Mineral Deposits and the Evolution of the Biosphere

will probably be clarified by the continued cooperative efforts of scientists such as those in the group that met in Berlin last September. The staff of Dahlem Konferenzen is responsible for making the meeting of this group memorably pleasant and pleasantly mem orable. Dr. Bernhard's gifts of charm, organizational skill, and administrative toughness assured that the conference was run elegantly, smoothly, and decisively, even down to the choice of editors for this volume. Marie Cervantes-Waldmann performed minor miracles extracting manuscripts gently but persistently from the authors and in turning the typescripts into a book. The other staff members of Dahlem Konferenzen were unfailingly helpful even under trying circumstances. They will be well rememberedbyall who were fortunate enough to be asked to Berlin for the first week in September, 1980. Mineral Deposits and the Evolution of the Biosphere, eds. H. D. Holland and M. Schidlowski, pp. 5-30. Dahlem Konferenzen, 1982. Berl in, Heidelberg, New York: Springer-Verlag. Microbial Processes in the Sulfur Cycle Through Time H. G. TrUper Institut f. Microbiologie, Rheinische Friedrich-Wilhelms-Universitat, 5300 Bonn 1, F. R. Germany Abstract. Two microbial processes are involved in the sulfur cycle of the earth's biosphere: anoxic dissimilatory sulfur oxidation by phototrophic bacteria and dissimilatory sulfate reduction by sulfate-reducing bacteria. In the presence of oxygen at chemoclines and redoxclines dissimilatory sulfur oxidation by chemolithotrophic bacteria (Thiobacillus, Beg giatoa, and others) occurs. In addition, dissimilatory sulfur reducing bacteria participate in the sulfur cycle.

Microbial Processes and Ecosystems.- Microbial Processes in the Sulfur Cycle Through Time.- The Organic Geochemistry of Benthic Microbial Ecosystems.- Microbiological Oxidation and Reduction of Iron.- The Morphological and Chemical Record of the Precambrian Biosphere.- The Pre-Phanerozoic Fossil Record.- Precambrian Evolutionary Genetics.- Content and Isotopic Composition of Reduced Carbon in Sediments.- Composition of Kerogen and Hydrocarbons in Precambrian Rocks.- Prebiotic Synthesis of Organic Compounds.- Biological Processes and the Formation of Mineral Deposits.- Stratified Sulfide Deposition in Modern and Ancient Environments.- Banded Iron-Formation: Distribution in Time and Paleoenvironmental Significance.- Variations in the Distribution of Mineral Deposits with Time.- Sedimentary Balance Through Geological Time.- Group Photo: Sedimentary Iron Deposits, Evaporites and Phosphorites.- Sedimentary Iron Deposits, Evaporites and Phosphorites.- Group Photo: Stratified Sulfide Deposits.- Stratified Sulfide Deposits.- Group Photo: Reduced Carbon Compounds in Sediments.- Reduced Carbon Compounds in Sediments.- Group Photo: Biogeochemical Evolution of the Ocean-Atmosphere System.- Biogeochemical Evolution of the Ocean-Atmosphere System.- List of Participants.- Author Index.