Exploiting a very-high-resolution Archean surface record
Final Report Abstract
The beginning of Earth history is difficult to reconstruct because virtually all old strata recording conditions at the Earth’s surface have either been subducted and molten or at least been intensely deformed. There are only two places on Earth where well-preserved Paleoarchean rocks are preserved: The Barberton Greenstone Belt (BGB) in South Africa and the Pilbara region in northwest Australia. In the BGB, the strata of the Moodies Group have recently been recognized to have been deposited within only a few Million years, a comparatively short time span compared to their total age, and to record Archean surface processes in exquisite detail. Research conducted here supported field work and limited geochemical analyses to explore some of the consequences of this highly detailed stratigraphic preservation: (1) Whether additional dating would confirm the age and allow an internal age stratigraphy to be constructed (it did); (2) whether stacked tidal strata recorded an ebb-and-flood signal from a much closer and faster-orbiting Moon than today (they probably do not, at least not at the sites we investigated); (3) whether a thick basaltic lava that covered an ancient coastal plain had weathered to a primitive soil (it probably did not but there are soils elsewhere); and (4) whether one could trace biological components in these strata through their elevated radioactivity (one probably cannot). Some of these aspects attract the attention of the South African public and have been incorporated in public talks, roadside panels, and popular-science guidebooks.
Publications
-
2012, A new date from an Archean volcanic unit, Moodies Group, Stolzburg Syncline, Barberton Greenstone Belt, South Africa: Tagungsband Annual Meeting Geologische Vereinigung (September 23rd-28th, 2012, Hamburg, Germany), p. 179
Luber, T., C. Heubeck, A. Zeh, J. Engelhardt and T. Giebner
-
2012, Near- Quaternary temporal resolution in the Archean Moodies Group, Barberton Greenstone Belt, South Africa: Tagungsband Annual Meeting Geologische Vereinigung (Sept. 23rd-28th, 2012, Hamburg, Germany), p. 123
Heubeck, C., J. Engelhardt, G. Byerly, A. Zeh, B. Sell,, T. Luber and D.R. Lowe
-
2012, Photosynthetic (?) microbial mats of the middle Archean Moodies Group, Barberton Greenstone Belt (South Africa): Annual Meeting Geol. Soc. Canada, St. John’s; Meeting Abstracts volume, p. 65
Homann, M., Heubeck, C., Engelhardt, J. and Drabon, N.
-
2013, Timing of deposition and deformation of the Moodies Group (Barberton Greenstone Belt, South Africa): Veryhigh-resolution of Archaean surface processes: Precambrian Research 231, 236– 262
Heubeck, C., J. Engelhardt, G.R. Byerly, A. Zeh, B. Sell, T. Luber, and D.R. Lowe
-
2013, U-Pb and Hf isotope data of detrital zircons from the Barberton Greenstone Belt: Constraints on provenance and Archaean crustal evolution: Journal of the Geological Society of London, 170, 215 –223
Zeh, A., A. Gerdes, C. Heubeck
