Chemosynthetic Organic Matter Reveals a Protracted Episode of Past Methane Seepage Activities at a Newly Discovered Cold Seep Site (Mannar Basin) Off the East Coast of India
Date
2025Author
Ghosh, A.
Mazumdar, A.
Sadique, M.
Peketi, A.
Zatale, A.
Sivan, K.
Pillai, S. R.
Sparsh, A.
Metadata
Show full item recordAbstract
Here, we present organic geochemical evidence of past methane-seepage events in a sediment core retrieved from a recently discovered methane cold-seep site off Mannar Basin, east coast of India. The significant negative C-isotope excursion of organic matter (?13CTOC) in the seep core compared to a reference non-seep core suggests a substantial contribution of methanotroph-derived organic carbon to the seep sediment organic pool. Based on archeal biomarker data, and the presence of relict chemosymbiont-bearing Calyptogena shells, we propose a protracted period of episodic methane seepage events spanning across the Marine Isotope Stage-3 to mid-Holocene, with a declining seepage intensity toward the Holocene. The episodic depletion in ?13CTOC reveals four intermittent high methane flux events. Our study highlights that ?13CTOC can be used as an important proxy for reconstructing the dynamic evolution of past methane-seep activities, particularly when integrated with lipid biomarkers and their isotopic fingerprints.
Collections
- Scholarly literature [9179]

