138-12 Using Quantitative Paleosecular Variation Analysis to Refine the Tempo of Deccan Eruptions

Session: The Cretaceous-Paleogene (K-Pg) Boundary Interval: From Large-Scale Geological Events to Mass Extinction Mechanisms

Presenting Author:

Courtney Sprain

Authors:

Sprain, Courtney Jean¹, Bristol, Katie E.², Mittal, Tushar³, Fendley, Isabel M.⁴, Tremblay, Marissa M.⁵, Mijjum, Moshammat⁶, Monteiro, Aristle⁷, Duraiswami, Raymond⁸

Abstract:

Large igneous provinces (LIPs) occur throughout Earth’s history and are commonly temporally linked with major environmental crises, most notably mass extinctions. Quantifying the tempo of LIP eruptions is critical for understanding the impact these volcanic systems have on the global environment. This is especially critical for LIPs where the influence of volcanism is still being debated, like the Deccan Traps and their association with the Cretaceous-Paleogene mass extinction. Recent work to constrain rates of Deccan eruption utilized high-precision geochronology to obtain absolute ages for flows and zircon-bearing red boles between flows. Although this work makes Deccan one of the most precisely dated LIPs, uncertainties on ages from high-precision geochronology techniques are still on the order of 10s of ka, with many dates overlapping within uncertainty over hundreds of meters of volcanic stratigraphy. Although higher resolution can be achieved using Bayesian age models, this resolution generally still cannot assess the duration of time between individual flows. Outside of absolute geochronologic methods, we have developed a new technique called Quantitative Paleosecular Variation to generate quantitative predictions about eruption tempo by combining geochronologic and paleomagnetic data, along with qualitative constraints from lava flow morphology and geochemistry. This technique utilizes a generalized forward modeling approach to compare real magnetic data with pseudo-paleomagnetic datasets, created using synthetic eruptive histories from down-sampled secular variation records, in a Bayesian inversion framework. This approach assesses the most likely eruption history including duration of eruptive pulses, active eruptive time, and hiatus duration between pulses, hence providing a quantitative estimate of eruption tempo at timescales less than 10,000 years. In this work, we have applied this method to new paleomagnetic data collected from the Matheran section in the Deccan Traps. Our results indicate that during this interval, eruptions occurred roughly every 3,000 yrs, with no significant hiatuses between eruptive pulses. As a result, the Deccan Traps likely caused a series of short-lived cooling intervals via sulfur emissions. However, the several thousand years between eruptions preclude the possibility of prolonged cooling due to the comparatively short decay timescale of sulfate aerosols in the atmosphere. 

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10066

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