Fig. 9

The paragenesis between polyhalite and other minerals. An = Anhydrite; H = Halite; Pol = Polyhalite. a Medium- to large-sized subhedral to anhedral crystals (or crystal twins) dispersed in halite matrix as inclusions. At 3439 m depth in Well HC3, XPL. b Banded polyhalite containing organic matter distributed in the halite matrix. At 3441.5 m depth in Well HC3, XPL. c Halite squeezed by polyhalite, with clear and straight boundary (solid line). At 3086 m depth in the Well ZK001, SEM. d Anhydrite and halite squeezed by polyhalite, with clear and straight boundaries. At 3100 m depth in Well ZK001, SEM. e No clear boundary (dashed line) between polyhalite and anhydrite, but very clear boundaries (solid lines) between other crystals. At 3088 m depth in Well ZK001, SEM. f Residual structure of anhydrite at the edges of a polyhalite aggregate. At 3100 m depth in Well ZK001, XPL. g Polyhalite encased in anhydrite, with no clear boundary. At 3089 m depth in Well ZK001, SEM. h Polyhalite replaced and encased by anhydrite. At 3100 m depth in Well ZK001, XPL