67 Long- and Short-Term Environmental Consequences of Large Igneous Provinces Throughout Earth’s History (Posters)

We invite submissions to an interdisciplinary session on Large Igneous Provinces (LIPs), exploring their environmental impacts using geochronology, paleomagnetism, geochemistry, paleoenvironmental proxies, and modeling to integrate diverse data into understanding LIP-induced environmental changes.

Sunday, 19 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Fluid Inclusion Analysis of Triassic-Jurassic Deep Sea Cherts Reveal Multiple Ocean Acidification Events Linked to the Central Atlantic Magmatic Province.

Paper number: 67-1
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

The Central Atlantic Magmatic Province (CAMP) has been proposed as the most temporally conspicuous trigger for the marine end-Triassic extinction (ETE; ~201.6 Ma). The CAMP may have caused the marine ETE via rapid ocean acidification by the degassing of magmatic CO2, as evidenced by a doubling of atmospheric pCO2 after each CAMP flow unit, along with the preferential extinction of marine calcifiers and a decrease in shallow marine carbonate deposition. In the deep Panthalassa, bedded chert sequences preserved in Japan record three closely temporally spaced extinctions that align conspicuously with the atmospheric perturbations associated with each pulse of the CAMP. We hypothesize the three extinction intervals in the chert sequences correspond to ocean acidification events that are temporally associated with each CAMP flow unit. We conducted fluid inclusion analyses on deep sea bedded cherts from Katsuyama and Kurusu, Japan, to reconstruct the deep ocean volatile content through the three extinction intervals to test the pulsed ocean acidification hypothesis. Cherts were mechanically decrepitated to release the trapped inclusion volatiles into a quadrupole mass spectrometer to quantify the major atmospheric gases. We found a tripling in CO2 mol% and [CO2]aq as well as a decrease in pH and Ωarag that coincide with the first (ETE) and the third extinction boundary. A temporal alignment using orbital cyclicity and biotic extinction, the first pulse of maximum CO2 and minimum pH values in the bedded cherts coincides with the onset of the oldest known CAMP lava flows in Morocco, whereas the second major pulse aligns with the third CAMP unit in the Newark Group. The increase in CO2 before the earliest of the preserved lava flows suggests a significant unknown earlier eruptive phase or metamorphic degassing of CO2 before the initial eruptive phase of the CAMP. The absence of a CO2 signal at the second extinction is consistent with observations from non-marine sections showing that the second CAMP flow had a more muted pCO2 effect compared to the first and third pulses. The calculated pH and Ωarag from the inclusion data suggests that the deep ocean experienced multiple intense and protracted acidification events prior to and during the initial and third extrusive phase of CAMP, supporting the hypothesis that CAMP was the primary kill mechanism for the marine ETE.

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

doi: 10.1130/abs/2025AM-411941

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