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

Exploring the Impacts of Large Igneous Province Emplacement On Global Ocean Chemistry

Paper number: 67-5
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

During International Ocean Discovery Program (IODP) Expedition 392, on the Agulhas Plateau, the science party made an observation of a 100 m thick bright green sedimentary units at Sites U1579 and U1580. A goal of the expedition was to investigate the emplacement of a Large Igneous Province (LIP). At Sites U1579 and U1580, secondary mineral formation occurred in sediments with evidence that basalt was eroded from the LIP and deposited in nearby deeper settings. Pore water data from Site U1580 shows a drawdown of alkalinity, dissolved inorganic carbon (DIC), and cations into the green sedimentary unit, likely from the formation of secondary minerals including glauconite, celadonite, or zeolites. The drawdown of alkalinity and DIC indicates that alteration of detrital basalt on the seafloor can impact the carbon cycle.

Based on results from a literature review of past ocean drilling expeditions of 220 sites from a total of 50 expeditions from the second phase of IODP to explore how common the observations of Expedition 392 were, we found that 35 site reports observed zeolites, 31 observed glauconite, 118 observed green sediments, and only 3 sites observed celadonite. To understand whether the same geochemical processes were dominant at sites with similar qualitative data, shipboard pore water data were compared to investigate whether alkalinity and cation cycling are similar, which may show that conditions on the Agulhas Plateau may not be an isolated event. Similarities included expeditions that targeted mid-ocean ridges (such as Expedition 390 Sites U1556 and U1557 and Expedition 393 Sites U1560 and U1583) and expeditions that targeted other regions of continental breakup and LIP events (such as Expedition 369 Site U1512). Expedition 369 Site U1512 is most similar to the Agulhas Plateau sites in terms of qualitative observations, depositional setting, and pore water geochemistry. Samples were requested from these locations for further analysis.

Here we present mineralogy (XRD) and geochemical (XRF) data of selected depths from expeditions 390, 393, 344, and 369. The minerals present are similar to those found in Expedition 392, consisting of common secondary minerals containing iron. Using these results, we explore how basalt mineral deposition and alteration at LIP sites compares to mid-ocean ridge settings to determine whether LIP emplacement has a unique impact on global ocean chemistry.

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

doi: 10.1130/abs/2025AM-412230

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