[en] 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 over-Published by Copernicus Publications on behalf of the IODP and the ICDP. 130 C. Heubeck et al.: BASE-drilling Paleoarchean coastal strata of the Barberton Greenstone Belt turned 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.
Disciplines :
Earth sciences & physical geography
Author, co-author :
Heubeck, Christoph ; Department of Geosciences, Friedrich-Schiller-Universität Jena, Jena, Germany
Beukes, Nic; Department of Geology, University of Johannesburg, Auckland Park, South Africa
De Kock, Michiel ; Department of Geology, University of Johannesburg, Auckland Park, South Africa
Homann, Martin; Department of Earth Sciences, University College London, London, UK
Javaux, Emmanuelle ; Université de Liège - ULiège > Astrobiology ; Bât. B22 Early Life Traces & Evolution-Astrobiology, Liège, Belgium
Kakegawa, Takeshi ; 402 Geosciences Building, Graduate School of Science, Tohoku University, Sendai, Japan
Lalonde, Stefan; UMR 6538, Laboratoire Géosciences Océan, Institut Universitaire Européen de la Mer, Brest, France
Mason, Paul; Department of Earth Sciences, Utrecht University, Utrecht, the Netherlands
Mashele, Phumelele ; Department of Geology, University of Johannesburg, Johannesburg, South Africa ; School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
Paprika, Dora; Department of Geology, University of Johannesburg, Johannesburg, South Africa ; The MSA Group, Greenacres Office Park, Henley House, Victoria Park, Randburg, Johannesburg, South Africa deceased
Rippon, Chris; South Africa ; January
Tice, Mike ; Department of Geology & Geophysics, Texas A&M University, College Station, USA
Tucker, Rodney; Wildlife Estate, Hoedspruit, Limpopo, South Africa
Tucker, Ryan; Wildlife Estate, Hoedspruit, Limpopo, South Africa
Ndazamo, Victor; Barberton Mines (Pty.) Ltd, Barberton, South Africa
Christianson, Astrid; Barberton Community Tourism, Barberton, South Africa
NASA - National Aeronautics and Space Administration DFG - Deutsche Forschungsgemeinschaft JSPS - Japan Society for the Promotion of Science F.R.S.-FNRS - Fonds de la Recherche Scientifique NWO - Nederlandse Organisatie voor Wetenschappelijk Onderzoek UiB - Universitetet i Bergen UNIL - Université de Lausanne
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