Reorienting the West African craton in Paleoproterozoic–Mesoproterozoic supercontinent Nuna

The location of the West African craton (WAC) has been poorly constrained in the Paleoproterozoic–Mesoproterozoic supercontinent Nuna (also known as Columbia). Previous Nuna reconstruction models suggested that the WAC was connected to Amazonia in a way similar to their relative position in Gondwana. By an integrated paleomagnetic and geochronological study of the Proterozoic mafic dikes in the Anti-Atlas Belt, Morocco, we provide two reliable paleomagnetic poles to test this connection. Incorporating our new poles with quality-filtered poles from the neighboring cratons of the WAC, we propose an inverted WAC-Amazonia connection, with the northern WAC attached to northeastern Amazonia, as well as a refined configuration of Nuna. Global large igneous province records also conform to our new reconstruction. The inverted WAC-Amazonia connection suggests a substantial change in their relative orientation from Nuna to Gondwana, providing an additional example of large-magnitude cumulative azimuthal rotations between adjacent continental blocks over supercontinental cycles.

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Lithostratigraphy of the Palaeoproterozoic Hekpoort Formation (Pretoria Group, Transvaal Supergroup), South Africa

South African Journal of Geology ◽

10.25131/sajg.123.0043 ◽

2020 ◽

Vol 123 (4) ◽

pp. 655-668

Author(s):

N. Lenhardt ◽

W. Altermann ◽

F. Humbert ◽

M. de Kock

Keyword(s):

South Africa ◽

Bushveld Complex ◽

Sedimentary Rocks ◽

Type Locality ◽

Large Igneous Province ◽

Braided River ◽

River Systems ◽

The West ◽

Igneous Province ◽

Transvaal Supergroup

Abstract The Palaeoproterozoic Hekpoort Formation of the Pretoria Group is a lava-dominated unit that has a basin-wide extent throughout the Transvaal sub-basin of South Africa. Additional correlative units may be present in the Kanye sub-basin of Botswana. The key characteristic of the formation is its general geochemical uniformity. Volcaniclastic and other sedimentary rocks are relatively rare throughout the succession but may be dominant in some locations. Hekpoort Formation outcrops are sporadic throughout the basin and mostly occur in the form of gentle hills and valleys, mainly encircling Archaean domes and the Palaeoproterozoic Bushveld Complex (BC). The unit is exposed in the western Pretoria Group basin, sitting unconformably either on the Timeball Hill Formation or Boshoek Formation, which is lenticular there, and on top of the Boshoek Formation in the east of the basin. The unit is unconformably overlain by the Dwaalheuwel Formation. The type-locality for the Hekpoort Formation is the Hekpoort farm (504 IQ Hekpoort), ca. 60 km to the west-southwest of Pretoria. However, no stratotype has ever been proposed. A lectostratotype, i.e., the Mooikloof area in Pretoria East, that can be enhanced by two reference stratotypes are proposed herein. The Hekpoort Formation was deposited in a cratonic subaerial setting, forming a large igneous province (LIP) in which short-termed localised ponds and small braided river systems existed. It therefore forms one of the major Palaeoproterozoic magmatic events on the Kaapvaal Craton.

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Structure, evolution and palaeogeography of the West African craton and bordering belts during the Neoproterozoic

Precambrian Research ◽

10.1016/0301-9268(94)90094-9 ◽

1994 ◽

Vol 69 (1-4) ◽

pp. 307-326 ◽

Cited By ~ 105

Author(s):

M. Villeneuve ◽

J.J. Cornée

Keyword(s):

West African ◽

Structure Evolution ◽

The West ◽

West African Craton

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The magmatic evolution at the Moroccan outboard of the West African craton between the Late Neoproterozoic and the Early Palaeozoic

Geological Society London Special Publications ◽

10.1144/sp297.16 ◽

2008 ◽

Vol 297 (1) ◽

pp. 329-343 ◽

Cited By ~ 13

Author(s):

H. Ezzouhairi ◽

M. L. Ribeiro ◽

N. Ait Ayad ◽

M. E. Moreira ◽

A. Charif ◽

...

Keyword(s):

West African ◽

Magmatic Evolution ◽

The West ◽

West African Craton ◽

Late Neoproterozoic ◽

Early Palaeozoic

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Geodynamic evolution of the 2.25-2.0 Ga Palaeoproterozoic magmatic rocks in the Man-Leo Shield of the West African Craton. A model of subsidence of an oceanic plateau

Geological Society London Special Publications ◽

10.1144/sp323.11 ◽

2009 ◽

Vol 323 (1) ◽

pp. 231-254 ◽

Cited By ~ 29

Author(s):

M. Lompo

Keyword(s):

West African ◽

Geodynamic Evolution ◽

The West ◽

West African Craton ◽

Oceanic Plateau ◽

Magmatic Rocks

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

10.5194/egusphere-egu21-13336 ◽

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

The West African Craton (WAC) is one of the major cratons in the Rodinia jigsaw puzzle (~1000&#8211;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 &#177; 8.5 Ma and 855 &#177; 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-S&#227;o Francisco were associated in a long-lived WABAMGO juxtaposition (~1100&#8211;800 Ma).Keywords: West Africa, Neoproterozoic, Tonian, Rodinia, paleomagnetism.&#160;

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