Barberton Barite Drilling Project

Archean life and ancient life-support systems on the Kaapvaal craton
A !Khure Africa project

The Barberton Greenstone Belt is located close to Swaziland and Mozambique. The Barite Syncline is located about 20 kilometers south of Barberton.

REASONS FOR DRILLING

The goal of this drilling operation was to obtain a representative sequence of altered komatiites, black cherts, shales, tuffaceous sandstones and siltstones, jasper deposits, and bedded barite. This sequence of ultramafics and clastic and chemical sediments represents a conspicuous assemblage of rock types that is typically seen in Early Archean seafloor hydrothermal settings. For instance, the Chert-Barite Unit of the Dresser Formation in the Pilbara Craton of Western Australia represents a very similar sequence of rock types. Two drill cores of this 3.49 Ga Chert-Barite Unit have been studied in great detail (Pilbara Drilling Project; see associated link; Van Kranendonk et al., 2008; Precambrian Reseach, 167, 93–124), and led to the recognition, among others results, of several traces of sulfur-based early life (Philippot et al., 2007, Science, 317, 1534-1537).

The origin of carbonaceous matter in black chert veins and carbonate beds in this unit suggests the presence of several additional forms of metabolism (photosynthesis, methanogenesis) in this ancient seafloor setting. At present it is not clear whether the Chert-Barite Unit in Australia represents a unique, semi-closed basin, or represents a typical seafloor environment that was ubiquitous in the Early Archean. The Barite Syncline stratigraphy closely resembles the Chert-Barite Unit of Pilbara in a stratigraphic way. In this respect, it is of great value to obtain a new drill core from such a stratigraphic unit that was located some 1000 km away from the Pilbara terrane during deposition. Detailed petrography and geochemical studies of drill cores from this unit can therefore greatly expand our insight in the Early Archean environment and associated evolution of early life.

Synthetic stratigraphic log of the Barberton Barite drill hole

PRELIMINARY RESULTS

The drilling site was chosen in the west limb of the barite syncline (25°54’24.8”S and 31°03’23.9”E) where bedded sedimentary rocks of the Mapepe Formation dip 40° to 55° to the southeast. The drillhole was sited to the east of the surface outcrops, in the stratigraphic hangingwall, and were oriented at 50° towards 288°, in order to intersect the bedding at about right angle. The hole was drilled with HQ core (75.7 mm diameter) and NQ core (47.6 mm diameter) to a depth of 182.4 m depth. A preliminary stratigraphic log of the drill core obtained is shown beneath. The diamond drillcore was oriented.

FUNDING

This project was supported by funds from the Centre National de la Recherche Scientifique and the Institut de Physique du Globe de Paris as part of the !Khure Africa project led by Vincent Courtillot of IPGP and Maarten de Wit of the Africa Earth Observatory Network (AEON) at the University of Cape Town.

DRILLING TEAM

Pascal Philippot, Professor at the University of Denis Diderot in Paris, France.

Mark van Zuilen, Research Fellow at the Centre of Geobiology in Bergen, Norway.

Yoram Teitler, PhD student at IPGP. My PhD is focused on environmental and climatic evolution of the Earth during the Late Archean (supervisors: F. Fluteau and P. Philippot).

ACKNOWLEDGMENTS

The BBDP was performed in continuation of the Barberton Scientific Drilling Project organized by Maarten de Wit from AEON and Harald Furnes from CGB. Many thanks to both of them and to Eugene Grosch and Nicola McLoughlin for their collaboration and great field excursions. Special thanks to Maarten de Wit for obtaining all permissions and administrative agreements, without which this work would not have been completed. André van Wyk and Grant Innes of “Drilling in Training” (DiT) and their crew are thanked for their professional work and enthusiasm in obtaining the drillcore.

CONTACTS – CORE ACCESS

Contact Pascal Philippot for more information on the scientific projects developed on the drill core as well as core availability and access ([email protected]).

More pictures and comments are available here