THE MOODIES GROUP (3.22-3.21 GA), BARBERTON GREENSTONE BELT: A MULTIDIMENSIONAL ARCHIVE OF ARCHEAN INFORMATION

Our knowledge of the Moodies Group of the Barberton Greenstone Belt (BGB), South Africa and Swaziland, has evolved from early generalized concepts illustrated by local examples to ongoing regional and stratigraphic differentiation as well as systematic data collection. Previous thoughts of the Moodies Group as a series of largely monotonous thick quartzarenites deposited in a “tectonic molasse” facies and derived from the Ancient Gneiss Complex to the south of the BGB have given way to significantly more differentiated views which recognized (1) a short time span of deposition (~1-10 Ma) between ~3223 and ~3217 Ma with correspondingly high sedimentation rates (~1mm/a); (2) thick turbiditic strata in prodelta settings; (3) syndepositional deformation in a complex paleogeography between rising volcanic-plutonic complexes; (4) abundant high-energy sandy tidal flats, colonized by extensive microbial mats; (5) a significant volcanic component from rhyodacitic air-fall tuffs; (6) a complex sandstone composition and age provenance, and (7) possibly significant diachroneity of lithologically similar units. The Moodies Group has (and continues to) yield very-high-resolution information on Archean surface processes.