Eight ICDP boreholes and three tunnels through 3.7 km of Paleoarchean shallow-water strata probe the setting of early life

The up to 3.7 km-thick Moodies Group (~3.22 Ga) of the Barberton Greenstone Belt, South Africa and Eswatini, comprises some of the oldest well-preserved sedimentary strata on Earth, deposited within only a few million years in prodeltaic to alluvial settings, with a dominance of tidal deltas and coastal plains. Moodies Group strata consist of polymict conglomerates, widespread quartzose, lithic and arkosic sandstones, siltstones, shales, and rare BIFs and jaspilites, all interbedded with tuffs and several lavas. They preserve abundant sedimentary structures and represent a very-high-resolution record of Paleoarchean surface conditions and processes. Widespread microbial mats, early-diagenetic vadose alteration zones and tidal rhythmites allow to investigate the environmental conditions under which bacterial life spread on early Earth. The ICDP Barberton Archean Surface Environments (BASE) Project drilled November 2021 to June 2022 eight inclined boreholes of 300-450 m length each through steeply inclined or overturned Moodies Group strata; the unweathered and continuous core record was complemented by sampling in three several-km-long tunnels and by detailed surface mapping. Two to three rigs operated concurrently, delivering twenty to sixty m of high-quality core daily, processed in a large, publicly accessible hall adjacent to the museum in downtown Barberton. An exhibition provided background explanations for visitors and related this fundamental geoscience research project to the recently established Barberton-Makhonjwa Mountains World Heritage Site.