Mineralogy and geochemical data

Authigenic pyrite, a characteristic mineral product of the anaerobic oxidation of methane coupled with sulfate reduction (AOM-SR) process in cold seeps, serves as a key indicator for tracing methane seepage and environmental evolution. To elucidate the mechanisms by which methane flux and benthic communities influence its morphological differentiation and evolution, we conducted a systematic study of sediment samples from the Wenhai I cold seep in the Qiongdongnan Basin, integrating gas isotope geochemistry, mineralogy, and AMS ¹⁴C dating. Results revealed a microbial-dominated mixed methane gas derived from terrigenous humic organic matter, exhibiting dual methanogenic pathways via CO₂ reduction and acetate fermentation (δ¹³C-CH₄ = -109.5‰ to -62.0‰), with ≥22 kyr of sustained seepage history forming a distinct methane flux gradient from vent centers to background areas. Authigenic pyrite across stations was confirmed as methane-derived with AOM-SR as the primary sulfur source, displaying a spatial pattern of high abundance/large grain size in mussel-bleached zones, medium values in mussel-thriving zones, low abundance/small grain size in tubeworm zones, and low abundance/narrow distribution in seep venting zones. The complete framboidal-overgrowth-euhedral pyrite evolutionary sequence was identified, demonstrating that pyrite formation and evolution are dominantly controlled by methane flux-benthic community coupling. The tripartite coupling model of methane flux-benthic community-pyritization established in this study further elucidates synergistic biogeochemical mechanisms in cold-seep systems, providing a theoretical foundation for quantitatively assessing ecological impacts during future energy resource exploration and development.