Extended Data Fig. 1

a, Representative samples collected from inactive and active hydrothermal vent deposits including photographs of bulk samples (A1-C1) as well as thin section micrographs viewed with transmitted (A2-C2) and reflected light (A3-C3); Anh, anhydrite; Atc, atacamite; Cpy,chalcopyrite; Fe-oxy, iron oxyhydroxide; Mc, marcasite, Py, pyrite; Ps, pore space. b, Bulk minerology of samples. Black denotes iron oxyhydroxides, Yellow denotes sulfides, and Blue denotes sulfates. c, Photograph of representative subdivided inactive vent sample from Lucky’s Mound used in carbon assimilation assays showing the three regions of interest (inner conduit, middle region, and outer crust).