Geologic framework and first results from ICDP BASE drilling in the Moodies Group (~3.22 Ga), Barberton Greenstone Belt, South Africa

The up to 3.5 km thick Moodies Group (ca. 3.22 Ga) of the Barberton Greenstone Belt, South Africa and Eswatini, exposes some of the oldest well-preserved sedimentary strata on Earth. Strata were deposited within only a few million years in prodeltaic to alluvial settings, with a dominance of tidal deltas and coastal plains; they provide a very-high-resolution record of Early Archean surface conditions. Widespread microbial mats, early diagenetic vadose-alteration zones and tidal rhythmites are common. Moodies strata provide a unique opportunity to investigate the conditions under which bacterial life spread and thrived on early Earth.

We show preliminary cross sections, overall core photographs and representative lithologic descriptions from the eight boreholes, each ca. 350-400 m in length, which were drilled November 2021 to May 2022 within the framework of the ICDP Barberton Archean Surface Environments (BASE) Project.