Journal article
No Cretaceous-Paleogene Boundary in Exposed Rajahmundry Traps: A Refined Chronology of the Longest Deccan Lava Flows From Ar-40/Ar-39 Dates, Magnetostratigraphy, and Biostratigraphy
Geochemistry, geophysics, geosystems : G3, v 21(9)
01 Sep 2020
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Abstract
Deccan Traps flood basalt volcanism affected ecosystems spanning the end-Cretaceous mass extinction, with the most significant environmental effects hypothesized to be a consequence of the largest eruptions. The Rajahmundry Traps are the farthest exposures (similar to 1,000 km) of Deccan basalt from the putative eruptive centers in the Western Ghats and hence represent some of the largest volume Deccan eruptions. Although the three subaerial Rajahmundry lava flows have been geochemically correlated to the Wai Subgroup of the Deccan Traps, poor precision associated with previous radioisotopic age constraints has prevented detailed comparison with potential climate effects. In this study, we use new Ar-40/Ar-39 dates, paleomagnetic and volcanological analyses, and biostratigraphic constraints for the Rajahmundry lava flows to ascertain the timing and style of their emplacement. We find that the lower and middle flows (65.92 +/- 0.25 and 65.67 +/- 0.08 Ma, +/- 1 sigma systematic uncertainty) were erupted within magnetochron C29r and were a part of the Ambenali Formation of the Deccan Traps. By contrast, the uppermost flow (65.27 +/- 0.08 Ma) was erupted in C29n as part of the Mahabaleshwar Formation. Given these age constraints, the Rajahmundry flows were not involved in the end-Cretaceous extinction as previously hypothesized. To determine whether the emplacement of the Rajahmundry flows could have affected global climate, we estimated their eruptive CO2 release and corresponding climate change using scalings from the LOSCAR carbon cycle model. We find that the eruptive gas emissions of these flows were insufficient to directly cause multi-degree warming; hence, a causal relationship with significant climate warming requires additional Earth system feedbacks.
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Details
- Title
- No Cretaceous-Paleogene Boundary in Exposed Rajahmundry Traps: A Refined Chronology of the Longest Deccan Lava Flows From Ar-40/Ar-39 Dates, Magnetostratigraphy, and Biostratigraphy
- Creators
- Isabel M. Fendley - Department of Earth & Planetary Science University of California – Berkeley Berkeley CA USACourtney J. Sprain - University of FloridaPaul R. Renne - Berkeley Geochronology CenterIgnacio Arenillas - University of ZaragozaJose A. Arz - University of ZaragozaVicente Gilabert - University of ZaragozaStephen Self - Department of Earth & Planetary Science University of California – Berkeley Berkeley CA USALoyc Vanderkluysen - Drexel UniversityKanchan Pande - Indian Institute of Technology BombayJan Smit - VU AmsterdamTushar Mittal - Department of Earth and Planetary Science University of California Berkeley Berkeley CA USA
- Publication Details
- Geochemistry, geophysics, geosystems : G3, v 21(9)
- Publisher
- Amer Geophysical Union
- Number of pages
- 20
- Grant note
- EAR-1615021; EAR-1736737; EAR-1615003 / National Science Foundation (NSF); National Research Foundation of Korea BES-2016-077800 / Spanish Ministry of Economy and Competitiveness; Spanish Government Esper S. Larsen Fund of UC Berkeley PGC2018-093890-B-I00 / MCIU/AEI/FEDER, UE NSF; National Science Foundation (NSF)
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Biodiversity, Earth, and Environmental Science (BEES)
- Web of Science ID
- WOS:000576630400008
- Scopus ID
- 2-s2.0-85091629359
- Other Identifier
- 991019169528904721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Geochemistry & Geophysics