Comment on "Molybdenum isotope evidence for widespread anoxia in mid-Proterozoic oceans"

• Published in: Science (American Association for the Advancement of Science) Vol. 309; no. 5737; pp. 1017; author reply 1017 - 1017
• Main Authors: Ling, H-F, Gao, J-F, Zhao, K-D, Jiang, S-Y, Ma, D-S
• Format: Journal Article
• Language: English
• Published: United States The American Association for the Advancement of Science 12.08.2005
• Subjects: Marine
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1108737

Arnold et al. reported Mo isotope compositions of mid-Proterozoic black shale, which were different from those of euxinic sediments in the Black Sea. On the basis of a mass balance model calculation, they claimed that "the area of oxic sedimentation in the mid-Proterozoic oceans was nearly a factor of 10 smaller than the modern value, or the area of euxinic sedimentation approached a factor of 10 larger than the modern value, or, most likely, an intermediate situation occurred involving both substantial contraction of the extent of oxic deposition and expansion of the euxinic deep ocean." Thus, they suggested that a widespread anoxia occurred in mid-Proterozoic oceans. However, this conclusion seems based on misinterpretation of their model calculation results.