Biomarker evidence for photosynthesis during neoproterozoic glaciation.
Laterally extensive black shales were deposited on the São Francisco craton in southeastern Brazil during low-latitude Neoproterozoic glaciation approximately 740 to 700 million years ago. These rocks contain up to 3.0 weight % organic carbon, which we interpret as representing the preserved record of abundant marine primary productivity from glacial times. Extractable biomarkers reflect a complex and productive microbial ecosystem, including both phototrophic bacteria and eukaryotes, living in a stratified ocean with thin or absent sea ice, oxic surface waters, and euxinic conditions within the photic zone. Such an environment provides important constraints for parts of the "Snowball Earth" hypothesis.
Olcott
Alison N
AN
Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089, USA. olcott@usc.edu
Sessions
Alex L
AL
Corsetti
Frank A
FA
Kaufman
Alan J
AJ
de Oliviera
Tolentino Flavio
TF
D018407:Bacterial Physiological Phenomena; D015415:Biomarkers / Q000032:analysis; D001938:Brazil; D002244:Carbon / Q000032:analysis*; D002247:Carbon Isotopes / Q000032:analysis; D002254:Carbonates / Q000032:analysis; D000458:Cyanobacteria / Q000502:physiology; D017753:Ecosystem; D019015:Geologic Sediments / Q000737:chemistry*; D046448:Ice Cover; D009930:Organic Chemicals / Q000032:analysis*; D010788:Photosynthesis; D012623:Seawater / Q000382:microbiology*; D013472:Sunlight
D015415:Biomarkers; D002247:Carbon Isotopes; D002254:Carbonates; D009930:Organic Chemicals; D002244:Carbon