THE CASE FOR SCIENTIFIC DRILLING OF PRECAMBRIAN SEDIMENTARY SEQUENCES: A MISSION TO EARLY EARTH

Research into the emergence and early evolution of life, particularly in relation to environmental conditions, has intensified in the past decade. The field is energized by controversy (e.g., over the history of atmospheric composition, ocean redox, climate and biochemical pathways) and by the application of new biogeochemical tools (e.g., ion probe in situ stable isotope studies; improved geochronological techniques; non-mass-dependent stable isotope effects; stable metal isotope systematics; advances in organic geochemistry/biomarkers). The past decade has also seen improved understanding of old tools (notably, S isotopes), and new perspectives on evolution and on microbial interaction with the environment borne of the genomics revolution. Recent papers demonstrate the potential for innovative research when such developments are integrated, as well as the limitations of present knowledge.

The chief limiting factor is not lack of scientists or advanced techniques, but availability of fresh samples from suitable successions. Where classic Precambrian stratigraphy exists, suitable rocks are rarely exposed due to interaction with the oxidizing atmosphere, occurrence of flat-lying strata or sedimentary cover. Available drill-cores are concentrated around ore bodies, and hence are inherently altered or not environmentally representative. Stratigraphic drilling using clean diamond drilling techniques, targeted in accord with scientific priorities, could provide samples of unmatched quality across the most interesting stratigraphic intervals. Diamond drilling is a proven, inexpensive technology for accessing subsurface material. The time is ripe to use this technology to secure the materials needed for further advances.

The Mission to Early Earth (MtEE) Focus Group of the NASA Astrobiology Institute is developing a case for the acquisition, curation and distribution of suitable samples, with a special focus on diamond drilling. A communal activity is envisioned, modeled after the Ocean Drilling Program but focussing on the Precambrian record. This poster will present information on MtEE, and plans for a pilot project developed as part of the Summer ’01 MtEE excursion to W. Australia.