Evolution of Fe-Ti-V oxides from the main magnetite layer, Upper Zone, Bushveld Complex, South Africa: a comparison across the Western, Northern and Eastern Lobes

10.21504/rur.13181222.v1 ◽

2020 ◽

Author(s):

Adina Iorga-Pavel

Keyword(s):

South Africa ◽

Bushveld Complex ◽

Data Set ◽

Magnetite Layer ◽

University Department

<div>Data set accompanying thesis:</div><div><br></div><small> Iorga-Pavel, Adina. 2017. </small><small>Evolution of Fe-Ti-V oxides from the main magnetite layer, Upper Zone, Bushveld Complex, South Africa: a comparison across the Western, Northern and Eastern Lobes. Thesis (MSc), Rhodes University, Department of Geolo. Available: </small><br><div><small>http://hdl.handle.net/10962/7357</small></div><div><small><br></small></div>

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Magnetite layer formation in the Bushveld Complex of South Africa

10.21203/rs.3.rs-673073/v1 ◽

2021 ◽

Author(s):

Zhuo-Sen Yao ◽

James Mungall

Keyword(s):

South Africa ◽

Alternative Model ◽

Ad Hoc ◽

Bushveld Complex ◽

Layer Formation ◽

Layered Intrusions ◽

Economic Significance ◽

Magnetite Layer ◽

Compositional Convection

Abstract The great economic significance of layered mafic-ultramafic intrusions like the Bushveld Complex of South Africa results from the existence within them of some layers highly concentrated in valuable elements. Here we address the origins of the Main Magnetite Layer, a globally important resource of Fe-Ti-V-rich magnetite. Previous models of in situ fractional magnetite crystallization require frequent ad hoc adjustments to the boundary conditions. An alternative model of rapid deposition of loose piles of magnetite crystals followed by compositional convection near the top of the pile and infiltration of the pile from beneath by migrating intercumulus melt fits observations without any adjustments. The data admit both explanations, but the latter model, with the fewest unconstrained interventions, is preferable. The choice of models has pivotal ramifications for understanding of the fundamental processes by which crystals accumulate and layers form in layered intrusions.

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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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