Highly siderophile elements in Archaean and Palaeoproterozoic marine shales of the Kaapvaal Craton, South Africa

Nwaila, Glen T.; Frimmel, Hartwig E.

doi:10.1007/s00710-018-0650-3

Cited by 11 publications

(1 citation statement)

References 74 publications

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“…Previous drilling showed that weathering extends up to ∼ 20 m depth. Analyzing short (and usually stratigraphically poorly located) underground drill core provided by producing gold mines along the northern margin of the BGB has occasionally been successful (Hessler et al, 2004;Hessler and Lowe, 2006;Javaux et al, 2010;Nwaila and Frimmel, 2019), but advanced and high-resolution geochemical research on mine material is commonly compromised by poor geographic and stratigraphic constraints and carries the risk of local hydrothermal alteration or contamination by drilling fluids (Toulkeridis et al, 2015).…”

Section: Scientific Objectivesmentioning

confidence: 99%

BASE (Barberton Archean Surface Environments) – drilling Paleoarchean coastal strata of the Barberton Greenstone Belt

Heubeck,

Beukes,

de Kock

et al. 2024

Sci. Dril.

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Abstract. The BASE (Barberton Archean Surface Environments) scientific drilling project aimed at recovering an unweathered continuous core from the Paleoarchean Moodies Group (ca. 3.2 Ga), central Barberton Greenstone Belt (BGB), South Africa. These strata comprise some of the oldest well-preserved sedimentary strata on Earth, deposited within only a few million years in alluvial, fluvial, coastal-deltaic, tidal, and prodeltaic settings. They represent a very-high-resolution record of Paleoarchean surface conditions and processes. Moodies Group strata consist of polymict conglomerates, widespread quartzose, lithic and arkosic sandstones, siltstones, shales, and rare banded-iron formations (BIFs) and jaspilites, interbedded with tuffs and several thin lavas. This report describes objectives, drilling, and data sets; it supplements the operational report. Eight inclined boreholes between 280 and 495 m length, drilled from November 2021 through July 2022, obtained a total of 2903 m of curated core of variable quality through steeply to subvertically dipping, in part overturned stratigraphic sections. All drilling objectives were reached. Boreholes encountered a variety of conglomerates, diverse and abundant, mostly tuffaceous sandstones, rhythmically laminated shale-siltstone and banded-iron formations, and several horizons of early-diagenetic silicified sulfate concretions. Oxidative weathering reached far deeper than expected. Fracturing was more intense, and BIFs and jaspilites were thicker than anticipated. Two ca. 1 km long mine adits and a water tunnel, traversing four thick stratigraphic sections within the upper Moodies Group in the central BGB, were also sampled. All boreholes were logged by downhole wireline geophysical instruments. The core was processed (oriented, slabbed, photographed, described, and archived) in a large, publicly accessible hall in downtown Barberton. A geological exhibition provided background explanations for visitors and related the drilling objectives to the recently established Barberton Makhonjwa Mountains World Heritage Site. A substantial education, outreach, and publicity program addressed the information needs of the local population and of local and regional stakeholders.

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Section: Scientific Objectivesmentioning

confidence: 99%

BASE (Barberton Archean Surface Environments) – drilling Paleoarchean coastal strata of the Barberton Greenstone Belt

Heubeck,

Beukes,

de Kock

et al. 2024

Sci. Dril.

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Controls on Pt/Pd ratios in Bushveld magmas and cumulates: a review complemented by new W isotope data

Maier

Mundl‐Petermeier

2022

Miner Deposita

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The Bushveld Complex of South Africa is underlain by a fine-grained sill complex which most workers interpret to represent the quenched parent magmas to the intrusion. The sills have unusually high Pt contents (up to ~ 25 ppb) and Pt/Pd ratios (average 1.50) exceeding those in most other mantle magmas globally. Unusually high Pt/Pd is also found in many Bushveld cumulates. Understanding the origin of the high Pt/Pd is important for exploration, in view of the contrasting monetary value of the metals, but also for unravelling the petrogenesis of the intrusion. Here, we review existing platinum-group element (PGE) data and present the first radiogenic W isotope data on a Bushveld rock, to evaluate a range of potential models, including PGE fractionation prior to final magma emplacement and within the Bushveld magma chamber, magma derivation from the sub-continental lithospheric mantle (SCLM), contamination of Bushveld magma with Pt-rich continental crust, and a meteoritic component in the mantle source to the magmas or in the crust with which the magmas interacted. We identify three key processes causing fractionation of metals prior to final magma emplacement and within the Bushveld chamber, namely crystallisation of Pt alloys, partial melting of cumulus sulfides triggered by flux of volatiles followed by sulfide melt percolation, and mobilisation of PGE by percolation of volatiles through the cumulate pile. The currently available W and Ru isotope data are inconsistent with derivation of the Bushveld magmas from mantle or crustal sources containing an enhanced meteoritic component relative to normal post-Hadean mantle.

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Spent Tea Leaves (Camellia sinensis), its Effect on the Leaching and Biosorption Characteristics of Lead from Waste Cupels

Gikunoo

Andrews

Ampong

et al. 2022

J. Sustain. Metall.

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Highly siderophile elements in Archaean and Palaeoproterozoic marine shales of the Kaapvaal Craton, South Africa

Cited by 11 publications

References 74 publications

BASE (Barberton Archean Surface Environments) – drilling Paleoarchean coastal strata of the Barberton Greenstone Belt

BASE (Barberton Archean Surface Environments) – drilling Paleoarchean coastal strata of the Barberton Greenstone Belt

Controls on Pt/Pd ratios in Bushveld magmas and cumulates: a review complemented by new W isotope data

Spent Tea Leaves (Camellia sinensis), its Effect on the Leaching and Biosorption Characteristics of Lead from Waste Cupels

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