The aim of the programme isto coordinate and encourage research on theenvironment of the early Earth and on the mannerin which life appeared and evolved. The mainresearch topics are:

(a) Composition and temperature of Archean atmosphere and oceans;

(b) The nature of Archean landmasses;(c) Interaction between Archean surface waters and

the oceanic and continental crust;(d) The nature and evolution of early life.

Activities

(a) Organization of workshops and sessions atconferences;

(b) Exchange visits of scientists and studentsbetween participating universities

(c) Promotion of a program of scientific drilling inthe 3.5 Ga Barberton belt, South Africa

Aims of the Barberton

Drilling Program

The aim of the project is to drill several shallow diamond

holes (100-500m) in the Barberton greenstone belt

• to obtain continuous drill-core through sections ofvolcanic and sedimentary rocks,

• to analyze these samples (petrology, paleontology,magnetic properties, geochemistry),

• to gain a better understanding of the conditions at thesurface of the Archean Earth, the geodynamics of theArchean crust and mantle, and the emergence andevolution of life

Barberton Greenstone Belt

- 3.5 billion years old

Barberton

Barberton Greenstone Belt, South Africa

Why drill the volcanic rocks?

• To obtain a thick section (300-500m?) through a series ofkomatiitic and basaltic units

• To sample complete sections through individual flows andtheir contacts

• To obtain fresh samples for complete mineralogical andgeochemical analysis

• To help understand the volcanic component of early crustan essential feature of the Archean surface environment;.

• Information relevant to origin of life as well as for Archeangeodynamic processes.

Barberton komatiites (ultramafic

lavas) in outcrop

3 Ga Pillow Lavas3 Ga Pillow Lavas

hydrated upper crustgabbroolivine cumulate

6 km

0°C

1200°C

Gradient = 200°C/km

Modern oceanic crusthydratedupper crust

gabbro

olivinecumulate

30 km

0°C

1500°C

Gradient = 50°C

/km

Archean oceanic crust

Archean oceanic crust is thickand composed of low-densitycomponents; the basal parts,which might be in the garnetstability field, do not containgarnet … how did it subduct?

Modern oceanic crust is thin andcool; it converts to eclogite to dragdown subducting plates

Archeanhydrothermalsystems

• On land - mafic and felsic“continents”• In the oceans - at ridges and onmargins of volcanic plateaux

But …What was the temperature and the

compositions of ocean water andhydrothermal fluids?

What was the typical water depth?What was the geometry and scale

of hydrothermal circulation?What was the composition of

oceanic crust and how did it behavein a subduction zone?

Emergence of Life

M. Russell, A. Hall, W. Martin, J. Milner-White, A. Mellersh

Chert Mountain in Barberton,

South Africa, 3.5 Ga

Banded Iron Formation

Proterozoic 2.4 Ga

Archean 3.5 Ga

Magnetite (Fe304)

Hematite (Fe203) and chert

Spherule beds -

impact debris?

Vredefort impact

breccia

Tidal cycles in 3 Ga sediments

one month

one day

Stromatolites

Biogeochemical goal:

Evolution of metabolism

What do we want to know?

- Nature of early microbial life

- Environments/ habitats where early microbes thrived

- Diversity of ancient microbial populations

Emergence of specific metabolisms remains unclear

e.g. oxygenic photosynthesis

stromatolite and isotope evidence are conflicting!

Limited by poor constraints on:

- Atmospheric evolution

- Early Archean ocean chemistry

- Biochemical vs inorganic controls on chemical/isotopic tracers

1. Origine (s) de la vie :

- La terre primitive

• Quelle est la chronologie de l’évolution de la t erre primitive (continents, océans,atmosphère, vie ?)

• Quelles sources endogènes de matière carbonée pour la chimie prébiotique ?• Quelles traces des sources hydothermales et d’une éventuelle synergie avec l’apport

extraterrestre de molécules organiques/matière carbonée ?• la nature de la croûte et le flux de chaleur à traverse la croûte ?• la nature et quantité de croûte « continentale » ?• les océans – pH, composition, oxydation ?• le flux de corps extraterrestres – est-ce qu’il y a eu une période de bombardement tardive

catastrophique, capable de détruire la vie si elle était déjà présente?• le flux des UV jusqu’à la surface de la Terre et l ’influence éventuelle sur une vie

« surficielle » ?

- La chimie prébiotique

• Quelle est la contribution effective des apports extraterrestres à la chimie prébiotique ?- Les molécules provenant du milieu interstellaire ont-elles été efficacement transmisesdans le système solaire primitif ?

- Quelle est la nature/quantité de molécules d’origine cométaire et/ou astéroïdale ayant atteintla terre ?

Why drill the sedimentary rocks?

1. Access to well-preserved continuous

sequences, including rocks that do

not outcrop well

2. To obtain ‘unaltered’ samples

3. Integrate approaches in

multidisciplinary program e.g. with

palaeomagnetic data that require

access to intact geomagnetic field

http://www.ipgp.jussieu.fr/pages/020204.php

Key lithological targets

Metasedimentary sequences- Silicified sandstones, siltstones, mudstones, conglomerates- Grey or black shales- Cherts- Tidal sequences- Barite/sulfide associations

Specific objectives

1. Types of microbial habitat

2. Types of metabolism and activity of

microorganisms

3. Origin of silicification

4. Sedimentology in absence of

vegetation

5. Dynamics of Earth-Moon system

6. Rate and consequences of meteorite

impacts

Methods

Micropaleontology

High resolution scanning SEM; TEM;

synchrotron techniques; microRaman;

nanoSIMS

Stable isotope geochemistry

C, N, O, S, Fe, Si, Se

Ar-Ar geochronology and noble gas studies

Paleomagnetism

Name Institute Discipline Name Institute DisciplineTraces of early life Volcanic rocks

Emmanuelle Javaux University of Liège, Belgium Biogeochemistry David Banks University of Leeds, UK Hydrothermal processesRicardo Amils Universidad Autonoma de Madrid Biogeochemistry Adam Kent Oregon State University, USA Komatiites and melt inclusionsChris Vasconcelos ETH Zurich, Switzerland Biogeochemistry and sediments Alex Sobolev Vernadsky Institute, Moscow, Russia Komatiites and melt inclusionsJudith Mckenzie ETH Zurich, Switzerland Biogeochemistry and sediments Nick Arndt Universite Grenoble, France KomatiitesPascal Philippot IPG Paris, France Geochemistry and geology Allan Wilson University Witwatersrand, South Africa KomatiitesBéatrice Luais CRPG Nancy, France Isotope geochemistry Euan Nisbet University of London, UK Komatiites and traces of lifeBernard Marty CRPG Nancy, France Isotope geochemistry Jesse Dann KomatiitesPieter Vroon Utrecht University, Netherlands Isotope geochemistry Mike Lesher Laurentian University, Canada Komatiites and ore depositsMark van Zuilen IPG Paris, France Isotope geochemistry Richard J. Walker DTM Washington, USA Komatiites -isotope geochemistryPaul Mason Utrecht University, Netherlands Isotope geochemistry and biogeochemistry Steve Shirey DTM Washington, USA Komatiites -isotope geochemistryMartin van Kranendonk Geological Survey Western Australia Isotope geochemistry and geology Wolf Maier University Western Australia KomatiitesMinik Rosing Geologisk Museum, Copenhagen Isotope geochemistry and geology Mathinus Cloete Council of Geosciences, South Africa Volcanics and tectonicsRoger Buick Washinton University, USA Isotope geochemistry and geologyManfred van Bergen Utrecht University, Netherlands Isotope geochemistry and geologyMichael Bau International University Bremen, Germany Isotope geochemistry and geologyCharles Cockell Open University, UK Traces of life - impactsFrances Westall Centre Biophysique Moléculaire, Orleans, FrancePaleontology

Sedimentary rocks Other disciplinesTanja Zegers Utrecht University, Netherlands Life and traces of life Francis Albarede ENS Lyon, France GeochemistryWlady Altermann Universitaet Munich, Germany Sedimentology Jan Kramers Universitaet Berne, Switzerland GeochemistryKen Eriksson Virginia Polytechnic Institute, USA Sedimentology Janne Blichert-Toft ENS Lyon, France GeochemistryNora Noffke Virginia Polytechnic Institute, USA Sedimentology Klaus Mezger Universitaet Munich, Germany GeochemistryBeate Orberger Université Paris sud, France Sediments - geochemistry Marian Tredoux University Free State, South Africa GeochemistryWolf Mueller University Quebec, Canada Sediments & komatiites Alfred Kroener Universitaet Mainz, Germany GeologyDon Lowe Stanford University, USA Sediments & spherules Carl Anhaeusser University Witwatersrand, South Africa GeologyGary Byerly University Louisiana, USA Sediments and komatiites Lew Ashwal University Witwatersrand, South Africa GeologyPat Eriksson University of Pretoria, South Africa Sediments and tectonics Paul Dirks University Witwatersrand, South Africa Geology, tectonicsAxel Hofmann University of Natal, South Africa Sediments geochemistry Thierry Augé BRGM, Orleans, France Ore depositsJens Gutzmer University Witwatersrand, South Africa Sediments geochemistry Chris Ballhaus Universitaet Muenster, Germany PetrologyMartin Whitehouse Swedish Museum of Natural History Sediments geochemistry Alex Kisters Stellenbosch University, South Africa TectonicsNic Beukes University Witwatersrand, South Africa Sediments geochemistry Gary Stevens Stellenbosch University, South Africa TectonicsWout Nijman Utrecht University, Netherlands Sediments geochemistry Annika Dziggel Universitaet Aarchen, Germany TectonicsBruce Simonson Oberlin College, USA Spherules and impacts Michael Meyer Universitaet Aarchen, Germany Tectonics, ore depositsUlrich Riller Humboldt-Universität, Berlin, Germany Spherules and impactsUwe Reimold Humboldt-Universität, Berlin, Germany Spherules and impacts

Budget: ca. 300 kEuros for 3000 m of drill core

Support from:

CNRS, ANR, CNES

European funding agencies - DFG, NERC, NWO, ESA …

NSF

Agouran foundation, minerals industry

The International Team involved in the Barberton Drilling Project

Meetings to Plan the Project

• October 16, 2006 - Johannesburg: Preliminarymeeting with South African participants

• December 11, 2006 - AGU San Francisco:Meeting with North American participants andNSF

• Late January, 2007 - Germany:Meeting with European participants

Please let me know if you wish to attend eithermeeting!