A redox-based model for carbonate platform drowning and Ocean Anoxic Events

Presenter

Dr. Ben Smith
Ph.D. Postdoctoral Scholar
Caltech University

Description

The deposition of marine carbonate rocks is influenced by climate and seawater chemistry. Carbonate platforms usually keep pace with subsidence and sea level, but ’platform drowning’ occurs when carbonate sedimentation slows or when siliciclastics replace carbonates. Identifying specific mechanism(s) behind platform drowning is critical for understanding global environmental changes such as Ocean Anoxic Events (OAES). We developed a model for OAEs which couples ocean basin redox processes to rates of carbonate sedimentation. Through anaerobic metabolisms, deep-ocean anoxia reduces adjusts the oceans’ delicate balance between carbonate precipitation and dissolution. This quasi-steady state response acts over long timescales and helps explain long-lived, spatially diverse patterns of platform drowning during Mesozoic OAEs and other Phanerozoic hyperthermal events.