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Project Progress

Stable isotope biogeochemistry was studied in four projects during this year. 1) Isotopic composition of fossil food webs in the Enspel formation. This 25 million year old deposit has recognizable fossils that have retained their original isotopic signatures. 2) Oxygen isotopes in oceanic phosphates. Oxygen isotopes in phosphate record bacterial turnover and could be used as biosignatures. 3) Carbon isotopes in the Apex cherts. These 3.5 billion year old samples are controversial as to whether the carbon in these rocks is biologically or non-biologically derived. 4) Fe oxidizing bacteria and autotrophic growth. These microorganisms are thought to be important CO₂ fixing bacteria at hydrothermal vents. The role in early life and on Mars is debated.