My main interest is the study of the earliest record of life on Earth. ThePrecambrian contains a very patchy record of microfossils and stromatolite structures. Fossils become increasingly scarce in the Early Archean. The oldest of microfossils and stromatolite structures are found in the 3.5 Ga old Warrawoona Group, Australia. Based on the morphological diversity of these fossils it has been recognized that prokaryotic life must have been present long before 3.5 Ga. Unfortunately, older sediments of Early Archaean time have been subject to high grade metamorphism, which destroyed any possible fossil evidence of early life. In the absence of morphofossils, the presence of life can only be inferred from chemical evidence. Carbonaceous inclusions protected within apatite crystals in several early Archean formations, including the metasediments of the > 3.7 Ga old Isua Supracrustal Belt and Akilia island in southern West Greenland, have been found to retain a biogenic carbon isotope signature. These 'chemofossils' strongly suggest that life was present before 3.7 Ga ago.

The objective my current research is to evaluate the possible use of trace elements in graphite occurrences in the Isua Supracrustal Belt, to distinguish between a biogenic and a nonbiogenic origin. Trace metals are found in natural kerogens of various type and some are known to be difficult to remove, even at high temperatures.The occurrence of trace metals in sedimentary organic material is in part due to endemic concentrations in living matter. An important process which leads to higher trace metal concentrations is the formation of metal complexes with biologically derived material during sedimentation and burial. During diagenesis and metamorphism the biomolecules become progressively altered, but the metals still remain in the resulting kerogen. Of special interest are vanadium and nickel, which are known to form resistant complexes with porphyrins, and are found in high concentrations in even extensively graphitized organic deposits. In order to evaluate the reliability of specific trace element concentrations in metamorphic graphite as indicators of a biogenic origin, it is necessary to establish the distribution coefficients for the elements in question between graphite and the metasomatic medium. The present investigation aims at such measurements, and at systematic analysis of graphite in metasedimentary rocks with presumed differences in origin of their carbon component.