleopoles of identical age from other Archean cratons, a comparison is made with a sequence of precisely dated poles from Superior Province dyke swarms, including those 40–50 million years older and 25 million years younger. It yields two options depending on the relative magnetic polarity assumed for data from the two cratons. The two cratons were either at similar latitudes, but not in their present relative orientations, when the swarms were emplaced, or separated in latitude by ∼40°–60°. In either case, they may have drifted separately or formed part of a single (super)continent that subsequently broke up with the two cratons drifting separately to attain their present configuration. Additional key paleopoles are required to distinguish between these interpretations.

Paleomagnetism and U-Pb geochronology of diabase dyke swarms of Minto block, Superior Province, Quebec, Canada

1998 ◽  
Vol 35 (9) ◽  
pp. 1054-1069 ◽  
Author(s):  
Kenneth L Buchan ◽  
James K Mortensen ◽  
Kenneth D Card ◽  
John A Percival
Keyword(s):  
Collaborative Study ◽  
Sedimentary Rocks ◽  
Dyke Swarm ◽  
Superior Province ◽  
Mafic Dyke ◽  
Magnetization Direction ◽  
Virtual Geomagnetic Pole ◽  
Southern Province ◽  
Geomagnetic Pole ◽  
Dyke Swarms

In the first collaborative study of paleomagnetism and precise U-Pb geochronology in the Minto block of the Superior Province, mafic dyke swarms with three widely divergent paleomagnetic signatures and isotopic ages have been identified. The 2505 ± 2 Ma Ptarmigan dykes trend north to northeast and have a virtual geomagnetic pole at 42°S, 220°E, similar to that of 2473-2446 Ma Matachewan dykes of the southern Superior Province. The ca. 2230 Ma Maguire dykes trend west to northwest and yield a paleopole at 9°S, 267°E, similar to those for 2216+8-4 Ma Senneterre dykes and 2217-2210 Ma Nipissing sills of the southern Superior and Southern provinces, respectively. The 2209 ± 1 Ma Klotz dykes trend west-northwest, but do not carry a consistent magnetization direction. Finally, 1998 ± 2 Ma Minto dykes of west-northwest to northwest trend, identical in age to the 1998 Ma ± 2 Ma Purtuniq ophiolite of the Cape Smith Belt, have a paleopole at 38°N, 174°E. The similarity of paleopoles for the ca. 2.23-2.21 Ga Maguire dykes of the Minto block, Senneterre dykes of the southern Superior, and Nipissing sills of the Southern Province demonstrates that these regions were in their present relative latitudes and orientations at that time. Likewise, the similarity of the Ptarmigan virtual geomagnetic pole and the Matachewan paleopole suggests little relative latitudinal movement or rotation of the two regions since ca. 2.5 Ga. The Maguire, Senneterre, and Klotz dykes form a roughly radiating pattern and may represent one quadrant of a giant radiating dyke swarm centred southeast of Ungava Bay, whose focus marks the location of a mantle plume responsible for ca. 2.22 Ga breakup along the eastern margin of the Superior Province. If so, the coeval Nipissing sills that intrude sedimentary rocks of the Huronian Supergroup of the Southern Province may have been fed laterally by Senneterre dykes from the Ungava plume centre.

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.

Amphibole and plagioclase chemistry in two Proterozoic dyke swarms and its relation to the uplift history of the Kapuskasing Structural Zone

1992 ◽  
Vol 29 (8) ◽  
pp. 1791-1801 ◽  
Author(s):  
H. C. Palmer ◽  
R. L. Barnett
Keyword(s):  
Country Rock ◽  
Magnetic Polarity ◽  
Dyke Swarm ◽  
Limited Data ◽  
History Of ◽  
Magnetite Particles ◽  
Differential Uplift ◽  
Highly Correlated ◽  
Dyke Swarms ◽  
Lower Crustal

The gneisses of the Chapleau portion of the Kapuskasing Structural Zone (KSZ) and of the Wawa Gneiss Terrane (WGT) can be partitioned into subregions on the basis of magnetic polarity of 2.45 Ga Matachewan diabase dykes emplaced within them. West of the Ivanhoe Lake fault zone (ILFZ) the polarity sequence across the trend of the dyke swarm is normal–reverse–normal (N–R–N) over a traverse distance >100 km. Highly correlated with dyke N polarity is the presence of tea-coloured groundmass plagioclase and hornblende with high Al, Na, and Ti content. Reversely magnetized dykes within the WGT and in dykes of either polarity in regions far removed from the KSZ have groundmass plagioclase with hydrous alteration and relatively Al-poor amphiboles. Although N and R magnetized dykes have groundmass plagioclase with comparable Fe contents, the plagioclase of N dykes and Kapuskasing dykes in the highest grade country rock contain discrete, micrometre-sized, Ti-poor magnetite particles. The mineralogical variations are independent of whole-rock bulk chemistry and are ascribed to greater crystallization depth for N magnetized dykes. The magnitude of the amphibole compositional change in dykes at the western N–R boundary within the WGT is comparable to that across the ILFZ. The western N–R boundary is wholly within the WGT, whereas the ILFZ juxtaposes upper and lower crustal levels. As a consequence, only some of the differential uplift between the KSZ and the Abitibi belt can be accounted for in post-Matachewan dyke time. Limited data from the amphiboles in the 2.04 Ga east-northeast-trending Kapuskasing dykes suggest that this phase of faulting along these block boundaries postdates Kapuskasing dyke emplacement.

Paleomagnetism, U–Pb geochronology, and geochemistry of Marathon dykes, Superior Province, and comparison with the Fort Frances swarm

1996 ◽  
Vol 33 (12) ◽  
pp. 1583-1595 ◽  
Author(s):  
Kenneth L. Buchan ◽  
Henry C. Halls ◽  
James K. Mortensen
Keyword(s):  
Major Element ◽  
Lake Superior ◽  
Magnetic Polarity ◽  
The Other ◽  
Dyke Swarm ◽  
Superior Province ◽  
Reverse Polarity ◽  
Element Geochemistry ◽  
Polar Wander ◽  
Collaborative Studies

We report the first detailed study of the paleomagnetism, U–Pb geochronology and major element geochemistry of Paleoproterozoic north-trending Marathon dykes north of Lake Superior. The paleomagnetic and geochemical results demonstrate that Marathon dykes can be divided into two subsets, one of normal magnetic polarity, the other of reverse polarity. Normal and reverse Marathon paleomagnetic poles, at 43°N, 196°E (dm = 9°, dp = 7°, number of dykes N = 16) and 51°N, 175°E (dm = 9°, dp = 6°, N = 12), respectively, are statistically distinct and may indicate different ages of normal and reverse dyke emplacement, A U–Pb baddeleyite age of [Formula: see text] Ma has been obtained at a normally magnetized Marathon paleomagnetic site. The reversely magnetized Marathon dykes are undated, but have a paleopole rather close to that of the reversely magnetized [Formula: see text] Ma Fort Frances dykes and major element geochemical signatures as portrayed on Jensen plots that are identical to those of the Fort Frances swarm. Therefore, reverse Marathon and Fort Frances dykes could define a giant radiating dyke swarm focused south of Lake Superior, supporting models that associate these dykes with Paleoproterozoic rifting along the southern margin of the Superior Province. The Marathon and Fort Frances paleopoles continue a northwesterly trend in southern Superior Province paleopoles, which has recently been defined by results for [Formula: see text] Ma Senneterre dykes and 2167 ± 2 Ma Biscotasing dykes. This trend contrasts with previous widely used polar wander paths for the same period that young in the opposite direction and illustrates the importance of collaborative studies of paleomagnetism and U–Pb geochronology.

Constraints on the nature of the Kapuskasing structural zone from the study of Proterozoic dyke swarms

1994 ◽  
Vol 31 (7) ◽  
pp. 1182-1196 ◽  
Author(s):  
H. C. Halls ◽  
H. C. Palmer ◽  
M. P. Bates ◽  
Wm. C. Phinney
Keyword(s):  
Magnetic Field ◽  
Fault Zone ◽  
Magnetic Polarity ◽  
High Alumina ◽  
Superior Province ◽  
Structural Studies ◽  
The West ◽  
Early Proterozoic ◽  
Dyke Swarms ◽  
Broad Scale

Petrochemical, paleomagnetic, and structural studies on Early Proterozoic dyke swarms show that the rocks of the Kapuskasing structural zone (KSZ), central Superior Province, were upthrust about 10–15 km along the Ivanhoe Lake fault after intrusion of 2.04 Ga Kapuskasing dykes. This uplift was part of a more widespread deformation in flanking terranes that involved sinistral motion along north–north-northwest-trending faults, dextral displacement along east-northeast–northeast-trending faults, and a distortion of the 2.45 Ga Matachewan swarm to the west and northwest of the Ivanhoe Lake fault. The most spectacular demonstration that the KSZ is largely a product of Proterozoic deformation is that Matachewan dykes change their magnetic polarity on crossing the zone, a consequence of remanence acquisition at deep crustal levels being delayed until after a reversal of the earth's magnetic field and prior to uplift of the dykes.Matachewan and Kapuskasing dykes within the amphibolite- to granulite-grade rocks of the KSZ are relatively fresh and contain a high-alumina green amphibole and feldspar laths that exhibit tea-coloured clouding due to the presence of submicroscopic inclusions of magnetite. These features may be diagnostic of crystallization at deeper crustal levels because they are found in regions where Rb–Sr biotite ages from tonalites suggest broad-scale uplift of the crust after about 2 Ga. About 50 km west of the KSZ, dykes exhibiting clouded feldspar and high-alumina amphiboles occur on the upthrown side of the Budd Lake fault zone, which has a trend similar to that of the Ivanhoe Lake fault. Therefore a second thrust block may exist, raising the possibility that the KSZ represents the basal member of a series of imbricate thrust slices that extends westwards from the Ivanhoe Lake fault. Radiometric age data suggest that the region affected by this Early Proterozoic deformation continues to the northwest for a further 300 km.

Regional variation in paleomagnetic polarity of the Matachewan dyke swarm related to the Kapuskasing Structural Zone, Ontario

1990 ◽  
Vol 27 (2) ◽  
pp. 200-211 ◽  
Author(s):  
M. P. Bates ◽  
H. C. Halls
Keyword(s):  
Lower Crust ◽  
Regional Variation ◽  
Canadian Shield ◽  
Dyke Swarm ◽  
Published Data ◽  
Superior Province ◽  
The North ◽  
Paleomagnetic Pole ◽  
Abitibi Subprovince

The 2.45 Ga Matachewan dykes from the Abitibi Subprovince of the Canadian Shield yield a mean paleomagnetic pole of 42°N, 58°E (α95 = 3°; N (sites) = 36), which is a composite of new and previously published data. Domains of paleomagnetic polarity are defined: an area of dykes predominantly of reversed magnetization in the Abitibi Subprovince contrasts with an area of exclusively normal dykes to the north. The polarity domains are separated by faults related to the 1.95 Ga uplift and exposure of the lower crust in the Kapuskasing Structural Zone and therefore reflect Hudsonian age tectonics in the Archean Superior Province.

Paleomagnetism of the ~860 Ma Manso dyke swarm, West Africa: implications for the assembly of Rodinia

2021 ◽  
Author(s):  
Paul Yves Jean Antonio ◽  
Lenka Baratoux ◽  
Ricardo Ivan Ferreira Trindade ◽  
Sonia Rousse ◽  
Anani Ayite ◽  
...  
Keyword(s):  
West Africa ◽  
West African ◽  
Dyke Swarm ◽  
Jigsaw Puzzle ◽  
The West ◽  
West African Craton ◽  
Contact Test ◽  
Fine Grained ◽  
Paleomagnetic Pole ◽  
Coarse To Fine

<p>The West African Craton (WAC) is one of the major cratons in the Rodinia jigsaw puzzle (~1000–750 Ma). In the Rodinian models, the position of West Africa is mainly constrained by the assumption that it had been a partner of Amazonia since the Paleoproterozoic. Unfortunately, no paleomagnetic data are available for these cratons when the Rodina supercontinent is considered tectonically stable (~1000-750 Ma). Thus, every new reliable paleomagnetic pole for the West African Craton during the Neoproterozoic times is of paramount importance to constrain its position and testing the Rodinia models. In this study we present a combined paleomagnetic and geochronological investigation for the Manso dyke swarm in the Leo-Man Shield, southern West Africa (Ghana). The ~860 Ma emplacement age for the NNW-trending Manso dykes is thus well-constrained by two new U-Pb apatite ages of 857.2 ± 8.5 Ma and 855 ± 16 Ma, in agreement with baddeleyite data. Remanence of these coarse-to-fine grained dolerite dykes is carried by stable single to pseudo-single domain (SD-PSD) magnetite. A positive baked-contact test, associated to a positive reversal test (Class-C), support the primary remanence obtained for these dykes (13 sites). Moreover, our new paleomagnetic dataset satisfy all the seven R-criteria (R=7). The ~860 Ma Manso pole can thus be considered as the first key Tonian paleomagnetic pole for West Africa. We propose that the West Africa-Baltica-Amazonia-Congo-São Francisco were associated in a long-lived WABAMGO juxtaposition (~1100–800 Ma).</p><p><strong>Keywords:</strong> West Africa, Neoproterozoic, Tonian, Rodinia, paleomagnetism.</p><p> </p>

scholarly journals METAMORPHISM OF THE CANADIAN SHIELD, ONTARIO, CANADA. I. THE SUPERIOR PROVINCE

2000 ◽  
Vol 38 (2) ◽  
pp. 287-317 ◽  
Author(s):  
R. M. Easton
Keyword(s):  
Canadian Shield ◽  
Superior Province

Age of the Grenville dyke swarm, Ontario–Quebec: implications for the timing of lapetan rifting

1995 ◽  
Vol 32 (3) ◽  
pp. 273-280 ◽  
Author(s):  
S. L. Kamo ◽  
T. E. Krogh ◽  
P. S. Kumarapeli
Keyword(s):  
Long Range ◽  
Volcanic Rocks ◽  
Canadian Shield ◽  
Dyke Swarm ◽  
Alkaline Complex ◽  
Southeastern Part ◽  
Time Marker ◽  
Continental Breakup ◽  
Iapetus Ocean

U–Pb baddeleyite and zircon ages for three diabase dykes from widely spaced localities within the Grenville dyke swarm indicate a single age of emplacement at [Formula: see text] Ma. The 700 km long Grenville dyke swarm, located in the southeastern part of the Canadian Shield, was emplaced syntectonically with the development of the Ottawa graben. This graben may represent a plume-generated lapetan failed arm that developed at the onset of the breakup of Laurentia. Other precisely dated lapetan rift-related units, such as the Callander Alkaline Complex and the Tibbit Hill Formation volcanic rocks, indicate a protracted 36 Ma period of rifting and magmatism prior to volcanism along this segment of the lapetan margin. The age of the Grenville dykes is the youngest in a progression of precisely dated mafic magmatic events from the 723 Ma Franklin dykes and sills to the 615 Ma Long Range dykes, along the northern and northeastern margins of Laurentia, respectively. Thus, the age for these dykes represents a key time marker for continental breakup that preceded the formation of the Iapetus ocean.

Some new measurements of heat flow in the Superior Province of the Canadian Shield

1987 ◽  
Vol 24 (7) ◽  
pp. 1486-1489 ◽  
Author(s):  
Malcolm Drury ◽  
Alan Taylor
Keyword(s):  
Standard Deviation ◽  
Heat Flow ◽  
Canadian Shield ◽  
Superior Province ◽  
Flow Measurements ◽  
Radiogenic Heat ◽  
Radiogenic Heat Production ◽  
Climatic Variations ◽  
The Mean ◽  
A Site

Borehole heat-flow measurements are reported from six new sites in the Superior Province of the Canadian Shield. Values adjusted for glaciation effects, but not for Holocene climatic variations, range from 42 to 56 mW/m2. When these new values are combined with 21 previously published borehole values the mean is 42 mW/m2 with a standard deviation of 11 mW/m2. The data for a site on the Lac du Bonnet batholith suggest that the batholith has a thin veneer, less than 3 km, of rock of high radiogenic heat production at the surface.

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