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Chapter 7.1 Searching for Earth's Earliest Life in Southern West Greenland – History, Current Status, and Future Prospects

2007; Elsevier BV; Linguagem: Inglês

10.1016/s0166-2635(07)15071-4

2452-1892

Martin J. Whitehouse, Christopher M. Fedo,

Geological Studies and Exploration

This chapter describes the history, status, and future prospects of the life in Southern West Greenland. As the most extensive outcrop of Eoarchean rocks on the Earth, the 3.6–3.9 Ga gneiss terrain of southern west Greenland, with its enclaves of supracrustal rocks, represents an obvious target for investigations aimed at finding the Earth's earliest life. Rocks of the Isua Greenstone Belt (IGB) have long represented a fruitful target for early life investigations as the recognition that much of the extensive supracrustal sequence is at least 3.7 billion years old. The highly strained nature of much of the IGB clearly complicates the preservation potential of any unicellular body fossil. The failure of claims for body fossils has given way to the search for biomarkers at Isua, in particular the one that is represented by isotopically light carbon. The metacarbonate and graphite samples have been demonstrated to be the product of metasomatic alteration and thus do not represent a suitable supracrustal host for microorganisms. The long-running Akilia debate has shown that high-grade metamorphic and strongly deformed rocks are inappropriate targets for such studies.