Abstract

Authigenic, complexly polyhedral limpid dolomite was discovered lining halite cubes and hoppers in Permian shallow-marine and sabkha deposits. When dissolved out of the halite the dolomite is crystal-clear and exhibits a variety of crystallographic forms, from the simple unit rhomb to complex vicinal facets. The dolomite is significantly depleted in 18 O relative to other dolomite from the Permian Basin. Bromide analyses indicate that the halite is recycled. Two hypotheses are proposed to account for the petrographic and geochemical properties of the halite-dolomite couplet. The first argues that the halite and dolomite precipitated cogenetically from a mixed solution of marine brine and meteoric runoff. The second hypothesis suggests that the dolomite formed some time later, also from a mixed solution, probably by metasomatic replacement of the halite.--Modified journal abstract.

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