Indian margin methane hydrate dissociation recorded in the carbon isotopes of benthic (Miliolida) foraminifera

• Published in: Earth and Planetary Science Letters
• Main Authors: Clemens, S.c., Thirumalai, K., Oppo, D.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier BV 2023
• Subjects: methane hydrate; Miliolida foraminifera; Pyrgo; Spiroloculina; Quinqueloculina; IODP Site U1446; Mahanadi basin; Bay of Bengal; Indian; Northwest Bay; Methane hydrate
• Online Access: https://archimer.ifremer.fr/doc/00828/93973/100793.pdf; https://archimer.ifremer.fr/doc/00828/93973/100794.xlsx; https://doi.org/10.1016/j.epsl.2023.118101; https://archimer.ifremer.fr/doc/00828/93973/

Methane hydrates in ocean sediments have been investigated across various timescales using a broad array of indicators to better understand hydrate dynamics and climate linkages. Here we report individual benthic and planktonic foraminiferal isotopic analyses at three sites from distinct oceanic environments in the northern Indian Ocean. The multi-species, multi-site analyses identify a unique C response in Miliolida benthic foraminifera Pyrgo spp., Quinqueloculina spp., and Spiroloculina spp. suggesting that some species within these genera record the location and timing of past methane hydrate dissociation in the stable carbon isotopic composition of their skeletal (test) material. Our results document that dissociation occurred in the Mahanadi offshore basin, northwest Bay of Bengal, during glacial, transitional, and interglacial intervals of the past 1.5 million years. More negative test C coupled with more positive O supports the inference of interglacial-age dissociation, likely driven by increased intermediate water temperatures.