Carbon Cycling, from Volcanoes to Source Rocks, a sedimentary perspective
Daniel Minisini, Shell
The deep Earth processes (e.g., tectonism, magmatism, volcanism) control the first order shape of the continental margins, the surface Earth processes (e.g., climate, erosion, sediment supply) reshape them through the redistribution of sediment. The interaction between the deep and the surface Earth processes impacts, among other things, the stratigraphic record and the carbon cycle. This contribution shows the interaction between volcanism, whose products drive long-term inputs of carbon dioxide and represent nutrients for marine organisms, and sedimentation, whose deposits include mudstones rich in organic carbon derived from the blooms of marine organisms, hence representing carbon sinks. The mudstones rich in organic carbon represents also a fundamental element of the petroleum system (together with migration, reservoir, trap, seal). Furthermore, since the “Unconventional Revolution” helped geologists to see the petroleum system with different eyes, the buried mudstone rich in organic carbon is considered now a stand-alone petroleum system that includes all the aforementioned elements. A rich and multidisciplinary dataset at different scales will show the connection of volcaniclastic material and organic matter, with cases from the Mesozoic in South and North America, and from the Holocene in the Mediterranean Sea. We will see how these rocks formed, what was their environment of deposition, and how we can produce energy from them. This simplified exposition of basic concepts important to the hydrocarbon exploration aims to bring together the mindsets of Industry and Academia, juxtaposing complex disciplines that rarely interact. I hope this form of interaction around the “carbon cycle” allows address in new ways some of the key questions we are tackling nowadays in hydrocarbon exploration: e.g., which are the predisposing factors and the triggers that allow the thickest and highest concentration of organic matter? How can we estimate quantities of hydrocarbon in these organic-rich mudstones? How do fluids migrate in pores just slightly larger than molecules? How do we optimize the production of hydrocarbons?