Permian trench-type cold seep biomes of manganese carbonates in the Altiads, central Asia

Deep-sea submersibles have unveiled the dark biosphere associated with cold seep carbonates; however, deep-time trench sedimentary and biological records remain largely unexplored. This study investigates manganese carbonates from the Engger Us mélange in northwestern China, providing insights into biological assemblages preserved within chert and manganese-bearing limestone in trench environment. Microfossil analysis reveals a close association of radiolarians, sponge spicules, and piezophilic bacteria within the manganese minerals. These Mn-carbonates exhibit highly negative δ¹³C values, indicative of a cold seep origin. Our findings suggest that the Engger Us mélange records an Early Permian trench-type biome, representing one of the earliest examples of such environments. Within the subduction factory, these deep-sea extremophiles were off-scraped and incorporated into an accretionary complex, ultimately preserved in a modern continental setting. This study highlights deep-sea carbonates as potential archives of ancient deep biosphere microbial processes, providing critical insights into the preservation of extremophile communities in subduction-related environments.