Reconciling Archean organic-rich mudrocks with low primary productivity before the Great Oxygenation Event.

ABSTRACT: The organic carbon content of ancient rocks provides a fundamental record of the biosphere on early Earth. For over 50 y, the high organic content of Archean (>2.5 Ga) mudrocks has puzzled geologists and evolutionary biologists, because high biological primary productivity was unexpected for the nascent biosphere before the rise of O₂. Here, we took a different approach to resolve this apparent paradox, by studying the accumulation rates of Archean organic-rich mudrocks. We evaluated the sedimentation rates of three sections of the Mount McRae Shale and Jeerinah Formation (2.68 to 2.48 Ga, Pilbara Craton, Australia) with new and recently published U-Pb zircon ages from intraformational ash beds. For comparison, we compiled Phanerozoic (<500 Ma) data from comparable depositional

SUBMITTER: Lotem N 

PROVIDER: S-EPMC11745403 | biostudies-literature | 2025 Jan

REPOSITORIES: biostudies-literature