Contributions of Volcanic Carbon Emissions to Environmental Change at the Cretaceous-Paleogene and Paleocene-Eocene Boundaries: Observational and Theoretical Constraints
Abstract
The terminations of both the Cretaceous Period (K-Pg) and Paleocene Epoch (P-E) coincided with episodes of extensive flood basalt/rift volcanism, the Deccan Traps (DT) and North Atlantic Igneous Province (NAIP), respectively. The latest radiometric data confirm that the main phases of magma extrusion of both DT and NAIP were concentrated over relatively short intervals (<<0.5 myr) further bolstering speculation on the role of volcanic C and other emissions in driving the observed environmental and biotic events of those terminations. Much of the speculation regarding C emissions has been derived from observations of changes in climate and/or ocean chemistry. Indeed, to drive detectable global warming and/or ocean acidification, C emissions would have to be significantly elevated over "typical" magmatic emission levels, thus requiring supplemental sources of C, most likely from intrusion driven combustion of organic matter and/or carbonate-rich crust. Here we compare marine geochemical records spanning both boundaries and with numerical models assess implications for C emissions and relations to the key environmental changes associated with each event. This assessment benefits from the recent development of high-fidelity (i.e., astronomically-tuned) proxy records of the climate and ocean carbon chemistry (e.g., SST, δ13C, pH) across both time intervals from globally distributed, stratigraphically complete marine sections. In the case of the K-Pg transition, the timing of changes in climate and ocean carbon chemistry along with other data indicate a comparatively inconsequential role of elevated C emissions on the major biotic event (i.e., extinction) marking that boundary. In contrast, with the P-E boundary, North Atlantic volcanism now appears to have been primary trigger/driver of climatic change, though positive feedbacks involving reduced C reservoirs (e.g., hydrates, permafrost) might have accelerated C emission rates at the onset of that event.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFMPP31D..03Z
- Keywords:
-
- 1520 Magnetostratigraphy;
- GEOMAGNETISM AND PALEOMAGNETISM;
- 4901 Abrupt/rapid climate change;
- PALEOCEANOGRAPHY;
- 4924 Geochemical tracers;
- PALEOCEANOGRAPHY;
- 4948 Paleocene/Eocene thermal maximum;
- PALEOCEANOGRAPHY