Exploiting a very-high-resolution Archean surface record

• Applicant: Professor Dr. Christoph Heubeck
• Subject Area: Palaeontology
• Term: from 2011 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 212154569

The Moodies Group of the Barberton Greenstone Belt (South Africa) likely preserves a rare, very-high-resolution Archaean surface record in alluvial, fluvial, shoreline, tidal and shallowmarine facies and may therefore offer unprecedented insights in Archean environmental dynamics. Depositional ages from volcanic strata at the base of the Moodies Group overlap those of thin tuffs interbedded with fluvial sandstones stratigraphically ~2.5 km higher (3227 +/-4 Ma vs. 3231+/-6 Ma), consistent with several geologic indications of continuously high but balanced subsidence and sedimentation rates. Preliminary results from highprecision age dating also show that +/- 1Ma resolution, required to reliably distinguish between datable Archean events possibly only a few Ma apart, is feasible. The inferred overall mean temporal resolution in the Moodies Group may thus be on the order of ~1 mm/year and preserve an archive of very short-term Archean environmental dynamics such asclimatic, seasonal, and tidal changes.Funds requested in this proposal will be used primarily for field work to test various aspects of this hypothesis. Objectives include (1) resampling datable locations and expanding their number; (2) identifying and sampling paleosol locations, including a prominent paleosol at the top of the Moodies Lava, and (3) investigating tidal rhythmicity in thick cross-bedded and biolaminated deposits.

• DFG Programme: Research Grants