PROJECT OVERVIEW

This proposal for a drilling project in the Pilbara district of Western Australia developed during fieldwork there in the summers of 1996 and 1999 by Prof. Ohmoto (PSARC, PI), Prof. Munetomo Nedachi of Kagoshima University in Japan (PSARC Associate), Prof. Mark Barley of the University of Western Australia (PSARC Associate) and Dr. Arthur Hickman (Geological Survey of Western Australia).

During the spring and summer of 2002, the concept evolved into an international project, named "The Archean Biosphere Drilling Project" (ABDP), which involves the following four major research groups and their associates: the NAI (represented by and through PSARC), Kagoshima University, the Geological Survey of Western Australia (GSWA), and the University of Western Australia (UWA).

The main objectives of the ABDP are to recover "fresh" (unweathered) Archean rocks (mostly sedimentary rocks 3.56 - 2.7 Ga in age) from the Pilbara district, Western Australia and use them to conduct systematic paleontological and biogeochemical investigations in order to increase our understanding of early Earth, specifically:

(a) the nature of the biosphere, in particular the types and distribution of organisms in the oceans, lakes, and on land;

(b) the climate;

(c) the chemistry of the atmosphere and oceans;

(d) the geochemical fluxes of O, C, S, Fe, N, and other bioessential elements in the atmosphere-oceans-continents-mantle system; and

(e) the cosmic fluxes on the early Earth.

The strategy of the ABDP is to target specific geologic formations that are ideal for studies designed to answer specific questions (e.g., the time of emergence and distribution of cyanobacteria, eukarya, sulfate reducers, and other organisms; the mechanisms for the creation of mass independent fractionation (MIF) of sulfur isotopes, and the temporal changes in the magnitude of MIF).

We selected seven drilling sites where the target formations have been least affected by metamorphism, hydrothermal processes, and/or weathering since their formation. Our plan was to recover the "fresh" target rocks through a series of shallow drilling, which typically extends to depths of 200 - 500 m (i.e., below the current and ancient groundwater tables), rather than through deep drilling at one or two sites.

Drilling commenced June 2003 and was completed by October 2003. The ABDP joined the Deep Time Drilling Project (Leaders: Roger Buick & Ariel Anbar) at two locations in the Pilbara district drilling that summer (July - August): the oldest (3.5 Ga) land surface (the Coonerunah Unconformity) and the underlying chert/basalt sequence; and stromatolite-rich carbonate beds and underlying lappilli tuffs of the 2.74 Ga Tumbiana Formation.

Splits of the cores are stored at the GSWA Core library in Perth, Australia, at PSARC and at the Core Library of Kochi University in Japan.

The ABDP is one of two drilling projects under the Astrobiology Drilling Program (ADP) of the NAI. Requests for core samples for specific scientific research may be made to any one of the four Executive Members of the ABDP (Ohmoto, Nedachi, Barley and Hickman) or to Dr. Steve D'Hondt (email), Chairman of the ADP Steering Committee.