Ocean anoxia, organic productivity, and perturbations of the Earth System as drivers of organic-matter preservation events and source rock deposition

OERA Webinar Silva
September 24, 2020

Dr. Ricardo L. Silva
Postdoctoral Fellow, Trinity College Dublin, The University of Dublin, Ireland

Some of the most relevant Jurassic and Cretaceous intervals of enhanced preservation of organic matter (OM), such as the Toarcian Oceanic Anoxic Event (T-OAE) or the Early Aptian OAE 1a, are being intensively investigated to constrain the mechanisms and feedback processes controlling oceanographic, biological, and climatic changes during past global environmental perturbations.

However, it is increasingly evident that OM preservation and burial, even when associated with widespread carbon sequestration events such as the T-OAE or OAE 1a, was modulated by local geography, bathymetry, climate, ocean chemistry, nutrient supply, biological communities and, consequently, the local depositional environment.

With many decades of research on the understanding of the processes leading to Jurassic and Cretaceous OM enrichment in marine and terrestrial sediments, much has been learned. Still, many open questions remain, especially relating to (1) determining the influence of local versus global factors in OM enrichment and (2) understanding the environmental and depositional constraints on OM production and preservation at a wide range of geological time intervals. In this presentation, I will discuss the interrelationship of OM preservation with the global carbon cycle and large-scale perturbations of Earth System components and how these could have been recorded on the Scotian Margin. Understanding how these worldwide events affected an area is of major relevance for the petroleum industry because they are usually associated with high-quality petroleum source rocks.