Authigenic pyrite and gypsum minerals in offshore Zhoushan sediments: morphology, formation, and environmental implications

Offshore Zhoushan sediments are a potential area for shallow gas resources in China, where authigenic pyrite is widely distributed. Pyrite content, size distribution, and morphology influenced by depositional conditions sensitive to environmental changes. This study investigated the pyrites or gypsums of core JC-1 offshore Zhoushan. Scanning electron microscopy was used observe identify various aggregations. Changes lithology, chlorine stable isotope values organic matter were analyzed indicate evolution ancient marine, floodplain estuary, tidal flat environments, marine sedimentary facies. The microcrystalline structure these types can be divided into spherical framboid aggregates, sub-euhedral euhedral with different Gypsum minerals coexistence gypsum found enriched at SMTZs. sources sulfate formed may originate from overlying seawater oxidation, whereas calcium ions come dissolution carbonate calcareous shells caused local acidification. aggregations observed related SO 4 -AOM environments. findings suggest that form due acidification oxidation. provides new perspective understanding responses environments sea level rise climate change.