Conference proceeding
High-precision (super 40) Ar/ (super 39) Ar dating of the Deccan Traps
American Geophysical Union Fall Meeting, Vol.2017
Dec 2017
Abstract
Almost forty years ago it was first hypothesized that greenhouse gases emitted from the Deccan Traps (DT) played a role in the Cretaceous-Paleogene boundary (KPB) mass extinction (McLean 1979, 1980, 1985). At that time, this hypothesis was dismissed due to insufficient geochronology and new evidence that a bolide impact coincided with the KPB. Since then, evidence such as records of protracted extinction and climate change in the Late Cretaceous, in addition to new high-precision geochronology of the DT, has bolstered the Deccan hypothesis. Recently, many models have been produced to simulate how DT volcanism may have perturbed global ecosystems. However, modeled outcomes are largely dependent upon variables such as the amount and species of gas released and the tempo of eruptions, which are not well constrained (Self et al., 2014). To better constrain climatic models and better understand the role DT volcanism played in the KPB extinction, we developed a high-precision geochronologic framework defining the timing and tempo of DT eruptions within the Western Ghats using high-precision (super 40) Ar/ (super 39) Ar geochronology. Our new results show that the DT erupted relatively continuously starting nearly equal 66.4 Ma and extending to at least nearly equal 65.3 Ma with no hiatuses longer than nearly equal 50 ka, invalidating the concept of three discrete eruption pulses in the Western Ghats (Chenet et al., 2007, 2009; Keller et al., 2008). Our new data further provide the first precise location of the KPB within the DT sequence and place this boundary at or near the Lonavala-Wai subgroup transition, roughly coincident with major changes in eruption frequency, flow-field volumes, and extent of crustal magma contamination. Taken together, these results suggest that a state shift occurred in the DT magmatic system around the time of the Chicxulub impact, consistent with the impact triggering hypothesis of Richards et al. (2015). Our work further shows that over 80% of the estimated volume of the DT within the Western Ghats erupted in nearly equal 600 ka; however, nearly equal 70% of this volume, erupted after the KPB calling for a reassessment of the role of DT volcanism played in the KPB mass extinction and subsequent recovery. It is important to note that current volume estimates are likely to change as we work to improve understanding of the distribution of chemical formations, both on and offshore.
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Details
- Title
- High-precision (super 40) Ar/ (super 39) Ar dating of the Deccan Traps
- Creators
- C. J. Sprain - University of LiverpoolP. R. RenneIsabel FendleyK. PandeS. SelfL. VanderkluysenM. A. RichardsAnonymous
- Publication Details
- American Geophysical Union Fall Meeting, Vol.2017
- Conference
- American Geophysical Union Fall Meeting (2017)
- Publisher
- American Geophysical Union
- Resource Type
- Conference proceeding
- Language
- English
- Academic Unit
- Biodiversity, Earth, and Environmental Science (BEES)
- Identifiers
- 991021015346804721