Large-scale hydrothermal chimney distribution and characteristics. a) Drone aerial photograph of a part of the SHCa. b) Adjacent massive chimneys, exhibiting crosscutting subparallel planar structures with orientation. c) Sublinear weakly-lithified carbonate and siliciclastic mixed materials outcropping on the surface between hydrothermal chimneys. d) Irregular-shaped collapsing crack observed across a hydrothermal chimney. e) & f) Hydrothermal chimneys exhibiting bulbous-shaped tops bounded by crosscutting subparallel planar structures, with orientation.