CARBON ISOTOPE STRATIGRAPHY IN THE GEOLOGIC TIME SCALE 2012

Temporal variations in the carbon isotopic composition of Dissolved Inorganic Carbon (DIC) in the world’s oceans have been documented through study of marine carbonates, and can be used to correlate sediments around the world because of the long residence of carbon relative to the mixing time of the oceans. The carbon isotope record on the geological timescales considered here is largely controlled by changes in the partitioning of carbon between organic carbon and carbonate, and therefore linked directly to changes in the global biosphere and carbon cycle. Indeed, debates surrounding many of the major global environmental changes and mass extinctions in Earth history (e.g., Snowball Earth, Permian-Triassic extinction, Cretaceous/Paleogene extinction, and Paleocene-Eocene Thermal Maximum) often boil down to how to best interpret the observed spatial and temporal changes in carbon isotopes.

We present the figures from the Carbon Isotope Stratigraphy chapter of the book ‘The Geologic Time Scale 2012’. These figures include composite carbon isotope curves from every geologic time period compiled from literature sources. Mid-Jurassic through Cenozoic curves are mainly derived from pelagic carbonates and exhibit relatively low amplitude variability compared to curves for the earlier part of the record. Curves for these earlier parts of the record are based primarily on data from platform carbonates, characterized by relatively larger amplitude changes and more spatial heterogeneity. All carbon isotope reference curves presented are works in progress and a primary goal of this poster is to work towards improved resolution through feedback from specialists in each time period.