New Palaeoproterozoic palaeomagnetic data from the Kaapvaal Craton, South Africa

Letts, S.; Torsvik, Trond H.; Webb, S. J.; Ashwal, Lewis D.

doi:10.1144/sp357.2

Cited by 17 publications

(3 citation statements)

References 37 publications

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“…1). Paleoproterozoic magnetizations that pass reversal and baked-contact tests were reported for the BHDS (Letts et al, 2005(Letts et al, , 2011Lubnina et al, 2010) and are confirmed by combined U-Pb geochronology, geochemistry, and paleomagnetic data sets (Olsson et al, 2016;Wabo et al, 2019). Baddeleyite U-Pb crystallization ages of 12 dikes range between ca.…”

Section: The Black Hills Dike Swarmsupporting

confidence: 57%

Late Paleoproterozoic mafic magmatism and the Kalahari craton during Columbia assembly

Djeutchou

Kock

Wabo

et al. 2021

Geology

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The 1.87–1.84 Ga Black Hills dike swarm of the Kalahari craton (South Africa) is coeval with several regional magmatic provinces used here to resolve the craton’s position during Columbia assembly. We report a new 1850 ± 4 Ma (U-Pb isotope dilution–thermal ionization mass spectrometry [ID-TIMS] on baddeleyite) crystallization age for one dike and new paleomagnetic data for 34 dikes of which 8 have precise U-Pb ages. Results are constrained by positive baked-contact and reversal tests, which combined with existing data produce a 1.87–1.84 Ga mean pole from 63 individual dikes. By integrating paleomagnetic and geochronological data sets, we calculate poles for three magmatic episodes and produce a magnetostratigraphic record. At 1.88 Ga, the Kalahari craton is reconstructed next to the Superior craton so that their ca. 2.0 Ga poles align. As such, magmatism forms part of a radiating pattern with the coeval ca. 1.88 Ga Circum-Superior large igneous province.

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Section: The Black Hills Dike Swarmsupporting

confidence: 57%

Late Paleoproterozoic mafic magmatism and the Kalahari craton during Columbia assembly

Djeutchou

Kock

Wabo

et al. 2021

Geology

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“…Goutham et al 2006;Pradhan et al 2008;Letts et al 2010;Pisarevsky et al 2013) to argue for the primary nature of magnetization in the absence of field tests, although remagnetization can also produce dual polarity results (e.g Evans et al 2002;De Kock et al 2015;. …”

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confidence: 99%

Palaeomagnetism of the uppermost carbonate units of the Purana basins in southern India: new demagnetization results from the Kaladgi and Bhima basins, Karnataka

et al. 2020

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Four unconformity-bound sequences can be identified in the Purana successions in southern India, of which the third sequence (Sequence III) has the widest distribution. Sequence III contains deep-water carbonate units with consistent sedimentological characteristics across the subcontinent. The current extent of field relationships and existing ages has not allowed the correlation and chronology of these carbonates to be established conclusively. Palaeomagnetism may help resolve this essential question for the Purana sedimentation. Here, we report new palaeomagnetic results (HIG+/– pole: 21.7° N, 81.1° E, radius of cone of 95% confidence A95 = 15.9°) from Sequence III carbonates in the Kaladgi (Badami Group) and Bhima (Bhima Group) basins. The HIG+/– magnetization, revealed after the removal of secondary magnetizations that include a present-day field and an Ediacaran–Cambrian overprint, is interpreted to be primary based on its dissimilarity to known younger magnetizations, the presence of distinctly different magnetic components in sites and a positive reversal test. Our HIG+/– pole differs from the c. 1.4 Ga pole and various c. 1.1 Ga and younger poles. Instead, it overlaps with the Harohalli dyke pole that was long considered to be c. 823 Ma in age, but has recently been suggested to be much older with an age of c. 1192 Ma. We therefore consider the uppermost carbonate beds of Badami and Bhima groups to have been deposited during late Mesoproterozoic times. A critical evaluation of parameters from which an earlier Neoproterozoic age for these carbonates was established indicates that the available 40Ar/39Ar, Rb–Sr and U–Pb ages in the Kaladgi and Bhima basins could reflect the timing of post-depositional alteration events.

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“…The chief mineral produced is copper, which is found in the copper-bearing rocks such as carbonatite and foskorite (Southwood and Cairncross, 2017). Copper-and magnetite-bearing rocks are all enclosed in the Palabora Igneous Complex, which is complex in formation with dimensions extending 6.5 km by 2.5 km (Southwood and Cairncross 2017;Letts et al, 2011).…”

Section: Background Of the Study Areamentioning

confidence: 99%

Drawpoint loading optimization strategies in block caving: A case study of Palabora Mining Company

Nyarela¹,

Khumalo²,

Nemathithi³

2023

J. S. Afr. Inst. Min. Metall.

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Palabora Mining Company is one of the largest low-grade copper mines globally. The mine uses block caving for the extraction of the orebody. This paper enumerates the drawpoint loading strategies for the overall head grade improvements, particularly for a block that is nearing depletion. A comprehensive literature review of various considerations relating to improving productivity in block caving is presented to contextualize the draw control in caving. From this study, an optimized draw control strategy is presented, which focuses on three parameters that include grade distribution, loading compliance, and tonnage splits per sector. An empirical method based on the relational study between various parameters is used to outline the key criteria to be used in the optimization of drawpoint loading in block caving.

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New Palaeoproterozoic palaeomagnetic data from the Kaapvaal Craton, South Africa

Cited by 17 publications

References 37 publications

Late Paleoproterozoic mafic magmatism and the Kalahari craton during Columbia assembly

Late Paleoproterozoic mafic magmatism and the Kalahari craton during Columbia assembly

Palaeomagnetism of the uppermost carbonate units of the Purana basins in southern India: new demagnetization results from the Kaladgi and Bhima basins, Karnataka

Drawpoint loading optimization strategies in block caving: A case study of Palabora Mining Company

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