Abstract
The middle Cretaceous was a period characterized by elevated sea-floor spreading rates, enhanced volcanism, high atmospheric CO2 levels, warming temperatures, and the peak eustatic highstand of the Mesozoic. Two well-known perturbations in the global carbon cycle mark this interval – the Cenomanian-Turonian Oceanic Anoxic Event 2 (OAE2) and the Mid-Cenomanian Event (MCE). Although studies during the past two decades have arrived at a consensus that the Caribbean Large Igneous Province (LIP) likely played a key role in triggering OAE2, arguably the most significant perturbation of the Late Cretaceous, the detailed environmental developments during the Mid-Late Cenomanian leading up to it have only recently been the focus of investigations. This study, based on previous studies of the Middle Cenomanian – Early Turonian climate, tectonics, sea level, and carbon isotope chemostratigraphy, tests plausible environmental scenarios to explain the behavior of the Middle Cenomanian to Early Turonian carbon cycle, via isotope-mass balance calculation in a simple carbon cycle box model. The model experiments successfully reproduce two distinctive features observed in the Mid-Late Cenomanian δ13C curves - 1) decoupling of δ13Ccarb and δ13Corg reflecting increasing isotope fractionation in response to steadily rising pCO2, driven by enhanced volcanic degassing of mantle-derived CO2, which likely preceded the presumed peak volcanism of the Caribbean LIP; and 2) a long-lived, secondary positive excursion that documents enhanced organic carbon burial in shallow shelf seas that expanded during global sea-level rise and highstand. We demonstrate a plausible combination of environmental forcings that pre-conditioned the mid-Cretaceous ocean-atmosphere system for a massive perturbation, OAE2.
Original language | English (US) |
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Article number | 103123 |
Journal | Earth-Science Reviews |
Volume | 203 |
DOIs | |
State | Published - Apr 2020 |
Funding
Constructive comments by Hugh Jenkyns and Jeremy Owens and the editorial handling from André Strasser are greatly appreciated. This study was supported by a Schlanger Fellowship from the Consortium for Ocean Leadership , as well as funding from the Institute for Sustainability and Energy at Northwestern (ISEN) . YJJ was supported by National Research Foundation of Korea funded by the Ministry of Science and ICT (grant number NRF-2019R1C1C1005550 ) while completing this manuscript. Special thanks to Mike Arthur and Lee Kump for laying the foundations and inspiring further inquiry in carbon cycle modeling.
Keywords
- Box model
- Carbon cycle
- Cretaceous
- Large Igneous Province
- Mid-Cenomanian Event
- Oceanic Anoxic Event 2
ASJC Scopus subject areas
- General Earth and Planetary Sciences