Mapping the 3D extent of the Northern Lobe of the Bushveld layered mafic intrusion from geophysical data

Finn, Carol A.; Bedrosian, Paul A.; Cole, Janine; Khoza, Tshepo David; Webb, S. J.

doi:10.1016/j.precamres.2015.07.003

Cited by 44 publications

(14 citation statements)

References 60 publications

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“…Due to long recording times and favorable noise conditions in many parts of the study area, the data quality at many sites is excellent throughout the period range. To date there have been a number of publications performing modeling and inversions for different subregions and profiles (Evans et al., 2011; Finn et al., 2015; Hamilton et al., 2006; Khoza et al., 2013; Miensopust et al., 2011; Moorkamp et al., 2019; Muller et al., 2009). In addition, maps of resistivity directly derived from the data at selected periods have been used to investigate the structure and composition of the lithosphere‐asthenosphere system (Jones et al., 2012, 2013) and multiobservable petrological‐geophysical models have been created based on subsets of the data (Fullea et al., 2011).…”

Section: The Samtex Data Setmentioning

confidence: 99%

Probing the Southern African Lithosphere With Magnetotellurics—Part I: Model Construction

et al. 2022

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The Southern African Magnetotelluric Experiment (SAMTEX) involved the collection of data at over 700 sites in Archean to Proterozoic southern Africa, spanning features including the Kalahari Craton, Bushveld Complex, and voluminous kimberlites. Here, we present the first 3D inversions of the full SAMTEX data set. In this paper, we focus on assessing the robustness of the 3D models by comparing two different inversion codes, jif3D and ModEM, and two different subsets of the data, one containing all acceptable data and the other containing a smaller selection of undistorted, high‐quality data. Results show that the main conductive and resistive features are imaged by all inversions, including deep resistive features in the central Kaapvaal Craton and southern Congo Craton and a lithospheric‐scale conductor beneath the Bushveld Complex. Despite this, differences exist between the jif3D and ModEM inverse models that derive mainly from the differences in regularization between the models, with jif3D producing models that are very smooth laterally and with depth, while ModEM produces models with more discrete conductive and resistive features. Analysis of the differences between these two inversions can provide a good indication of the model resolution. More minor differences are apparent between models run with different subsets of data, with the models containing all acceptable data featuring higher wavelength conductivity variations than those run with fewer stations but also demonstrating poorer data fit.

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Section: The Samtex Data Setmentioning

confidence: 99%

Probing the Southern African Lithosphere With Magnetotellurics—Part I: Model Construction

et al. 2022

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“…The 2.05 billion-year-old Bushveld Complex in South Africa is the largest ma c-ultrama c layered intrusion into the Earth's crust. It occupies an area that most likely exceeds 100,000 km 2 and extends ~450 km east-west and ~350 km north-south 24,[31][32][33] . Despite its enormous size, this complex is merely the remaining portion of an originally much larger intrusion that has subsequently been eroded to an unknown extent by surface processes.…”

Section: Incremental Growth Of the Bushveld Complexmentioning

confidence: 99%

A 5-km-thick reservoir with >380,000 km3 of magma within the ancient Earth's crust

Latypov

Chistyakova

Hornsey³

et al. 2021

Preprint

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Several recent studies have argued that large, long-lived and molten magma chambers1–10 may not occur in the shallow Earth’s crust11–23. Here we present, however, field-based observations from the Bushveld Complex24 that provide evidence to the contrary. In the eastern part of the complex, the magmatic layering was found to continuously drape across a ~4-km-high sloping step in the chamber floor. Such deposition of magmatic layering implies that the resident melt column was thicker than the stepped relief of the chamber floor. Prolonged internal differentiation within such a thick magma column is further supported by evolutionary trends in crystallization sequence and mineral compositions through the sequence. The resident melt column in the Bushveld chamber during this period is estimated to be >5-km-high in thickness and >380,000 km3 in volume. This amount of magma is three orders of magnitude larger than any known super-eruptions in the Earth’s history25 and is only comparable to the extrusive volumes of some of Earth’s large igneous provinces26. This suggests that super-large, entirely molten and long-lived magma chambers, at least occasionally, occur in the geological history of our planet. Therefore, the classical view of magma chambers as ‘big magma tanks’1–10 remains a viable research concept for some of Earth’s magmatic provinces.

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“…The 2.05 billion-year-old Bushveld Complex in South Africa is the largest mafic–ultramafic layered intrusion into the Earth’s crust. It occupies an area that most likely exceeds 100,000 km 2 and extends ~ 450 km east–west and ~ 350 km north-south 25 – 28 . Despite its enormous size, this complex is merely the remaining portion of an originally much larger intrusion that has subsequently been eroded to an unknown extent by surface processes.…”

Section: Introductionmentioning

confidence: 99%

A 5-km-thick reservoir with > 380,000 km3 of magma within the ancient Earth's crust

Latypov

Chistyakova

Hornsey

et al. 2022

Sci Rep

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Several recent studies have argued that large, long-lived and molten magma chambers may not occur in the shallow Earth’s crust. Here we present, however, field-based observations from the Bushveld Complex that provide evidence to the contrary. In the eastern part of the complex, the magmatic layering continuously drapes across a ~ 4-km-high sloping step in the chamber floor. Such deposition of magmatic layering implies that the resident melt column was thicker than the stepped relief of the chamber floor. Prolonged internal differentiation within this thick magma column is further supported by evolutionary trends in crystallization sequence and mineral compositions through the sequence. The resident melt column in the Bushveld chamber during this period is estimated at > 5-km in thickness and > 380,000 km3 in volume. This volume of magma is three orders of magnitude larger than any known super-eruption in the Earth’s history and is only comparable to the extrusive volumes of some of Earth’s large igneous provinces. This suggests that super-large, entirely molten, and long-lived magma chambers occur, at least occasionally, in the geological history of our planet. Therefore, the classical view of magma chambers as ‘big magma tanks’ remains a viable research concept for some of Earth’s magmatic provinces.

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Mapping the 3D extent of the Northern Lobe of the Bushveld layered mafic intrusion from geophysical data

Cited by 44 publications

References 60 publications

Probing the Southern African Lithosphere With Magnetotellurics—Part I: Model Construction

Probing the Southern African Lithosphere With Magnetotellurics—Part I: Model Construction

A 5-km-thick reservoir with >380,000 km3 of magma within the ancient Earth's crust

A 5-km-thick reservoir with > 380,000 km3 of magma within the ancient Earth's crust

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Mapping the 3D extent of the Northern Lobe of the Bushveld layered mafic intrusion from geophysical data

Cited by 44 publications

References 60 publications

Probing the Southern African Lithosphere With Magnetotellurics—Part I: Model Construction

Probing the Southern African Lithosphere With Magnetotellurics—Part I: Model Construction

A 5-km-thick reservoir with &gt;380,000 km3 of magma within the ancient Earth's crust

A 5-km-thick reservoir with > 380,000 km3 of magma within the ancient Earth's crust

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A 5-km-thick reservoir with >380,000 km3 of magma within the ancient Earth's crust